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Web Services Over Infrastructure-less Networks

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Web Services Over Infrastructure-less NetworksArvind M Bhusate, Dr Hermann De MeerD e p a r t m e n t o fE l e c t r o n i c&E l e c t r i c a l E n g i n e e r i n g U n i v e r s i t y C o l l e g e L o n d o n,2003Abstract:This paper discusses the possibility of the convergence between web services and infrastructure-less networks such as Ad-hoc and P2P. Convergence meaning the operation of web services over networks such as Ad-hoc and P2P. The paper highlights parts of the detailed analysis carried out and the conclusions formed from this in these areas. It also reviews the fundamental web services technology components, along with that of ad hoc and p2p networks.1. IntroductionWeb services tend to be accessed at all times and at all places. Clients employ a wide range of devices including desktops, laptops, palm or hand held devices, and smart phones that are connected to the Internet using very different kinds of networks such as wireless LAN, cell phone network, broadband network, telephone network, or local area network. Frequent disconnections and unreliable bandwidth characterise some of these networks. The availability of Web services is thus a significant concern to consumers using mobile devices and working in different kinds of mobile networks either with or without an infrastructure. Therefore this research is necessary to be carried out to discover any models or analyse existing models/ architectures to enhance and diversify the use of web services (such as over infrastructure-less networks). This paper discusses possible ways that convergence maybe applicable, the issues involved in each case and also the problems that will be encountered with such proposals. 2. Web ServicesWeb Services are self-contained, modular applications that can be described, published, located, and invoked over a network. They are based on service-oriented architecture (SOA) and enable new and existing applications to be integrated through the use of XML as a data format over standard network protocols such as HTTP for transportation.Web Services eliminate the interoperability issues of existing solutions, such as CORBA and DCOM, by using open Internet standards such as: WSDL, SOAP, UDDI. The WSDL (Web Services Description Language)is an XML-based format, which holds information such as the services available methods, parameter types and the actual SOAP end point for the service. The WSDL is like the “Users Manual” for a Web Service. The SOAP (Simple Object Access Protocol)is the XML-based protocol for sending requests and responses to and from Web Services. The UDDI (Universal Description, Discovery, and Integration), also known as the “Yellow Pages” for Web Services, is like the meeting place for web services. The UDDI registry stores descriptions about companies and the services they have to offer in a XML format.There are three components of service-oriented architecture: 1) Service Provider: is responsible for creating and publishing the interfaces of services, providing the actual implementation of these services, and responding to any requests for the use thereof. 2) Service Broker: registers and categorises public services published by various service providers and offers services such as search. Service brokers act like a yellow pages for Web Services. 3) Service Requestor: This component is the actual user of Web Services. Service requestors discover Web Services and then invoke these services by communicating with the actual service providers [1].The three most basic operations through which the SOA participants interact are: 1) Publish operation, using WSDL, allowing the service provider to publish its services and interface requirements with a service broker. 2) Find operation, using UDDI registry, allowing a service requestor to locate, search and discover the services published via a service broker that is offered by a specific service provider. 3) Bind operation, using SOAP based XML messages, enabling a service requestor to actually bind and use a service provided by a service provider [2].3. Ad hoc NetworksAd hoc networks are infrastructure-less networks and are basically made up of mobile nodes. The network is mobile and is also a form of wireless communication. Ad hoc networks are flexible, self-configuring and robust against disasters. There are minimal wiring difficulties and they are very speedy and easy to deploy. The problem with these networks however is that deployment costs are high, and there is a limited wireless spectrum (licensing and low bandwidth) [3]. Ad hoc networks are formed when two or more devices (or hosts) are in proximity of each other. More devices may join at any time and can also leave at any time and thus may become unreachable. Two ad hoc networks mayalso merge to become one at anytime, and one Ad hoc network may partition into two. No base station is necessary, however a shared vision is.Ad hoc networks require multi-hop routing [4] (using algorithms such as AODV, ad-hoc on demand distance vector routing algorithm) and each device acts as a router/switch in order for communication to take place. An alternative approach to this would be for the designated devices to act as routers, and the others simply as end nodes.4. P2P NetworksP2P is a communication model in which each party has the same capabilities and either party can initiate a communication sessi on. Users can use the Internet to exchange files with each other directly or through a mediating server. P2P’s architecture allows for decentralised application design, moving from a centralised server model to a distributed model where each peer, independent of software and hardware platforms, can benefit from being connected to millions of other peers. Napster and Gnutella are examples of P2P using the Internet.A P2P application should be able to discover other peers in the network. Since P2P networks cannot operate in an environment of stable connectivity and fixed IP addresses, the nodes have to operate outside the Domain Name Service (this converts names to IP addresses) system. This is fundamental to the nature of P2P systems, and is how they w ork. If they used stable IP addresses, they would be no different from a normal infrastructured network [4]. So, the method used by the peers to locate each other is achieved in a pure P2P-based architecture by network broadcasting.Once an application is able to locate other peers, it should be able to communicate with them using messages. Once the communication is established with other peers, the application should be able to receive and