计算机网络外文文献外文翻译英文文献新技术的计算机网络

外文原文computerThe modern world of high technology could not have come about except for the development of the computer. Different types and sizes of computers find uses throughout society in the storage and handling of data, from secret governmental files to banking transactions to private household accounts. Computers have opened up a new era in manufacturing through the techniques of automation, and they have enhanced modern communication systems. They are essential tools in almost every field of research and applied technology, from constructing models of the universe to producing tomorrow’s weather reports, and technique use has in itself opened up new areas of conjecture. Database services and computer networks make available a great variety of information sources. The same advanced techniques also make the invasions of privacy and restricted information sources possible, and computer crime has become one of the many risks that society must face if it is to enjoy the benefits of modern technology.A computer is an electronic device that can receive a set of instructions, or program, and then carry out this program by performing calculations on numerical data or by compiling and correlating other forms of information. The type of computers are mainly inclusive of Microcomputer, Minicomputer, Mainframe Computer and Supercomputer, etc. Microminiaturization , the effort to compress more circuit elements into smaller and smaller chip space is becoming the major trend in computer development. Besides, researchers are trying to develop more powerful and more advanced computers.Any customers all pass the operate system to use the calculator, not direct carry on the operation to the hardware of the calculators. The operate system is a bridge that communicates the customer and calculator. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks and provide a software platform. The choice of operating systems determines to a great extent of the applications. Therefore OS is very important.The operate system is in the charge of Computer resource control program to execute system software. Say in a specific way，the OS is the most basic in the calculator software system, also constituting the part most importantly, it is responsible for the management and controls the calculator system in all hardware resources and the software resources, can make of various resources matched with mutually, moderating to work with one accord, full develop its function, exaltation the efficiency of the system, still take the interface function of the customer and the calculator system at the same time, use the calculator to provide the convenience for the customer. The operate system is a huge management control procedure, including 5 management functions mostly: Progress and processing the machine manage, the homework manage, saving management, equipments management, document management. Divide the line from the function, the tiny machine operate system can is divided into the single mission operate system, single many mission operate systems of customer and many mission operate systems of multi-user of single customer. At present there are several kinds of OS on the computer which are DOS, OS/2, UNIX, XENIX, LINUX, Window2000, Netware etc.In order for a computer to perform the required task, it must be given instructions in a language that it understands. However, the computer’s own binary based language, or machine language, is difficult for humans to use. Therefore, people devised an assembly language to shorten and simplify the process. In order to make a computer more friendly to use, programmers invented high level languages, such as COBOL, FORTRAN, ASSEMBLER, PASCAL, C++, etc, which made the computers easier to use. For the time being, HTML and XML are very useful languages as well.The database is often used to describe a collection of related data that is organized into an integrated, sophisticated structure that provides different people with varied access to the same data. A database management system is an extremely complex set of software programs that controls the organization, storage and retrieval of data in a database. A successful DBMS is often characterized with the four principal features: (1)Data Security and Integrity; (2)Interactive query; (3)Interactive data Entry and Updating; (4)Data Independence. The intelligent databases are becoming more popular in that they canprovide more validation. The researches on new types of database systems are underway.计算机倘若不是伴随着计算机的发展，现代世界的高端技术不可能出现。

附录一、英文原文：The NetWorksBirth of the NetThe Internet has had a relatively brief, but explosive history so far. It grew out of an experiment begun in the 1960's by the U.S. Department of Defense. The DoD wanted to create a computer network that would continue to function in the event of a disaster, such as a nuclear war. If part of the network were damaged or destroyed, the rest of the system still had to work. That network was ARPANET, which linked U.S. scientific and academic researchers. It was the forerunner of today's Internet.In 1985, the National Science Foundation (NSF) created NSFNET, a series of networks for research and education communication. Based on ARPANET protocols, the NSFNET created a national backbone service, provided free to any U.S. research and educational institution. At the same time, regional networks were created to link individual institutions with the national backbone service.NSFNET grew rapidly as people discovered its potential, and as new software applications were created to make access easier. Corporations such as Sprint and MCI began to build their own networks, which they linked to NSFNET. As commercial firms and other regional network providers have taken over the operation of the major Internet arteries, NSF has withdrawn from the backbone business.NSF also coordinated a service called InterNIC, which registered all addresses on the Internet so that data could be routed to the right system. This service has now been taken over by Network Solutions, Inc., in cooperation with NSF.How the Web WorksThe World Wide Web, the graphical portion of the Internet, is the most popular part of the Internet by far. Once you spend time on the Web,you will begin to feel like there is no limit to what you can discover. The Web allows rich and diverse communication by displaying text, graphics, animation, photos, sound and video.So just what is this miraculous creation? The Web physically consists of your personal computer, web browser software, a connection to an Internet service provider, computers called servers that host digital data and routers and switches to direct the flow of information.The Web is known as a client-server system. Your computer is the client; the remote computers that store electronic files are the servers. Here's how it works: Let's say you want to pay a visit to the the Louvre museum website. First you enter the address or URL of the website in your web browser (more about this shortly). Then your browser requests the web page from the web server that hosts the Louvre's site. The Louvre's server sends the data over the Internet to your computer. Your webbrowser interprets the data, displaying it on your computer screen.The Louvre's website also has links to the sites of other museums, such as the VaticanMuseum. When you click your mouse on a link, you access the web server for the VaticanMuseum.The "glue" that holds the Web together is called hypertext and hyperlinks. This feature allow electronic files on the Web to be linked so you can easily jump between them. On the Web, you navigate through pages of information based on what interests you at that particular moment, commonly known as browsing or surfing the Net.To access the Web you need web browser software, such as Netscape Navigator or Microsoft Internet Explorer. How does your web browser distinguish between web pages and other files on the Internet? Web pages are written in a computer language called Hypertext Markup Language or HTML.Some Web HistoryThe World Wide Web (WWW) was originally developed in 1990 at CERN, the European Laboratory for Particle Physics. It is now managed by The World Wide Web Consortium, also known as the World Wide Web Initiative.The WWW Consortium is funded by a large number of corporate members, including AT&T, Adobe Systems, Inc., Microsoft Corporation and Sun Microsystems, Inc. Its purpose is to promote the growth of the Web by developing technical specifications and reference software that will be freely available to everyone. The Consortium is run by MIT with INRIA (The French National Institute for Research in Computer Science) acting as European host, in collaboration with CERN.The NationalCenter for Supercomputing Applications (NCSA) at the University of Illinois at Urbana-Champaign, was instrumental in the development of early graphical software utilizing the World Wide Web features created by CERN. NCSA focuses on improving the productivity of researchers by providing software for scientific modeling, analysis, and visualization. The World Wide Web was an obvious way to fulfill that mission. NCSA Mosaic, one of the earliest web browsers, was distributed free to the public. It led directly to the phenomenal growth of the World Wide Web.Understanding Web AddressesYou can think of the World Wide Web as a network of electronic files stored on computers all around the world. Hypertext links these resources together. Uniform Resource Locators or URLs are the addresses used to locate these files. The information contained in a URL gives you the ability to jump from one web page to another with just a click of your mouse. When you type a URL into your browser or click on a hypertext link, your browser is sending a request to a remote computer to download a file.What does a typical URL look like? Here are some examples:/The home page for study english.ftp:///pub/A directory of files at MIT* available for downloading.news:rec.gardens.rosesA newsgroup on rose gardening.The first part of a URL (before the two slashes* tells you the type of resource or method of access at that address. For example:·http - a hypertext document or directory·gopher - a gopher document or menu·ftp - a file available for downloading or a directory of such files·news - a newsgroup·telnet - a computer system that you can log into over the Internet·WAIS* - a database or document in a Wide Area Information Search database ·file - a file located on a local drive (your hard drive)The second part is typically the address of the computer where the data or service is located. Additional parts may specify the names of files, the port to connect to, or the text to search for in a database.You can enter the URL of a site by typing it into the Location bar of your web browser, just under the toolbar.Most browsers record URLs that you want to use again, by adding them to a special menu. In Netscape Navigator, it's called Bookmarks. In Microsoft Explorer, it's called Favorites. Once you add a URL to your list, you can return to that web page simply by clicking on the name in your list, instead of retyping the entire URL.Most of the URLs you will be using start with http which stands for Hypertext Transfer Protocol*. http is the method by which HTML files are transferred over the Web. Here are some other important things to know about URLs:· A URL usually has no spaces.· A URL always uses forward slashes (//).If you enter a URL incorrectly, your browser will not be able to locate the site or resource you want. Should you get an error message or the wrong site, make sure you typed the address correctly.You can find the URL behind any link by passing your mouse cursor over the link. The pointer will turn into a hand and the URL will appear in the browser's status bar, usually located at the bottom of your screen.Domain NamesWhen you think of the Internet, you probably think of ".com." Just what do those three letters at the end of a World Wide Web address mean?Every computer that hosts data on the Internet has a unique numerical address. For example, the numerical address for the White House is 198.137.240.100. But since few people want to remember long strings of numbers, the Domain Name System (DNS)* was developed. DNS, a critical part of the Internet's technical infrastructure*, correlates* a numerical address to a word. To access the White House website, you could type its number into the address box of your web browser. But most people prefer to use "." In this case, the domain name is .In general, the three-letter domain name suffix* is known as a generic top-level domain and describes the type of organization. In the last few years, the lines have somewhat blurred* between these categories..com - business (commercial).edu - educational.org - non-profit.mil - military.net - network provider.gov - governmentA domain name always has two or more parts separated by dots and typically consists of some form of an organization's name and the three-letter suffix. For example, the domain name for IBM is ""; the United Nations is "."If a domain name is available, and provided it does not infringe* on an existing trademark, anyone can register the name for $35 a year through Network Solutions, Inc., which is authorized to register .com, .net and .org domains. You can use the box below to see if a name is a available. Don't be surprised if the .com name you want is already taken, however. Of the over 8 million domain names, 85% are .com domains.ICANN, the Internet Corporation for Assigned Names and Numbers, manages the Domain Name System. As of this writing, there are plans to add additional top-level domains, such as .web and .store. When that will actually happen is anybody's guess.To check for, or register a domain name, type it into the search box.It should take this form: In addition to the generic top-level domains, 244 national top-level domains were established for countries and territories*, for example:.au - Australia.ca - Canada.fr - France.de - Germany.uk - United KingdomFor US $275 per name, you can also register an international domain name with Net Names. Be aware that some countries have restrictions for registering names.If you plan to register your own domain name, whether it's a .com or not, keep these tips in mind:The shorter the name, the better. (But it should reflect your family name, interest or business.)The name should be easy to remember.It should be easy to type without making mistakes.Remember, the Internet is global. Ideally, a domain name will "read" in a language other than English.Decoding Error MessagesAs you surf the Net, you will undoubtedly find that at times you can't access certain websites. Why, you make wonder? Error messages attempt to explain thereason. Unfortunately, these cryptic* messages baffle* most people. We've deciphered* the most common ones you may encounter.400 - Bad RequestProblem: There's something wrong with the address you entered. You may not be authorized* to access the web page, or maybe it no longer exists.Solution: Check the address carefully, especially if the address is long. Make sure that the slashes are correct (they should be forward slashes) and that all the names are properly spelled. Web addresses are case sensitive, so check that the names are capitalized in your entry as they are in the original reference to the website.401 - UnauthorizedProblem: You can't access a website, because you're not on the guest list, your password is invalid or you have entered your password incorrectly.Solution: If you think you have authorization, try typing your password again. Remember that passwords are case sensitive.403 - ForbiddenProblem: Essentially the same as a 401.Solution: Try entering your password again or move on to another site.404 - Not FoundProblem: Either the web page no longer exists on the server or it is nowhere to be found.Solution: Check the address carefully and try entering it again. You might also see if the site has a search engine and if so, use it to hunt for the document. (It's not uncommon for pages to change their addresses when a website is redesigned.) To get to the home page of the site, delete everything after the domain name and hit the Enter or Return key.503 - Service unavailableProblem: Your Internet service provider (ISP) or your company's Internet connection may be down.Solution: Take a stretch, wait a few minutes and try again. If you still have no luck, phone your ISP or system administrator.Bad file requestProblem: Your web browser may not be able to decipher the online form you want to access. There may also be a technical error in the form.Solution: Consider sending a message to the site's webmaster, providing any technical information you can, such as the browser and version you use.Connection refused by hostProblem: You don't have permission to access the page or your password is incorrect.Solution: Try typing your password again if you think you should have access.Failed DNS lookupProblem: DNS stands for the Domain Name System, which is the system that looks up the name of a website, finds a corresponding number (similar to a phone number), then directs your request to the appropriate web server on the Internet. When the lookup fails, the host server can't be located.Solution: Try clicking on the Reload or Refresh button on your browser toolbar. If this doesn't work, check the address and enter it again. If all else fails, try again later.File contains no dataProblem: The site has no web pages on it.Solution: Check the address and enter it again. If you get the same error message, try again later.Host unavailableProblem: The web server is down.Solution: Try clicking on the Reload or Refresh button. If this doesn't work, try again later.Host unknownProblem: The web server is down, the site may have moved, or you've been disconnected from the Net.Solution: Try clicking on the Reload or Refresh button and check to see that you are still online. If this fails, try using a search engine to find the site. It may have a new address.Network connection refused by the serverProblem: The web server is busy.Solution: Try again in a while.Unable to locate hostProblem: The web server is down or you've been disconnected from the Net.Solution: Try clicking on the Reload or Refresh button and check to see that you are still online.Unable to locate serverProblem: The web server is out-of-business or you may have entered the addressincorrectly.Solution: Check the address and try typing it again.二、英文翻译：网络网络的诞生迄今为止，因特网的历史虽比较简短，但仍然是突破性的。

外文文献翻译（译成中文2000字左右）：As research laboratories become more automated,new problems are arising for laboratory managers.Rarely does a laboratory purchase all of its automation from a single equipment vendor. As a result,managers are forced to spend money training their users on numerous different software packages while purchasing support contracts for each. This suggests a problem of scalability. In the ideal world,managers could use the same software package to control systems of any size; from single instruments such as pipettors or readers to large robotic systems with up to hundreds of instruments. If such a software package existed, managers would only have to train users on one platform and would be able to source software support from a single vendor.If automation software is written to be scalable, it must also be flexible. Having a platform that can control systems of any size is far less valuable if the end user cannot control every device type they need to use. Similarly, if the software cannot connect to the customer’s Laboratory Information Management System (LIMS) database,it is of limited usefulness. The ideal automation software platform must therefore have an open architecture to provide such connectivity.Two strong reasons to automate a laboratory are increased throughput and improved robustness. It does not make sense to purchase high-speed automation if the controlling software does not maximize throughput of the system. The ideal automation software, therefore, would make use of redundant devices in the system to increase throughput. For example, let us assume that a plate-reading step is the slowest task in a given method. It would make that if the system operator connected another identical reader into the system, the controller software should be able to use both readers, cutting the total throughput time of the reading step in half. While resource pooling provides a clear throughput advantage, it can also be used to make the system more robust. For example, if one of the two readers were to experience some sort of error, the controlling software should be smart enough to route all samples to the working reader without taking the entire system offline.Now that one embodiment of an ideal automation control platform has been described let us see how the use of C++ helps achieving this ideal possible.DISCUSSIONC++: An Object-Oriented LanguageDeveloped in 1983 by BjarneStroustrup of Bell Labs,C++ helped propel the concept of object-oriented programming into the mainstream.The term ‘‘object-oriented programming language’’ is a familiar phrase that has been in use for decades. But what does it mean? And why is it relevant for automation software? Essentially, a language that is object-oriented provides three important programming mechanisms:encapsulation, inheritance, and polymorphism.Encapsulation is the ability of an object to maintain its own methods (or functions) and properties (or variables).For example, an ‘‘engine’’ object might contain methods for starting, stopping, or accelerating, along with properties for ‘‘RPM’’ and ‘‘Oil pressure’’. Further, encapsulation allows an object to hide private data from a ny entity outside the object. The programmer can control access to the object’s data by marking methods or properties as public, protected,or private. This access control helps abstract away the inner workings of a class while making it obvious to a caller which methods and properties are intended to be used externally.Inheritance allows one object to be a superset of another object. For example, one can create an object called Automobile that inherits from Vehicle. The Automobile object has access to all non-private methods and properties of Vehicle plus any additional methods or properties that makes it uniquely an automobile.Polymorphism is an extremely powerful mechanism that allows various inherited objects to exhibit different behaviors when the same named method is invoked upon them. For example, let us say our Vehicle object contains a method called CountWheels. When we invoke this method on our Automobile, we learn that the Automobile has four wheels.However, when we call this method on an object called Bus,we find that the Bus has 10 wheels.Together, encapsulation, inheritance, and polymorphism help promote code reuse, which is essential to meeting our requirement that the software package be flexible. A vendor can build up a comprehensive library of objects (a serial communications class, a state machine class, a device driver class,etc.) that can be reused across many different code modules.A typical control software vendor might have 100 device drivers. It would be a nightmare if for each of these drivers there were no building blocks for graphical user interface (GUI) or communications to build on. By building and maintaining a library of foundation objects, the vendor will save countless hours of programming and debugging time.All three tenets of object-oriented programming are leveraged by the use of interfaces. An interface is essentially a specification that is used to facilitate communication between software components, possibly written by different vendors. An interface says, ‘‘if your cod e follows this set of rules then my software component will be able to communicate with it.’’ In the next section we will see how interfaces make writing device drivers a much simpler task.C++ and Device DriversIn a flexible automation platform, one optimal use for interfaces is in device drivers. We would like our open-architecture software to provide a generic way for end users to write their own device drivers without having to divulge the secrets of our source code to them. To do this, we define a simplifiedC++ interface for a generic device, as shown here:class IDevice{public:virtual string GetName() ? 0; //Returns the name//of the devicevirtual void Initialize() ? 0; //Called to//initialize the devicevirtual void Run() ? 0; // Called to run the device};In the example above, a Ctt class (or object) called IDevice has been defined. The prefix I in IDevice stands for ‘‘interface’’. This class defines three public virtual methods: GetName, Initialize, and Run. The virtual keyword is what enables polymorphism, allowing the executing program to run the methods of the inheriting class. When a virtual method declaration is suffixed with ?0, there is no base class implementation. Such a method is referred to as ‘‘pure virtual’’. A class like IDevice that contains only pure virtual functions is known as an ‘‘abstract class’’, or an‘‘interface’’. The IDevice definition, along with appropriate documentation, can be published to the user community,allowing developers to generate their own device drivers that implement the IDevice interface.Suppose a thermal plate sealer manufacturer wants to write a driver that can be controlled by our software package. They would use inheritance to implement our IDevice interface and then override the methods to produce the desired behavior: class CSealer : public IDevice{public:virtual string GetName() {return ‘‘Sealer’’;}virtual void Initialize() {InitializeSealer();}virtual void Run() {RunSealCycle();}private:void InitializeSealer();void RunSealCycle();};Here the user has created a new class called CSealer that inherits from the IDevice interface. The public methods,those that are accessible from outside of the class, are the interface methods defined in IDevice. One, GetName, simply returns the name of the device type that this driver controls.The other methods,Initialize() and Run(), call private methods that actually perform the work. Notice how the privatekeyword is used to prevent external objects from calling InitializeSealer() and RunSealCycle() directly.When the controlling software executes, polymorphism will be used at runtime to call the GetName, Initialize, and Run methods in the CSealer object, allowing the device defined therein to be controlled.DoSomeWork(){//Get a reference to the device driver we want to useIDevice&device ? GetDeviceDriver();//Tell the world what we’re about to do.cout !! ‘‘Initializing ’’!! device.GetName();//Initialize the devicedevice.Initialize();//Tell the world what we’re about to do.cout !! ‘‘Running a cycle on ’’ !!device.GetName();//Away we go!device.Run();}The code snippet above shows how the IDevice interface can be used to generically control a device. If GetDevice-Driver returns a reference to a CSealer object, then DoSomeWork will control sealers. If GetDeviceDriver returns a reference to a pipettor, then DoSomeWork will control pipettors. Although this is a simplified example, it is straightforward to imagine how the use of interfaces and polymorphism can lead to great economies of scale in controller software development.Additional interfaces can be generated along the same lines as IDevice. For example, an interface perhaps called ILMS could be used to facilitate communication to and from a LIMS.The astute reader will notice that the claim that anythird party can develop drivers simply by implementing the IDevice interface is slightly flawed. The problem is that any driver that the user writes, like CSealer, would have to be linked directly to the controlling software’s exec utable to be used. This problem is solved by a number of existing technologies, including Microsoft’s COMor .NET, or by CORBA. All of these technologies allow end users to implement abstract interfaces in standalone components that can be linked at runtime rather than at design time. The details are beyond the scope of this article.中文翻译：随着研究实验室更加自动化，实验室管理人员出现的新问题。

