云计算毕业设计外文文献

关于云计算的英语作文英文回答：Cloud computing has revolutionized the way businesses and individuals store, process, and access data and applications. As a result, there are multiple benefits of cloud computing, including improved flexibility, reduced costs, increased security, enhanced collaboration, and innovative services.Flexibility is one of the key advantages of cloud computing. It allows users to access their data and applications from anywhere with an internet connection. This makes it easier for businesses to operate remotely and for individuals to work from home.Reduced costs are another advantage of cloud computing. Businesses can avoid the upfront costs of purchasing and maintaining their own IT infrastructure. Instead, they can pay for cloud services on a pay-as-you-go basis.Increased security is another key benefit of cloud computing. Cloud providers have invested heavily insecurity measures to protect their customers' data. This makes cloud computing a more secure option than storingdata on-premises.Enhanced collaboration is another advantage of cloud computing. Cloud-based applications make it easier forteams to collaborate on projects. This is because cloud applications can be accessed from anywhere, and they allow users to share files and collaborate in real-time.Innovative services are another key benefit of cloud computing. Cloud providers are constantly developing new services, such as artificial intelligence, machine learning, and data analytics. These services can help businesses improve their operations and make better decisions.Overall, cloud computing offers a number of benefitsthat can help businesses and individuals improve their operations, reduce costs, and increase innovation.中文回答：云计算的优势。

淮阴工学院毕业设计说明书（论文）作者: ** 学号：10813013**学院: 计算机工程专业: 计算机科学与技术题目: 专家系统指导者：(姓名) (专业技术职务)评阅者：(姓名) (专业技术职务)年月毕业设计说明书（论文）中文摘要系统介绍：专家系统是一种计算机程序，是计算机科学的一个分支主要研究人工智能。