provide information, such as content.5. The Convergence1A good solution to convergence should be transparently deployable and generally applicable. Transparent deployment means that the solution must not require changes to the implementation of the Web services, either to the server and client side modules or to the communication protocol between them. The growth in the number of Web services has been huge and hence applying changes to existing Web services is an improbable proposition. For the same reason, the solution should also be scalable and general enough to apply to all the Web services.5.1 Web Services With P2PThere are quite a few common features of P2P and Web Services technologies, as they both aim to become a common stack for publishing and discovery across networks. Since P2P networks are based on a decentralised model and its primary focus is on supplying processing power, content, or applications to peers in a distributed manner, it is less focused on messaging formats and communication protocols. Web Services, on the other hand, is based on a centralised model and its primary focus is on standardising messaging formats and communication protocols. The convergence of these two systems would enable companies to use the processing power benefits of the P2P networks, through the standard formats for discovery and content exchange over the standard communication protocols of the Web Services world [5].Web Services provide a very elegant way to handle: registration, discovery, and content lookup for P2P applications. As Web Services mature, their security standards would also ensure the integrity of data and services accessed by P2P software. Both user and application centered Web Services would play a role in P2P systems as the clients or nodes of a P2P system, ranging from a user, desktop, laptop, PDA, or Pocket PC to a server.Some examples of how large hardware and software vendors are planning to support P2P and Web Services platforms together: 1) Intel is building P2P components and services on top of Microsoft's .NET platform. Microsoft's Visual Studio .NET and Intel's P2P services are intended to serve as infrastructure for vendors developing P2P services like instant messaging (IM), knowledge management, and collaboration. 2) The Project JXTA P2P platform, supported by Sun Microsystems, is being changed at the core to make peers interoperate with Web Services using protocols like SOAP and WSDL [6]. 3) The Microsoft .NET Framework provides a rich platform for building P2P applications [7].Both P2P and Web Services technologies help to reduce some of the core complexities of each other. The communication between different peer systems should be based on open standards. This would allow companies to have different architectures and platforms for their P2P systems. Thus it is safe tosay that both P2P services and Web Services would rely on WSDL and SOAP for service descriptions and invocations [5].Many design problems associated with directory services, communication protocols, and message formats are being addressed by P2P applications. UDDI i s expected to reduce the complexity and amount of effort required to create P2P applications. As far as directory services are concerned, P2P technology has a lot to offer to Web Services technology as well. Using P2P, the Web Services implementation of using a single central UDDI registry, which contains the service description of Web Services, can be converted into a decentralised mode. It would be extremely difficult for a single registry provider to maintain that information and provide a high level of service. Since a P2P network is completely decentralised, the Web Services descriptions (the content of the UDDI registry) can be described and indexed locally to a given peer. The realistic vision is that the P2P systems would continue using the decentralised discovery model, while Web Services continue using the centralised discovery model of UDDI. Search engines would probably be the most widely used applications based on P2P and Web Services technologies, such as Google.There are a few challenges of P2P and Web Services converging that arise. A critical factor of the success of P2P technology and its convergence with Web Services is the available network bandwidth. As the number of peers searching for content or communicating in the network increases, the resulting traffic can potentially block the whole network bandwidth. P2P applications eliminate central servers and create a loose, dynamic network of peers. Thus any content retrieval operation, such as a search for a specific item in a database, all the peers in the network are searched, using a lot of network bandwidth. As this network size increases and becomes more distributed, it may be affected by poor and slow connections [5]. The decentralised and distributed architecture of P2P is also one of its largest weaknesses. P2P applications are a major security threat to companies, as by definition they distribute data and computing resources over several peers. The architecture of P2P-based applications with or without Web Services integrated is ex tremely complex. It involves security issues and use of distributed resources in an optimal way, making decentralised and independent systems work as one. Maintenance of such applications is much more difficult since it is extremely difficult to identify, replicate, and fix application or network related problems.The technologies enabling this convergence are some of the leading P2P protocols such as Jabber and JXTA. Jabber is an instant messaging and presence notification, open source XML-based protocol. It is platform neutral, thus Jabber is interoperable with messaging across both wireless and browser based messaging services. The real-time messages are exchanged as XML streams. Jabber's open XML protocol contains three top level XML elements, which in turn contain data through attributes and namespaces [8]. Project JXTA is an open network platform for P2P computing. It provides a framework and a set of protocols that standardise the way in which peers discover and advertise network resources, and communicate and cooperate with each other to form secure peer groups. Publishing and exchanging XML messages among participating peers perform all the functions supported by JXTA. JXTA is independent of programming language. Heterogeneous digital devices such as PCs, servers, PDA’s, and appliances with completely different software stacks can interoperate with JXTA protocols. Moreover, it is independent of transport protocols such as TCP/IP and HTTP and can be implemented on top of them like SOAP [6].5.2 Web Services With Ad Hoc NetworksA possible solution for web services