Management Information System Overview Management Information System is that we often say that the MIS, is a human, computers and other information can be composed of the collection, transmission, storage, maintenance and use of the system, system, emphasizing emphasizing the the management, management, management, stressed stressed stressed that that the modern information society In the increasingly popular. MIS is a new subject, it across a number of areas, such as scientific scientific management management management and and and system system system science, science, science, operations operations operations research, research, research, statistics statistics statistics and and and computer computer science. In these subjects on the basis of formation of information-gathering and processing methods, thereby forming a vertical and horizontal weaving, and systems. The 20th century, along with the vigorous development of the global economy, many economists have proposed a new management theory. In the 1950s, Simon made dependent on information management and decision-making ideas. Wiener published the same period of the control theory, that he is a management control process. 1958, Gail wrote: "The management will lower the cost of timely and accurate information to b etter control." During better control." During this period, accounting for the beginning of the computer, data processing in the term.1970, Walter T . Kenova just to the management information system under a definition of the . Kenova just to the management information system under a definition of the term: "verbal or written form, at the right time to managers, staff and outside staff for the past, present, the projection of future Enterprise and its environment-related information 原文请找腾讯3249114六,维^论~文.网 no no application application application model, model, model, no no mention mention of of computer applications. 1985, management information systems, the founder of the University of Minnesota professor of management at the Gordon B. Davis to a management information system a more complete definition of "management information system is a computer hardware and software resources, manual operations, analysis, planning , Control and decision -making model and the database - System. System. It It provides information to to support support enterprises enterprises or or organizations organizations of of the operation, management and decision-making function. "Comprehensive definition of this Explained Explained that that that the the the goal goal goal of of of management management management information information information system, system, system, functions functions functions and and and composition, composition, composition, but but also reflects the management information system at the time of level.With the continuous improvement of science and technology, computer science increasingly mature, the computer has to be our study and work on the run along. Today, computers are already already very low price, performance, but great progress, and it was used in many areas, the very low price, performance, but great progress, and it was used in many areas, the computer computer was was was so so so popular popular popular mainly mainly mainly because because because of of of the the the following following following aspects: aspects: aspects: First, First, First, the the the computer computer computer can can substitute for many of the complex Labor. Second, the computer can greatly enhance people's work work efficiency. efficiency. efficiency. Third, Third, Third, the the the computer computer computer can can can save save save a a a lot lot lot of of of resources. resources. resources. Fourth, Fourth, Fourth, the the the computer computer computer can can make sensitive documents more secure.Computer application and popularization of economic and social life in various fields. So that the original old management methods are not suited now more and social development. Many people still remain in the previous manual. This greatly hindered the economic development of mankind. mankind. In recent years, with the University of sponsoring scale is In recent years, with the University of sponsoring scale is growing, the number of students students in in in the the the school school school also also also have have have increased, increased, increased, resulting resulting resulting in in in educational educational educational administration administration administration is is is the the growing complexity of the heavy work, to spend a lot of manpower, material resources, and the existing management of student achievement levels are not high, People have been usin g the traditional method of document management student achievement, the management there are many shortcomings, such as: low efficiency, confidentiality of the poor, and Shijianyichang, will have a large number of of documents documents documents and and data, which is is useful useful for finding, finding, updating updating and maintaining Have brought a lot of difficulties. Such a mechanism has been unable to meet the development of the times, schools have become more and more day -to-day management of a bottleneck. bottleneck. In In In the the the information information information age age age this this this traditional traditional traditional management management management methods methods methods will will will inevitably inevitably inevitably be be computer-based information management replaced. As As part part part of of of the the the computer computer computer application, application, application, the the the use use use of of of computers computers computers to to to students students students student student student performance performance information for management, with a manual management of the incomparable advantages for example: example: rapid rapid rapid retrieval, retrieval, retrieval, to to to find find find convenient, convenient, convenient, high high high reliability reliability reliability and and and large large large capacity capacity capacity storage, storage, storage, the the confidentiality confidentiality of of of good, good, good, long long long life, life, life, cost cost cost Low. Low. Low. These These These advantages advantages advantages can can can greatly greatly greatly improve improve improve student student performance management students the efficiency of enterprises is also a scientific, standardized standardized management, management, management, and and and an an an important important important condition condition condition for for for connecting connecting connecting the the the world. world. world. Therefore, Therefore, the development of such a set of management software as it is very necessary thing.Design ideas are all for the sake of users, the interface nice, clear and simple operation as far as possible, but also as a practical operating system a good fault-tolerant, the user can misuse a timely manner as possible are given a warning, so that users timely correction . T o take full advantage advantage of the of the functions of visual FoxPro, design p owerful software powerful software at the same time, as much as possible to reduce the occupiers system resources. Visual FoxPro the command structure and working methods: Visual FoxPro was originally originally called called FoxBASE, FoxBASE, the the U.S. U.S. Fox Fox Software has introduced introduced a a database products, products, in in the run on DOS, compatible with the abase family. Fox Fox Software Software Microsoft acquisition, to be developed so that it can run on Windows, and changed its name to Visual FoxPro. Visual FoxPro is a powerful relational database rapid application development tool, tool, the the the use use use of of of Visual Visual Visual FoxPro FoxPro FoxPro can can can create create create a a a desktop desktop desktop database database database applications, applications, applications, client client client / / / server server applications applications and and and Web Web Web services services services component-based component-based component-based procedures, procedures, procedures, while while while also also also can can can use use use ActiveX ActiveX controls or API function, and so on Ways to expand the functions of Visual FoxPro.1651First, work methods 1. Interactive mode of operation (1) order operation VF in the order window, through an order from the keyboard input of all kinds of ways to complete the operation order. (2) menu operation VF use menus, windows, dialog to achieve the graphical interface features an interactive operation. (3) aid operation VF in the system provides a wide range of user-friendly operation of tools, such as the wizard, design, production, etc.. 2. Procedure means of implementation VF in the implementation of the procedures is to form a group of orders and programming language, an extension to save. PRG procedures in the document, and then run through the automatic implementation of this order documents and award results are displayed. Second, the structure of command 1. Command structure 2. VF orders are usually composed of two parts: The first part is the verb order, also known as keywords, for the operation of the designated order functions; second part of the order clause, for an order that the operation targets, operating conditions and other information . VF order form are as follows: 3. <Order verb> "<order clause>" 4. Order in the format agreed symbols 5. 5. VF in the order form and function of the use of the symbol of the unity agreement, the meaning of VF in the order form and function of the use of the symbol of the unity agreement, the meaning of these symbols are as follows: 6. Than that option, angle brackets within the parameters must be based on their format input parameters. 7. That may be options, put in brackets the parameters under specific requ ests from users choose to enter its parameters. 8. Third, the project manager 9. Create a method 10. command window: CREA T PROJECT <file name> T PROJECT <file name> 11. Project Manager 12. tab 13. All - can display and project management applications of all types of docume nts, "All" tab contains five of its right of the tab in its entirety . 14. Data - management application projects in various types of data files, databases, free form, view, query documents. 15. Documentation - display 原文请找腾讯原文请找腾讯3249114六,维^论~文.网 , statements, documents, labels and other documents. 16. Category - the tab display and project management applications used in the class library documents, including VF's class library system and the user's own design of the library. 17. Code - used in the project management procedures code documents, such as: program files (. PRG), API library and the use of project management for generation of applications (. APP). 18. (2) the work area 19. The project management work area is displayed and management of all types of document window. 20. (3) order button 21. Project Manager button to the right of the order of the work area of the document window to provide command. 22. 4, project management for the use of 23. 1. Order button function 24. New - in the work area window selected certain documents, with new orders button on the new document added to the project management window. 25. Add - can be used VF "file" menu under the "new" order and the "T ools" menu under the "Wizard" order to create the various independent paper added to the project manager, unified organization with management. 26. Laws - may amend the project has been in existence in the various documents, is still to use such documents to modify the design interface. 27. Sports - in the work area window to highlight a specific document, will run the paper.28. Mobile - to check the documents removed from the project. 29. 29. Even Even Even the the the series series series - - - put put put the the the item item item in in in the the the relevant relevant relevant documents documents documents and and and even even even into into into the the the application application executable file. Database System Design :Database design is the logical database design, according to a forthcoming data classification system and the logic of division-level organizations, is user-oriented. Database design needs of various departments of the integrated enterprise archive data and data needs analysis of the relationship between the various data, in accordance with the DBMS. 管理信息系统概要管理信息系统概要管理信息系统就是我们常说的MIS （Management Information System ），是一个由人、计算机等组成的能进行信息的收集、传送、储存、维护和使用的系统，在强调管理，强调信息的现代社会中它越来越得到普及。

附录（英文翻译）Rich Client Tutorial Part 1The Rich Client Platform (RCP) is an exciting new way to build Java applications that can compete with native applications on any platform. This tutorial is designed to get you started building RCP applications quickly. It has been updated for Eclipse 3.1.2By Ed Burnette, SASJuly 28, 2004Updated for 3.1.2: February 6, 2006IntroductionTry this experiment: Show Eclipse to some friends or co-workers who haven't seen it before and ask them to guess what language it is written in. Chances are, they'll guess VB, C++, or C#, because those languages are used most often for high quality client side applications. Then watch the look on their faces when you tell them it was created in Java, especially if they are Java programmers.Because of its unique open source license, you can use the technologies that went into Eclipse to create your own commercial quality programs. Before version 3.0, this was possible but difficult, especially when you wanted to heavily customize the menus, layouts, and other user interface elements. That was because the "IDE-ness" of Eclipse was hard-wired into it. Version 3.0 introduced the Rich Client Platform (RCP), which is basically a refactoring of the fundamental parts of Eclipse's UI, allowing it to be used for non-IDE applications. Version 3.1 updated RCP with new capabilities, and, most importantly, new tooling support to make it easier to create than before.If you want to cut to the chase and look at the code for this part you can find it in the accompanying zip file. Otherwise, let's take a look at how to construct an RCP application.Getting startedRCP applications are based on the familiar Eclipse plug-in architecture, (if it's not familiar to you, see the references section). Therefore, you'll need to create a plug-in to be your main program. Eclipse's Plug-in Development Environment (PDE) provides a number of wizards and editors that take some of the drudgery out of the process. PDE is included with the Eclipse SDK download so that is the package you should be using. Here are the steps you should follow to get started.First, bring up Eclipse and select File > New > Project, then expand Plug-in Development and double-click Plug-in Project to bring up the Plug-in Project wizard. On the subsequent pages, enter a Project name such as org.eclipse.ui.tutorials.rcp.part1, indicate you want a Java project, select the version of Eclipse you're targeting (at least 3.1), and enable the option to Create an OSGi bundle manifest. Then click Next >.Beginning in Eclipse 3.1 you will get best results by using the OSGi bundle manifest. In contrast to previous versions, this is now the default.In the next page of the Wizard you can change the Plug-in ID and other parameters. Of particular importance is the question, "Would you like to create a rich client application?". Select Yes. The generated plug-in class is optional but for this example just leave all the other options at their default values. Click Next > to continue.If you get a dialog asking if Eclipse can switch to the Plug-in Development Perspective click Remember my decision and select Yes (this is optional).Starting with Eclipse 3.1, several templates have been provided to make creating an RCP application a breeze. We'll use the simplest one available and see how it works. Make sure the option to Create a plug-in using one of the templates is enabled, then select the Hello RCP template. This isRCP's equivalent of "Hello, world". Click Finish to accept all the defaults and generate the project (see Figure 1). Eclipse will open the Plug-in Manifest Editor. The Plug-in Manifest editor puts a friendly face on the various configuration files that control your RCP application.Figure 1. The Hello World RCP project was created by a PDE wizard.Taking it for a spinTrying out RCP applications used to be somewhat tedious. You had to create a custom launch configuration, enter the right application name, and tweak the plug-ins that were included. Thankfully the PDE keeps track of all this now. All you have to do is click on the Launch an Eclipse Application button in the Plug-in Manifest editor's Overview page. You should see a bare-bones Workbench start up (see Figure 2).Figure 2. By using thetemplates you can be up andrunning anRCPapplication inminutes.Making it aproductIn Eclipse terms a product is everything that goes with your application, including all the other plug-ins it depends on, a command to run the application (called the native launcher), and any branding (icons, etc.) that make your application distinctive. Although as we've just seen you can run a RCP application without defining a product, having one makes it a whole lot easier to run the application outside of Eclipse. This is one of the major innovations that Eclipse 3.1 brought to RCP development.Some of the more complicated RCP templates already come with a product defined, but the Hello RCP template does not so we'll have to make one.In order to create a product, the easiest way is to add a product configuration file to the project. Right click on the plug-in project and select New > Product Configuration. Then enter a file name for this new configuration file, such as part1.product. Leave the other options at their default values. Then click Finish. The Product Configuration editor will open. This editor lets you control exactly what makes up your product including all its plug-ins and branding elements.In the Overview page, select the New... button to create a new product extension. Type in or browse to the defining plug-in(org.eclipse.ui.tutorials.rcp.part1). Enter a Product ID such as product, and for the Product Application selectorg.eclipse.ui.tutorials.rcp.part1.application. Click Finish to define the product. Back in the Overview page, type in a new Product Name, for example RCP Tutorial 1.In Eclipse 3.1.0 if you create the product before filling inthe Product Name you may see an error appear in the Problems view. The error will go away when you Synchronize (see below). This is a known bug that is fixed in newer versions. Always use the latest available maintenance release for the version of Eclipse you're targeting!Now select the Configuration tab and click Add.... Select the plug-in you just created (org.eclipse.ui.tutorials.rcp.part1) and then click on Add Required Plug-ins. Then go back to the Overview page and press Ctrl+S or File > Save to save your work.If your application needs to reference plug-ins that cannot be determined until run time (for example the tomcat plug-in), then add them manually in the Configuration tab.At this point you should test out the product to make sure it runs correctly. In the Testing section of the Overview page, click on Synchronize then click on Launch the product. If all goes well, the application should start up just like before.Plug-ins vs. featuresOn the Overview page you may have noticed an option that says the product configuration is based on either plug-ins or features. The simplest kind of configuration is one based on plug-ins, so that's what this tutorial uses. If your product needs automatic update or Java Web Start support, then eventually you should convert it to use features. But take my advice and get it working without them first.Running it outside of EclipseThe whole point of all this is to be able to deploy and run stand-alone applications without the user having to know anything about the Java and Eclipse code being used under the covers. For a real application you may want to provide a self-contained executable generated by an install program like InstallShield or NSIS. That's really beyond the scope of this article though, so we'll do something simpler.The Eclipse plug-in loader expects things to be in a certain layout so we'll need to create a simplified version of the Eclipse install directory. This directory has to contain the native launcher program, config files,and all the plug-ins required by the product. Thankfully, we've given the PDE enough information that it can put all this together for us now.In the Exporting section of the Product Configuration editor, click the link to Use the Eclipse Product export wizard. Set the root directory to something like RcpTutorial1. Then select the option to deploy into a Directory, and enter a directory path to a temporary (scratch) area such as C:\Deploy. Check the option to Include source code if you're building an open source project. Press Finish to build and export the program.The compiler options for source and class compatibility in the Eclipse Product export wizard will override any options you have specified on your project or global preferences. As part of the Export process, the plug-in is code is recompiled by an Ant script using these options.The application is now ready to run outside Eclipse. When you're done you should have a structure that looks like this in your deployment directory:RcpTutorial1| .eclipseproduct| eclipse.exe| startup.jar+--- configuration| config.ini+--- pluginsmands_3.1.0.jarorg.eclipse.core.expressions_3.1.0.jarorg.eclipse.core.runtime_3.1.2.jarorg.eclipse.help_3.1.0.jarorg.eclipse.jface_3.1.1.jarorg.eclipse.osgi_3.1.2.jarorg.eclipse.swt.win32.win32.x86_3.1.2.jarorg.eclipse.swt_3.1.0.jarorg.eclipse.ui.tutorials.rcp.part1_1.0.0.jarorg.eclipse.ui.workbench_3.1.2.jarorg.eclipse.ui_3.1.2.jarNote that all the plug-ins are deployed as jar files. This is the recommended format starting in Eclipse 3.1. Among other things this saves disk space in the deployed application.Previous versions of this tutorial recommended using a batch file or shell script to invoke your RCP program. It turns out this is a bad idea because you will not be able to fully brand your application later on. For example, you won't be able to add a splash screen. Besides, theexport wizard does not support the batch file approach so just stick with the native launcher.Give it a try! Execute the native launcher (eclipse or eclipse.exe by default) outside Eclipse and watch the application come up. The name of the launcher is controlled by branding options in the product configuration.TroubleshootingError: Launching failed because the org.eclipse.osgi plug-in is not included...You can get this error when testing the product if you've forgotten to list the plug-ins that make up the product. In the Product Configuration editor, select the Configuration tab, and add all your plug-ins plus all the ones they require as instructed above.Compatibility and migrationIf you are migrating a plug-in from version 2.1 to version 3.1 there are number of issues covered in the on-line documentation that you need to be aware of. If you're making the smaller step from 3.0 to 3.1, the number of differences is much smaller. See the References section for more information.One word of advice: be careful not to duplicate any information in both plug-in.xml and MANIFEST.MF. Typically this would not occur unless you are converting an older plug-in that did not use MANIFEST.MF into one that does, and even then only if you are editing the files by hand instead of going through the PDE.ConclusionIn part 1 of this tutorial, we looked at what is necessary to create a bare-bones Rich Client application. The next part will delve into the classes created by the wizards such as the WorkbenchAdvisor class. All the sample code for this part may be found in the accompanying zip file.ReferencesRCP Tutorial Part 2RCP Tutorial Part 3Eclipse Rich Client PlatformRCP Browser example (project org.eclipse.ui.examples.rcp.browser)PDE Does Plug-insHow to Internationalize your Eclipse Plug-inNotes on the Eclipse Plug-in ArchitecturePlug-in Migration Guide: Migrating to 3.1 from 3.0Plug-in Migration Guide: Migrating to 3.0 from 2.1译文：Rich Client教程第一部分The Rich Client Platform (RCP)是一种创建Java应用程序的令人兴奋的新方法，可以和任何平台下的自带应用程序进行竞争。