人工智能的科学目标是能让计算机程序展示智能行为。

它关注象征性的推理或推理的概念和方法，以及如何使用知识将这些理论放入一台机器内。

当然，长期的智能包含了很多认知技能，包括解决问题，学习，理解语言的能力，人工智能能解决所有的这些问题。

但大多数已经取得的进展，已经取得了该问题的解决。

人工智能程序到达专家级解决问题的能力在任务地区将承担的知识有关的具体任务是所谓的知识或专家系统。

通常，长期的专家系统是保留程序的基础知识，包含人类专家的知识。

和教科书或非专家知识的对比，往往，专家系统和基于知识的系统公司同义。

两者合计，他们代表了人工智能应用最广泛的类型。

在专家系统捕获人类智力活动的区域被称为任务域。

域是指正在执行任务的区域，任务是指一些以目标位向导，解决问题的活动。

典型的任务是诊断，规则，调度，配置和设计。

专家系统被称为知识工程及其从业人员被称为知识的工程师。

知识工程师必须确保计算机的所有知识需要解决一个问题。

知识工程师必须选择一个或多个形式，代表所需的知识为符号模式在计算机的内存——也就是说，他（或她）必须选择一种知识表示。

他还必须确保计算机可以使用的知识有效地选择从一个几个推理方法。

实践知识工程描述。

我们首先描述了专家系统的组成部分。

专家系统的组成：每一个专家系统由两个主要部分组成：知识库和推理或推论，发动机专家系统的知识库包含事实和启发式知识。

事实性知识是任务域被广泛共享，通常在教科书或期刊，并共同商定后，在特定领域的那些知识渊博的知识启发式知识是不太严格，更多体验，更多的判断性能的知识。

在事实性知识，启发式知识很少被讨论，主要是个人主义。

本文档包括该专题的：外文文献、文献综述文献标题：An exploratory study on factors affecting the adoption of cloud computing by information professionals作者：Aharony, Noa期刊：The Electronic Library, 33(2), 308-328.年份：2015一、外文文献An exploratory study on factors affecting the adoption of cloud computing byinformation professionals(影响云计算采用与否的一个探索性研究)Aharony, NoaPurpose- The purpose of this study explores what factors may influence information professionals to adopt new technologies, such as cloud computing in their organizations. The objectives of this study are as follows: to what extent does the technology acceptance model (TAM) explain information professionals intentions towards cloud computing, and to what extent do personal characteristics, such as cognitive appraisal and openness to experience, explain information professionals intentions to use cloud computing.Design/methodology/approach- The research was conducted in Israel during the second semester of the 2013 academic year and encompassed two groups of information professionals: librarians and information specialists. Researchers used seven questionnaires to gather the following data: personal details, computer competence, attitudes to cloud computing, behavioral intention, openness to experience, cognitive appraisal and self-efficacy. Findings- The current study found that the behavioral intention to use cloud computing was impacted by several of the TAM variables, personal characteristics and computer competence.Originality/value- The study expands the scope of research about the TAM by applying it to information professionals and cloud computing and highlights the importance of individual traits, such as cognitive appraisal, personal innovativeness, openness to experience and computer competence when considering technology acceptance. Further, the current study proposes that if directors of information organizations assume that novel technologies may improve their organizations' functioning, they should be familiar with both the TAM and the issue of individual differences. These factors may help them choose the most appropriate workers.Keywords: Keywords Cloud computing, TAM, Cognitive appraisal, Information professionals, Openness to experienceIntroductionOne of the innovations that information technology (IT) has recently presented is thephenomenon of cloud computing. Cloud computing is the result of advancements in various technologies, including the Internet, hardware, systems management and distributed computing (Buyya et al. , 2011). Armbrust et al. (2009) suggested that cloud computing is a collection of applications using hardware and software systems to deliver services to end users via the Internet. Cloud computing offers a variety of services, such as storage and different modes of use (Leavitt, 2009). Cloud computing enables organizations to deliver support applications and avoid the need to develop their own IT systems (Feuerlicht et al. , 2010).Due to the growth of cloud computing use, the question arises as to what factors may influence information professionals to adopt new technologies, such as cloud computing, in their organizations. Assuming that using new technologies may improve the functioning of information organizations, this study seeks to explore if information professionals, who often work with technology and use it as an important vehicle in their workplace, are familiar with technological innovations and whether they are ready to use them in their workplaces. As the phenomenon of cloud computing is relatively new, there are not many surveys that focus on it and, furthermore, no one has so far focussed on the attitudes of information professionals towards cloud computing. The research may contribute to an understanding of the variables that influence attitudes towards cloud computing and may lead to further inquiry in this field.The current study uses the well-known technology acceptance model (TAM), a theory for explaining individuals' behaviours towards technology (Davis, 1989; Venkatesh, 2000), as well as personal characteristics, such as cognitive appraisal and openness to new experiences, as theoretical bases from which we can predict factors which may influence information professionals adopting cloud computing in their workplaces. The objectives of this study are to learn the following: the extent to which the TAM explains information professionals' attitudes towards cloud computing, and the extent to which personal characteristics, such as cognitive appraisal and openness to experiences, explain the intention of information professionals to use cloud computing.Theoretical backgroundCloud computingResearchers have divided cloud computing into three layers: Software as a Service (SaaS), Platform as a Service (PaaS) and Infrastructure as a Service (IaaS). SaaS has changed the concept of software as a product to that of a service instead. The software runs in the cloud and the user can access it via the Internet to work on an application. PaaS enables powerful tools for developers to create the applications, without having to deal with concerns about the infrastructure. IaaS provides complete infrastructure resources (e.g. servers, software, network equipment and storage). With IaaS, consumers do not have to purchase the latest technology, perform maintenance, upgrade software or buy software licenses (Anuar et al. , 2013). Cloud computing deployment can be divided into four types: private clouds, public clouds, community clouds and hybrid clouds (Mell and Grance, 2011). Public clouds have open access, private clouds run within organizations, community clouds containresources that are shared with others in the community and hybridclouds encompass two or more cloud models. Anuar et al. (2013) presented the main characteristics of cloud computing: flexible scale that enables flexible-scale capabilities for computing; virtualization that offers a new way of getting computing resources remotely, regardless of the location of the user or the resources; high trust , as the cloud offers more reliability to end users than relying on local resources; versatility , because cloud services can serve different sectors in various disciplines use the same cloud; and on demand service , as end users can tailor their service needs and pay accordingly.As cloud computing is relatively new, there are not a lot of surveys that focus on it. Several researchers conducted in-depth interviews investigating respondents' attitudes towards keeping their virtual possessions in the online world (Odom et al. , 2012). Teneyuca (2011) reported on a survey of cloud computing usage trends that included IT professionals as respondents. Results revealed preferences for virtualization and cloud computing technologies. However, the major reasons for cloud computing adoption being impeded were the lack of cloud computing training (43 per cent) and security concerns (36 per cent). Another report showed that nearly 40 per cent of Americans think that saving data to their hard drive is more secure than saving it to a cloud (Teneyuca, 2011). A further study (Ion et al., 2011) explored private users' privacy attitudes and beliefs about cloud computing in comparison with those in companies. Anuar et al. (2013) investigated cloud computing in an academic institution, claiming that cloud computing technology enhances performance within the academic institution. A study that was carried out in the education arena examined factors that led students to adopt cloud computing technology (Behrend et al. , 2010). Technology acceptance modelThe TAM (Davis, 1989) is a socio-technical model which aims to explain user acceptance of an information system. It is based on the theory of reasoned action (TRA) (Fishbein and Ajzen, 1975) which seeks to understand how people construct behaviours. The model suggests that technology acceptance can be explained according to the individual's beliefs, attitudes and intentions (Davis, 1989). The TAM hypothesizes that one's intention is the best predictor of usage behaviour and suggests that an individual's behavioural intention to use technology is determined by two beliefs: perceived usefulness (PU) and perceived ease of use (PEOU). PU refers to the individual's perception that using a technology will improve performance and PEOU addresses a user's perceptions that using a particular system would be free of effort (Davis, 1989). The current study concentrates on PEOU as the researchers wanted to examine if information professionals' perceptions about new technology is affected by its simplicity and friendly interface. Earlier research mainly investigated personal behaviour to use new information systems and technology in the following: corporate environments (Gefen and Straub, 1997);Web shopping (Chang et al. , 2002; Lin and Lu, 2000);education, particularly e-learning (Park, 2009) and m-learning (Aharony, 2014); and the library arena (Aharony, 2011; Park et al. , 2009).Personal innovativenessA construct which may contribute to information professionals' intention behaviour to use cloud computing is personal innovativeness, a major characteristic in innovation diffusion research in general (Agarwal and Prasad, 1998; Rogers, 1983, 1995). Agarwal and Prasad (1998) have coined the term "personal innovativeness in the domain of IT" (PIIT), which describes a quite stable characteristic of the individual across situational considerations. Previous studies found that personal innovativeness is a significant determinant of PEOU, as well as of PU (Agarwal and Karahanna, 2000; Lewis et al. , 2003). Several researchers have suggested that innovative people will search for intellectually or sensorially stimulating experiences (Uray and Dedeoglu, 1997).Openness to experienceAnother variable that may predict respondents' perspectives towards cloud computing is openness to experience which addresses the tendency to search for new and challenging experiences, to think creatively and to enjoy intellectual inquiries (McCrae and Sutin, 2009). People who are highly open to experience are perceived as also open to new challenges, thoughts and emotions (McCrae and Costa, 2003). Studies reported that there is a positive relation between openness to experience and intelligence tests (Gignac et al. , 2004). According to Weiss et al. (2012), challenging transitions may influence differently those who are high or low in openness to experience. Those who are high may approach these situations with curiosity, emphasizing the new possibilities offered to them. However, those who are low in openness may be threatened and try to avoid them by adhering to predictable environments. Various researchers note that people who are high in openness to experience are motivated to resolve new situations (McCrae, 1996; Sorrentino and Roney, 1999). Furthermore, openness to experience is associated with cognitive flexibility and open-mindedness (McCrae and Costa, 1997), and negatively associated with rigidity, uncertainty and inflexibility (Hodson and Sorrentino, 1999). Thus, people who are less open to experience tend to avoid novelty and prefer certainty. Studies reveal that openness to experience declines in the later years (Allemand et al. , 2007; Donnellan and Lucas, 2008).Challenge and threatThe following section will focus on the personality characteristics of challenge and threat that might affect information professionals' behavioural intention to use cloud computing. Challenge and threat are the main variables of a unidimensional, bipolar motivational state. They are the result of relative evaluations of situational demands and personal resources that are influenced both by cognitive and affective processes in motivated performance situations (Vick et al. , 2008). According to Lazarus and Folkman (1984), challenge refers to the potential for growth or gain and is characterized by excitement and eagerness, while threat addresses potential harm and is characterized by anxiety, fear and anger. Situations that suggest low demands and high resources are described as challenging, while those that suggest high demands and low resources are perceived as threatening (Seginer, 2008). In general, challenge or threat can take place in situations such as delivering a speech, taking a test, sports competitions or performing with another person on a cooperative or competitive task.The challenge appraisal suggests that with effort, the demands of the situation can be overcome (Lazarus et al. , 1980; Park and Folkman, 1997). On the other hand, threat appraisal indicates potential danger to one's well-being or self-esteem (Lazarus, 1991; Lazarus and Folkman, 1984), as well as low confidence in one's ability to cope with the threat (Bandura, 1997; Lazarus, 1991; Lazarus and Folkman, 1984). Different studies (Blascovich et al. , 2002; Blascovich and Mendes, 2000; Lazarus and Folkman, 1984; Lazarus et al. , 1980) have found that challenge leads to positive feelings associated with enjoyment, better performance, eagerness and anticipation of personal rewards or benefits. Several studies which focussed on the threat and challenge variable were carried out in the library and information science environment as well (Aharony, 2009, 2011).Self-efficacyAn additional variable which may influence individuals' behavioural intention to use cloud computing is self-efficacy. The concept of self-efficacy was developed in the discipline of "social learning theory" by Bandura (1997). Self-efficacy addresses individuals' beliefs that they possess the resources and skills needed to perform and succeed in a specific task. Therefore, individuals' previous performance and their perceptions of relevant resources available may influence self-efficacy beliefs (Bandura, 1997). Self-efficacy is not just an ability perception, it encompasses the motivation and effort required to complete the