working over this network could be the caching of web services. Since mobile nodes join and leave when they please there are times of disconnection from the Internet and as a result from the web service. Caching the web services to support this disconnected operation between nodes, which are connected to one another but not to the gateway providing the communication to the Internet seams to be a feasible solution for web services working over infrastructure-less networks. Service discovery would obviously have to be done when one the mobile nodes of the ad hoc network are connected to the Internet and using the AODV algorithm to route messages to the other nodes also trying to discover a web service and invoke operations on it.An experiment conducted as part of research at Microsoft in which a caching proxy was placed between Microsoft’s .NET My Services web service and the sample clients that ship with these services. The .NET My Services were chosen for this experiment because they were the only example of publicly available, non-trivial XML Web services that support both query and update operations [9]. An HTTP proxy server was built and deployed on the client device. All HTTP messages originating at the client, including those generated by Web clients and Internet browsers were made to pass through the proxy server. The proxy server acts as a simple tunnel for all HTTP packets that are not SOAP messages. A cache for storing SOAP messages was added to the proxy server. This cache stores SOAP messages received in response to SOAP requests. Whenever the network is connected, the SOAP request received is sent to the server. The received SOAP response is stored in the cache associatedwith the request, replacing the old response if it exists. In the case where the cache contained a previous response for the same request, the new SOAP response is compared to the previous response and the result of the comparison is recorded in a log file. These comparisons provide valuable insight into what kind of operations can be cached and what other operations affect the validity of the cached responses. If the network is disconnected, the SOAP response stored in the cache is returned to the client and the SOAP request is stored in a write back queue. All requests are stored in the write back queue for later replay since the cache manager cannot determine which requests modify the service state and which are simply non-update queries. Whenever the connection to the Web service is restored, the queued up SOAP requests are played back to the server and the SOAP responses are stored in the cache [10].The experiment was able to demonstrate that web services such as the one examined can be used during dis connections with little awareness of the disconnection. It also proved that caching everything works well for the large class of Web services that only provide query operations on fairly static data, such as map services, currency conversion services and yellow page services. However, the experiment also exposed a number of issues that need to be handled in order achieve a significant improvement in the consistency and availability of offline access to Web services.When operating in disconnected mode, a cache manager cannot provide strong consistency (maintenance of correctness and validity of data) guarantees since it does not have access to updates performed by other users. In order to maintain correctness, the earlier response in the cache would have to be either correctly modified or deleted from the cache [9]. Ideally, a user should obtain the same experience when disconnected as when connected. However, achieving the ideal goal is not practically feasible, especially if the Web client is unaware of the existence of the cache.To eliminate some of the issues arising from the standard caching architecture an enhanced Web services cache architecture has been developed. This adjusts its behavior for different Web services and is based on WSDL annotations to improve availability of Web services[10]. The Web service cache resides in a HTTP proxy server on the client device as before. A Custom Cache Manager is a new addition to enhanced web services cache that is generated automatically for each Web service that has an annotated WSDL specification. The custom cache manager controls the behavior of the cache according to the annotations described in the WSDL document. For regularly used Web services, annotating the services WSDL documents is recommended so that custom cache managers can be used. The default cache manager can be useful in those cases where annotations are not available.6. ConclusionsIt seems the integration of web services with infrastructure-less networks is a very useful concept and should definitely be deployed seamlessly in the future when the web service technology it self has matured along with the P2P and Ad hoc without a doubt. Even now it is possible but with many limitations in place and also without maximum transparency or full scalability. The models discussed in section 5 require further evaluation and research before they can be widely adopted for everyday use. Further work for this project includes implementing simple web services over infrastructured networks (including wireless networks) to show what does work and to show the diversity of web services. In addition to this, further expanding on the models and technologies reviewed in this paper to complete the detailed analysis.References[1] Web Services Architecture: Direction & Position Paper, Donald F. Ferguson, dff@IBM Corporation Paper for W3C Web Services Workshop, April 11-12, 2001[2] The Java Web Servcies Tutorial, Eric Armstrong, Stephanie Bodoff, Debbie Carson, MaydeneFisher, Dale Green, Kim Haase, August 1, 2002,/webservices/tutorial.html[3] Ad hoc networking, C. E Perkins, Addison Wesl ey, 2001[4] Distributed Systems Concepts and Design, George Coulouris, Jean Dollimore, Tim Kindberg,Third Edition, Addison Wesley, ISBN: 0201-61918-0, 2001[5] Web Services and P2P Computing, Gunjan Samtani, Dimple Sadhwani, Tect, 2002, 29 SouthLaSalle St. Suite 520 Chicago Illinois 60603, USA, [6] Project JXTA v2.0: Java Programmer’s Guide, Sun Microsystems, May 2003,/docs/JxtaProgGuide_v2.pdf[7] Support WebCast: Microsoft .NET: Introduction to Web Services, published under Q324881,2003, /default.aspx?scid=kb;en-us;324881&gssnb=1[8] Jabber Technology Overview,Jabber Software Foundation, 2002, /[9] Caching of XML Web Services for Disconnected Operation, Venugopalan Ramasubramanian andDouglas B. Terry, Microsoft Research, 1065 La Avenida, Mountain View, CA 94043, 2002 [10] Caching XML web services for mobility, DOUGLAS B. TERRY AND VENUGOPALANRAMASUBRAMANIAN, 2002, /people/ramasv。