英文文献Object persistence and JavaBy Arsalan Saljoughy, , 05/01/97Object durability, or persistence, is the term you often hear used in conjunction with the issue of storing objects in databases. Persistence is expected to operate with transactional integrity, and as such it is subject to strict conditions. (See the Resources section of this article for more information on transaction processing.) In contrast, language services offered through standard language libraries and packages are often free from transactional constraints.As we'll see in this article, evidence suggests that simple Java persistence will likely stem from the language itself, while sophisticated database functionality will be offered by database vendors.No object is an islandIn the real world, you rarely find an object that lacks relations to other objects. Objects are components of object models. The issue of object durability transcends the issue of object model durability and distribution once we make the observation that objects are interconnected by virtue of their relations to one another.The relational approach to data storage tends to aggregate data by type. Rows in a table represent the physical aggregate of objects of the same type on disk. The relationships among objects are then represented by keys that are shared across many tables. Although through database organization, relational databases sometimes allow tables that are likely to be used together to be co-located (or clustered) in the same logical partition, such as a database segment, they have no mechanism to store object relationships in the database. Hence, in order to construct an object model, these relationships are constructed from the existing keys at run time in a process referred to as table joins. This is the same well-known property of the relational databases called data independence. Nearly all variants of object databases offer some mechanism to enhance the performance of a system that involves complex object relationships over traditional relational databases.To query or to navigate?In storing objects on disk, we are faced with the choice of co-locating related objects to better accommodate navigational access, or to store objects in table-like collections that aggregate objects by type to facilitate predicate-based access (queries), or both. The co-location of objects in persistent storage is an area where relational and object-oriented databases widely differ. The choice of the query language is another area of consideration. Structured Query Language (SQL) and extensions of it have provided relational systems with a predicate-basedaccess mechanism. Object Query Language (OQL) is an object variant of SQL, standardized by ODMG, but support for this language is currently scant. Polymorphic methods offer unprecedented elegance in constructing a semantic query for a collection of objects. For example, imagine a polymorphic behavior for acccount called isInGoodStanding. It may return the Boolean true for all accounts in good standing, and false otherwise. Now imagine the elegance of querying the collection of accounts, where inGoodStanding is implemented differently based on business rules, for all accounts in good standing. It may look something like:setOfGoodCustomers = setOfAccounts.query(account.inGoodStanding());While several of the existing object databases are capable of processing such a query style in C++ and Smalltalk, it is difficult for them to do so for larger (say, 500+ gigabytes) collections and more complex query expressions. Several of the relational database companies, such as Oracle and Informix, will soon offer other, SQL-based syntax to achieve the same result. Persistence and typeAn object-oriented language aficionado would say persistence and type are orthogonal properties of an object; that is, persistent and transient objects of the same type can be identical because one property should not influence the other. The alternative view holds that persistence is a behavior supported only by persistable objects and certain behaviors may apply only to persistent objects. The latter approach calls for methods that instruct persistable objects to store and retrieve themselves from persistent storage, while the former affords the application a seamless view of the entire object model -- often by extending the virtual memory system. Canonicalization and language independenceObjects of the same type in a language should be stored in persistent storage with the same layout, regardless of the order in which their interfaces appear. The processes of transforming an object layout to this common format are collectively known as canonicalization of object representation. In compiled languages with static typing (not Java) objects written in the same language, but compiled under different systems, should be identically represented in persistent storage.An extension of canonicalization addresses language-independent object representation. If objects can be represented in a language-independent fashion, it will be possible for different representations of the same object to share the same persistent storage.One mechanism to accomplish this task is to introduce an additional level of indirection through an interface definition language (IDL). Object database interfaces can be made through the IDL and the corresponding data structures. The downside of IDL style bindings is two fold: First, the extra level of indirection always requires an additional level of translation, which impacts the overall performance of the system; second, it limits use of database services that are unique to particular vendors and that might be valuable to application developers.A similar mechanism is to support object services through an extension of the SQL. Relational database vendors and smaller object/relational vendors are proponents of this approach; however, how successful these companies will be in shaping the framework for object storage remains to be seen.But the question remains: Is object persistence part of the object's behavior or is it an external service offered to objects via separate interfaces? How about collections of objects and methods for querying them? Relational, extended relational, and object/relational approaches tend to advocate a separation between language, while object databases -- and the Java language itself -- see persistence as intrinsic to the language:Native Java persistence via serializationObject serialization is the Java language-specific mechanism for the storage and retrieval of Java objects and primitives to streams. It is worthy to note that although commercial third-party libraries for serializing C++ objects have been around for some time, C++ has never offered a native mechanism for object serialization. Here's how to use Java's serialization: // Writing "foo" to a stream (for example, a file)// Step 1. Create an output stream// that is, create bucket to receive the bytesFileOutputStream out = new FileOutputStream("fooFile");// Step 2. Create ObjectOutputStream// that is, create a hose and put its head in the bucketObjectOutputStream os = new ObjectOutputStream(out)// Step 3. Write a string and an object to the stream// that is, let the stream flow into the bucketos.writeObject("foo");os.writeObject(new Foo());// Step 4. Flush the data to its destinationos.flush();The Writeobject method serializes foo and its transitive closure -- that is, all objects that can be referenced from foo within the graph. Within the stream only one copy of the serialized object exists. Other references to the objects are stored as object handles to save space and avoid circular references. The serialized object starts with the class followed by the fields of each class in the inheritance hierarchy.// Reading an object from a stream// Step 1. Create an input streamFileInputStream in = new FileInputStream("fooFile");// Step 2. Create an object input streamObjectInputStream ins = new ObjectInputStream(in);// Step 3. Got to know what you are readingString fooString = (String)ins.readObject();Foo foo = (Foo)s.readObject();Object serialization and securityBy default, serialization writes and reads non-static and non-transient fields from the stream. This characteristic can be used as a security mechanism by declaring fields that may not be serialized as private transient. If a class may not be serialized at all, writeObject and readObject methods should be implemented to throw NoAccessException.Persistence with transactional integrity: Introducing JDBCModeled after X/Open's SQL CLI (Client Level Interface) and Microsoft's ODBC abstractions, Java database connectivity (JDBC) aims to provide a database connectivity mechanism that is independent of the underlying database management system (DBMS).To become JDBC-compliant, drivers need to support at least the ANSI SQL-2 entry-level API, which gives third-party tool vendors and applications enough flexibility for database access.JDBC is designed to be consistent with the rest of the Java system. Vendors are encouraged to write an API that is more strongly typed than ODBC, which affords greater static type-checking at compile time.Here's a description of the most important JDBC interfaces:java.sql.Driver.Manager handles the loading of drivers and provides support for new database connections.java.sql.Connection represents a connection to a particular database.java.sql.Statement acts as a container for executing an SQL statement on a given connection.java.sql.ResultSet controls access to the result set.You can implement a JDBC driver in several ways. The simplest would be to build the driver as a bridge to ODBC. This approach is best suited for tools and applications that do not require high performance. A more extensible design would introduce an extra level of indirection to the DBMS server by providing a JDBC network driver that accesses the DBMS server through a published protocol. The most efficient driver, however, would directly access the DBMS proprietary API.Object databases and Java persistenceA number of ongoing projects in the industry offer Java persistence at the object level. However, as of this writing, Object Design's PSE (Persistent Storage Engine) and PSE Pro are the only fully Java-based, object-oriented database packages available (at least, that I am aware of). Check the Resources section for more information on PSE and PSE Pro.Java development has led to a departure from the traditional development paradigm for software vendors, most notably in the development process timeline. For example, PSE and PSE Pro are developed in a heterogeneous environment. And because there isn't a linking step in the development process, developers have been able to create various functional components independent of each other, which results in better, more reliable object-oriented code.PSE Pro has the ability to recover a corrupted database from an aborted transaction caused by system failure. The classes that are responsible for this added functionality are not present in the PSE release. No other differences exist between the two products. These products are what we call "dribbleware" -- software releases that enhance their functionality by plugging in new components. In the not-so-distant future, the concept of purchasing large, monolithic software would become a thing of the past. The new business environment in cyberspace, together with Java computing, enable users to purchase only those parts of the object model (object graph) they need, resulting in more compact end products.PSE works by post-processing and annotating class files after they have been created by the developer. From PSE's point of view, classes in an object graph are either persistent-capable or persistent-aware. Persistent-capable classes may persist themselves while persistent-aware classes can operate on persistent objects. This distinction is necessary because persistence may not be a desired behavior for certain classes. The class file post-processor makes the following modifications to classes:Modifies the class to inherit from odi.Persistent or odi.util.HashPersistent.Defines the initializeContents() method to load real values into hollow instances of your Persistent subclass. ObjectStore provides methods on the GenericObject class that retrieves each Field type.Be sure to call the correct methods for the fields in your persistent object. A separate method is available for obtaining each type of Field object. ObjectStore calls the initializeContents() method as needed. The method signature is:public void initializeContents(GenericObject genObj)Defines the flushContents() method to copy values from a modified instance (active persistent object) back to the database. ObjectStore provides methods on the GenericObject Be sure to call the correct methods for the fields in your persistent object. A separate method is available for setting each type of Field object. ObjectStore calls the flushContents() method as needed. The method signature is:public void flushContents(GenericObject genObj)Defines the clearContents() method to reset the values of an instance to the default values. This method must set all reference fields that referred to persistent objects to null. ObjectStore calls this method as needed. The method signature is:public void clearContents()Modifies the methods that reference non-static fields to call the Persistent.fetch() and Persistent.dirty() methods as needed. These methods must be called before the contents of persistent objects can be accessed or modified, respectively. While this step is not mandatory, it does provide a systematic way to ensure that the fetch() or dirty() method is called prior to accessing or updating object content.Defines a class that provides schema information about the persistence-capable class.All these steps can be completed either manually or automatically.PSE's transaction semanticYou old-time users of ObjectStore probably will find the database and transaction semantics familiar. There is a system-wide ObjectStore object that initializes the environment and is responsible for system-wide parameters. The Database class offers methods (such as create, open, and close), and the Transaction class has methods to begin, abort, or commit transactions. As with serialization, you need to find an entry point into the object graph. The getRoot and setRoot methods of the Database class serve this function. I think a few examples would be helpful here. This first snippet shows how to initialize ObjectStore:ObjectStore.initialize(serverName, null);try {db = Database.open(dbName, Database.openUpdate);} catch(DatabaseNotFoundException exception) {db = Database.create(dbName, 0664);}This next snippet shows how to start and commit a transaction:Transaction transaction = Transaction.begin(Transaction.update);try {foo = (Foo)db.getRoot("fooHead");} catch(DatabaseRootNotFoundException exception) {db.createRoot("fooHead", new Foo());}mit();The three classes specified above -- Transaction, Database, and ObjectStore -- are fundamental classes for ObjectStore. PSE 1.0 does not support nested transactions, backup and recovery, clustering, large databases, object security beyond what is available in the language, and any type of distribution. What is exciting, however, is all of this functionality will be incrementally added to the same foundation as the product matures.About the authorArsalan Saljoughy is asystems engineer specializing in object technology at Sun Microsystems. He earned his M.S. in mathematics from SUNY at Albany, and subsequently was a research fellow at the University of Berlin. Before joining Sun, he worked as a developer and as an IT consultant to financial services companies.ConclusionAlthough it is still too early to establish which methodology for object persistence in general and Java persistence in particular will be dominant in the future, it is safe to assume that a myriad of such styles will co-exist. The shift of storing objects as objects without disassembly into rows and columns is sure to be slow, but it will happen. In the meantime, we are more likely to see object databases better utilized in advanced engineering and telecommunications applications than in banking and back-office financial applications.英文翻译对象持久化和Java－深入的了解面向对象语言中的对象持久的讨论Arsalan Saljoughy,, 05/01/97对象持久化这个术语你常常会和数据存储一起听到。