task and it helps determine which activities are required, the effort in pursuing these activities and persistence when facing obstacles (Bandura, 1986, 1997). The construct of self-efficacy is made up of four principal sources of information:"mastery experience" refers to previous experience, including success and failure; "vicarious experience" addresses observing the performances, successes and failures of others;"social persuasion" includes verbal persuasion from peers, colleagues and relatives; and"physiological and emotional states" from which people judge their strengths, capabilities and vulnerabilities (Bandura, 1986, 1994, 1995).As self-efficacy is based on self-perceptions regarding different behaviours, it is considered to be situation specific. In other words, a person may exhibit high levels of self-efficacy within one domain, while exhibiting low levels within another (Cassidy and Eachus, 2002). Thus, self-efficacy has generated research in various disciplines such as medicine, business, psychology and education (Kear, 2000; Lev, 1997; Schunk, 1985; Koul and Rubba, 1999). Computer self-efficacy is a sub-field of self-efficacy. It is defined as one's perceived ability to accomplish a task with the use of a computer (Compeau and Higgins, 1995). Various studies have noted that training and experience play important roles in computer self-efficacy (Compeau and Higgins, 1995; Kinzie et al. , 1994; Stone and Henry, 2003). Several studies have investigated the effect of computer self-efficacy on computer training performance (Compeau and Higgins, 1995) and on IT use (Easley et al. , 2003).HypothesesBased on the study objectives and assuming that PEOU, personal innovativeness,cognitive appraisal and openness to experience may predict information professionals' behavioural intention to use cloud computing, the underlying assumptions of this study are as follows:H1. High scores in respondent PEOU will be associated with high scores in their behavioural intention to use cloud computing.H2. High scores in respondents' personal innovativeness will be associated with high scores in their behavioural intention to use cloud computing.H3. Low scores in respondents' threat and high scores in respondents' challenge will be associated with high scores in their behavioural intention to use cloud computing. H4. High scores in respondents' self-efficacy will be associated with high scores in their behavioural intention to use cloud computing.H5. High scores in respondents' openness to experience will be associated with high scores in their behavioural intention to use cloud computing.H6. High scores in respondents' computer competence and in social media use will be associated with high scores in their behavioural intention to use cloud computing. MethodologyData collectionThe research was conducted in Israel during the second semester of the 2013 academic year and encompassed two groups of information professionals: librarians and information specialists. The researchers sent a message and a questionnaire to an Israeli library and information science discussion group named "safranym", which included school, public and academic librarians, and to an Israeli information specialist group named "I-fish", which consists of information specialists that work in different organizations. Researchers explained the study's purpose and asked their members to complete the questionnaire. These two discussion groups consist of about 700 members; 140 responses were received, giving a reply percentage of 20 per cent. Data analysisOf the participants, 25 (17.9 per cent) were male and 115 (82.1 per cent) were female. Their average age was 46.3 years.MeasuresThe current study is based on quantitative research. Researchers used seven questionnaires to gather the following data: personal details, computer competence, attitudes towards cloud computing, behavioural intention, openness to experience, cognitive appraisal and self-efficacy.The personal details questionnaire had two statements. The computer competence questionnaire consisted of two statements rated on a 5-point Likert scale (1 = strongest disagreement; 5 = strongest agreement). The cloud computing attitude questionnaire, based on Liuet al. (2010), was modified for this study and consisted of six statements rated on a seven-point Likert scale (1 = strongest disagreement; 7 = strongest agreement). A principal components factor analysis using Varimax rotation with Kaiser Normalization was conducted and explained 82.98 per cent of the variance. Principal components factor analysis revealed two distinct factors. The first related to information professionals' personal innovativeness (items 2, 3 and 5), and the second to information professionals' perceptions about cloud computing ease ofuse (PEOU) (items 1, 4, and 6); the values of Cronbach's Alpha were 0.89 and 0.88, respectively.The behavioural intention questionnaire, based on Liu et al. (2010), was modified for this study and consisted of three statements rated on a six-point Likert scale (1 = strongest disagreement; 6 = strongest agreement). Its Cronbach's Alpha was 0.79. The openness to experience questionnaire was derived from the Big Five questionnaire (John et al. , 1991) and consisted of eight statements rated on a five-point Likert scale (1 = strongest disagreement; 5 = strongest agreement); Cronbach's Alpha was 0.81. The cognitive appraisal questionnaire measured information professionals' feelings of threat versus challenge when confronted with new situations. It consisted of 10 statements rated on a six-point scale (1 = fully disagree; 6 = fully agree). This questionnaire was previously used (Aharony, 2009, 2011; Yekutiel, 1990) and consisted of two factors: threat (items 1, 2, 3, 5, 7 and 8) and challenge (items 4, 6, 9 and 10). Cronbach's Alpha was 0.70 for the threat factor and 0.89 for the challenge factor.The self-efficacy questionnaire was based on Askar and Umay's (2001) questionnaire and consisted of 18 statements rated on a five-point scale (1 = fully disagree; 5 = fully agree); Cronbach's Alpha was 0.96.FindingsTo examine the relationship between openness to experience, cognitive appraisal (threat, challenge and self-efficacy), TAM variables (personal innovativeness and PEOU), and behavioural intention to use cloud computing, researchers performed Pearson correlations, which are given in Table I.Table I presents significant correlations between research variables and the dependent variable (behavioural intention to use cloud computing). All correlations are positive, except the one between threat and behavioural intention to use cloud computing. Hence, the higher these measures, the greater the behavioural intention to use cloud computing. A significant negative correlation was found between threat and the dependent variable. Therefore, the more threatened respondents are, the lower is their behavioural intention to use cloud computing.Regarding the correlations between research variables, significant positive correlations were found between openness to experience and challenge, self-efficacy, personal innovativeness and PEOU. A significant negative correlation was found between openness to experience and threat. That is, the more open to experience respondents are, the more challenged they are, the higher is their self-efficacy, personal innovativeness, and PEOU and the less threatened they are. In addition, significant negative correlations were found between threat and self-efficacy, personal innovativeness and PEOU. We can conclude that the more threatened respondents are, the less they are self-efficient, personally innovative and the less they perceive cloud computing as easy to use. Significant positive correlations were also found between self-efficacy and personal innovativeness and PEOU. Thus, the more self-efficient respondents are, the more personally innovative they are and the more they perceive cloud computing as easy to use.The study also examined two variables associated with computer competence:computer use and social media use. Table II presents correlations between these two variables and the other research variables.Significant, high correlations were found between computer competence variables and openness to experience, self-efficacy, personal innovativeness, PEOU and behavioural intention to use cloud computing. Hence, the higher respondents' computer competence, the more they are open to experience, self-efficient and personally innovative, and perceive cloud computing as easy to use, the higher is their behavioural intention to use cloud computing.Researchers also examined relationships with demographic variables. To examine the relationship between age and other research variables, the researchers performed Pearson correlations. A significant negative correlation was found between age and PEOU, r = -0.21, p < 0.05. We may assume that the younger the respondents are, the more they perceive cloud computing as easy to use. To examine whether there are differences between males and females concerning the research variables, a MANOV A was performed and did not reveal a significant difference between the two groups concerning research variables, F (7,130) = 1.88, p > 0.05.The researchers also conducted a hierarchical regression using behavioural intention to use cloud computing as a dependent variable. The predictors were entered as five steps:respondents' openness to experience;respondents' computer competence (computer use and social media use);cognitive appraisal (threat, challenge and self-efficacy);TAM variables (personal innovativeness and PEOU); andinteractions with the TAM variables.The entrance of the four first steps was forced, while the interactions were done according to their contribution to the explained variance of behavioural intention to use cloud computing. The regression explained 54 per cent of behavioural intention to use cloud computing. Table III presents the standardized and unstandardized coefficients of the hierarchical regression of respondents' behavioural intention to use cloud computing.The first step introduced the openness variable that contributed significantly by adding 13 per cent to the explained variance of behavioural intention to use cloud computing. The beta coefficient of the openness variable is positive; hence, the more open to experience respondents are, the higher is their behavioural intention to use cloud computing. The second step introduced the two computer competence variables (computer use and social media use) which contributed 5 per cent to the explained variance of behavioural intention. Of these two variables, only the social media variable contributed significantly and its beta coefficient was positive. In other words, the more respondents use social media, the higher is their behavioural intention to use cloud computing. Note that Pearson correlations found significant positive correlations between these two variables and behavioural intention to use cloud computing. It seems that because of the correlation between these two variables, r = 0.33, p < 0.001, the computer use variable did not contribute to the regression.As the third step, researchers added respondents' personal appraisal variables (threat and challenge, and self-efficacy), and this also contributed significantly by adding 25 per cent to the explained variance of behavioural intention. The beta coefficients of challenge and of self-efficacy were positive, while that of threat was negative. Therefore, we may conclude that the more respondents perceived themselves as challenged and self-efficient, and the less they perceived themselves as threatened, the higher is their behavioural intention to use cloud computing. The inclusion of this step caused a decrease in the [beta] size of the openness to experience variable that changed it into an insignificant one, and may suggest a possibility of mediation. Sobel tests indicated that self-efficacy mediates between openness to experience and behavioural intention (z = 4.68, p < 0.001). Hence, the more respondents are open to experience, the higher is their self-efficacy and, as a result, the higher is their behavioural intention to use cloud computing.The fourth step added the TAM variables (respondents' PEOU and personal innovation), and this also contributed significantly by adding 9 per cent to the explained variance of behavioural intention to use cloud computing. The beta coefficient of this variable was positive; therefore, the more respondents perceived themselves to be personally innovative and cloud computing as easy to use, the higher is their behavioural intention to use cloud computing. Note that in this step there was a decrease in the [beta] size of self-efficacy. Sobel tests indicated that of the two variables, PEOU mediates between self-efficacy and behavioural intention (z = 4.77, p < 0.001). Thus, the more respondents perceive themselves as self-efficient, the higher they perceive cloud computing's PEOU and, as a result, the higher is their behavioural intention to use it.As the fifth step, researchers added the interaction between computer use X personal innovativeness. This interaction added 2 per cent to the explained variance of behavioural intention to use cloud computing and is presented in Figure 1.Figure 1 shows a correlation between personal innovation and behavioural intention to use cloud computing among respondents who are low and high in computer use. This correlation is higher among respondents who are low in computer use, [beta] = . 40, p < 0.05, than among those who are high in computer use, [beta] = 0.04, p < 0.05. It seems that especially among participants who are low in computer use, the higher their personal innovativeness, the higher is their behavioural intention to use cloud computing.DiscussionThe present research explored the extent to which the TAM and personal characteristics, such as threat and challenge, self-efficacy and openness to experience, explain information professionals' perspectives on cloud computing. Researchers divided the study hypotheses into three categories. The first (consisting of H1 -H2 ) refers to the TAM, the second (H3 -H5 ) to personality characteristics and, finally, H6 to computer competence. All hypotheses were accepted. Regarding the first category of hypotheses, results show that both were accepted. Findings suggest that high scores in PEOU and personal innovativeness are associated with high scores in respondents' intention to adopt cloud computing. These findings can be associated with previous。