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Amazon Web Services (AWS)安全性白皮书说明书

Amazon Web Services (AWS)安全性白皮书说明书

WHITE PAPERExecutive SummaryOrganizations are turning to Amazon Web Services (AWS) in vast numbers to extend internal data centers and take advantage of the elasticity of the cloud. While AWS secures the infrastructure, AWS end-users are responsible for protecting everything residing within it—as described in the AWS Shared Responsibility Model. Faced with a fluid, fast-growing attack surface, however, organizations continue to rely on a multiplicity of disparate security technologies, platforms, and management tools to protect their AWS environments.This fragmented, complex approach to managing security across every AWS instance means that organizations lack transparent security visibility and control. They also find themselves in a reactive security mode instead of taking a proactive approach in responding to threats. Moreover, one of the reasons end-users opt for AWS is its elasticity—the ability to quickly scale up and down cloud services based on business requirements and user demands. This elasticity means it is difficult to extend and scale security components to meet this rapid change.What Keeps AWS On Top?AWS is shaking up the cloud computing market in the same way parent company Amazon has changed the retail landscape. Indeed, the popularity of AWS—from servers, storage, and networking to remote computing, email, and security—is such that the organization now comprises 10% of Amazon’s total revenues and more than 50% of the parent company’s profits1.AWS is also the market leader in Infrastructure-as-a-Service (IaaS), with 33% market share.2 And its other offerings such as Platform-as-a-Service (PaaS) continue to gain momentum. It thus should be no surprise that AWS boasts a global customer base that spans the newest startup companies to Fortune 500 companies.What makes AWS so successful? Four criteria dominate. First, AWS is innovating at lightning speed, keeping pace with industry trends and rapidly adding new services like data analytics and machine learning. Second, the organization has a vast, global customer and partner ecosystem. Third, AWS has market experience, having been among the first to market for public cloud services more than 10 years ago. Finally, there’s the fiscal argument. Developing, deploying, and managing critical applications in AWS delivers a 64% savings when compared with deploying the same resources in onpremises or hosted environments.3Addressing Security Challenges For Workloads With AWSIT and business leaders welcome the adoption of AWS’ on-demand infrastructure and services and are capitalizing on the promise of increased agility, lower costs, and improved flexibility. However, as often is the case with new opportunities, challenges also occur when moving workloads onto AWS. While the AWS infrastructure has embedded security tools and controls, the individual AWS environments—public, private, and hybrid—lack a consolidated security architecture. This results in various security challenges that CISOs must tackle.1. Cloud Proliferation Creates Security SilosThe surge in demand for AWS results in a proliferation of AWS cloud environments. A survey by RightScale found that enterprisesare running applications in an average of 4.8 clouds (3.1 clouds in production and experimenting with 1.7).4 Another discovered that companies use an average of 16 cloud-based Software-as-aService (SaaS) applications to help run their business.5 While these organizations may have other cloud providers outside of AWS, the likelihood is that they have multiple AWS instances.When it comes to security, the result is a multi-cloud environment that leverages security within silos. When Shadow IT is added to the mix, where individual departments or teams use cloud services and applications outside of the corporate IT procurement process, the complexity of managing these multiple cloud instances, including AWS, increases.AWS security is based on a Shared Responsibility Model. AWS is responsible for the security of the cloud, including the compute, storage, and database resources. End-users, meanwhile, are responsible for security in the cloud, such as data, applications, operating systems, and firewalls. But when security tools and processes reside within each AWS deployment, this incurs inefficiencies, diminishes