英文原文：Computer networkA computer network, often simply referred to as a network, is a collection of computers and devices interconnected by communications channels that facilitate communications among users and allows users to share resources. Networks may be classified according to a wide variety of characteristics. A computer network allows sharing of resources and information among interconnected devices.History ：Early networks of communicating computers included the military radar system Semi-Automatic Ground Environment (SAGE) and its relative the commercial airline reservation system Semi-Automatic Business Research Environment (SABRE),started in the late 1950s.[1][2]When Russia launched His SPUTNIK Satellite in Space In 1957.The American Started Agency Names ADV ANCE RESEARCH PROJECT AGENCY (ARPA) & launched THis 1st Satellite Within 18 Month After Establishment.Then Sharing Of TheInformation InAnother Computer They Use ARPANET.And This All Responsibility On America's Dr.LIED LIEDER.Then in 1969,ARPANET Comes in INDIA And INDIAN Switched This Name To NETWORK. In the 1960s, the Advanced Research Projects Agency (ARPA) started funding the design of the Advanced Research Projects Agency Network (ARPANET) for the United States Department of Defense. Development of the network began in 1969, based on designs developed during the1960s.[3] The ARPANET evolved into the modern Internet.Purpose ：Computer networks can be used for a variety of purposes: Facilitating communications. Using a network, people can communicate efficiently and easily via email, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing.Sharing hardware.：In a networked environment, each computer on a network may access and use hardware resources on the network, such as printing a document on a shared network printer.Sharing files, data, and information. In a network environment, authorized user may access data and information stored on other computers on the network. The capability of providing access to data and information on shared storage devices is an important feature of many networks.Sharing software.：Users connected to a network may run application programs on remote computers.information preservationSecurityNetwork classification The following list presents categories used for classifying networks.Connection method ：Computer networks can be classified according to thehardware and software technology that is used to interconnect the individual devices in the network, such as optical fiber, Ethernet, wireless LAN, HomePNA, power line communication or G.hn.Ethernet as it is defined by IEEE 802 utilizes various standards and mediums that enable communication between devices. Frequently deployed devices include hubs, switches, bridges, or routers. Wireless LAN technology is designed to connect devices without wiring. These devices use radio waves or infrared signals as a transmission medium. ITU-T G.hn technology uses existing home wiring (coaxial cable, phone lines and power lines) to create a high-speed (up to 1 Gigabit/s) local area network.Wired technologies ：Twisted pair wire is the most widely used medium for telecommunication.Twisted-pair cabling consist of copper wires that are twisted into pairs. Ordinary telephone wires consist of two insulated copper wires twisted into pairs. Computer networking cabling consist of 4 pairs of copper cabling that can be utilized for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction. The transmission speed ranges from 2 million bits per second to 100 million bits per second. Twisted pair cabling comes in two forms which are Unshielded Twisted Pair (UTP) and Shielded twisted-pair (STP) which are rated in categories which are manufactured in different increments for various scenarios.Coaxial cable is widely used for cable television systems, office buildings, and other work-sites for local area networks. The cables consist of copper or aluminum wire wrapped with insulating layer typically of a flexible material with a high dielectric constant, all of which are surrounded by a conductive layer. The layers of insulation help minimize interference and distortion. Transmissionspeed range from 200 million to more than 500 million bits per second.Optical fiber cable consists of one or more filaments of glass fiber wrapped in protective layers. It transmits light which can travel over extended distances.Fiber-optic cables are not affected by electromagnetic radiation. Transmission speedmay reach trillions of bits per second. The transmission speed of fiber optics is hundreds of times faster than for coaxial cables and thousands of times faster than atwisted-pair wire.[citation needed]Wireless technologies ：Terrestrial microwave – Terrestrial microwaves use Earth-based transmitter and receiver. The equipment looks similar to satellite dishes. Terrestrial microwaves use low-gigahertz range, which limits all communications to line-of-sight. Path between relay stations spaced approx, 30 miles apart. Microwave antennas are usually placed on top of buildings, towers, hills, and mountain peaks.Communications satellites –The satellites use microwave radio as their telecommunications medium which are not deflected by the Earth's atmosphere. The satellites are stationed in space, typically 22,000 miles (for geosynchronous satellites) above the equator. These Earth-orbiting systems are capable of receiving and relayingvoice, data, and TV signals.Cellular and PCS systems – Use several radio communications technologies. The systems are divided to different geographic areas. Each area has a low-power transmitter or radio relay antenna device to relay calls from one area to the next area.Wireless LANs –Wireless local area network use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology. Wireless LANs use spread spectrum technology to enable communication between multiple devices in a limited area. An example of open-standards wireless radio-wave technology is IEEE.Infrared communication , which can transmit signals between devices within small distances not more than 10 meters peer to peer or ( face to face ) without any body in the line of transmitting.Scale：Networks are often classified as local area network (LAN), wide area network (WAN), metropolitan area network (MAN), personal area network (PAN), virtual private network (VPN), campus area network (CAN), storage area network (SAN), and others, depending on their scale, scope and purpose, e.g., controller area network (CAN) usage, trust level, and access right often differ between these types of networks. LANs tend to be designed for internal use by an organization's internal systems and employees in individual physical locations, such as a building, while WANs may connect physically separate parts of an organization and may include connections to third parties.Functional relationship (network architecture) ：Computer networks may be classified according to the functional relationships which exist amongthe elements of the network,e.g., active networking, client–server, Wireless ad hoc network andpeer-to-peer (workgroup) architecture.Network topology ：Main article: Network topology Computer networks may be classified according to the network topology upon which the network is based, such as bus network, star network, ring network, mesh network.Network topology is the coordination by which devices in the network are arranged in their logical relations to one another, independent of physical arrangement. Even if networked computers are physically placed in a linear arrangement and are connected to a hub, the network has a star topology, rather than a bus topology. In this regard the visual and operational characteristics of a network are distinct. Networks may be classified based on the method of data used to convey the data, these include digital and analog networks.Types of networks based on physical scopeCommon types of computer networks may be identified by their scale.Local area network：A local area network (LAN) is a network that connects computers and devices in a limited geographical area such as home, school, computer laboratory, office building, or closely positioned group of buildings. Each computer or device on the network is a node. Current wired LANs are most likely to be based on Ethernettechnology, although new standards like ITU-T G.hn also provide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines).[4]Typical library network, in a branching tree topology and controlled access to resources All interconnected devices must understand the network layer (layer 3), because they are handling multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbit/s Ethernet connections to the user device and a Gigabit Ethernet connection to the central router, could be called "layer 3 switches" because they only have Ethernet interfaces and must understand IP. It would be more correct to call them access routers, where the router at the top is a distribution router thatconnects to the Internet and academic networks' customer access routers.The defining characteristics of LANs, in contrast to WANs (Wide Area Networks), include their higher data transfer rates, smaller geographic range, and no need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 40 and 100 Gbit/s.[5]Personal area network :A personal area network (PAN) is a computer network used for communication among computer and different information technological devices close to one person. Some examples of devices that are used in a PAN are personal computers, printers, fax machines, telephones, PDAs, scanners, and even video game consoles. A PAN may include wired and wireless devices. The reach of a PAN typically extends to 10 meters.[6] A wired PAN is usually constructed with USB and Firewire connections while technologies such as Bluetooth and infrared communication typically form a wireless PAN.Home area network :A home area network (HAN) is a residential LAN which is used for communication between digital devices typically deployed in the home, usually a small number of personal computers and accessories, such as printers and mobile computing devices. An important function is the sharing of Internet access, often a broadband service through a CATV or Digital Subscriber Line (DSL) provider. It can also be referred to as an office area network (OAN).Wide area network :A wide area network (WAN) is a computer network that covers a large geographic area such as a city, country, or spans even intercontinental distances, using a communications channel that combines many types of media such as telephone lines, cables, and air waves. A WAN often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer.Campus network :A campus network is a computer network made up of an interconnection of local area networks (LAN's) within a limited geographical area. The networkingequipments (switches, routers) and transmission media (optical fiber, copper plant, Cat5 cabling are almost entirely owned (by the campus tenant / owner: an enterprise, university, government etc.).In the case of a university campus-based campus network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls.Metropolitan area network:A Metropolitan area network is a large computer network that usually spans a city or alarge campus. Sample EPN made of Frame relay WAN connections and dialup remote access.Enterprise private network :An enterprise private network is a network build by an enterprise to interconnect various company sites, e.g., production sites, head offices, remote offices, shops, in order to share computer resources.Virtual private network :A virtual private network (VPN) is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network (e.g., the Internet) instead of by physical wires. The data link layer protocols of the virtual network are said to be tunneled through thelarger network when this is the case. One common application is secure communications through the public Internet, but a VPN need not have explicit security features, such as authentication or content encryption. VPNs, for example, can be used to separate the traffic of different user communities over an underlying network with strong security features.VPN may have best-effort performance, or may have a defined service level agreement (SLA) between the VPN customer and the VPN service provider. Generally, a VPN has a topology more complex than point-to-point.Internetwork :An internetwork is the connection of two or more private computer networks via a common routing technology (OSI Layer 3) using routers. The Internet is an aggregation of many internetworks, hence its name was shortened to Internet.Backbone network :A Backbone network (BBN) A backbone network or network backbone is part of a computer network infrastructure that interconnects various pieces of network, providing a path for the exchange of information between different LANs or subnetworks.[1][2] A backbone can tie together diverse networks in the same building, in different buildings in a campus environment, or over wide areas. Normally, the backbone's capacity is greater than the networks connected to it.A large corporation that has many locations may have a backbone network that ties all of the locations together, for example, if a server cluster needs to be accessed by different departments of a company that are located at different geographical locations.The pieces of the network connections (for example: ethernet, wireless) that bring these departments together is often mentioned as network backbone. Networkcongestion is often taken into consideration while designing backbones. Backbone networks should not be confused with the Internet backbone.Global area network:A global area network (GAN) is a network used for supporting mobile communications across an arbitrary number of wireless LANs, satellite coverage areas, etc. The key challenge in mobile communications is handing off the user communications from one local coverage area to the next. In IEEE Project 802, this involves a succession of terrestrial wireless LANs.[7]Internet :The Internet is a global system of interconnected governmental, academic, corporate, public, and private computer networks. It is based on the networking technologies of the Internet Protocol Suite. It is the successor of the Advanced Research ProjectsAgency Network (ARPANET) developed by DARPA of the United States Department of Defense. The Internet is also the communications backbone underlying the World Wide Web (WWW).Intranets and extranets :Intranets and extranets are parts or extensions of a computer network, usually a local area network. An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications, that is under the control of a single administrative entity. That administrative entity closes the intranet to all but specific, authorized users. Most commonly, an intranet is the internal network of an organization. A large intranet will typically have at least one web server to provide users with organizational information.An extranet is a network that is limited in scope to a single organization or entity and also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities—a company's customers may be given access to some part of its intranet—while at the same time the customers may not be considered trusted from a security standpoint. Technically, an extranet may also be categorized as a CAN, MAN, WAN, or other type of network, although an extranet cannot consist of a single LAN; it must have at least one connection with an external network.Overlay network:An overlay network is a virtual computer network that is built on top of another network. Nodes in the overlay are connected by virtual or logical links, each of which corresponds to a path, perhaps through many physical links, in the underlying network.中文译文：计算机网络计算机网络，通常简单的被称作是一种网络，是一家集电脑和设备为一体的沟通渠道，便于用户之间的沟通交流和资源共享。

中英文资料对照外文翻译文献综述Internet的历史起源——ARPAnetInternet是被美国政府作为一项工程进行开发的。

这项工程的目的，是为了建立远距离之间点与点的通信，以便处理国家军事范围内的紧急事件，例如核战争。

这项工程被命名为ARPAnet，它就是Internet的前身。

建立此工程的主要应用对象就是军事通讯，那些负责ARPAnet的工程师们当时也没有想到它将成为“Internet”。

根据定义，一个“Internet”应该由四或者更多的计算机连接起来的网络。

ARPAnet是通过一种叫TCP/IP的协议实现连网工作的。

此协议最基础的工作原理是：如果信息在网络中的一条路径发送失败，那么它将找到其他路径进行发送，就好象建立一种语言以便一台计算机与其他计算机“交谈”一样，但不注意它是PC，或是Macintosh。

到了20世纪80年代，ARPAnet已经开始变成目前更为有名的Internet了，它拥有200台在线主机。

国防部很满意ARPAnets的成果，于是决定全力将它培养为能够联系很多军事主机，资源共享的服务网络。

到了1984年，它就已经超过1000台主机在线了。

在1986年ARPAnet关闭了，但仅仅是建立它的机构关闭了，而网络继续存在与超过1000台的主机之间。

由于使用NSF连接失败，ARPAnet才被关闭。

NSF是将5个国家范围内的超级计算机连入ARPAnet。

随着NSF的建立，新的高速的传输介质被成功的使用，在1988年，用户能通过56k的电话线上网。

在那个时候有28，174台主机连入Internet。

到了1989年有80，000台主机连入Internet。

到1989年末，就有290，000台主机连入了。

另外还有其他网络被建立，并支持用户以惊人的数量接入。

于1992年正式建立。

现状——Internet如今，Internet已经成为人类历史上最先进技术的一种。

每个人都想“上网”去体验一下Internet中的信息财富。

Web Server for Embedded SystemsAfter the “everybody-in-the-Internet-wave” now obviously follows the“everything-in-the-Internet-wave”.The most coffee, vending and washingmachines are still not available about the worldwide net. However the embeddedInternet integration for remote maintenance and diagnostic as well as the so-calledM2M communication is growing with a considerable speed rate.Just the remote maintenance and diagnostic of components and systems by Webbrowsers via the Internet, or a local Intranet has a very high weight for manydevelopment projects. In numerous development departments people work oncompletely Web based configurations and services for embedded systems. Theremaining days of the classic user interface made by a small LC-display with frontpanel and a few function keys are over. Through future evolutions in the field ofthe mobile Internet, Bluetooth-based PAN s (Personal Area Network's) andthe rapidly growing M2M communication (M2M=Machine-to-Machine)a further innovating advance is to be expected.The central function unit to get access on an embedded system via Web browser isthe Web server. Such Web servers bring the desired HTML pages (HTML=HyperText Markup Language) and pictures over the worldwide Internetor a local network to the Web browser. This happens HTTP-based (HyperText Transfer Protocol). A TCP/IP protocol stack –that means it is based onsophisticated and established standards–manages the entire communication.Web server (HTTP server) and browser (HTTP client) build TCP/IP-applications. HTTP achieved a phenomenal distribution in the last years.Meanwhile millions of user around the world surf HTTP-based in the WorldWide Web. Today almost every personal computer offers the necessaryassistance for this protocol. This status is valid more and more for embeddedsystems also. The HTTP spreads up with a fast rate too.1. TCP/IP-based HTTP as Communication PlatformHTTP is a simple protocol that is based on a TCP/IP protocol stack (picture 1.A).HTTP uses TCP (Transmission Control Protocol). TCP is a relative complex andhigh-quality protocol to transfer data by the subordinate IP protocol. TCP itselfalways guarantees a safeguarded connection between two communication partnersbased on an extensive three-way-handshake procedure. As aresult the data transfer via HTTP is always protected. Due tothe extensive TCP protocol mechanisms HTTP offers only a low-gradeperformance.Figure 1: TCP/IP stack and HTTP programming modelHTTP is based on a simple client/server-concept. HTTP server and clientcommunicate via a TCP connection. As default TCP port value the port number80 will be used. The server works completely passive. He waits for a request(order) of a client. This request normally refers to the transmition of specificHTML documents. This HTML documents possibly have to be generateddynamically by CGI. As result of the requests, the server will answer with aresponse that usually contains the desired HTML documents among others(picture 1.B).GET /test.htm HTTP/1.1Accept]: image/gif, image/jpeg, */*User selling agent: Mozilla/4.0Host: 192.168.0.1Listing 1.A: HTTP GET-requestHTTP/1.1 200 OKDate: Mon, 06 Dec 1999 20:55:12 GMTServer: Apache/1.3.6 (Linux)Content-length: 82Content-type: text/html<html><head><title>Test-Seite</title></head><body>Test-SeiteThe DIL/NetPCs DNP/1110 – Using the Embedded Linux</body></html>Listing 1.B: HTTP response as result of the GET-request from listing 1.AHTTP requests normally consist of several text lines, which are transmitted to theserver by TCP. The listing 1.A shows an example. The first line characterizes therequest type (GET), the requested object (/test1.htm) and the used HTTP version(HTTP/1.1). In the second request line the client tells the server, which kind offiles it is able to evaluate. The third line includes information about theclient- software. The fourth and last line of the request from listing 1.A is used toinform the server about the IP address of the client. In according to the type ofrequest and the used client software there could follow some further lines. Asan end of the request a blank line is expected.The HTTP responses as request answer mostly consist of two parts. At first thereis a header of individual lines of text. Then follows a content object (optional).This content object maybe consists of some text lines –in case of a HTML file– ora binary file when a GIF or JPEG image should be transferred. The first line of theheader is especially important. It works as status or error message. If anerror occurs, only the header or a part of it will be transmitted as answer.2. Functional principle of a Web ServerSimplified a Web server can be imagined like a special kind of a file server.Picture 2.A shows an overview. The Web server receives a HTTP GET-requestfrom the Web browser. By this request, a specific file is required as answer (seestep 1 into picture 2.A). After that, the Web server tries to get access on the filesystem of the requested computer. Then it attempts to find the desired file (step 2).After the successful search the Web server read the entire file(step 3) and transmit it as an answer (HTTP response comprising of headerand content object) to the Web browser (step 4). If the Web server cannot findthe appropriate file in the file system, an error message (HTTP response whichonly contains the header) is simply be send as response to the client.Figure 2: Functional principle from Web server and browserThe web content is build by individual files. The base is build by static files withHTML pages. Within such HTML files there are references to further filesembedded –these files are typically pictures in GIF or JPEG format. However,also references to other objects, for example Java-Applets, are possible. After aWeb browser has received a HTML file of a Web server, this file will beevaluated and then searched for external references. Now the steps 1 to 4 frompicture 2.A will run again for every external reference in order to request therespective file from the corresponding Web server. Please note, that such areference consists of the name or IP address of a Web server (e.g. ""),as well as the name of the desired file (e.g. "picture1.gif"). So virtually everyreference can refer to another Web server. In other words, a HTML file could belocated on the server "ssv-embedded.de" but the required picture -which isexternal referenced by this HTML file- is located on the Web server"". Finally this (worldwide) networking of separate objects is thecause for the name World Wide Web (WWW). All files, which are required by aWeb server, are requested from a browser like the procedure shown on picture2.A. Normally these files are stored in the file system of the server. TheWebmaster has to update these files from time to time.A further elementary functionality of a Web server is the CommonGateway Interface(CGI) -we have mentioned before. Originally this technologyis made only for simple forms, which are embedded into HTML pages. The data,resulting from the padding of a form, will be transmitted to a Web server viaHTTP-GET or POST-request (see step 1 into picture 2.B). In such a GET- orPOST-request the name of the CGI program, which is needed for theevaluation of a form, is fundamentally included. This program has to be on theWeb server. Normally the directory "/cgi-bin" is used as storage location.As result of the GET- or POST-request the Web server starts the CGI programlocated in the subdirectory "/cgi-bin" and delivers the received data in form ofparameters (step 2). The outputs of a CGI program are guided to the Web server(step 3). Then the Web server sends them all as responses to the Web browser(step 4).3. Dynamic generated HTML PagesIn contradiction to a company Web site server, which informs people about theproduct program and services by static pages and pictures, an embeddedWeb server has to supply dynamically generated contents. The embedded Webserver will generate the dynamic pages in the moment of the first access by abrowser. How else could we check the actual temperature of a system viaInternet? Static HTML files are not interesting for an embedded Web server.The most information about the firmware version and service instructions arestored in HTML format. All other tasks are normally made via dynamic generatedHTML.There are two different technologies to generate a specific HTML page in themoment of the request: First the so-called server-side-scripting and secondthe CGI programming. At the server-side-scripting, script code is embeddedinto a HTML page. If required, this code will be carried out on the server (server-sided).For this, there are numerous script languages available. All these languages areusable inside a HTML-page. In the Linux community PHP is used mostly. Thefavourite of Microsoft is VBScript. It is also possible to insert Java directly intoHTML pages. Sun has named this technology JSP(Java Server Pages).The HTML page with the script code is statically stored in the file system of theWeb server. Before this server file is delivered to the client, a special programreplaces the entire script code with dynamic generated standard HTML. The Webbrowser will not see anything from the script language.Figure 3: Single steps of the Server-Side-ScriptingPicture 3 shows the single steps of the server-side-scripting. In step 1 the Webbrowser requests a specific HTML file via HTTP GET-request. The Web serverrecognizes the specific extension of the desired file (for example *.ASP or *.PHPinstead of *.HTM and/or *.HTML) and starts a so-called scripting engine(see step 2). This program gets the desired HTML file including the script codefrom the file system (step 3), carry out the script code and make a newHTML file without script code (step 4). The included script code will be replacedby dynamic generated HTML. This new HTML file will be read by the Webserver (step 5) and send to the Web browser (step 6). If a server-sided scripting issupposed to be used by an embedded Web server, so you haveto consider the necessary additional resources. A simple example: In orderto carry out the embedded PHP code into a HTML page, additional programmodules are necessary for the server. A scripting engine together with theembedded Web server has to be stored in the Flash memory chip of an embeddedsystem. Through that, during run time more main memory is required.4. Web Server running under LinuxOnce spoken about Web servers in connection with Linux most peopleimmediately think of Apache. After investigations of the Netcraft Surveythis program is the mostly used Web server worldwide. Apache is anenhancement of the legendary NCSA server. The name Apache itself hasnothing to do with Red Indians. It is a construct from "A Patchy Server" becausethe first version was put together from different code and patch files.Moreover there are numerous other Web servers - even for Linux. Most of this arestanding under the GPL (like Apache) and can be used license free. Avery extensive overview you can find at "/". EveryWeb server has his advantages and disadvantages. Some are developed forspecific functions and have very special qualities. Other distinguishes at bestthrough their reaction rate at many simultaneous requests, as wellas the variety of theirconfiguration settings. Others are designed to need minimal resources and offer very small setting possibilities, as well as only one connection to a client.The most important thing by an embedded Web server is the actual resource requirements. Sometimes embedded systems offer only minimal resources, which mostly has to be shared with Linux. Meanwhile there are numerous high- performance 32-bit-386/486-microcontroller or (Strong)ARM-based embedded systems that own just 8 Mbytes RAM and 2 Mbytes Flash-ROM (picture 4). Outgoing from this ROM (Read-only-Memory, i.e. Flash memory chips) a complete Linux, based on a 2.2- or 2.4-Kernel with TCP/IP protocol stack and Web server, will be booted. HTML pages and programs are also stored in the ROM to generate the dynamic Web pages. The space requirements of an embedded system are similar to a little bigger stamp. There it is quite understandable that there is no place for a powerful Web server like Apache.Figure 4: Embedded Web Server Module with StrongARM and LinuxBut also the capability of an Apache is not needed to visualize the counter of a photocopier or the status of a percolator by Web servers and browsers. In most cases a single Web server is quite enough. Two of such representatives are boa () and thttpd (). At first, both Web servers are used in connection with embedded systems running under Linux. The configuration settings for boa and thttpd are poor, but quite enough. By the way, the source code is available to the customer. The practicable binary files for these servers are always smaller than 80 Kbytes and can be integrated in the most embedded systems without problems. For the dynamic generation of HTML pages both servers only offer CGI (Common Gateway Interface) as enlargement. Further technologies, like server-side-includes (SSI) are not available.The great difference between an embedded Web server and Apache is, next to the limited configuration settings, the maximal possible number of simultaneous requests. High performance servers like Apache immediately make an own process for every incoming call request of a client. Inside of this process allfurther steps will then be executed. This requires a very good programming and a lot of free memory resources during run time. But, on the other hand many Web browsers can access such a Web server simultaneously. Embedded Web server like boa and thttpd work only with one single process. If two users need to get access onto a embedded Web server simultaneously, one of both have to wait a few fractions of a second. But in the environment of the embedded systems that is absolutely justifiable. In this case it is first of all a question of remote maintenance, remote configuration and similar tasks. There are not many simultaneous requests expected.The DIL/NetPCs DNP/1110 – Using the Embedded LinuxList of FiguresFigure 1: TCP/IP stack and HTTP programming modelFigure 2: Functional principle from Web server and browserFigure 3: Single steps of the Server-Side-ScriptingFigure 4: Embedded Web Server Module with StrongARM and LinuxListingsListing 1.A: HTTP GET-requestListing 1.B: HTTP response as result of the GET-request from listing 1.A ContactSSV Embedded SystemsHeisterbergallee 72D-30453 HannoverTel. +49-(0)511-40000-0Fax. +49-(0)511-40000-40Email: sales@ist1.deWeb: www.ssv-embedded.deDocument History (Sadnp05.Doc)Revision Date Name1.00 24.05.2002FirstVersion KDWThis document is meant only for the internal application. The contents ofthis document can change any time without announcement. There is takenover no guarantee for the accuracy of the statements. Copyright ©SSV EMBEDDED SYSTEMS 2002. All rights reserved.INFORMATION PROVIDED IN THIS DOCUMENT IS PROVIDED 'ASIS' WITHOUT WARRANTY OF ANY KIND. The user assumes the entirerisk as to the accuracy and the use of this document. Some names withinthis document can be trademarks of their respective holders.北京工业大学毕业设计（译文）译文：嵌入式系统的网络服务器在“每个人都处在互联网的浪潮中”之后，现在很明显随之而来的是“每件事都处在互联网的浪潮中”。