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。

云计算外文翻译参考文献(文档含中英文对照即英文原文和中文翻译)原文:Technical Issues of Forensic Investigations in Cloud Computing EnvironmentsDominik BirkRuhr-University BochumHorst Goertz Institute for IT SecurityBochum, GermanyRuhr-University BochumHorst Goertz Institute for IT SecurityBochum, GermanyAbstract—Cloud Computing is arguably one of the most discussedinformation technologies today. It presents many promising technological and economical opportunities. However, many customers remain reluctant to move their business IT infrastructure completely to the cloud. One of their main concerns is Cloud Security and the threat of the unknown. Cloud Service Providers(CSP) encourage this perception by not letting their customers see what is behind their virtual curtain. A seldomly discussed, but in this regard highly relevant open issue is the ability to perform digital investigations. This continues to fuel insecurity on the sides of both providers and customers. Cloud Forensics constitutes a new and disruptive challenge for investigators. Due to the decentralized nature of data processing in the cloud, traditional approaches to evidence collection and recovery are no longer practical. This paper focuses on the technical aspects of digital forensics in distributed cloud environments. We contribute by assessing whether it is possible for the customer of cloud computing services to perform a traditional digital investigation from a technical point of view. Furthermore we discuss possible solutions and possible new methodologies helping customers to perform such investigations.I. INTRODUCTIONAlthough the cloud might appear attractive to small as well as to large companies, it does not come along without its own unique problems. Outsourcing sensitive corporate data into the cloud raises concerns regarding the privacy and security of data. Security policies, companies main pillar concerning security, cannot be easily deployed into distributed, virtualized cloud environments. This situation is further complicated by the unknown physical location of the companie’s assets. Normally,if a security incident occurs, the corporate security team wants to be able to perform their own investigation without dependency on third parties. In the cloud, this is not possible anymore: The CSP obtains all the power over the environmentand thus controls the sources of evidence. In the best case, a trusted third party acts as a trustee and guarantees for the trustworthiness of the CSP. Furthermore, the implementation of the technical architecture and circumstances within cloud computing environments bias the way an investigation may be processed. In detail, evidence data has to be interpreted by an investigator in a We would like to thank the reviewers for the helpful comments and Dennis Heinson (Center for Advanced Security Research Darmstadt - CASED) for the profound discussions regarding the legal aspects of cloud forensics. proper manner which is hardly be possible due to the lackof circumstantial information. For auditors, this situation does not change: Questions who accessed specific data and information cannot be answered by the customers, if no corresponding logs are available. With the increasing demand for using the power of the cloud for processing also sensible information and data, enterprises face the issue of Data and Process Provenance in the cloud [10]. Digital provenance, meaning meta-data that describes the ancestry or history of a digital object, is a crucial feature for forensic investigations. In combination with a suitable authentication scheme, it provides information about who created and who modified what kind of data in the cloud. These are crucial aspects for digital investigations in distributed environments such as the cloud. Unfortunately, the aspects of forensic investigations in distributed environment have so far been mostly neglected by the research community. Current discussion centers mostly around security, privacy and data protection issues [35], [9], [12]. The impact of forensic investigations on cloud environments was little noticed albeit mentioned by the authors of [1] in 2009: ”[...] to our knowledge, no research has been published on how cloud computing environments affect digital artifacts,and on acquisition logistics and legal issues related to cloud computing env ironments.” This statement is also confirmed by other authors [34], [36], [40] stressing that further research on incident handling, evidence tracking and accountability in cloud environments has to be done. At the same time, massive investments are being made in cloud technology. Combined with the fact that information technology increasingly transcendents peoples’ private and professional life, thus mirroring more and more of peoples’actions, it becomes apparent that evidence gathered from cloud environments will be of high significance to litigation or criminal proceedings in the future. Within this work, we focus the notion of cloud forensics by addressing the technical issues of forensics in all three major cloud service models and consider cross-disciplinary aspects. Moreover, we address the usability of various sources of evidence for investigative purposes and propose potential solutions to the issues from a practical standpoint. This work should be considered as a surveying discussion of an almost unexplored research area. The paper is organized as follows: We discuss the related work and the fundamental technical background information of digital forensics, cloud computing and the fault model in section II and III. In section IV, we focus on the technical issues of cloud forensics and discuss the potential sources and nature of digital evidence as well as investigations in XaaS environments including thecross-disciplinary aspects. We conclude in section V.II. RELATED WORKVarious works have been published in the field of cloud security and privacy [9], [35], [30] focussing on aspects for protecting data in multi-tenant, virtualized environments. Desired security characteristics for current cloud infrastructures mainly revolve around isolation of multi-tenant platforms [12], security of hypervisors in order to protect virtualized guest systems and secure network infrastructures [32]. Albeit digital provenance, describing the ancestry of digital objects, still remains a challenging issue for cloud environments, several works have already been published in this field [8], [10] contributing to the issues of cloud forensis. Within this context, cryptographic proofs for verifying data integrity mainly in cloud storage offers have been proposed,yet lacking of practical implementations [24], [37], [23]. Traditional computer forensics has already well researched methods for various fields of application [4], [5], [6], [11], [13]. Also the aspects of forensics in virtual systems have been addressed by several works [2], [3], [20] including the notionof virtual introspection [25]. In addition, the NIST already addressed Web Service Forensics [22] which has a huge impact on investigation processes in cloud computing environments. In contrast, the aspects of forensic investigations in cloud environments have mostly been neglected by both the industry and the research community. One of the first papers focusing on this topic was published by Wolthusen [40] after Bebee et al already introduced problems within cloud environments [1]. Wolthusen stressed that there is an inherent strong need for interdisciplinary work linking the requirements and concepts of evidence arising from the legal field to what can be feasibly reconstructed and inferred algorithmically or in an exploratory manner. In 2010, Grobauer et al [36] published a paper discussing the issues of incident response in cloud environments - unfortunately no specific issues and solutions of cloud forensics have been proposed which will be done within this work.III. TECHNICAL BACKGROUNDA. Traditional Digital ForensicsThe notion of Digital Forensics is widely known as the practice of identifying, extracting and considering evidence from digital media. Unfortunately, digital evidence is both fragile and volatile and therefore requires the attention of special personnel and methods in order to ensure that evidence data can be proper isolated and evaluated. Normally, the process of a digital investigation can be separated into three different steps each having its own specificpurpose:1) In the Securing Phase, the major intention is the preservation of evidence for analysis. The data has to be collected in a manner that maximizes its integrity. This is normally done by a bitwise copy of the original media. As can be imagined, this represents a huge problem in the field of cloud computing where you never know exactly where your data is and additionallydo not have access to any physical hardware. However, the snapshot technology, discussed in section IV-B3, provides a powerful tool to freeze system states and thus makes digital investigations, at least in IaaS scenarios, theoretically possible.2) We refer to the Analyzing Phase as the stage in which the data is sifted and combined. It is in this phase that the data from multiple systems or sources is pulled together to create as complete a picture and event reconstruction as possible. Especially in distributed system infrastructures, this means that bits and pieces of data are pulled together for deciphering the real story of what happened and for providing a deeper look into the data.3) Finally, at the end of the examination and analysis of the data, the results of the previous phases will be reprocessed in the Presentation Phase. The report, created in this phase, is a compilation of all the documentation and evidence from the analysis stage. The main intention of such a report is that it contains all results, it is complete and clear to understand. Apparently, the success of these three steps strongly depends on the first stage. If it is not possible to secure the complete set of evidence data, no exhaustive analysis will be possible. However, in real world scenarios often only a subset of the evidence data can be secured by the investigator. In addition, an important definition in the general context of forensics is the notion of a Chain of Custody. This chain clarifies how and where evidence is stored and who takes possession of it. Especially for cases which are brought to court it is crucial that the chain of custody is preserved.B. Cloud ComputingAccording to the NIST [16], cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications and services) that can be rapidly provisioned and released with minimal CSP interaction. The new raw definition of cloud computing brought several new characteristics such as multi-tenancy, elasticity, pay-as-you-go and reliability. Within this work, the following three models are used: In the Infrastructure asa Service (IaaS) model, the customer is using the virtual machine provided by the CSP for installing his own system on it. The system can be used like any other physical computer with a few limitations. However, the additive customer power over the system comes along with additional security obligations. Platform as a Service (PaaS) offerings provide the capability to deploy application packages created using the virtual development environment supported by the CSP. For the efficiency of software development process this service model can be propellent. In the Software as a Service (SaaS) model, the customer makes use of a service run by the CSP on a cloud infrastructure. In most of the cases this service can be accessed through an API for a thin client interface such as a web browser. Closed-source public SaaS offers such as Amazon S3 and GoogleMail can only be used in the public deployment model leading to further issues concerning security, privacy and the gathering of suitable evidences. Furthermore, two main deployment models, private and public cloud have to be distinguished. Common public clouds are made available to the general public. The corresponding infrastructure is owned by one organization acting as a CSP and offering services to its customers. In contrast, the private cloud is exclusively operated for an organization but may not provide the scalability and agility of public offers. The additional notions of community and hybrid cloud are not exclusively covered within this work. However, independently from the specific model used, the movement of applications and data to the cloud comes along with limited control for the customer about the application itself, the data pushed into the applications and also about the underlying technical infrastructure.C. Fault ModelBe it an account for a SaaS application, a development environment (PaaS) or a virtual image of an IaaS environment, systems in the cloud can be affected by inconsistencies. Hence, for both customer and CSP it is crucial to have the ability to assign faults to the causing party, even in the presence of Byzantine behavior [33]. Generally, inconsistencies can be caused by the following two reasons:1) Maliciously Intended FaultsInternal or external adversaries with specific malicious intentions can cause faults on cloud instances or applications. Economic rivals as well as former employees can be the reason for these faults and state a constant threat to customers and CSP. In this model, also a malicious CSP is included albeit he isassumed to be rare in real world scenarios. Additionally, from the technical point of view, the movement of computing power to a virtualized, multi-tenant environment can pose further threads and risks to the systems. One reason for this is that if a single system or service in the cloud is compromised, all other guest systems and even the host system are at risk. Hence, besides the need for further security measures, precautions for potential forensic investigations have to be taken into consideration.2) Unintentional FaultsInconsistencies in technical systems or processes in the cloud do not have implicitly to be caused by malicious intent. Internal communication errors or human failures can lead to issues in the services offered to the costumer(i.e. loss or modification of data). Although these failures are not caused intentionally, both the CSP and the customer have a strong intention to discover the reasons and deploy corresponding fixes.IV. TECHNICAL ISSUESDigital investigations are about control of forensic evidence data. From the technical standpoint, this data can be available in three different states: at rest, in motion or in execution. Data at rest is represented by allocated disk space. Whether the data is stored in a database or in a specific file format, it allocates disk space. Furthermore, if a