the security posture, and increases complexity.2WHITE PAPER |Solores Tiassiti Alit Esti Autent Ut Repta Doluptati2. Lack of Security Visibility and ControlsWith AWS cloud environments residing within their own silos, this prevents end-users from seeing across and between each AWS instance, not to mention having a consolidated view of the entire attack surface and security components that includes each AWS instance.This creates manual processes for cybersecurity teams that are already overburdened, as they must build and consolidate security logs for each AWS account and deploy and manage security policies accordingly. Since there are currently 1 million unfilled cybersecurity positions today, a number that is expected to grow to 3.5 million in a few years, security leaders—even if they have budget to add more security headcount—cannot find the subject-matter security professionals needed to fulfill these additional security tasks.63. Growing, Evolving Attack SurfaceMigration of on-premises infrastructure to AWS and the adoption of new digital transformation (DX) initiatives on AWS expand the attack surface. Moreover, cloud deployments aren’t static, experiencing fluctuations and changes based on traffic and data volumes and business demands. As a result, it is more difficult to seamlessly extend security tools to accommodate these variables, with already overtaxed security teams typically turning to manual processes to overcome the problem.4. Cloud Agility and Scalability Complicates Security ProtectionsDynamic cloud workloads have peak and off-peak hours. Indeed, it is this scalability that makes AWS such an appealing proposition for organizations. However, the effective application of AWS cloud security requires an ability to scale up and down in concert with the workload. But traditional security architectures don’t meet this requirement. Connections between security elements and cloud silos break and must be manually reconnected. And as workloads scale horizontally, security protections can be compromised. One option to address the latter issue is to deploy more network security firewalls, but this can be prohibitively expensive, with firewalls frequently sitting idle during nonpeak sessions.5. Threat Prevention and DetectionMany attacks are multivector and polymorphic. With separate AWS instances, organizations lack the ability to share real-time threat intelligence across their AWS environment as well as with other potential access points in their IT infrastructure—endpoints, email, data center, and so forth. Disaggregated security also prevents security organizations from automating processes such as compliance tracking and reporting and real-time threat-intelligence sharing. Additionally, it is impossible for security teams to segment users, applications, and devices and to centrally manage security policies and controls across them. All of these issues create security gaps that hacktivists can exploit.ConclusionAs more and more organizations migrate workloads, data, and applications to AWS, their cloud environments quickly evolve. These AWS instances present significant security challenges, as complexity escalates, visibility gets obscured, manual processes burgeon, and overall risk postures increase. Traditional security approaches cannot scale to protect this expanding attack surface, and the lack of integration thwarts automation of processes and protections. They also cannot accommodate the rapid and evolving changes taking place in the threat landscape, where attacks target multiple entry points concurrently and zero-day threats are increasingly accessible to all types of bad actors. Security leaders are unable to extract themselves and their teams from a reactive security approach and develop a proactive security model that reduces risks.1 Jordan Novet, “Amazon cloud revenue jumps 45 percent in fourth quarter,” CNBC, February 1, 2018.2 Mike Robuck, “Report: Amazon Web Services still rules the cloud roost for market share,” FierceTelecom, April 27, 2018.3 Larry Carvalho and Matthew Marden, “Quantifying the Business Value of Amazon Web Services,” IDC, May 2015.。

电子商务课程知识点总结

电子商务课程知识点总结

2014年《电子商务》知识点总结第一章：1、电子商务的狭义和广义概念；电子商务的类型。

●狭义的电子商务定义(EC)：单纯地从商品或服务的交易角度定义电子商务，指借助互联网及相关通讯技术从事信息、产品和服务的买卖和交换的过程。

●广义的电子商务定义(EB)：从整个供应链角度定义电子商务，是指企业从原料供应到生产、分销、零售等全部经营过程与经营活动的信息化、网络化，公司内部部门之间以及公司与供应商、分销商、零售商直至客户之间的协同和信息共享是EB的主要特征，如Dell()、IBM()。