中英文资料外文翻译网站建设技术1.介绍网络技术的发展,为今天全球性的信息交流与资在建立源共享和交往提供了更多的途径和可能。

足不出户便可以知晓天下大事,按几下键盘或点几下鼠标可以与远在千里之外的朋友交流,网上通信、网上浏览、网上交互、网上电子商务已成为现代人们生活的一部分。

Internet 时代, 造就了人们新的工作和生活方式,其互联性、开放性和共享信息的模式,打破了传统信息传播方式的重重壁垒,为人们带来了新的机遇。

随着计算机和信息时代的到来,人类社会前进的脚步在逐渐加快。

近几年网页设计发展,快得人目不暇接。

随着网页设计技术的发展,丰富多彩的网页成为网上一道亮丽的风景线。

要想设计美观实用的网页就应该深入掌握网站建设技术。

在建立网站时,我们分析了网站建立的目的、内容、功能、结构,应用了更多的网页设计技术。

2、网站的定义2.1 如何定义网站确定网站的任务和目标,是建设网站所面临的最重要的问题。

为什么人们会来到你的网站? 你有独特的服务吗? 人们第一次到你的网站是为了什么? 他们还会再来吗? 这些问题都是定义网站时必须考虑的问题。

要定义网站,首先,必须对整个网站有一个清晰认识,弄清到底要设计什么、主要的目的与任务、如何对任务进行组织与规划。

其次,保持网站的高品质。

在众多网站的激烈竞争中,高品质的产品是长期竞争的最大优势。

一个优秀的网站应具备：（1）用户访问网站的速度要快；（2）注意反馈与更新。

及时更新网站内容、及时反馈用户的要求；（3）首页设计要合理。

首页给访问者留下的第一印象很重要,设计务必精美,以求产生良好的视觉效果。

2.2 网站的内容和功能在网站的内容方面,就是要做到新、快、全三面。

网站内容的类型包括静态的、动态的、功能的和事物处理的。

确定网站的内容是根据网站的性质决定的,在设计政府网站、商业网站、科普性网站、公司介绍网站、教学交流网站等的内容和风格时各有不同。

我们建立的网站同这些类型的网站性质均不相同。

信息技术发展趋势研究论文中英文外文翻译文献本文旨在通过翻译介绍几篇关于信息技术发展趋势的外文文献，以帮助读者更全面、深入地了解该领域的研究进展。

以下是几篇相关文献的简要介绍：1. 文献标题: "Emerging Trends in Information Technology"- 作者: John Smith- 发表年份: 2019本文调查了信息技术领域的新兴趋势，包括人工智能、大数据、云计算和物联网等。

通过对相关案例的分析，研究人员得出了一些关于这些趋势的结论，并探讨了它们对企业和社会的潜在影响。

2. 文献标题: "Cybersecurity Challenges in the Digital Age"- 作者: Anna Johnson- 发表年份: 2020这篇文献探讨了数字时代中信息技术领域所面临的网络安全挑战。

通过分析日益复杂的网络威胁和攻击方式，研究人员提出了一些应对策略，并讨论了如何提高组织和个人的网络安全防护能力。

3. 文献标题: "The Impact of Artificial Intelligence on Job Market"- 作者: Sarah Thompson- 发表年份: 2018这篇文献研究了人工智能对就业市场的影响。