file is deleted, the disk space is de-allocated for the operating system but the data is still accessible since the disk space has not been re-allocated and overwritten. This fact is often exploited by investigators which explore these de-allocated disk space on harddisks. In case the data is in motion, data is transferred from one entity to another e.g. a typical file transfer over a network can be seen as a data in motion scenario. Several encapsulated protocols contain the data each leaving specific traces on systems and network devices which can in return be used by investigators. Data can be loaded into memory and executed as a process. In this case, the data is neither at rest or in motion but in execution. On the executing system, process information, machine instruction and allocated/de-allocated data can be analyzed by creating a snapshot of the current system state. In the following sections, we point out the potential sources for evidential data in cloud environments and discuss the technical issues of digital investigations in XaaS environmentsas well as suggest several solutions to these problems.A. Sources and Nature of EvidenceConcerning the technical aspects of forensic investigations, the amount of potential evidence available to the investigator strongly diverges between thedifferent cloud service and deployment models. The virtual machine (VM), hosting in most of the cases the server application, provides several pieces of information that could be used by investigators. On the network level, network components can provide information about possible communication channels between different parties involved. The browser on the client, acting often as the user agent for communicating with the cloud, also contains a lot of information that could be used as evidence in a forensic investigation. Independently from the used model, the following three components could act as sources for potential evidential data.1) Virtual Cloud Instance: The VM within the cloud, where i.e. data is stored or processes are handled, contains potential evidence [2], [3]. In most of the cases, it is the place where an incident happened and hence provides a good starting point for a forensic investigation. The VM instance can be accessed by both, the CSP and the customer who is running the instance. Furthermore, virtual introspection techniques [25] provide access to the runtime state of the VM via the hypervisor and snapshot technology supplies a powerful technique for the customer to freeze specific states of the VM. Therefore, virtual instances can be still running during analysis which leads to the case of live investigations [41] or can be turned off leading to static image analysis. In SaaS and PaaS scenarios, the ability to access the virtual instance for gathering evidential information is highly limited or simply not possible.2) Network Layer: Traditional network forensics is knownas the analysis of network traffic logs for tracing events that have occurred in the past. Since the different ISO/OSI network layers provide several information on protocols and communication between instances within as well as with instances outside the cloud [4], [5], [6], network forensics is theoretically also feasible in cloud environments. However in practice, ordinary CSP currently do not provide any log data from the network components used by the customer’s instances or applications. For instance, in case of a malware infection of an IaaS VM, it will be difficult for the investigator to get any form of routing information and network log datain general which is crucial for further investigative steps. This situation gets even more complicated in case of PaaS or SaaS. So again, the situation of gathering forensic evidence is strongly affected by the support the investigator receives from the customer and the CSP.3) Client System: On the system layer of the client, it completely depends on the used model (IaaS, PaaS, SaaS) if and where potential evidence could beextracted. In most of the scenarios, the user agent (e.g. the web browser) on the client system is the only application that communicates with the service in the cloud. This especially holds for SaaS applications which are used and controlled by the web browser. But also in IaaS scenarios, the administration interface is often controlled via the browser. Hence, in an exhaustive forensic investigation, the evidence data gathered from the browser environment [7] should not be omitted.a) Browser Forensics: Generally, the circumstances leading to an investigation have to be differentiated: In ordinary scenarios, the main goal of an investigation of the web browser is to determine if a user has been victim of a crime. In complex SaaS scenarios with high client-server interaction, this constitutes a difficult task. Additionally, customers strongly make use of third-party extensions [17] which can be abused for malicious purposes. Hence, the investigator might want to look for malicious extensions, searches performed, websites visited, files downloaded, information entered in forms or stored in local HTML5 stores, web-based email contents and persistent browser cookies for gathering potential evidence data. Within this context, it is inevitable to investigate the appearance of malicious JavaScript [18] leading to e.g. unintended AJAX requests and hence modified usage of administration interfaces. Generally, the web browser contains a lot of electronic evidence data that could be used to give an answer to both of the above questions - even if the private mode is switched on [19].B. Investigations in XaaS EnvironmentsTraditional digital forensic methodologies permit investigators to seize equipment and perform detailed analysis on the media and data recovered [11]. In a distributed infrastructure organization like the cloud computing environment, investigators are confronted with an entirely different situation. They have no longer the option of seizing physical data storage. Data and processes of the customer are dispensed over an undisclosed amount of virtual instances, applications and network elements. Hence, it is in question whether preliminary findings of the computer forensic community in the field of digital forensics apparently have to be revised and adapted to the new environment. Within this section, specific issues of investigations in SaaS, PaaS and IaaS environments will be discussed. In addition, cross-disciplinary issues which affect several environments uniformly, will be taken into consideration. We also suggest potential solutions to the mentioned problems.1) SaaS Environments: Especially in the SaaS model, the customer does notobtain any control of the underlying operating infrastructure such as network, servers, operating systems or the application that is used. This means that no deeper view into the system and its underlying infrastructure is provided to the customer. Only limited userspecific application configuration settings can be controlled contributing to the evidences which can be extracted fromthe client (see section IV-A3). In a lot of cases this urges the investigator to rely on high-level logs which are eventually provided by the CSP. Given the case that the CSP does not run any logging application, the customer has no opportunity to create any useful evidence through the installation of any toolkit or logging tool. These circumstances do not allow a valid forensic investigation and lead to the assumption that customers of SaaS offers do not have any chance to analyze potential incidences.a) Data Provenance: The notion of Digital Provenance is known as meta-data that describes the ancestry or history of digital objects. Secure provenance that records ownership and process history of data objects is vital to the success of data forensics in cloud environments, yet it is still a challenging issue today [8]. Albeit data provenance is of high significance also for IaaS and PaaS, it states a huge problem specifically for SaaS-based applications: Current global acting public SaaS CSP offer Single Sign-On (SSO) access control to the set of their services. Unfortunately in case of an account compromise, most of the CSP do not offer any possibility for the customer to figure out which data and information has been accessed by the adversary. For the victim, this situation can have tremendous impact: If sensitive data has been compromised, it is unclear which data has been leaked and which has not been accessed by the adversary. Additionally, data could be modified or deleted by an external adversary or even by the CSP e.g. due to storage reasons. The customer has no ability to proof otherwise. Secure provenance mechanisms for distributed environments can improve this situation but have not been practically implemented by CSP [10]. Suggested Solution: In private SaaS scenarios this situation is improved by the fact that the customer and the CSP are probably under the same authority. Hence, logging and provenance mechanisms could be implemented which contribute to potential investigations. Additionally, the exact location of the servers and the data is known at any time. Public SaaS CSP should offer additional interfaces for the purpose of compliance, forensics, operations and security matters to their customers. Through an API, the customers should have the ability to receive specific information suchas access, error and event logs that could improve their situation in case of aninvestigation. Furthermore, due to the limited ability of receiving forensic information from the server and proofing integrity of stored data in SaaS scenarios, the client has to contribute to this process. This could be achieved by implementing Proofs of Retrievability (POR) in which a verifier (client) is enabled to determine that a prover (server) possesses a file or data object and it can be retrieved unmodified [24]. Provable Data Possession (PDP) techniques [37] could be used to verify that an untrusted server possesses the original data without the need for the client to retrieve it. Although these cryptographic proofs have not been implemented by any CSP, the authors of [23] introduced a new data integrity verification mechanism for SaaS scenarios which could also be used for forensic purposes.2) PaaS Environments: One of the main advantages of the PaaS model is that the developed software application is under the control of the customer and except for some CSP, the source code of the application does not have to leave the local development environment. Given these circumstances, the customer obtains theoretically the power to dictate how the application interacts with other dependencies such as databases, storage entities etc. CSP normally claim this transfer is encrypted but this statement can hardly be verified by the customer. Since the customer has the ability to interact with the platform over a prepared API, system states and specific application logs can be extracted. However potential adversaries, which can compromise the application during runtime, should not be able to alter these log files afterwards. Suggested Solution:Depending on the runtime environment, logging mechanisms could be implemented which automatically sign and encrypt the log information before its transfer to a central logging server under the control of the customer. Additional signing and encrypting could prevent potential eavesdroppers from being able to view and alter log data information on the way to the logging server. Runtime compromise of an PaaS application by adversaries could be monitored by push-only mechanisms for log data presupposing that the needed information to detect such an attack are logged. Increasingly, CSP offering PaaS solutions give developers the ability to collect and store a variety of diagnostics data in a highly configurable way with the help of runtime feature sets [38].3) IaaS Environments: As expected, even virtual instances in the cloud get compromised by adversaries. Hence, the ability to determine how defenses in the virtual environment failed and to what extent the affected systems havebeen compromised is crucial not only for recovering from an incident. Also forensic investigations gain leverage from such information and contribute to resilience against future attacks on the systems. From the forensic point of view, IaaS instances do provide much more evidence data usable for potential forensics than PaaS and SaaS models do. This fact is caused throughthe ability of the customer to install and set up the image for forensic purposes before an incident occurs. Hence, as proposed for PaaS environments, log data and other forensic evidence information could be signed and encrypted before itis transferred to third-party hosts mitigating the chance that a maliciously motivated shutdown process destroys the volatile data. Although, IaaS environments provide plenty of potential evidence, it has to be emphasized that the customer VM is in the end still under the control of the CSP. He controls the hypervisor which is e.g. responsible for enforcing hardware boundaries and routing hardware requests among different VM. Hence, besides the security responsibilities of the hypervisor, he exerts tremendous control over how customer’s VM communicate with the hardware and theoretically can intervene executed processes on the hosted virtual instance through virtual introspection [25]. This could also affect encryption or signing processes executed on the VM and therefore leading to the leakage of the secret key. Although this risk can be disregarded in most of the cases, the impact on the security of high security environments is tremendous.a) Snapshot Analysis: Traditional forensics expect target machines to be powered down to collect an image (dead virtual instance). This situation completely changed with the advent of the snapshot technology which is supported by all popular hypervisors such as Xen, VMware ESX and Hyper-V.A snapshot, also referred to as the forensic image of a VM, providesa powerful tool with which a virtual instance can be clonedby one click including also the running system’s mem ory. Due to the invention of the snapshot technology, systems hosting crucial business processes do not have to be powered down for forensic investigation purposes. The investigator simply creates and loads a snapshot of the target VM for analysis(live virtual instance). This behavior is especially important for scenarios in which a downtime of a system is not feasible or practical due to existing SLA. However the information whether the machine is running or has been properly powered down is crucial [3] for the investigation. Live investigations of running virtual instances become more common providing evidence data that。