●Fivegenerale-commercecategories:Business-to-consumer(B2C)⏹Business-to-business(B2B)⏹Businessprocessesthatsupportbuyingandsellingactivities(B2E)⏹Business-to-government(B2G)⏹Consumer-to-consumer(C2C)⏹Consumer-to-Business(C2B)2、电子商务的商业模式及其六要素1.Direct sales （直销）Intermediary （中介）Content provider （内容提供商）Full-service provider （服务提供商）Shared public infrastructure （公共基础设施）Software supplier （软件提供商）Virtual community （虚拟社区）Consolidator of service（综合服务商）●Six elements of a business model include:A.Customers to be served and the company’s relationships with these customersincluding customers’ value proposition.B.All products and services the business will offerC.The business process required to make and deliver the products and servicesD.The resources required and the identification of which ones are available, which will bedeveloped in house, and which will need to be acquiredE.The organization’s supply chain, including suppliers and other business partnersF.The revenues expected (revenue model),anticipated costs, sources of financing, andestimated profitability (financial viability)3、电子商务的盈利模式与商业模式的区别及联系●Business Model: how a company operates its business processes and generates its corecompetition.●Revenue model: Description of how the company or an EC project will earn revenue●The major revenue models are:A.SalesB.Transaction feesC.Subscription feesD.Advertising feesE.Affiliate feesF.Other revenue source4、网络外部性Network externalitiesWhen the value of a technology, product, or service depends upon the number of other entities using it, the phenomenon is called network externality.5、梅奥法则●Metcalfe's law（梅特卡夫定律）states that the value of a telecommunications network isproportional to the square of the number of connected users of the system (n2).●Metcalfe's Law is related to the fact that the number of unique connections in a network of anumber of nodes (n) can be expressed mathematically as n(n−1), which is proportional to n2 asymptotically.6、电子商务如何降低了企业的交易成本？Businesses and individuals can use electronic commerce to reduce transaction costs by:●Improving the flow of information●Increasing coordination of actions7、波特的价值链模型●把企业内外价值增加的活动分为基本活动和支持性活动，基本活动涉及企业生产、销售、进料后勤、发货后勤、售后服务。

云计算技术英语

云计算技术英语

云计算技术英语Title: Understanding Cloud Computing TechnologiesCloud computing has revolutionized the way businesses and individuals interact with technology. At its core, cloud computing is the delivery of computing resources and data storage over the internet. These resources are provided on-demand and can be scaled up or down as needed. Thisflexibility allows users to pay only for the services they use, rather than investing in expensive hardware and software that may not always be fully utilized.The foundation of cloud computing is built upon a myriadof technologies that work in harmony to provide seamless services. These technologies include virtualization, utility computing, service-oriented architecture, autonomic computing, and network-based computing, among others. Let's delve deeper into each of these key technologies.Virtualization is a cornerstone of cloud computing. It enables the creation of virtual machines (VMs) which are software-based emulations of physical servers. These VMs can run multiple operating systems and applications on a single physical server, maximizing resource utilization and reducing costs. Virtualization also allows for the rapid deployment and decommissioning of environments, providing agility and scalability to cloud services.Utility computing extends the concept of virtualization by treating computing resources like a metered service, similar to how utilities like electricity are billed based on consumption. This model allows cloud providers to offer flexible pricing plans that charge for the exact resources used, without requiring long-term contracts or minimum usage commitments.Service-Oriented Architecture (SOA) is a design pattern that structures an application as a set of interoperableservices. Each service performs a unique task and can be accessed independently through well-defined interfaces and protocols. In the cloud, SOA enables the creation of modular, scalable, and reusable services that can be quickly assembled into complex applications.Autonomic computing is a self-managing system that can automatically optimize its performance without human intervention. It uses advanced algorithms and feedback mechanisms to monitor and adjust resources in real-time. This technology is essential in the cloud where the demand for resources can fluctuate rapidly, and immediate responses are necessary to maintain optimal performance.Network-based computing focuses on the connectivity between devices and the efficiency of data transmission. Cloud providers invest heavily in high-speed networks to ensure low latency and high bandwidth for their services. The reliability and security of these networks are paramount toensure uninterrupted access to cloud resources and to protect sensitive data from breaches.In addition to these foundational technologies, cloud computing also relies on advanced security measures, such as encryption and multi-factor authentication, to safeguard data and applications. Disaster recovery strategies, includingdata backups and replication across multiple geographic locations, are also critical to ensure business continuity in the event of a failure or disaster.Cloud computing models are typically categorized intothree types: Infrastructure as a Service (IaaS), Platform asa Service (PaaS), and Software as a Service (SaaS). IaaS provides virtualized infrastructure resources such as servers, storage, and networking. PaaS offers a platform fordevelopers to build, test, and deploy applications, while abstracting the underlying infrastructure layers. SaaSdelivers complete software applications to end-users via theinternet, eliminating the need for local installations and maintenance.Choosing the right cloud service provider is crucial for businesses looking to leverage cloud computing. Providerslike Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Platform (GCP) offer a range of services tailored to different needs and budgets. These platforms are designed to be highly scalable, reliable, and secure, with features such as automated scaling, load balancing, and comprehensive monitoring tools.Furthermore, cloud providers often offer specialized services for specific industries or use cases. For example, AWS offers Amazon S3 for object storage, Amazon EC2 for virtual servers, and Amazon RDS for managed databases. Microsoft Azure provides Azure Active Directory for identity management and Azure Machine Learning for building predictivemodels. GCP offers BigQuery for big data analytics and App Engine for scalable web application hosting.As cloud computing continues to evolve, new trends and innovations emerge. Edge computing, for instance, aims to bring computation closer to data sources by processing data at the edge of the network, reducing latency and bandwidth usage. Serverless computing, another rising trend, allows developers to focus solely on writing code without worrying about the underlying infrastructure, as the cloud provider dynamically manages the execution environment.In conclusion, cloud computing technologies have enabled a paradigm shift in how we approach IT resource management and consumption. By understanding the various technologies and models at play, businesses can make informed decisions about adopting cloud solutions that align with their strategic goals. As the landscape of cloud computing continues to mature, it will undoubtedly present newopportunities and challenges that must be navigated with a keen eye on technological advancements and market dynamics.。