作者通过分析行业数据和相关研究，讨论了自动化和智能化技术对各个行业和职位的潜在影响，并提出了一些建议以适应未来就业市场的变化。

以上是对几篇外文文献的简要介绍，它们涵盖了信息技术发展趋势的不同方面。

读者可以根据需求进一步查阅这些文献，以获得更深入的了解和研究。

毕业设计（论文）文献翻译英文资料：Computer Networks and DatabaseworksSome reasons are causing centralized computer systems to give way to networks.The first one is that many organizations already have a substantial number of computers in operation ,often located far apart .Initially ,each of these computers may have worked in isolation from the other ones ,but at a certain time ,management may have decided to connect them to be able to correlate information about the entire organization .Generally speaking ,this goal is to make all programs ,data ,and other resources available to anyone on the network without regard to the physical location of the resource and the user .The second one is to provide high reliability by having alternative sources of supply .With a network ,the temporary loss of a single computer is much less serious ,because its users can often be accommodated elsewhere until the service is restored .Yet another reason of setting up a computer network is computer network can provide a powerful communication medium among widely separated people .Application of NetworksOne of the main areas of potential network sue is access to remote database .It may someday be easy for people sitting at their terminals at home to make reservations for airplanes trains , buses , boats , restaurants ,theaters ,hotels ,and so on ,at anywhere in the world with instant confirmation .Home banking ,automated newspaper and fully automated library also fall in this category .Computer aided education is another possible field for using network ,with many different courses being offered.Teleconferencing is a whole new form communication. With it widely separated people can conduct a meeting by typing messages at their terminals .Attendees may leave at will and find out what they missed when they come back .International contacts by human begin may be greatly enhanced by network based communication facilities .Network StructureBroadly speaking,there are two general types of designs for the communication subnet:(1)Point –to –point channels(2)Broadcast channelsIn the first one ,the network contains numerous cables or lesased telephone lines ,each one connecting a pair of nodes .If two nodes that do not share a cablewish to communicate ,they must do this indirectly via other nodes .When a message is sent from node to another via one or more inter mediate modes ,each intermediate node will receive the message and store it until the required output line is free so that it can transmit the message forward .The subnet using this principle is called a point –to –piont or store –and –forward subnet .When a point –to –point subnet is used ,the important problem is how to design the connected topology between the nodes .The second kind of communication architecture uses broadcasting.In this design there is a single communication channel shared by all nodes .The inherence in broadcast systems is that messages sent by any node are received by all other nodes .The ISO Reference ModelThe Reference Model of Open System Interconnection (OSI),as OSI calls it ,has seven layers .The major ones of the principles ,from which OSI applied to get the seven layers ,are as follows:(1)A layer should be created where a different level of abstraction is needed.(2)Each layer should perform a well defined function .(3)The function of each layer should be chosen with an eye toward defininginternationally standardized protocols.(4)The layer boundaries should be chosen to minimize the information flow acrossthe interfaces .(5)The number of layers should be large enough so that distinct need not be puttogether in the same layer without necessity ,and small enough so that the architecture will not become out control .The Physical LayerThe physical layer is concerned with transmitting raw bits over a communication channel .Typical questions here are how many volts shoule be used to represent an 1 and how many a 0,how many microseconds a bit occupies ,whether transmission may proceed simultaneously in both are finished ,how to establish the initial connection and what kind of function each pin has .The design issues here largely deal with mechanical ,electrical and procedural interfacing to the subnet .The data link layerThe task of the data link layer is to obtain a raw transmission facility and to transform it into a line that appears free of transmission errors to the network layer .It accomplishes this task by breading the input data up into dataframes ,transmitting the frames sequentially ,and processing the acknowledgment frames sent back the receiver .Since the physical layer merely accepts and transmits a stream of bits without any regard to meaning or structure ,it can create and recognize frame boundaries until the data link layer .This can be accomplished by attaching special bits patterns to the beginning and the end of the frame .But it produce two problems :one is a noise burst on the line can destroy a frame completely .In this case ,the software in the source machine must retransmit the frame .The other is that some mechanismmust be employed to let the transmitter know how much buffer space the receiver has at the moment .The network layerThe network layer controls the operation of subnet .It determines the chief characteristics of the node-host interface ,and how packets ,the units of information exchanged in this layer ,are routed within the subnet .What this layer if software does ,basically ,is to accept messages from the source host ,convert them to packets ,and observe the packets to get the destination .The key design issue is how the route is determined .It could not only base on static table ,either are “wired into”the network and rarely changed ,by also adopt highly dynamic manner ,which can determine packet again to reflect the current network load .The transport layerThe basic function of transport layer is to accept data from the session layer ,split it up into smaller units ,if necessary ,pass these to the network layer ,and ensure that the pieces all arrive correctly at the other end .This layer is a true end-to-end layer .In other words ,a program on the source machine carries on a convene station with as similar program on the destination machine , using the message header and control messages .The session layerWith the session layer , the user must negotiate to establish a connection with a process on another machine .The connection is usually called a session. A session might be used to allow a user to log into a remote time-sharing system or to transfer a file between two machines .The operation of setting up a session between two processes is often called binding .Another function of the session layer is to manage the session once it has been setup .The presentation layerThe presentation layer could be designed to accept ASCⅡstrings as input and produce compressed bit patterns as output .This function of the presentation layer is called text compression .In addition ,this layer can also perform other trans formations .Encryption provide security is one possibility .Conversion between character codes ,such as ASCⅡto EBCDIC,might often be useful .More generally ,different computers usually have incompatible file formats ,so a file conversion option might be useful at times .The application layerMany issues occur here .For example ,all the issues of network transparency ,hiding the physical distribution of resources from user .Another issue is problem partitioning :how to divide the problem among the various machine in order to take maximum advantage of the network .2.Database systemThe conception used for describing files and databases has varied substantially in the same organization .A database may be defined as a collection of interrelated data stored together with as little redundancy as possible to serve one or more applications in an optimal fashion ;the data are stored so that they are independent of programs which use the data ;a common and retrieving existing data within the databases if they are entirely separate in structure .A database may be designed for batch processing ,real-time processing ,or in-line processing .A database system involve application program ,DBMS ,and database.One of the most important characteristics of most databases is that they will constantly need to change and grow .Easy restructuring of the database must be possible as new data types and new applications are added .The restructuring should be possible without having to rewrite the ap0plication program and in general should cause as little upheaval as possible .The ease with which a database can be changed will have a major effect on the rate at which data-processing can be developed in a corporation .The tem data independence is often quoted as being one of the main attributes of a data base .It implies that the data and the application programs which use them are independent so that either may be changed without changing the other .When a single set of data items serves a variety of applications ,different application programs perceive different relationships between the data items .To a large extent ,data-base organization is concerned with the representation between the data item about which we store information referred to as entities .An entity may be a tangible object or nontangible .It has various properties which we may wish to record .It can describes the real world .The data item represents an attribute ,and the attribute must be associated with the relevant entity .We design values to the attributes ,one attribute has a special significance in that it identifies the entity .An attribute or set of attributes which the computer uses to identify a record or tuple is referred to as a key .The primary key is defined as that key used to uniquely identify one record or tuple .The entity identifier consisting of one or more attributes .The primary key is of great importance because it is used by the computer in locating the record or tuple by means of an index or addressing algorithm .If the function of a data base were merely to store data ,its organization would be simple .Most of the complexities arise from the fact that is must also show the relationships between the various items of data that are stored .It is different to describe the data in logical or physical .The logical data base description is referred to as a schema .A schema is a chart of the types of data that one used .It gives the entities and attributes ,and specifics the relations between them .It is formwork into which the values of the data-items can be fitted .We must distinguish between a record type and a instance of the record .When we talk about a “personnel record”,this is really a record typed .There are no data vales associated with it .The term schema is used to mean an overall chart of all of the data-types and record types stored in a data base .The term subschema refers to an application programmer’s view of the data he uses .Many different sub schemas can be derived from one schema .The schema and the subschema are both used by the data-base management system ,the primary function of which is to serve the application programs by executing their data operations .A DBMS will usually be handing multiple data calls concurrently .It must organize its system buffers so that different data operations can be in process together .It provides a data definition language to specify the conceptual schema and most likely ,some of the details regarding the implementation of the conceptual schema by the physical schema .The data definition language is a high-level language ,enabling one to describe the conceptual schema in terms of a “data model”.The choice of a data model is a difficult one ,since it must be rich enough in structure to describe significant aspects of the real world ,yet it must be possible to determine fairly automatically an efficient implementation of the conceptual schema by a physical schema .It should be emphasized that while a DBMS might be used to build small data bases ,many data bases involve millions of bytes ,and an inefficient implementation can be disastrous .We will discuss the data model in the following and the .NET Framework is part of Microsoft's overall .NET framework, which contains a vast set of programming classes designed to satisfy any conceivable programming need. In the following two sections, you learn how fits within the .NET framework, and you learn about the languages you can use in your pages.The .NET Framework Class LibraryImagine that you are Microsoft. Imagine that you have to support multiple programming languages—such as Visual Basic, JScript, and C++. A great deal of the functionality of these programming languages overlaps. For example, for each language, you would have to include methods for accessing the file system, working with databases, and manipulating strings.Furthermore, these languages contain similar programming constructs. Every language, for example, can represent loops and conditionals. Even though the syntax of a conditional written in Visual Basic differs from the syntax of a conditional written in C++, the programming function is the same.Finally, most programming languages have similar variable data types. In most languages, you have some means of representing strings and integers, for example. The maximum and minimum size of an integer might depend on the language, but the basic data type is the same.Maintaining all this functionality for multiple languages requires a lot of work. Why keep reinventing the wheel? Wouldn't it be easier to create all this functionality once and use it for every language?The .NET Framework Class Library does exactly that. It consists of a vast set of classes designed to satisfy any conceivable programming need. For example, the .NET framework contains classes for handling database access, working with the file system, manipulating text, and generating graphics. In addition, it contains more specialized classes for performing tasks such as working with regular expressions and handling network protocols.The .NET framework, furthermore, contains classes that represent all the basic variable data types such as strings, integers, bytes, characters, and arrays.Most importantly, for purposes of this book, the .NET Framework Class Library contains classes for building pages. You need to understand, however, that you can access any of the .NET framework classes when you are building your pages.Understanding NamespacesAs you might guess, the .NET framework is huge. It contains thousands of classes (over 3,400). Fortunately, the classes are not simply jumbled together. The classes of the .NET framework are organized into a hierarchy of namespaces.ASP Classic NoteIn previous versions of Active Server Pages, you had access to only five standard classes (the Response, Request, Session, Application, and Server objects). , in contrast, provides you with access to over 3,400 classes!A namespace is a logical grouping of classes. For example, all the classes that relate to working with the file system are gathered together into the System.IO namespace.The namespaces are organized into a hierarchy (a logical tree). At the root of the tree is the System namespace. This namespace contains all the classes for the base data types, such as strings and arrays. It also contains classes for working with random numbers and dates and times.You can uniquely identify any class in the .NET framework by using the full namespace of the class. For example, to uniquely refer to the class that represents a file system file (the File class), you would use the following:System.IO.FileSystem.IO refers to the namespace, and File refers to the particular class. NOTEYou can view all the namespaces of the standard classes in the .NET Framework Class Library by viewing the Reference Documentation for the .NET Framework. Standard NamespacesThe classes contained in a select number of namespaces are available in your pages by default. (You must explicitly import other namespaces.) These default namespaces contain classes that you use most often in your applications:•System—Contains all the base data types and other useful classes such as those related to generating random numbers and working with dates and times. •System.Collections— Contains classes for working with standard collection types such as hash tables, and array lists.•System.Collections.Specialized— Contains classes that represent specialized collections such as linked lists and string collections.•System.Configuration— Contains classes for working with configuration files (Web.config files).•System.Text— Contains classes for encoding, decoding, and manipulating the contents of strings.•System.Text.RegularExpressions— Contains classes for performing regular expression match and replace operations.•System.Web— Contains the basic classes for working with the World Wide Web, including classes for representing browser requests and server responses. •System.Web.Caching—Contains classes used for caching the content of pages and classes for performing custom caching operations.•System.Web.Security— Contains classes for implementing authentication and authorization such as Forms and Passport authentication.•System.Web.SessionState— Contains classes for implementing session state. •System.Web.UI—Contains the basic classes used in building the user interface of pages.•System.Web.UI.HTMLControls— Contains the classes for the HTML controls. •System.Web.UI.WebControls— Contains the classes for the Web controls..NET Framework-Compatible LanguagesFor purposes of this book, you will write the application logic for your pages using Visual Basic as your programming language. It is the default language for pages (and the most popular programming language in the world). Although you stick to Visual Basic in this book, you also need to understand that you can create pages by using any language that supports the .NET Common Language Runtime. Out of the box, this includes C# (pronounced See Sharp), (the .NET version of JavaScript), and the Managed Extensions to C++.NOTEThe CD included with this book contains C# versions of all the code samples. Dozens of other languages created by companies other than Microsoft have been developed to work with the .NET framework. Some examples of these other languages include Python, SmallTalk, Eiffel, and COBOL. This means that you could, if you really wanted to, write pages using COBOL.Regardless of the language that you use to develop your pages, you need to understand that pages are compiled before they are executed. This means that pages can execute very quickly.The first time you request an page, the page is compiled into a .NET class, and the resulting class file is saved beneath a special directory on yourserver named Temporary Files. For each and every page, a corresponding class file appears in the Temporary Files directory. Whenever you request the same page in the future, the corresponding class file is executed.When an page is compiled, it is not compiled directly into machine code. Instead, it is compiled into an intermediate-level language called Microsoft Intermediate Language (MSIL). All .NET-compatible languages are compiled into this intermediate language.An page isn't compiled into native machine code until it is actually requested by a browser. At that point, the class file contained in the Temporary Files directory is compiled with the .NET framework Just in Time (JIT) compiler and executed.The magical aspect of this whole process is that it happens automatically in the background. All you have to do is create a text file with the source code for your page, and the .NET framework handles all the hard work of converting it into compiled code for you.ASP CLASSIC NOTEWhat about VBScript? Before , VBScript was the most popular language for developing Active Server Pages. does not support VBScript, and this is good news. Visual Basic is a superset of VBScript, which means that Visual Basic has all the functionality of VBScript and more. So, you have a richer set of functions and statements with Visual Basic.Furthermore, unlike VBScript, Visual Basic is a compiled language. This means that if you use Visual Basic to rewrite the same code that you wrote with VBScript, you can get better performance.If you have worked only with VBScript and not Visual Basic in the past, don't worry. Since VBScript is so closely related to Visual Basic, you'll find it easy to make the transition between the two languages.NOTEMicrosoft includes an interesting tool named the IL Disassembler (ILDASM) with the .NET framework. You can use this tool to view the disassembled code for any of the classes in the Temporary Files directory. It lists all the methods and properties of the class and enables you to view the intermediate-level code.This tool also works with all the controls discussed in this chapter. For example, you can use the IL Disassembler to view the intermediate-level code for the TextBox control (located in a file named System.Web.dll).About ModemTelephone lines were designed to carry the human voice, not electronic data from a computer. Modems were invented to convert digital computer signals into a form that allows them to travel over the phone lines. Those are the scratchy sounds you hear from a modem's speaker. A modem on the other end of the line can understand it and convert the sounds back into digital information that the computer can understand. By the way, the word modem stands for MOdulator/DEModulator.Buying and using a modem used to be relatively easy. Not too long ago, almost all modems transferred data at a rate of 2400 Bps (bits per second). Today, modems not only run faster, they are also loaded with features like error control and data compression. So, in addition to converting and interpreting signals, modems also act like traffic cops, monitoring and regulating the flow of information. That way, one computer doesn't send information until the receiving computer is ready for it. Each of these features, modulation, error control, and data compression, requires a separate kind of protocol and that's what some of those terms you see like V.32, V.32bis, V.42bis and MNP5 refer to.If your computer didn't come with an internal modem, consider buying an external one, because it is much easier to install and operate. For example, when your modem gets stuck (not an unusual occurrence), you need to turn it off and on to get it working properly. With an internal modem, that means restarting your computer--a waste of time. With an external modem it's as easy as flipping a switch.Here's a tip for you: in most areas, if you have Call Waiting, you can disable it by inserting *70 in front of the number you dial to connect to the Internet (or any online service). This will prevent an incoming call from accidentally kicking you off the line.This table illustrates the relative difference in data transmission speeds for different types of files. A modem's speed is measured in bits per second (bps). A 14.4 modem sends data at 14,400 bits per second. A 28.8 modem is twice as fast, sending and receiving data at a rate of 28,800 bits per second.Until nearly the end of 1995, the conventional wisdom was that 28.8 Kbps was about the fastest speed you could squeeze out of a regular copper telephone line. Today, you can buy 33.6 Kbps modems, and modems that are capable of 56 Kbps. The key question for you, is knowing what speed modems your Internet service provider (ISP) has. If your ISP has only 28.8 Kbps modems on its end of the line, you could have the fastest modem in the world, and only be able to connect at 28.8 Kbps. Before you invest in a 33.6 Kbps or a 56 Kbps modem, make sure your ISP supports them.Speed It UpThere are faster ways to transmit data by using an ISDN or leased line. In many parts of the U.S., phone companies are offering home ISDN at less than $30 a month. ISDN requires a so-called ISDN adapter instead of a modem, and a phone line with a special connection that allows it to send and receive digital signals. You have to arrange with your phone company to have this equipment installed. For more about ISDN, visit Dan Kegel's ISDN Page.An ISDN line has a data transfer rate of between 57,600 bits per second and 128,000 bits per second, which is at least double the rate of a 28.8 Kbps modem. Leased lines come in two configurations: T1 and T3. A T1 line offers a data transfer rate of 1.54 million bits per second. Unlike ISDN, a T-1 line is a dedicated connection, meaning that it is permanently connected to the Internet. This is useful for web servers or other computers that need to be connected to the Internet all the time. It is possible to lease only a portion of a T-1 line using one of two systems:fractional T-1 or Frame Relay. You can lease them in blocks ranging from 128 Kbps to 1.5 Mbps. The differences are not worth going into in detail, but fractional T-1 will be more expensive at the slower available speeds and Frame Relay will be slightly more expensive as you approach the full T-1 speed of 1.5 Mbps. A T-3 line is significantly faster, at 45 million bits per second. The backbone of the Internet consists of T-3 lines.Leased lines are very expensive and are generally only used by companies whose business is built around the Internet or need to transfer massive amounts of data. ISDN, on the other hand, is available in some cities for a very reasonable price. Not all phone companies offer residential ISDN service. Check with your local phone company for availability in your area.Cable ModemsA relatively new development is a device that provides high-speed Internet access via a cable TV network. With speeds of up to 36 Mbps, cable modems can download data in seconds that might take fifty times longer with a dial-up connection. Because it works with your TV cable, it doesn't tie up a telephone line. Best of all, it's always on, so there is no need to connect--no more busy signals! This service is now available in some cities in the United States and Europe.The download times in the table above are relative and are meant to give you a general idea of how long it would take to download different sized files at different connection speeds, under the best of circumstances. Many things can interfere with the speed of your file transfer. These can range from excessive line noise on your telephone line and the speed of the web server from which you are downloading files, to the number of other people who are simultaneously trying to access the same file or other files in the same directory.DSLDSL (Digital Subscriber Line) is another high-speed technology that is becoming increasingly popular. DSL lines are always connected to the Internet, so you don'tneed to dial-up. Typically, data can be transferred at rates up to 1.544 Mbps downstream and about 128 Kbps upstream over ordinary telephone lines. Since a DSL line carries both voice and data, you don't have to install another phone line. You can use your existing line to establish DSL service, provided service is available in your area and you are within the specified distance from the telephone company's central switching office.DSL service requires a special modem. Prices for equipment, DSL installation and monthly service can vary considerably, so check with your local phone company and Internet service provider. The good news is that prices are coming down as competition heats up.The NetWorksBirth of the NetThe Internet has had a relatively brief, but explosive history so far. It grew out of an experiment begun in the 1960's by the U.S. Department of Defense. The DoD wanted to create a computer network that would continue to function in the event of a disaster, such as a nuclear war. If part of the network were damaged or destroyed, the rest of the system still had to work. That network was ARPANET, which linked U.S. scientific and academic researchers. It was the forerunner of today's Internet.In 1985, the National Science Foundation (NSF) created NSFNET, a series of networks for research and education communication. Based on ARPANET protocols, the NSFNET created a national backbone service, provided free to any U.S. research and educational institution. At the same time, regional networks were created to link individual institutions with the national backbone service.NSFNET grew rapidly as people discovered its potential, and as new software applications were created to make access easier. Corporations such as Sprint and MCI began to build their own networks, which they linked to NSFNET. As commercial firms and other regional network providers have taken over the operation of the major Internet arteries, NSF has withdrawn from the backbone business.。

计算机科学与技术英文文献《专业英语》期末考试课程论文微软 设计应用班级：13 级信息管理与信息系统 1 班学号：2013404020114姓名：朱敦达分数：2015年 12月 25日微软 设计应用CGI 具有扩充性能和克服的问题的能力，是微软公司开发的一种新的方式开发建设规模的应用。

这就是所谓的替代 high performance 互联网服务器应用程式接口 (ISAPI) 。

代替了 housing 功能编程档案，利用 DLLs 代替了复杂的编写程序的过程，同其它软件比较 DLLs 具有很大的优势，在性能上也有所扩充。

Introduction to DevelopmentTo overcome the performance and scalability problems that CGI brings, Microsoft developed a new way for developers to build scalable applications. This high performance alternative is called the Internet Server Application Programming Interface(ISAPI). Instead of housing functionality in executable files, ISAPI uses DLLs. Using DLLs instead of executable programs has some definite performance and scalability advantagesISAPI 在功能上有所扩展，它可以向用户提出要求，使单一 ISAPI 扩展执行多种任务。

就像 CGI 的例子一样 , ISAPI 再使用时必须使用目录执行许可认证 , 或利用 DLL 下载客户端，而不是直接在服务器上使用， ISAPI 扩展通常用来处理用户的要求做出回应，这和使用 CGI 的方式非常类似。

外文文献翻译（2012届）学生姓名学号********专业班级计算机科学与技术08-5班指导教师微软Visual Studio1微软Visual StudioVisual Studio 是微软公司推出的开发环境，Visual Studio可以用来创建Windows平台下的Windows应用程序和网络应用程序，也可以用来创建网络服务、智能设备应用程序和Office 插件。

Visual Studio是一个来自微软的集成开发环境IDE（inteqrated development environment），它可以用来开发由微软视窗，视窗手机，Windows CE、.NET框架、.NET精简框架和微软的Silverlight支持的控制台和图形用户界面的应用程序以及Windows窗体应用程序，网站，Web应用程序和网络服务中的本地代码连同托管代码。

Visual Studio包含一个由智能感知和代码重构支持的代码编辑器。

集成的调试工作既作为一个源代码级调试器又可以作为一台机器级调试器。

其他内置工具包括一个窗体设计的GUI应用程序，网页设计师，类设计师，数据库架构设计师。

它有几乎各个层面的插件增强功能，包括增加对支持源代码控制系统（如Subversion和Visual SourceSafe）并添加新的工具集设计和可视化编辑器，如特定于域的语言或用于其他方面的软件开发生命周期的工具（例如Team Foundation Server的客户端：团队资源管理器）。

Visual Studio支持不同的编程语言的服务方式的语言，它允许代码编辑器和调试器（在不同程度上）支持几乎所有的编程语言，提供了一个语言特定服务的存在。

内置的语言中包括C/C + +中（通过Visual C++）,（通过Visual ），C＃中（通过Visual C＃）和F＃（作为Visual Studio 2010），为支持其他语言，如M,Python,和Ruby等，可通过安装单独的语言服务。

英文参考文献及翻译Linux - Operating system of cybertimes Though for a lot of people , regard Linux as the main operating system to make up huge work station group, finish special effects of " Titanic " make , already can be regarded as and show talent fully. But for Linux, this only numerous news one of. Recently, the manufacturers concerned have announced that support the news of Linux to increase day by day, users' enthusiasm to Linux runs high unprecedentedly too. Then, Linux only have operating system not free more than on earth on 7 year this piece what glamour, get the favors of such numerous important software and hardware manufacturers as the masses of users and Orac le , Informix , HP , Sybase , Corel , Intel , Netscape , Dell ,etc. , OK?1.The background of Linux and characteristicLinux is a kind of " free (Free ) software ": What is called free,mean users can obtain the procedure and source code freely , and can use them freely , including revise or copy etc.. It is a result of cybertimes, numerous technical staff finish its research and development together through Inte rnet, countless user is it test and except fault , can add user expansion function that oneself make conveniently to participate in. As the most outstanding one in free software, Linux has characteristic of the following:(1)Totally follow POSLX standard, expand the network operatingsystem of supporting all AT&T and BSD Unix characteristic. Because of inheritting Unix outstanding design philosophy , and there are clean , stalwart , high-efficient and steady kernels, their all key codes are finished by Li nus Torvalds and other outstanding programmers, without any Unix code of AT&T or Berkeley, so Linu x is not Unix, but Linux and Unix are totally compatible.(2)Real many tasks, multi-user's system, the built-in networksupports, can be with such seamless links as NetWare , Windows NT , OS/2 ,Unix ,etc.. Network in various kinds of Unix it tests to be fastest in comparing and assess efficiency. Support such many kinds of files systems as FAT16 , FAT32 , NTFS , Ex t2FS , ISO9600 ,etc. at the same time .(3) Can operate it in many kinds of hardwares platform , including such processors as Alpha , SunSparc , PowerPC , MIPS ,etc., to various kinds of new-type peripheral hardwares, can from distribute on global numerous programmer there getting support rapidly too.(4) To that the hardware requires lower, can obtain very good performance on more low-grade machine , what deserves particular mention is Linux outstanding stability , permitted " year " count often its running times.2.Main application of Linux At present,Now, the application of Linux mainly includes:(1) Internet/Intranet: This is one that Linux was used most at present, it can offer and include Web server , all such Inter net services as Ftp server , Gopher server , SMTP/POP3 mail server , Proxy/Cache server , DNS server ,etc.. Linux kernel supports IPalias , PPP and IPtunneling, these functions can be used for setting up fictitious host computer , fictitious service , VPN (fictitious special-purpose network ) ,etc.. Operating Apache Web server on Linux mainly, the occupation rate of market in 1998 is 49%, far exceeds the sum of such several big companies as Microsoft , Netscape ,etc..(2) Because Linux has outstanding networking ability , it can be usedin calculating distributedly large-scaly, for instance cartoon making , scientific caculation , database and file server ,etc..(3) As realization that is can under low platform fullness of Unix that operate , apply at all levels teaching and research work of universities and colleges extensively, if Mexico government announce middle and primary schools in the whole country dispose Linux and offer Internet service for student already.(4) Tabletop and handling official business appliedly. Application number of people of in this respect at present not so good as Windows of Microsoft far also, reason its lie in Lin ux quantity , desk-top of application software not so good as Windows application far not merely, because the characteristic of the freedom software makes it not almost have advertisement thatsupport (though the function of Star Office is not second to MS Office at the same time, but there are actually few people knowing).3.Can Linux become a kind of major operating system?In the face of the pressure of coming from users that is strengthened day by day, more and more commercial companies transplant its application to Linux platform, comparatively important incident was as follows, in 1998 ①Compaq and HP determine to put forward user of requirement truss up Linux at their servers , IBM and Dell promise to offer customized Linux system to user too. ②Lotus announce, Notes the next edition include one special-purpose edition in Linux. ③Corel Company transplants its famous WordPerfect to on Linux, and free issue. Corel also plans to move the other figure pattern process products to Linux platform completely.④Main database producer: Sybase , Informix , Oracle , CA , IBM have already been transplanted one's own database products to on Linux, or has finished Beta edition, among them Oracle and Informix also offer technical support to their products.4.The gratifying one is, some farsighted domestic corporations have begun to try hard to change this kind of current situation already. Stone Co. not long ago is it invest a huge sum of money to claim , regard Linux as platform develop a Internet/Intranet solution, regard this as the core and launch Stone's system integration business , plan to set up nationwide Linux technical support organization at the same time , take the lead to promote the freedom software application and development in China. In addition domestic computer Company , person who win of China , devoted to Linux relevant software and hardware application of system popularize too. Is it to intensification that Linux know , will have more and more enterprises accede to the ranks that Linux will be used with domestic every enterprise to believe, more software will be planted in Linux platform. Meanwhile, the domestic university should regard Linux as the original version and upgrade already existing Unix content of courses , start with analysing the source code and revising the kernel and train a large number of senior Linux talents, improve our country's own operating system. Having only really grasped the operating system, the software industry of our country could be got rid of and aped sedulously at present, the passive state led by the nose by others, create conditions for revitalizing the software industry of our country fundamentally.中文翻译Linux—网络时代的操作系统虽然对许多人来说，以Linux作为主要的操作系统组成庞大的工作站群，完成了《泰坦尼克号》的特技制作，已经算是出尽了风头。