计算机毕设英文参考文献当涉及到毕业设计或者毕业论文的参考文献时，你可以考虑以下一些经典的计算机科学领域的文献：1. D. E. Knuth, "The Art of Computer Programming," Addison-Wesley, 1968.2. A. Turing, "On Computable Numbers, with an Application to the Entscheidungsproblem," Proceedings of the London Mathematical Society, 1936.3. V. Bush, "As We May Think," The Atlantic Monthly, 1945.4. C. Shannon, "A Mathematical Theory of Communication," Bell System Technical Journal, 1948.5. E. W. Dijkstra, "Go To Statement Considered Harmful," Communications of the ACM, 1968.6. L. Lamport, "Time, Clocks, and the Ordering of Events in a Distributed System," Communications of the ACM, 1978.7. T. Berners-Lee, R. Cailliau, "WorldWideWeb: Proposal for a HyperText Project," 1990.8. S. Brin, L. Page, "The Anatomy of a Large-Scale Hypertextual Web Search Engine," Computer Networks and ISDN Systems, 1998.这些文献涵盖了计算机科学领域的一些经典工作，包括算法、计算理论、分布式系统、人机交互等方面的内容。

云计算外文翻译参考文献(文档含中英文对照即英文原文和中文翻译)原文:Technical Issues of Forensic Investigations in Cloud Computing EnvironmentsDominik BirkRuhr-University BochumHorst Goertz Institute for IT SecurityBochum, GermanyRuhr-University BochumHorst Goertz Institute for IT SecurityBochum, GermanyAbstract—Cloud Computing is arguably one of the most discussedinformation technologies today. It presents many promising technological and economical opportunities. However, many customers remain reluctant to move their business IT infrastructure completely to the cloud. One of their main concerns is Cloud Security and the threat of the unknown. Cloud Service Providers(CSP) encourage this perception by not letting their customers see what is behind their virtual curtain. A seldomly discussed, but in this regard highly relevant open issue is the ability to perform digital investigations. This continues to fuel insecurity on the sides of both providers and customers. Cloud Forensics constitutes a new and disruptive challenge for investigators. Due to the decentralized nature of data processing in the cloud, traditional approaches to evidence collection and recovery are no longer practical. This paper focuses on the technical aspects of digital forensics in distributed cloud environments. We contribute by assessing whether it is possible for the customer of cloud computing services to perform a traditional digital investigation from a technical point of view. Furthermore we discuss possible solutions and possible new methodologies helping customers to perform such investigations.I. INTRODUCTIONAlthough the cloud might appear attractive to small as well as to large companies, it does not come along without its own unique problems. Outsourcing sensitive corporate data into the cloud raises concerns regarding the privacy and security of data. Security policies, companies main pillar concerning security, cannot be easily deployed into distributed, virtualized cloud environments. This situation is further complicated by the unknown physical location of the companie’s assets. Normally,if a security incident occurs, the corporate security team wants to be able to perform their own investigation without dependency on third parties. In the cloud, this is not possible anymore: The CSP obtains all the power over the environmentand thus controls the sources of evidence. In the best case, a trusted third party acts as a trustee and guarantees for the trustworthiness of the CSP. Furthermore, the implementation of the technical architecture and circumstances within cloud computing environments bias the way an investigation may be processed. In detail, evidence data has to be interpreted by an investigator in a We would like to thank the reviewers for the helpful comments and Dennis Heinson (Center for Advanced Security Research Darmstadt - CASED) for the profound discussions regarding the legal aspects of cloud forensics. proper manner which is hardly be possible due to the lackof circumstantial information. For auditors, this situation does not change: Questions who accessed specific data and information cannot be answered by the customers, if no corresponding logs are available. With the increasing demand for using the power of the cloud for processing also sensible information and data, enterprises face the issue of Data and Process Provenance in the cloud [10]. Digital provenance, meaning meta-data that describes the ancestry or history of a digital object, is a crucial feature for forensic investigations. In combination with a suitable authentication scheme, it provides information about who created and who modified what kind of data in the cloud. These are crucial aspects for digital investigations in distributed environments such as the cloud. Unfortunately, the aspects of forensic investigations in distributed environment have so far been mostly neglected by the research community. Current discussion centers mostly around security, privacy and data protection issues [35], [9], [12]. The impact of forensic investigations on cloud environments was little noticed albeit mentioned by the authors of [1] in 2009: ”[...] to our knowledge, no research has been published on how cloud computing environments affect digital artifacts,and on acquisition logistics and legal issues related to cloud computing env ironments.” This statement is also confirmed by other authors [34], [36], [40] stressing that further research on incident handling, evidence tracking and accountability in cloud environments has to be done. At the same time, massive investments are being made in cloud technology. Combined with the fact that information technology increasingly transcendents peoples’ private and professional life, thus mirroring more and more of peoples’actions, it becomes apparent that evidence gathered from cloud environments will be of high significance to litigation or criminal proceedings in the future. Within this work, we focus the notion of cloud forensics by addressing the technical issues of forensics in all three major cloud service models and consider cross-disciplinary aspects. Moreover, we address the usability of various sources of evidence for investigative purposes and propose potential solutions to the issues from a practical standpoint. This work should be considered as a surveying discussion of an almost unexplored research area. The paper is organized as follows: We discuss the related work and the fundamental technical background information of digital forensics, cloud computing and the fault model in section II and III. In section IV, we focus on the technical issues of cloud forensics and discuss the potential sources and nature of digital evidence as well as investigations in XaaS environments including thecross-disciplinary aspects. We conclude in section V.II. RELATED WORKVarious works have been published in the field of cloud security and privacy [9], [35], [30] focussing on aspects for protecting data in multi-tenant, virtualized environments. Desired security characteristics for current cloud infrastructures mainly revolve around isolation of multi-tenant platforms [12], security of hypervisors in order to protect virtualized guest systems and secure network infrastructures [32]. Albeit digital provenance, describing the ancestry of digital objects, still remains a challenging issue for cloud environments, several works have already been published in this field [8], [10] contributing to the issues of cloud forensis. Within this context, cryptographic proofs for verifying data integrity mainly in cloud storage offers have been proposed,yet lacking of practical implementations [24], [37], [23]. Traditional computer forensics has already well researched methods for various fields of application [4], [5], [6], [11], [13]. Also the aspects of forensics in virtual systems have been addressed by several works [2], [3], [20] including the notionof virtual introspection [25]. In addition, the NIST already addressed Web Service Forensics [22] which has a huge impact on investigation processes in cloud computing environments. In contrast, the aspects of forensic investigations in cloud environments have mostly been neglected by both the industry and the research community. One of the first papers focusing on this topic was published by Wolthusen [40] after Bebee et al already introduced problems within cloud environments [1]. Wolthusen stressed that there is an inherent strong need for interdisciplinary work linking the requirements and concepts of evidence arising from the legal field to what can be feasibly reconstructed and inferred algorithmically or in an exploratory manner. In 2010, Grobauer et al [36] published a paper discussing the issues of incident response in cloud environments - unfortunately no specific issues and solutions of cloud forensics have been proposed which will be done within this work.III. TECHNICAL BACKGROUNDA. Traditional Digital ForensicsThe notion of Digital Forensics is widely known as the practice of identifying, extracting and considering evidence from digital media. Unfortunately, digital evidence is both fragile and volatile and therefore requires the attention of special personnel and methods in order to ensure that evidence data can be proper isolated and evaluated. Normally, the process of a digital investigation can be separated into three different steps each having its own specificpurpose:1) In the Securing Phase, the major intention is the preservation of evidence for analysis. The data has to be collected in a manner that maximizes its integrity. This is normally done by a bitwise copy of the original media. As can be imagined, this represents a huge problem in the field of cloud computing where you never know exactly where your data is and additionallydo not have access to any physical hardware. However, the snapshot technology, discussed in section IV-B3, provides a powerful tool to freeze system states and thus makes digital investigations, at least in IaaS scenarios, theoretically possible.2) We refer to the Analyzing Phase as the stage in which the data is sifted and combined. It is in this phase that the data from multiple systems or sources is pulled together to create as complete a picture and event reconstruction as possible. Especially in distributed system infrastructures, this means that bits and pieces of data are pulled together for deciphering the real story of what happened and for providing a deeper look into the data.3) Finally, at the end of the examination and analysis of the data, the results of the previous phases will be reprocessed in the Presentation Phase. The report, created in this phase, is a compilation of all the documentation and evidence from the analysis stage. The main intention of such a report is that it contains all results, it is complete and clear to understand. Apparently, the success of these three steps strongly depends on the first stage. If it is not possible to secure the complete set of evidence data, no exhaustive analysis will be possible. However, in real world scenarios often only a subset of the evidence data can be secured by the investigator. In addition, an important definition in the general context of forensics is the notion of a Chain of Custody. This chain clarifies how and where evidence is stored and who takes possession of it. Especially for cases which are brought to court it is crucial that the chain of custody is preserved.B. Cloud ComputingAccording to the NIST [16], cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications and services) that can be rapidly provisioned and released with minimal CSP interaction. The new raw definition of cloud computing brought several new characteristics such as multi-tenancy, elasticity, pay-as-you-go and reliability. Within this work, the following three models are used: In the Infrastructure asa Service (IaaS) model, the customer is using the virtual machine provided by the CSP for installing his own system on it. The system can be used like any other physical computer with a few limitations. However, the additive customer power over the system comes along with additional security obligations. Platform as a Service (PaaS) offerings provide the capability to deploy application packages created using the virtual development environment supported by the CSP. For the efficiency of software development process this service model can be propellent. In the Software as a Service (SaaS) model, the customer makes use of a service run by the CSP on a cloud infrastructure. In most of the cases this service can be accessed through an API for a thin client interface such as a web browser. Closed-source public SaaS offers such as Amazon S3 and GoogleMail can only be used in the public deployment model leading to further issues concerning security, privacy and the gathering of suitable evidences. Furthermore, two main deployment models, private and public cloud have to be distinguished. Common public clouds are made available to the general public. The corresponding infrastructure is owned by one organization acting as a CSP and offering services to its customers. In contrast, the private cloud is exclusively operated for an organization but may not provide the scalability and agility of public offers. The additional notions of community and hybrid cloud are not exclusively covered within this work. However, independently from the specific model used, the movement of applications and data to the cloud comes along with limited control for the customer about the application itself, the data pushed into the applications and also about the underlying technical infrastructure.C. Fault ModelBe it an account for a SaaS application, a development environment (PaaS) or a virtual image of an IaaS environment, systems in the cloud can be affected by inconsistencies. Hence, for both customer and CSP it is crucial to have the ability to assign faults to the causing party, even in the presence of Byzantine behavior [33]. Generally, inconsistencies can be caused by the following two reasons:1) Maliciously Intended FaultsInternal or external adversaries with specific malicious intentions can cause faults on cloud instances or applications. Economic rivals as well as former employees can be the reason for these faults and state a constant threat to customers and CSP. In this model, also a malicious CSP is included albeit he isassumed to be rare in real world scenarios. Additionally, from the technical point of view, the movement of computing power to a virtualized, multi-tenant environment can pose further threads and risks to the systems. One reason for this is that if a single system or service in the cloud is compromised, all other guest systems and even the host system are at risk. Hence, besides the need for further security measures, precautions for potential forensic investigations have to be taken into consideration.2) Unintentional FaultsInconsistencies in technical systems or processes in the cloud do not have implicitly to be caused by malicious intent. Internal communication errors or human failures can lead to issues in the services offered to the costumer(i.e. loss or modification of data). Although these failures are not caused intentionally, both the CSP and the customer have a strong intention to discover the