雅思阅读全真模考题：短信电视的进化版

雅思阅读全真模考题：短信电视的进化版

雅思阅读全真模考题：短信电视的进化版小站独家，最新雅思阅读全真模拟试题。

一切患有雅思阅读刷题强迫症的烤鸭，请看这里。

小站精心整理了一批雅思阅读模拟试题。

如果你的剑桥雅思阅读已是烂熟于心，那么这一系列的模拟题真的很适合你，搭配上绝对原创的讲解，还有全文的中文翻译，这等阅读大餐，还等什么！Texting! the television 2A THERE was a time when any self-respecting television show,particularly one aimed at a young audience, had to have an e-mail address. But on Europe's TV screens, such addresses are increasingly being pushed aside in favour of telephone numbers to which viewers can send text messages from their mobile phones. And no wonder: according to research about to be published by Gartner, aconsultancy, text messaging has recently overtaken Internet use in Europe. One of the fastest-growing uses of text messaging, moreover, is interacting with television. Gartner’s figures show that 20% of teenagers in France, 11 % in Britain and 9% in Germany have sent messages in response to TV shows.B This has much to do with the boom in “reality TV” shows, such as“Big Brother”, in which viewers’ voles decide theoutcome. Most reality shows now allow text-message voting, and in some cases, such as the most recent series of “Big Brother” in Norway, the majority of votes are cast in this way. But there is more to TV-texting thanvoting. News shows encourage viewers to send in comments; games shows allow viewers to compete; music shows take requests by text message;and broadcasters operate on-screen chartrooms. People tend to have their mobiles with them on the sofa, so “it’s a very natural for m of interaction,” says Adam Daum of Gartner.C It can also be very lucrative, since mobile operators charge premiumrates for messages to particular numbers. The most recent British series of “Big Brother”, for example, generated 5.4m text-message votes and ￡1.35m (S2. lm) in revenue. According to a re port from Van Dusseldorp& Partners, a consultancy based in Amsterdam, the German edition of MTV's “Videoclash”，which invites viewers to vote for one of two rival videos, generates up to 40,000 messages an hour, each costing curo0.30 ($0.29). A text contest alongside the Belgian quiz show “1 Against 100” (以一敌百)attracted 110.000 players ina month, each of whom paid euro 0.50 per question in an eight-roundcontest. In Spain, a cryptic-crossword(神秘的猜字游戏) clue is displayed before the evening news broadcast; viewers are invited to text in their answers at a cost of euro 1, for a chance to win a curo300 prize. On a typical day, 6,000 people take part. TV-related text messaging now accounts for an appreciable share of mobile operators' data revenues. In July, a British operator, mmO2, reportedbetter-than-expected financial results, thanks to the flood of messages caused by “Big Brother”. Operators typically lake 40-50% of the revenue from each message, with the rest divided between the broadcaster, the programme maker and the firm providing themessage-processing system. Text-message revenues are already a vital element of the business model for many shows. Inevitably, there is grumbling（怨言）that the operators take too much of thepie. Endemol, the Netherlands-based production company behind “Big Brother”, and many other reality TV shows has started building its own database of mobile-phone users. The next step will be to establish direct billing relationships with them, and bypassthe operators(运营商).D Why has the union of television and text message suddenly proved sosuccessful? One important factor is the availability of special four-, five- or six-digit numbers, called “shortcodes”(简码).Each operator controls its own shortcodes, and only relatively recently have operators realised that it makes sense to co-operate and offer shortcodes that work across all networks. The availability of such common shortcodes was a breakthrough, says Lars Becker of Flytxt, a mobile-marketing firm, since shortcodes are far easier to remember when flashed up on the screen.E The operators' decision to co-operate in order to expand the marketis part of a broader trend, observes Katrina Bond of Analysys, a consultancy. Faced with a choice