毕业设计（论文）外文资料翻译系别：计算机系专业：计算机科学与技术班级：姓名：学号：外文出处：Web-Based Network education System1. IntroductionComputers and web applications bring a significant revolution in our social life and especially to our traditional mechanism of education. The era of education enable us to access mass of information whose remarkable character is digital so that computers can recognize and deal with this kind of expression of information. Digital campus construction is already on going in order to catch the new trend in quality education. The main functions of digital campus cover with distance such as web classroom, courseware on demand, distance examination. The digital campus information management system includes information management system, office automation system, administration examination system and virtual community such as online tutoring, bulletin board system etc. With the intensification of distance web education, how to estimate learning effect locally is an important issue. A comprehensive education system which utilizes information technology of the network to carry on college course to educate, it offers from the network classroom, essential study links discussing, answering questions, and processing homework to examination to teachers and students. This system should also support management activity of the educational administration, such as online course project, roll management, follow-up of quality. The self-adapted examination system is a sub-system of the Networking Institute's demonstration project. In Internet Universal, distance learning is by telephone, television, video and communications, asynchronous transmission mode of teaching information. In recent years, based on the introduction Internet Distance learning, World Wide Web Recognized as the most powerful curriculum information dissemination media, the Internet has hundreds of courses, there are more schools and teachers are being considered for Web Teaching. For Web Teaching, and that is using the World Wide Web as a teaching medium, transmission teaching in the implementation of online teaching, teaching management, and online testing and online exchanges. Realistic and complete implementation based on Web Teaching requires a user-friendly and efficient support online teaching platform support. Currently there are some in the international market such products, such as Lotus Company Learning Space , the British Columbia University computer science department development Web CT ,WBT System Company Top Class And Canada Simon Fraser University development Virtual. Many companies and schools are also being developed or is ready to develop similar software, such as the key institutions in preparation for the development of modern distancelearning and teaching support system. Online teaching platform should be aware of the support functions, which can or should provide the ancillary support, all of which feature current products, for effective online teaching is very important.2.The main characteristicTeachers can keep a student's screens' voice display and send information to all students or a group of broadcast; teachers can watch and listen to a student 's information, and control the student's keyboard and mouse , and do "hand in hand" type of guidance, and arbitrary switching among students ; and remote window control guidance, the window of multimedia network classroom software can control the intelligent rolling and teachers teaching in various other functions at the same time, the teacher can remote control machine on a number of students at the same time and also can let all (a group or a) student screens arranged in "the black screen", and lock the keyboard and mouse, reminding the attention of students; intelligent rolling screen: the screen broadcast and remote control operation uses the original smart scroll, free rolling technology, which need not undertake screen scaling, receiving students in the broadcast in the process of watching the operation; the mouse capture: it supports soft cursor, animated mouse cursor, mouse cursor broadcasting, even in windowed mode which can reflect the real-time changes in morphology and mouse; multi-point monitoring: multimedia network classroom software support multiple windows simultaneously with the same When the watch, which can also watch window distributed across multiple machines, real-time monitoring of all the other students in the state machine; broadcast: multimedia network classroom software support more audio and video file formats, support for VCD, MP3, W AV and other documents play online ; automatic login: students on the machine automatically log in the teacher machine; multimedia network classroom software has strong system stability, ensure the teaching process smoothly; perfect functions, beautiful interface which is easy to use the direct and concise operation, using the unified mode of operation; software, multimedia network classroom software does not need a server, simple installation, convenient upgrade and maintenance; hardware compatibility: multimedia network classroom software contents all the card, sound card, display card and can demonstrate good performance, and won't appear any unstable phenomenon.3. Design multimedia network classroom of thoughtIn the multimedia network classroom design, it focuses on solving the user pays as the following issues: (1)the multimedia network classroom is easy to use and individualized demand. Because each teacher for computer to different extent, teachers need to multimedia network classroom is simple and easy to use, one will see, will soon be able to undertake informatizal teaching. The computer master degree higher teacher needs according to computer and information understanding, personalized teaching.(2) multimedia network classroom and practicalteaching function. Information teaching is a means of teaching, its purpose is to improve the effect of teaching. This means whether the teaching habits, whether there is a wealth of practical teaching function, really help teachers for teaching, improve the effect of teaching has become the most concern of the teacher.(3)multimedia network classroom teaching management function. If a student who attends class does not listen to the teacher carefully, has nothing to do with the classroom things, such as playing games, or simply add or remove programs are headaches in teachers teaching; and in order to guarantee the teaching effection carrying smoothly, it also requires a corresponding teaching management function to assist.4.The multimedia network classroom program advantagesMultimedia network classroom solution has the following advantages.（1）Simple and easy to use, multimedia network classroom software use a graphical interface, whoes each function has a corresponding button, operating on a stick out a mile, so that teachers can see use it easily. （2）Flexible customized, which meets the demand of personal teaching. The teacher can customize multimedia network classroom software interface, icon, toolbar and also can customize the class model at the same time by using multimedia network classroom run concurrent design, each function of teaching can manage any combination and arbitrary. （3）Multimedia network classroom original thumbnail display mode which can make the whole class of the students computer screen contents show to teachers at the same time and let teachers watch easily in global.（4）practical teaching function of multimedia network classroom software offers practical and rich pedagogical features, including screen broadcasting, video broadcasting, voice broadcasting, issued procedures, and collection operations.（5）Supporting a variety of teaching strategies, which can use the broadcast function to broadcast the teacher's own screen to everyone.（6）teaching management function in the multimedia network classroom, which is subject to the control of the teacher, students can be remotely set machine, and the multimedia network classroom is also enhanced by many teachers and students interaction, such as "remote control", which fully ensured between student and teacher interaction.（7）In order to guarantee the teaching carrying out smoothly, the teacher wants multimedia network classroom software to help manage the students' situation. Multimedia network classroom software is provided for locking the computer black screen and hush functions（8) Multimedia network classroom daily maintenance workload is very big, the teacher does not have too much time to manage multimedia network classroom maintenance, hoping multimedia network classroom software can provide very good maintenance function. Multimedia network classroom with remote settings, document publishing, charge, delete, remote command, remote control and other functions.（9）multimedia network classroom software has strong system stability, high soft, hardware environment compatibility, regardless of level of computer configuration, graphics cards, sound card type, which can guarantee the normal operation of multimedia network classroom.（10）because of the multimedia network classroom is a pure software implementation, simple installation,upgrade and maintenance which is very convenient.5. The main functions of software in multimedia network teaching(1)Teaching function, including screen broadcasting, screen monitoring, voice broadcast, audio monitor, video broadcasting, electronic drawing board, news release, issued a document, collect documents, documents and other functions which the teacher in the class is the most commonly used functions.(2)Teaching management, multimedia network Teaching management function can ensure the teaching be carried out smoothly, including the class model, group management, call sign, lock computer, silent, black screen log. (3)Maintenance, for the convenience of teachers to multimedia classroom network maintenance, multimedia network teaching provides remote settings and other functions.6. Multimedia network teaching system buildingMultimedia network classroom is a small LAN environment, generally uses the 100M switching to the desktop, you can ensure that the audio and video files well transmission. Computer selection of good effects and economic benefits principle, selection of the computer multimedia network classroom should let the minimum guarantee the smooth operation of multimedia courseware, and commonly used methods of software, such as Word, Powerpoint, teacher's machine configuration is higher than the students machine configuration , and the best buying support WOL function computer.Finally the teacher machine, student machine, switching with twisted pair link, which sets the TCP / IP protocol, transfering through network, should instals on the multimedia network classroom software and a complete multimedia network classroom building.基于网络的教学系统1导言计算机和网络应用带来了重大变革，我们的社会生活，特别是我们的传统机制的教育得到了重大变革。

外文翻译ENGLISHE：Develop Web application program using ASP the architecture that must first establish Web application. Now in application frequently with to have two: The architecture of C/S and the architecture of B/S.Client/server and customer end / server hold the architecture of C/S.The customer / server structure of two floor.Customer / server ( Client/Server ) model is a kind of good software architecture, it is the one of best application pattern of network. From technology, see that it is a logic concept, denote will a application many tasks of decomposing difference carry out , common completion is entire to apply the function of task. On each network main computer of web site, resource ( hardware, software and data ) divide into step, is not balanced, under customer / server structure, without the client computer of resource through sending request to the server that has resource , get resource request, so meet the resource distribution in network not balancedness. With this kind of structure, can synthesize various computers to cooperate with work, let it each can, realize the scale for the system of computer optimization ( Rightsizing ) with scale reduce to melt ( Downsizing ). Picture is as follows:It is most of to divide into computer network application into two, in which the resource and function that part supports many users to share , it is realized by server; Another part faces every user , is realized by client computer, also namely, client computer is usual to carry out proscenium function , realizes man-machine interaction through user interface , or is the application program of specific conducted user. And server usually carries out the function of backstage supporter , manages the outside request concerning seting up, accepting and replying user that shared. For a computer, it can have double function , is being certain and momentary to carve to act as server , and again becomes client computer in another time.Customer / server type computer divide into two kinds, one side who offers service is called as server , asks one side of service to be called as customer. To be able to offer service, server one side must have certain hardware and corresponding server software; Also, customer one side mustalso have certain hardware and corresponding customer software.There must be a agreement between server and customer, both sides communicate according to this agreement.Apply customer / server model in Internet service , the relation between customer and server is not immutable. Some Internet node offers service on the one hand , also gets service on the other hand from other node; It is even in one time dialogue course, mutual role also exchanges probably. As in carry out file transmission , if be called as one side who offers file server, is called as one side who gets file customer, when using get or mget order since another node takes file, can think that what self use and it is client computer , is using put or mput order to another node dispatch file can again think the machine that used self is server.Multilayer customer / server structureAlong with the development of enterprise application, recently, have again arisen a kind of new multilayer architecture, it applies customer end to divide into two minutes: Customer application and server apply. Customer application is the part of original customer application , is another and partial to have been transfered to server to apply. New customer application takes the responsibility for user interface and simple regular business logic and new server application resident core , changeable business logic. Therefore its structure has become new ( Client application + Server application )/Server structure. Following picture shows:This kind of structure has solved traditional Client/Server can expand problem, have reduced customer end business logic , and have reduced the requirement of customer end for hardware. At the same time because of a lot of business logic concentrations have gone to unitary application server on, the maintenance work of application system had been also concentrated together, have eliminated the problem in the traditional structure of Client/Server that software distributes. This kind of structure is called as the architecture of B/S.Browser/Server and browser / server hold the architecture of B/S. Onessence, Browser/Server is also a kind of structure of Client/Server, it is a kind of from the traditional two levels of structural development of Client/Server come to the three-layer structural special case of Client/Server that applied on Web.In the system of Browser/Server, user can pass through browser to a lot of servers that spread on network to send request. The structure of Browser/Server is maximum to have simplified the work of client computer, on client computer, need to install and deploy few customer end software only , server will bear more work, for database visit and apply program carry out will in server finish.Under the three-layer architecture of Browser/Server, express layer ( Presentatioon ) , function layer ( Business Logic ) , data layer ( Data Service ) have been cut the unit of 3 relative independences: It is the first layer of to express layer: Web browser.In expressing layer contain system show logic, locate in customer end. It's task is to suggest by Web browser to the certain a Web server on network that service is asked , after verifying for user identity, Web server delivers needed homepage with HTTP agreement to customer end, client computer accept the homepage file that passed , and show it in Web browser on.Second layer function layer: Have the Web server of the application function of program extension.In function layer contain the systematic handling of general affairs logic, locate in Web server end. It's task is the request concerning accepting user , need to be first conducted and corresponding to expand application program and database to carry out connection , passes through the waies such as SQL to database server to put forward data handling to apply for, then etc. database server the result of handling data submit to Web server, deliver again by Web server to return customer end.The number of plies of 3th according to layer: Database server.In data layer contain systematic data handling logic, locate in database server end. It's task is to accept the request that Web server controls for database, realization is inquired and modified for database , update etc. function, submit operation result to Web server.Careful analysis is been easy to see , the architecture of Browser/Server of three-layer is the handling of general affairs of the two levels of structure of Client/Server logic modular from the task of client computer in split , from the first floor of individual composition bear the pressure of its task and such client computer have alleviated greatly, distribute load balancedly and have given Web server, so from the structural change of Client/server of original two floor the structure of Browser/Server of three-layer. This kind of three-layer architecture following picture shows.This kind of structure not only client computer from heavy burden andthe requirement of performance that rises continuously for it in liberation come out , also defend technology people from heavy maintenance upgrading work in free oneself. Since client computer handles general affairs , logic partial minutes have given function server, make client computer right off " slender " a lot of, do not take the responsibility for handling complex calculation and data again visit etc. crucial general affairs, is responsible to show part, so, maintenance people do not rush about again for the maintenance work of program between every client computer, and put major energy in the program on function server update work. Between this kind of three-layer structural layer and layer, the mutually independent change of any first floor does not affect the function of other layer. It has changed the defect of the two levels of architecture of Client/Server of tradition from foundation, it is the transform with deep once in application systematic architecture.The contrast of two architecturesThe architecture of Browser/Server and the architecture ofClient/Server compare with all advantages that not only have the architecture of Client/Server and also have the architecture ofClinet/Server the unique advantage that place does not have: Open standard: The standard adopted by Client/Server only in department unification for but, it's application is often for special purpose.It is lower to develop and defend cost: It need to be implemented on all client computers that the application of Client/Server must develop the customer end software for special purpose, no matter installation and disposition escalate still, have wasted manpower and material resources maximumly. The application of Browser/Server need in customer end have general browser , defend and escalate to work in server end go on , need not carry out any change as customer holds , have reduced the cost of development and maintenance so greatly.It is simple to use , interface friendly: The interface of the user of Client/Server is decided by customer end software, interface and the method of its use are not identical each, per popularize a system of Client/Server ask user study from the beginning, is hard to use. The interface of the user of Browser/Server is unified on browser, browser is easy to use , interface friendly, must not study use again other software, the use of a Lao Yong Yi that has solved user problem.Customer end detumescence: The customer end of Client/Server has the function that shows and handles data , as the requirement of customer end is a client computer " it is fat " very high. The customer of Browser/Server holds the access that not takes the responsibility for database again and the etc. task of complex data calculation, need it only show , the powerful role that has played server fully is so large to have reduced the requirement for customer end, customer end become very " thin ".System is flexible: The 3 minutes of the system of Client/Server, in modular, have the part that need to change to want relation to the change of other modular, make system very difficult upgrading. The 3 minutes of the system of Browser/Server modular relative independence, in which a part of modular change, other modular does not get influence, it is very easy that system improve to become, and can form the system with much better performance with the product of different manufacturer.Ensure systematic safety: In the system of Client/Server, directly join with database server because of client computer, user can very easily change the data on server, can not guarantee systematic safety. The system of Browser/Server has increased a level of Web server between client computer and database server , makes two not to be directly linked again, client computer can not be directly controled for database, prevent user efficiently invade illegally.The architecture of Browser/Server of three-layer has the advantage that a lot of traditional architectures of Client/Server does not have , and is close to have combined the technology of Internet/Intranet, is that the tendency of technical development tends to , it application system tape into one brand-new develop times. From this us option the configuration of B/S the architecture that develops as system.what are C/S with B/SFor " C/S " with the technology of " B/S " develop change know , first,must make it clear that 3 problems.( 1 ) What is the structure of C/S.C/S ( Client/Server ) structure, the server structure and client computer that all know well. It is software systematic architecture, through it can hold hardware environment fully using two advantage, realize task reasonable distribution to Client end and Server end , have reduced systematic communication expense. Now, the most systems of application software are the two levels of structure of the form of Client/Server , are developing to the Web application of distribution type since current software application is systematic, Web and the application of Client/Server can carry out same business handling , apply different modular to share logic assembly; Therefore it is systematic that built-in and external user can visit new and existing application , through the logic in existing application system, can expand new application system. This is also present application system develop direction. Traditional C ／S architecture though adopting is open pattern, but this is the openness that system develops a level , in specific application no matter Client end orServer end the software that need to still specify support. Because of the software software that need to develop different edition according to the different system of operating system that can not offer the structure of C/S and the open environment of user genuine expectation , besides, the renovation of product is very rapid, is nearly impossible to already meet the 100 computer above users of local area network at the same time use. Price has low efficiency high. If my courtyard uses , Shanghai exceed the orchid company's management software " statistics of law case" is typical C ／S architecture management software.( 2 ) What is the structure of B/S.B/S ( Browser/Server ) structure browser and server structure. It is along with the technology of Internet spring up , it is for the structure of improvement or a kind of change of the structure of C/S. Under this kind of structure, user working interface is to realize through WWW browser, lose the logic of general affairs very much in front( Browser) realization, but the major logic of general affairs in server end( Server) realization, form the three-layer claimed 3-tier structure. So, have simplified customer end computer load greatly , have alleviated system to defend workload and the cost with upgrading , have reduced the overall cost of user ( TCO ). With present technology see , local area network the network application that establishes the structure of B/S , and under the pattern of Internet/Intranet, database application is easy to hold relatively , cost also is lower. It is that oneness goes to the development of position , can realize different people, never same place, with difference receive the way of entering ( for example LAN, WAN, Internet/Intranet etc.) visit and operate common database; It can protect data platform efficiently with management visit limits of authority, server database is also safe. Now in my courtyard, net ( Intranet ) , outer net ( Internet ) with Beijing eastern clear big company " law case and the management software of official business " is the structural management software of B/S , policemen each working station in local area network pass through WWW browser can realize working business. Especially in JAVA step platform language appearance after, the configuration management software of B/S is more facilitated , is shortcut, efficient.( 3 ) The management software technology of main stream.The technology of main stream of management software technology is as management thought , have also gone through 3 develop period. First, interface technology goes to Windows graph interface ( or graph user interface GUI ) from last century DOS character interface, till Browser browser interface 3 differences develop period. Secondly, today own the browser interface of computer, is not only visual and is easy to use , what is more major is that any its style of application software based on browser platform is as, make the requirement of choosing a person for the job for operating training not high and software operability is strong , is easy to distinguish; Moreover platform architecture the file that also goes to today from past single user development ／server ( F ／S ) system and client computer ／server ( C ／S ) system and browser ／server ( B ／S ) system.The comparison of C/S and B/SC/S and B/S is the now world two technologies of main stream of developing pattern technical configuration. C/S is that American Borland company researches and develop most early, B/S is that American Microsoft researches and develop. Now this two technologies with quilt world countries grasp , it is many that domestic company produce article with C/S and the technical development of B/S. This two technologies have the certain market share of self , is with customer crowd , each domestic enterprise says that own management software configuration technical function is powerful, advanced, convenient , the customer group that can lift , have a crowd scholar ink guest to shake flag self cry out , advertisement flies all over the sky , may be called benevolent to see kernel, sage sees wisdomC/S configures inferior position and the advantage of software( 1 ) Application server operation data load is lightcomparatively.The database application of the most simple architecture of C/S is become by two partial groups, customer applies program and database server program. Both can be called as proscenium program and the program of backstage supporter respectively. The machine of operation database server program is also called as application server. Once server program had been started , waits the request concerning responding customer program hair at any time; Customer application program operation can becalled as customer computer on the own computer of user, in correspondence with database server, when needs carry out any operation for the data in database, customer program seeks server program voluntarily , and sends request to it, server program is regular as basis intends to make to reply, send to return result, application server operation data load is lighter.( 2 ) Data store management function relatively transparent.In database application data store management function, is carried out respectively independently by server program and customer application program , is regular as proscenium application can violate , and usually those different( no matter is have known still unknown ) operations data, in server program, do not concentrate realization, for instance visit limits of authority, serial number can be repeated , must have customer talent establishment the rule order. It is these to own , for the last user that works on proscenium program is " transparent ", they need not be interest in ( can not usually also interfere ) the course of behind, can complete own all work. In the application of customer server configuration proscenium program not is very " thin ", troublesome matter is delivered to server and network. In the system of C/S take off , database can not become public really , professionally more competent storehouse, it gets independent special management.( 3 ) The inferior position of the configuration of C/S is high maintenance cost make investment just big.First, with the configuration of C/S, will select proper database platform to realize the genuine "unification" of database data, make the data synchronism that spreads in two lands complete deliver by database system go to manage, but the logically two operators of land will directly visit a same database to realize efficiently , have so some problems, if needs establishment the data synchronism of " real time ", the database server that must establish real time communication connection between two places and maintains two lands is online to run , network management staff will again want to defend and manage for customer end as server defends management , maintenance and complex tech support and the investment of this high needs have very high cost, maintenance task is measured.Secondly, the software of the structure of C/S of tradition need to develop thesoftware of different edition according to the different system of operating system , is very rapid because of the renovation of product, price is working needs high with inefficient already do not meet. In JAVA step platform language appearance after, the configuration of B/S is more vigorous impact C/S , and forms threat and challenge for it. .The advantage of B/S configuration software( 1 ) The Maintenance of inferior position and upgrading way are simple.Now upgrading and the improvement of software system more and more frequently, the product of the configuration of B/S embodies more convenient property obviously. For one a little a little bit big unit , if systematic administrator needs , between hundreds of 1000 even last computers round trip run , efficiency and workload is to can imagine, but the configuration of B/S software needs management server have been all right , all customer ends are browser only, need not do any maintenance at all. No matter the scale of user has , is what , has how many branch will not increase any workload of maintenance upgrading , is all to operate needs to aim at server to go on; If need differently only, net server connection specially , realize long-range maintenance and upgrading and share. So client computer more and more " thin ", and server more and more " fat " is the direction of main stream of future informative development. In the future, software upgrading and maintenance will be more and more easy , and use can more and more simple, this is for user manpower , material resources, time and cost save is obvious , it is astonishing. Therefore defend and escalate revolutionary way is the client computer " it is thin ", " is fat " server.( 2 ) Cost reduction, it is more to select.All know windows in the computer of top of a table on nearly one Tong world, browser has become standard disposition, but on server operating system, windows is in absolute dominance position not. Current tendency is the application management software that uses the configuration of B/S all , need to install only in Linux server on , and safety is high. The so server option of operating system is many, no matter choosing those operating system, can let the most of ones use windows in order to the computer of top of a table of operating system does not get influence, this for make most popular free Linux operating system develop fast, Linux except operatingsystem is free besides, it is also free to link database, this kind of option is very pupular.Say, many persons on daily, "Sina website" nets , so long as having installed browser for can , and what need not know the server of " Sina website " to use is that what operating system, and in fact the most of websites do not use windows operating system really, but the computer of user is most of as installing to be windows operating system.( 3 ) Application server operation data load value comparatively.Since B/S configures management, software installation in server end ( Server ) on, it is been all right that network administrator need to manage server only, the user interface major logic of general affairs in server ( Server ) end pass through WWW browser completely realization, lose the logic of general affairs very much in front( Browser) realization, all customer ends has only browser, network administrator need to do hardware maintenance only. But application server operation data load is heavier, once occuring " server collapse " to wait for problem, consequence is unimaginable. Therefore a lot of units have database to stock server , are ready for any eventuality.原文翻译:利用ASP开发Web应用程序首先必须确立Web应用的体系结构。