reasons and deploy corresponding fixes.IV. TECHNICAL ISSUESDigital investigations are about control of forensic evidence data. From the technical standpoint, this data can be available in three different states: at rest, in motion or in execution. Data at rest is represented by allocated disk space. Whether the data is stored in a database or in a specific file format, it allocates disk space. Furthermore, if a file is deleted, the disk space is de-allocated for the operating system but the data is still accessible since the disk space has not been re-allocated and overwritten. This fact is often exploited by investigators which explore these de-allocated disk space on harddisks. In case the data is in motion, data is transferred from one entity to another e.g. a typical file transfer over a network can be seen as a data in motion scenario. Several encapsulated protocols contain the data each leaving specific traces on systems and network devices which can in return be used by investigators. Data can be loaded into memory and executed as a process. In this case, the data is neither at rest or in motion but in execution. On the executing system, process information, machine instruction and allocated/de-allocated data can be analyzed by creating a snapshot of the current system state. In the following sections, we point out the potential sources for evidential data in cloud environments and discuss the technical issues of digital investigations in XaaS environmentsas well as suggest several solutions to these problems.A. Sources and Nature of EvidenceConcerning the technical aspects of forensic investigations, the amount of potential evidence available to the investigator strongly diverges between thedifferent cloud service and deployment models. The virtual machine (VM), hosting in most of the cases the server application, provides several pieces of information that could be used by investigators. On the network level, network components can provide information about possible communication channels between different parties involved. The browser on the client, acting often as the user agent for communicating with the cloud, also contains a lot of information that could be used as evidence in a forensic investigation. Independently from the used model, the following three components could act as sources for potential evidential data.1) Virtual Cloud Instance: The VM within the cloud, where i.e. data is stored or processes are handled, contains potential evidence [2], [3]. In most of the cases, it is the place where an incident happened and hence provides a good starting point for a forensic investigation. The VM instance can be accessed by both, the CSP and the customer who is running the instance. Furthermore, virtual introspection techniques [25] provide access to the runtime state of the VM via the hypervisor and snapshot technology supplies a powerful technique for the customer to freeze specific states of the VM. Therefore, virtual instances can be still running during analysis which leads to the case of live investigations [41] or can be turned off leading to static image analysis. In SaaS and PaaS scenarios, the ability to access the virtual instance for gathering evidential information is highly limited or simply not possible.2) Network Layer: Traditional network forensics is knownas the analysis of network traffic logs for tracing events that have occurred in the past. Since the different ISO/OSI network layers provide several information on protocols and communication between instances within as well as with instances outside the cloud [4], [5], [6], network forensics is theoretically also feasible in cloud environments. However in practice, ordinary CSP currently do not provide any log data from the network components used by the customer’s instances or applications. For instance, in case of a malware infection of an IaaS VM, it will be difficult for the investigator to get any form of routing information and network log datain general which is crucial for further investigative steps. This situation gets even more complicated in case of PaaS or SaaS. So again, the situation of gathering forensic evidence is strongly affected by the support the investigator receives from the customer and the CSP.3) Client System: On the system layer of the client, it completely depends on the used model (IaaS, PaaS, SaaS) if and where potential evidence could beextracted. In most of the scenarios, the user agent (e.g. the web browser) on the client system is the only application that communicates with the service in the cloud. This especially holds for SaaS applications which are used and controlled by the web browser. But also in IaaS scenarios, the administration interface is often controlled via the browser. Hence, in an exhaustive forensic investigation, the evidence data gathered from the browser environment [7] should not be omitted.a) Browser Forensics: Generally, the circumstances leading to an investigation have to be differentiated: In ordinary scenarios, the main goal of an investigation of the web browser is to determine if a user has been victim of a crime. In complex SaaS scenarios with high client-server interaction, this constitutes a difficult task. Additionally, customers strongly make use of third-party extensions [17] which can be abused for malicious purposes. Hence, the investigator might want to look for malicious extensions, searches performed, websites visited, files downloaded, information entered in forms or stored in local HTML5 stores, web-based email contents and persistent browser cookies for gathering potential evidence data. Within this context, it is inevitable to investigate the appearance of malicious JavaScript [18] leading to e.g. unintended AJAX requests and hence modified usage of administration interfaces. Generally, the web browser contains a lot of electronic evidence data that could be used to give an answer to both of the above questions - even if the private mode is switched on [19].B. Investigations in XaaS EnvironmentsTraditional digital forensic methodologies permit investigators to seize equipment and perform detailed analysis on the media and data recovered [11]. In a distributed infrastructure organization like the cloud computing environment, investigators are confronted with an entirely different situation. They have no longer the option of seizing physical data storage. Data and processes of the customer are dispensed over an undisclosed amount of virtual instances, applications and network elements. Hence, it is in question whether preliminary findings of the computer forensic community in the field of digital forensics apparently have to be revised and adapted to the new environment. Within this section, specific issues of investigations in SaaS, PaaS and IaaS environments will be discussed. In addition, cross-disciplinary issues which affect several environments uniformly, will be taken into consideration. We also suggest potential solutions to the mentioned problems.1) SaaS Environments: Especially in the SaaS model, the customer does notobtain any control of the underlying operating infrastructure such as network, servers, operating systems or the application that is used. This means that no deeper view into the system and its underlying infrastructure is provided to the customer. Only limited userspecific application configuration settings can be controlled contributing to the evidences which can be extracted fromthe client (see section IV-A3). In a lot of cases this urges the investigator to rely on high-level logs which are eventually provided by the CSP. Given the case that the CSP does not run any logging application, the customer has no opportunity to create any useful evidence through the installation of any toolkit or logging tool. These circumstances do not allow a valid forensic investigation and lead to the assumption that customers of SaaS offers do not have any chance to analyze potential incidences.a) Data Provenance: The notion of Digital Provenance is known as meta-data that describes the ancestry or history of digital objects. Secure provenance that records ownership and process history of data objects is vital to the success of data forensics in cloud environments, yet it is still a challenging issue today [8]. Albeit data provenance is of high significance also for IaaS and PaaS, it states a huge problem specifically for SaaS-based applications: Current global acting public SaaS CSP offer Single Sign-On (SSO) access control to the set of their services. Unfortunately in case of an account compromise, most of the CSP do not offer any possibility for the customer to figure out which data and information has been accessed by the adversary. For the victim, this situation can have tremendous impact: If sensitive data has been compromised, it is unclear which data has been leaked and which has not been accessed by the adversary. Additionally, data could be modified or deleted by an external adversary or even by the CSP e.g. due to storage reasons. The customer has no ability to proof otherwise. Secure provenance mechanisms for distributed environments can improve this situation but have not been practically implemented by CSP [10]. Suggested Solution: In private SaaS scenarios this situation is improved by the fact that the customer and the CSP are probably under the same authority. Hence, logging and provenance mechanisms could be implemented which contribute to potential investigations. Additionally, the exact location of the servers and the data is known at any time. Public SaaS CSP should offer additional interfaces for the purpose of compliance, forensics, operations and security matters to their customers. Through an API, the customers should have the ability to receive specific information suchas access, error and event logs that could improve their situation in case of aninvestigation. Furthermore, due to the limited ability of receiving forensic information from the server and proofing integrity of stored data in SaaS scenarios, the client has to contribute to this process. This could be achieved by implementing Proofs of Retrievability (POR) in which a verifier (client) is enabled to determine that a prover (server) possesses a file or data object and it can be retrieved unmodified [24]. Provable Data Possession (PDP) techniques [37] could be used to verify that an untrusted server possesses the original data without the need for the client to retrieve it. Although these cryptographic proofs have not been implemented by any CSP, the authors of [23] introduced a new data integrity verification mechanism for SaaS scenarios which could also be used for forensic purposes.2) PaaS Environments: One of the main advantages of the PaaS model is that the developed software application is under the control of the customer and except for some CSP, the source code of the application does not have to leave the local development environment. Given these circumstances, the customer obtains theoretically the power to dictate how the application interacts with other dependencies such as databases, storage entities etc. CSP normally claim this transfer is encrypted but this statement can hardly be verified by the customer. Since the customer has the ability to interact with the platform over a prepared API, system states and specific application logs can be extracted. However potential adversaries, which can compromise the application during runtime, should not be able to alter these log files afterwards. Suggested Solution:Depending on the runtime environment, logging mechanisms could be implemented which automatically sign and encrypt the log information before its transfer to a central logging server under the control of the customer. Additional signing and encrypting could prevent potential eavesdroppers from being able to view and alter log data information on the way to the logging server. Runtime compromise of an PaaS application by adversaries could be monitored by push-only mechanisms for log data presupposing that the needed information to detect such an attack are logged. Increasingly, CSP offering PaaS solutions give developers the ability to collect and store a variety of diagnostics data in a highly configurable way with the help of runtime feature sets [38].3) IaaS Environments: As expected, even virtual instances in the cloud get compromised by adversaries. Hence, the ability to determine how defenses in the virtual environment failed and to what extent the affected systems havebeen compromised is crucial not only for recovering from an incident. Also forensic investigations gain leverage from such information and contribute to resilience against future attacks on the systems. From the forensic point of view, IaaS instances do provide much more evidence data usable for potential forensics than PaaS and SaaS models do. This fact is caused throughthe ability of the customer to install and set up the image for forensic purposes before an incident occurs. Hence, as proposed for PaaS environments, log data and other forensic evidence information could be signed and encrypted before itis transferred to third-party hosts mitigating the chance that a maliciously motivated shutdown process destroys the volatile data. Although, IaaS environments provide plenty of potential evidence, it has to be emphasized that the customer VM is in the end still under the control of the CSP. He controls the hypervisor which is e.g. responsible for enforcing hardware boundaries and routing hardware requests among different VM. Hence, besides the security responsibilities of the hypervisor, he exerts tremendous control over how customer’s VM communicate with the hardware and theoretically can intervene executed processes on the hosted virtual instance through virtual introspection [25]. This could also affect encryption or signing processes executed on the VM and therefore leading to the leakage of the secret key. Although this risk can be disregarded in most of the cases, the impact on the security of high security environments is tremendous.a) Snapshot Analysis: Traditional forensics expect target machines to be powered down to collect an image (dead virtual instance). This situation completely changed with the advent of the snapshot technology which is supported by all popular hypervisors such as Xen, VMware ESX and Hyper-V.A snapshot, also referred to as the forensic image of a VM, providesa powerful tool with which a virtual instance can be clonedby one click including also the running system’s mem ory. Due to the invention of the snapshot technology, systems hosting crucial business processes do not have to be powered down for forensic investigation purposes. The investigator simply creates and loads a snapshot of the target VM for analysis(live virtual instance). This behavior is especially important for scenarios in which a downtime of a system is not feasible or practical due to existing SLA. However the information whether the machine is running or has been properly powered down is crucial [3] for the investigation. Live investigations of running virtual instances become more common providing evidence data that。