between protecting theirmargins and allowing a new medium to emerge, operators have always chosen the first. WAP(无线应用协议），a technology for reading cut-down web pages on mobile phones, failed because operators were reluctant to share revenue with content providers. Having learnt their lesson, operators are changing their time. In France, one operator. Orange, has even gone so far as to publish a rate card for text-message revenue-sharing, a degree of transparency(透明度）that would once have been unthinkable.F At a recent conference organised by Van Dusseldorp &Partners, HanWeegink of CMG, a firm that provides text-message infrastructure, noted that all this is subtly changing the nature of television.Rather than presenting content to viewers, an increasing number of programmes involve content that reacts to the viewer's input. That was always the promise of interactive TV, of course. Interactive TV was supposed to revolve around fancy set-top boxes that plug directly into the television. But that approach has a number of drawbacks, says MrDaum. It is expensive to develop and test software for multiple and incompatible types of set-top box, and the market penetration, at 40% or less, is lower than that for mobile phones, which are now owned by around 85% of Europeans. Also, mobile-phoneappli cations can be quickly developed and set up. “You can get to market faster, and with fewer grasping(贪婪的) intermediaries,”says MrDaum. Providers of set-top box technology are addingtext-messaging capabilities to their products.G The success of TV-related texting is a reminder of howeasily anelaborate technology can be unexpectedly overtaken by a simpler, lower-tech approach. It does not mean that the traditional approach to interactive TV is doomed: indeed, it demonstrates that there is strong demand for interactive services. People, it seems, really do want to do more than just stare at the screen. If nothing else, couch potatoes like to exercise their thumbs.Questions 28-32The reading passage has seven paragraphs, A-EChoose the correct heading for paragraphs A-E from the list below. Write the correct number, i-ix, in boxes 28-32 on your answer sheet.List of Headingsi an existed critical system into operating in a new wayii Overview of a fast growing businessiii profitable games are gaining more concernsiv Netherlands takes the leading rolev a new perspective towards sharing the businessopportunitiesvi opportunities for all round prevalent applicationsvii revenue gains and bonus shareviii the simpler technology prevails over complex onesix set-top box provider changed their mind28 Paragraph A29 Paragraph B30 Paragraph C31 Paragraph D32 Paragraph EQuestions 33-35Choose the correct letter, A, B, C or D.Write your answers in boxes 33-35 on your answer sheet.33 33.In Europe, a consultancy suggested that young audiences spend moremoney on:A thumbing text messageB writing E-mailC watching TV programD talking through Mobile phones34 What happened when some TV show invited audience to participate:A get attractive bonusB shows are more popular in Norway than in other countriesC change to invite them to the reality showD their participation could change the result35 Interactive TV change their mind of concentrating set-top box butswitched to:A increase their share in the marketB change a modified set-top boxC build an embedded message platformD march into European marketQuestions 36-40Use the information in the passage to match the people (listed A-E) with opinions or deeds below. Write the appropriate letters A-F in boxes 36-40 on your answer sheet.A Lars Becker FlytxtB Katrina Bond of AnalysysC EndemolD CMCE mmO2F Gartner36 offer mobile phone message technology37 earned considerable amount of money through a famous program38 shortcodes are convenient to remember when turn up39 build their own mobile phone operating applications40 it is easy for people to send messages in an interactive TV结构（一句话概括每段大意）A段：短信在电视节目中日趋盛行B段：短信在节目中流行的原因C段：短信为运营商带来巨大收益D段：简码的运用是电视短信成功的重要因素E段：运营商的利益分配机制F段：互动电视的利与弊雅思阅读全真模考题:短信-电视的进化版。