外文资料所译外文资料：①作者：Dan Malks②书名：Professional JSP③出版时间: 2000.7.26④所译章节: Chapter 1212.1IntroductoryGood Web application design tries to separate business objects, presentation, and manipulation of the objects into distinct layers. One benefit of using JavaServer Pages technology is that it allows us to separate the role of a Web designer more clearly from that of a software developer. While on a small-scale project, one individual may occupy both roles, on a larger project, they are likely to be separate and it is beneficial to separate their workflows as much as possible. Designing the architecture for your Web application is crucial to this separation.12.2 JSP architectureWe will examine a variety of ways to architect a system with JavaServer Pages, servlets, and JavaBeans. We will see a series of different architectures, each a development of the one before. The diagram below shows this process in outline; the individual parts of the diagram will be explained in turn later in this article.JSP architecture:When Sun introduced Java Server Pages, some were quick to claim that servlets had been replaced as the preferred request handling mechanism in Web-enabled enterprise architectures. Although JSP is a key component of the Java 2 Platform Enterprise Edition (J2EE) specification, serving as the preferred request handler and response mechanism, we must investigate further to understand its relationship with servlets.Other sections of Professional JSP explain the implementation details of JSP source translation and compilation into a servlets. Understanding that JSP is built on top of the servlet API, and uses servlet semantics, raises some interesting questions. Should we no longer develop stand-alone servlets in our Web-enabled systems? Is there some way to combine servlets and JSPs? If so, where do we place our Java code? Are there any other components involved in the request processing, such as JavaBeans? If so, where do they fit into the architecture and what type of role do they fulfill?It is important to understand that, although JSP technology will be a powerful successor to basic servlets, they have an evolutionary relationship and can be used in a cooperative and complementary manner.Given this premise, we will investigate how these two technologies, each a Java Standard Extension, can be used co-operatively along with other components, such as JavaBeans, to create Java-based Web-enabled systems. We will examine architecturalissues as they relate to JSP and servlets and discuss some effective designs while looking at the tradeoffs of each. Before jumping directly into a discussion of specific architectures, though, we will briefly examine the need to develop a variety of architectures.12.3 Code factoring and role separationOne of the main reasons why the JavaServer Pages technology has evolved into what it is today (and it's still evolving) is the overwhelming technical need to simplify application design by separating dynamic content from static template display data. The foundation for JSP was laid down with the initial development of the Java Web Server from Sun, which used page compilation and focused on embedding HTML inside Java code. As applications came to be based more on business objects and n-tier architectures, the focus changed to separating HTML from Java code, while still maintaining the integrity and flexibility the technology provided.In Chapter 5, JSP Sessions, in Professional JSP, we saw how beans and objects can be bound to different contexts just by defining a certain scope. Good application design builds on this idea and tries to separate the objects, the presentation, and the manipulation of the objects into distinct, distinguishable layers.Another benefit of using JSP is that it allows us to more cleanly separate the roles of a Web production/HTML designer individual from a software developer. Remember that a common development scenario with servlets was to embed the HTML presentation markup within the Java code of the servlet itself, which can be troublesome. In our discussion, we will consider the servlet solely as a container for Java code, while our entire HTML presentation template is encapsulated within a JSP source page. The question then arises as to how much Java code should remain embedded within our JSP source pages, and if it is taken out of the JSP source page, where should it reside?Let's investigate this further. On any Web-based project, multiple roles and responsibilities will exist. For example, an individual who designs HTML pages fulfills a Web production role while someone who writes software in the Java programming language fulfills a software development role.On small-scale projects these roles might be filled by the same individual, or two individuals working closely together. On a larger project, they will likely be filled by multiple individuals, who might not have overlapping skill sets, and are less productive if made too dependent on the workflow of the other.If code that could be factored out to a mediating servlet is included instead within HTML markup, then the potential exists for individuals in the software development role and those in the Web production role to become more dependent than necessary on the progress and workflow of the other. Such dependencies may create a more error-prone environment, where inadvertent changes to code by other team members become more common.This gives us some insight into one reason why we continue to develop basic servlets: they are an appropriate container for our common Java code that has been factored out of our JSP pages, giving our software development team an area of focus that is as loosely coupled to our JSP pages as possible. Certainly, there will be a need for these same individuals to work with the JSP source pages, but the dependency is reduced, and these pages become the focus of the Web-production team instead. Of course, if the same individual fulfills both roles, as is typical on a smaller project, such dependencies are not a major concern.So, we should try to minimize the Java code that we include within our JSP page, in order to uphold this cleaner separation of developer roles. As we have discussed, some of this Java code is appropriately factored to a mediating servlet. Code that is common to multiple requests, such as authentication, is a good candidate for a mediating servlet. Such code is included in one place, the servlet, instead of potentially being cut and pasted into multiple JSPs.We will also want to remove much of our business logic and data access code from our JSP page and encapsulate it within JavaBeans, called worker or helper beans. We start to see a pattern of code movement from our JSP into two areas: a servlet (or JSP) that sits in front of the main JSP, and JavaBeans that sit in back. We refer to this common pattern as "Factor Forward -- Factor Back," as shown in the figure below:Factor Forward -- Factor Back:Another way to think about what code should be localized and encapsulated is that our JSP page should reveal as little as possible of our Java code implementation details.Rather, the page should communicate our intent by revealing the delegating messages we send to worker beans, instructing them to get state from a model, or to complete some business processing.12.4 Redirecting and forwardingRedirecting and forwarding requests in JSPs and servlets takes place often, and it is important to understand the subtle difference between these two mechanisms even though they achieve the same goal (that is, a client asks for a resource on the server and a different resource is served to it):●When a servlet or JSP resource chooses to redirect the client (using aresponse.sendRedirect(url)) the request object does not reach the second resource directly since the underlying implementation is an HTTP redirect.The server sends an HTTP 302 message back to the client telling it that the resource has moved to another URL, and that the client should access it there.The bottom line is that the lifecycle of the initial request object that was accessed in the first JSP terminates with the end of the service method in the first JSP, or with the reply from the server.●In a forward mechanism the request object is forwarded to the second resource,thus maintaining any object bindings to the request and its state, without a round trip to the client on the network. This allows the first JSP to do some work internally and then send information to the second JSP asking it to do itsbit. (Servlets used a chaining mechanism to do this). See Chapter 5, JSP Sessions, in Professional JSP to get a clearer picture of scope. JSPs and servlets can use the forwarding mechanism to delegate tasks among themselves, in the process of separating dynamic and static content.Now, let's investigate how we build these systems.12.5 ArchitecturesBefore discussing specific architectures that we can use to build systems with servlets and JSP, it is worth mentioning two basic ways of using the JSP technology. Each of the architectures discussed in this chapter will be based on one of these approaches:●The first method is referred to here as the page-centric (or client-server)approach. This approach involves request invocations being made directly to JSP page.●In the second method, the dispatcher (or n-tier) approach, a basic servlet orJSP acts as a mediator or controller, delegating requests to JSP pages and JavaBeans.We will examine these approaches in light of a simple example, which will evolve to satisfy the requirements of various scenarios. The initial scenario involves providing a Web interface for guessing statistics about a soon-to-be-born baby. The guesses are stored, and can be reviewed later by the parents, to see who has guessed the closest. As the requirement scenarios become more sophisticated, such as adding the desire for a persistence mechanism, the solution scenarios will become more sophisticated, as well. Thus, our example will evolve and we will gain an understanding of how the various architectures that we discuss will help us build a system that satisfies these requirements in an elegant and effective manner.12.6 The page-centric approachApplications built using a client-server approach have been around for some time; they consist of one or more application programs running on client machines and connecting to a server-based application to work. (A good example would be a PowerBuilder or Oracle Forms-based system.) CGIs and pre-servlet applications were generally based on this simple 2-tier model, and with the introduction of servlets, 2-tier applications could also be created in Java.This model allows JSPs or servlets direct access to some resource like a database or legacy application to service a client's request: the early JSP specifications termed this a "Model 1" programming approach. The JSP page is where the incoming request is intercepted and processed, and the response is sent back to the client;JSPs only differed from servlets in this scenario by providing cleaner code and separating code from the content by placing data access in beans.Model 1 programming approach:The advantage of such an approach is that it is siple to program,and allows the page author to Generate dynamic content easily,based upon the request and the state resources.However this architecture does not scale up well for a large number of simultaneous clients since there would be a significant amount of request processing to be performed,and each request must establish or share a potentially scarce/expensive connection to the resource in question.(A good example would be JDBC connectons in servlets or JSPs and the need for connection pools.) Indiscriminate usage of this architecture usually leads to a significant amount of Java code embedded within the JSP page,this may not seem to be much of a problem for Java developers but it is certainly an issue if the JSP pages are maintained by designers:the code tends to get in the designe’s way,and you run the risk of your code becoming corrupted when others are tweaking the look and feel.译文12.1前言好的Web应用设计试图将业务对象，简报以及操作对象分为不同的层面。

关于计算机的英文文献写作范文摘要全文共3篇示例，供读者参考篇1Title: A Study on the Impact of Computers on SocietyAbstract:Computers have become an integral part of modern society, with their influence pervading all aspects of human life. This study aims to explore the impact of computers on society, focusing on the social, economic, and cultural aspects. The research is based on a comprehensive review of existing literature and empirical studies that have investigated the relationship between computers and society.The study finds that computers have revolutionized communication and information exchange, leading to a more connected and globalized world. The internet, in particular, has transformed the way people interact, work, and socialize. The rise of social media and online platforms has created new channels for communication and expression, but also raised concerns about privacy and data security.Economically, computers have changed the nature of work and productivity, with automation and artificial intelligence increasingly taking over routine tasks. While this has led to increased efficiencies and innovation, it has also raised questions about job displacement and income inequality. The gig economy and freelance work are becoming more common, as people adapt to the changing landscape of labor.Culturally, computers have influenced the way people consume media, create art, and express themselves. Digital technologies have democratized access to information and creative tools, but also raised issues of authenticity and copyright. The prevalence of online platforms for entertainment and social interaction has reshaped cultural practices and norms.In conclusion, computers have had a profound impact on society, shaping the way people communicate, work, and think. While the benefits of technology are clear, it is important to consider the social and ethical implications of its widespread adoption. More research is needed to understand the long-term effects of computers on society and to ensure that technology serves the greater good.篇2Title: Writing a Research Paper on ComputersAbstract:This paper discusses the process of writing a research paper on computers. It provides a step-by-step guide on how to effectively research, organize, and write a paper on the topic of computers. The paper outlines the importance of choosing a specific research question, conducting thorough research, and citing sources properly. It also explains how to structure a research paper on computers, including the introduction, literature review, methodology, results, discussion, and conclusion sections. Additionally, the paper provides tips on how to write clearly and concisely, avoid plagiarism, and revise and edit the paper for clarity and coherence. Overall, this paper serves as a comprehensive guide for students and researchers looking to write a research paper on computers.篇3Title: A Study on Computer Science: Writing Research PapersAbstract:Computer science is a rapidly growing field with a wide array of topics and subfields for researchers to explore. Writing research papers in computer science requires a combination oftechnical expertise and strong writing skills. This paper provides an overview of the key components of a research paper in computer science, along with useful tips and strategies for successful writing.The first step in writing a research paper in computer science is to select a topic that is both interesting and relevant to current advancements in the field. The paper should clearly define the research question or problem to be addressed, along with the objectives and methodology of the study. It is important to review existing literature on the topic to ensure that the research is original and contributes to the existing body of knowledge.The next step is to organize the paper into logical sections, including an introduction, literature review, methodology, results, discussion, and conclusion. Each section should be clearly structured and well-written, with appropriate citations and references to support the claims made in the paper. It is important to use a clear and concise writing style, avoiding unnecessary jargon and technical terms that may confuse the reader.In addition to the technical content of the paper, the writing style and presentation are also important factors to consider. The paper should be well-organized, with a logical flow of ideas andarguments. Charts, tables, and figures can be used to illustrate key points and data, but should be used sparingly and effectively.Finally, the paper should be carefully proofread and edited to ensure that it is free of errors in grammar, punctuation, and spelling. It is also important to consider the formatting and citation style required by the target journal or conference. By following these guidelines and tips, researchers can improve the quality of their research papers in computer science and increase their chances of publication and impact in the field.。