The development and tendency of Big DataAbstract: "Big Data" is the most popular IT word after the "Internet of things" and "Cloud computing". From the source, development, status quo and tendency of big data, we can understand every aspect of it. Big data is one of the most important technologies around the world and every country has their own way to develop the technology.Key words: big data; IT; technology1 The source of big dataDespite the famous futurist Toffler propose the conception of “Big Data” in 1980, for a long time, because the primary stage is still in the development of IT industry and uses of information sources, “Big Data” is not get enough attention by the people in that age[1].2 The development of big dataUntil the financial crisis in 2008 force the IBM ( multi-national corporation of IT industry) proposing conception of “Smart City”and vigorously promote Internet of Things and Cloud computing so that information data has been in a massive growth meanwhile the need for the technology is very urgent. Under this condition, some American data processing companies have focused on developing large-scale concurrent processing system, then the “Big Data”technology become available sooner and Hadoop mass data concurrent processing system has received wide attention. Since 2010, IT giants have proposed their products in big data area. Big companies such as EMC、HP、IBM、Microsoft all purchase other manufacturer relating to big data in order to achieve technical integration[1]. Based on this, we can learn how important the big data strategy is. Development of big data thanks to some big IT companies such as Google、Amazon、China mobile、Alibaba and so on, because they need a optimization way to store and analysis data. Besides, there are also demands of health systems、geographic space remote sensing and digital media[2].3 The status quo of big dataNowadays America is in the lead of big data technology and market application. USA federal government announced a “Big Data’s research and development” plan in March,2012, which involved six federal government department the National Science Foundation, Health Research Institute, Department of Energy, Department of Defense, Advanced Research Projects Agency and Geological Survey in order to improve the ability to extract information and viewpoint of big data[1]. Thus, it can speed science and engineering discovery up, and it is a major move to push some research institutions making innovations.The federal government put big data development into a strategy place, which hasa big impact on every country. At present, many big European institutions is still at the primary stage to use big data and seriously lack technology about big data. Most improvements and technology of big data are come from America. Therefore, there are kind of challenges of Europe to keep in step with the development of big data. But, in the financial service industry especially investment banking in London is one of the earliest industries in Europe. The experiment and technology of big data is as good as the giant institution of America. And, the investment of big data has been maintained promising efforts. January 2013, British government announced 1.89 million pound will be invested in big data and calculation of energy saving technology in earth observation and health care[3].Japanese government timely takes the challenge of big data strategy. July 2013, Japan’s communications ministry proposed a synthesize strategy called “Energy ICT of Japan” which focused on big data application. June 2013, the abe cabinet formally announced the new IT strategy----“The announcement of creating the most advanced IT country”. This announcement comprehensively expounded that Japanese new IT national strategy is with the core of developing opening public data and big data in 2013 to 2020[4].Big data has also drawn attention of China government.《Guiding opinions of the State Council on promoting the healthy and orderly development of the Internet of things》promote to quicken the core technology including sensor network、intelligent terminal、big data processing、intelligent analysis and service integration. December 2012, the national development and reform commission add data analysis software into special guide, in the beginning of 2013 ministry of science and technology announced that big data research is one of the most important content of “973 program”[1]. This program requests that we need to research the expression, measure and semantic understanding of multi-source heterogeneous data, research modeling theory and computational model, promote hardware and software system architecture by energy optimal distributed storage and processing, analysis the relationship of complexity、calculability and treatment efficiency[1]. Above all, we can provide theory evidence for setting up scientific system of big data.4 The tendency of big data4.1 See the future by big dataIn the beginning of 2008, Alibaba found that the whole number of sellers were on a slippery slope by mining analyzing user-behavior data meanwhile the procurement to Europe and America was also glide. They accurately predicting the trend of world economic trade unfold half year earlier so they avoid the financial crisis[2]. Document [3] cite an example which turned out can predict a cholera one year earlier by mining and analysis the data of storm, drought and other natural disaster[3].4.2 Great changes and business opportunitiesWith the approval of big data values, giants of every industry all spend more money in big data industry. Then great changes and business opportunity comes[4].In hardware industry, big data are facing the challenges of manage, storage and real-time analysis. Big data will have an important impact of chip and storage industry,besides, some new industry will be created because of big data[4].In software and service area, the urgent demand of fast data processing will bring great boom to data mining and business intelligence industry.The hidden value of big data can create a lot of new companies, new products, new technology and new projects[2].4.3 Development direction of big dataThe storage technology of big data is relational database at primary. But due to the canonical design, friendly query language, efficient ability dealing with online affair, Big data dominate the market a long term. However, its strict design pattern, it ensures consistency to give up function, its poor expansibility these problems are exposed in big data analysis. Then, NoSQL data storage model and Bigtable propsed by Google start to be in fashion[5].Big data analysis technology which uses MapReduce technological frame proposed by Google is used to deal with large scale concurrent batch transaction. Using file system to store unstructured data is not lost function but also win the expansilility. Later, there are big data analysis platform like HA VEn proposed by HP and Fusion Insight proposed by Huawei . Beyond doubt, this situation will be continued, new technology and measures will come out such as next generation data warehouse, Hadoop distribute and so on[6].ConclusionThis paper we analysis the development and tendency of big data. Based on this, we know that the big data is still at a primary stage, there are too many problems need to deal with. But the commercial value and market value of big data are the direction of development to information age.忽略此处..[1] Li Chunwei, Development report of China’s E-Commerce enterprises, Beijing , 2013,pp.268-270[2] Li Fen, Zhu Zhixiang, Liu Shenghui, The development status and the problems of large data, Journal of Xi’an University of Posts and Telecommunications, 18 volume, pp. 102-103,sep.2013 [3] Kira Radinsky, Eric Horivtz, Mining the Web to Predict Future Events[C]//Proceedings of the 6th ACM International Conference on Web Search and Data Mining, WSDM 2013: New York: Association for Computing Machinery,2013,pp.255-264[4] Chapman A, Allen M D, Blaustein B. It’s About the Data: Provenance as a Toll for Assessing Data Fitness[C]//Proc of the 4th USENIX Workshop on the Theory and Practice of Provenance, Berkely, CA: USENIX Association, 2012:8[5] Li Ruiqin, Zheng Janguo, Big data Research: Status quo, Problems and Tendency[J],Network Application,Shanghai,1994,pp.107-108[6] Meng Xiaofeng, Wang Huiju, Du Xiaoyong, Big Daya Analysis: Competition and Survival of RDBMS and ManReduce[J], Journal of software, 2012,23(1): 32-45。

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。