黄色在线观看视频-黄色在线免费看-黄色在线视频免费-黄色在线视频免费看-免费啪啪网-免费啪啪网站

首頁 考試吧論壇 Exam8視線 考試商城 網絡課程 模擬考試 考友錄 實用文檔 求職招聘 論文下載
2011中考 | 2011高考 | 2012考研 | 考研培訓 | 在職研 | 自學考試 | 成人高考 | 法律碩士 | MBA考試
MPA考試 | 中科院
四六級 | 職稱英語 | 商務英語 | 公共英語 | 托福 | 雅思 | 專四專八 | 口譯筆譯 | 博思 | GRE GMAT
新概念英語 | 成人英語三級 | 申碩英語 | 攻碩英語 | 職稱日語 | 日語學習 | 法語 | 德語 | 韓語
計算機等級考試 | 軟件水平考試 | 職稱計算機 | 微軟認證 | 思科認證 | Oracle認證 | Linux認證
華為認證 | Java認證
公務員 | 報關員 | 銀行從業資格 | 證券從業資格 | 期貨從業資格 | 司法考試 | 法律顧問 | 導游資格
報檢員 | 教師資格 | 社會工作者 | 外銷員 | 國際商務師 | 跟單員 | 單證員 | 物流師 | 價格鑒證師
人力資源 | 管理咨詢師考試 | 秘書資格 | 心理咨詢師考試 | 出版專業資格 | 廣告師職業水平
駕駛員 | 網絡編輯
衛生資格 | 執業醫師 | 執業藥師 | 執業護士
會計從業資格考試會計證) | 經濟師 | 會計職稱 | 注冊會計師 | 審計師 | 注冊稅務師
注冊資產評估師 | 高級會計師 | ACCA | 統計師 | 精算師 | 理財規劃師 | 國際內審師
一級建造師 | 二級建造師 | 造價工程師 | 造價員 | 咨詢工程師 | 監理工程師 | 安全工程師
質量工程師 | 物業管理師 | 招標師 | 結構工程師 | 建筑師 | 房地產估價師 | 土地估價師 | 巖土師
設備監理師 | 房地產經紀人 | 投資項目管理師 | 土地登記代理人 | 環境影響評價師 | 環保工程師
城市規劃師 | 公路監理師 | 公路造價師 | 安全評價師 | 電氣工程師 | 注冊測繪師 | 注冊計量師
繽紛校園 | 實用文檔 | 英語學習 | 作文大全 | 求職招聘 | 論文下載 | 訪談 | 游戲
您現在的位置: 考試吧(Exam8.com) > 軟件水平考試 > 計算機專業英語 > 正文

Object-Oriented Web Engineering

  Resource-based Web Implementation

  Originally, the World-Wide Web was designed as information medium for distributed research teams. A deliberately simple implementation model was chosen to make it as simple as possible for authors to contribute documents to the web, and to maintain these in the sense of updating content. This implementation model is centered around the notion of resources, usually file-based. For the originally intended use of the web, resources presented a useful abstraction, as they related to relatively self-contained chunks of information such as research publications and home pages. Such chunks of information typically could be set up and maintained independently of other resources, so that resources were the appropriate abstraction for composition and modification.

  The use of the web, though, has moved far beyond the originally anticipated scope. In its use as information medium, the web has moved into high standard publishing with complex requirements related to corporate identity and to integrity of large webs. Resources are no longer easily maintained by themselves as they have to adhere to web site conventions regarding layout, interlinking, navigation and so on. Further, the web is not only used as information medium but has become a general integration platform for distributed appications. In development, management and maintenance of such applications, resources as abstraction are not very useful. Resources are too coarse-grained and too specific as entities for design, reuse, management and modification of web applications. Problems with the resource-based web implementation model are discussed in the subsequent section with respect to design, reuse and evolution.

  Mapping Design Concepts to a Web Implementation

  As the web implementation model based on resources is semantically so poor, the mapping of higher-level design concepts to a web implementation is hardly reversible. Higher-level design concepts such as graph structures in hypertext, dialogue in session-based applications, user interface objects in interactive applications (and so on ...) get lost in a web implementation because of the simplicity of the underlying model. For example, hypertext graphs, navigation structures and other hypertext concepts are implemented in Web links embedded in resources; once implemented, the relationship between these links, that is their "hypertext meaning", is lost. While design methods and tools are available for mapping higher-level concepts to web implementations are available (for hypertext e.g. OOHDM [3], RMM [4] and RMCase [5]), management and maintenance of higher-level concepts is hard. A specific instance of this problem is link integrity which has been much discussed but which is really just one instance of a very general problem in web application maintenance.

  The maintenance of design concepts is all the more problematic, as there is a split of roles in development of larger web applications, with maintenance carried out by site engineers and not by original designers/authors of content. In general, a multitude of people are involved in a web application life cycle in all sorts of different roles. This results in the problem of site engineers having to mentally reconstruct higher-level concepts from an implementation at hand in order to maintain them and protect in the case of modification. Naturally, this easily leads to introduction of errors and loss of application integrity.

  Reuse of Designs and Code

  Resources are specific entities to be served by web servers. Very little work has been done toward abstract resources abstracting from some implementation detail in order to be reusable. An example for abstractions are style sheets in HTML that allow to factor out some reusable layout components from HTML pages, or server-side includes for reuse of HTML fragments in many resources. These abstractions, though, are very limited and by far not generally applicable.

  Design concepts often relate not too exactly one resource but for example to fragments within a resource, to structures composed of such fragments, or to interlinked resources. As these concepts are not easily accessible from within a resource-based web implementation, they are hard to reuse. Further, design concepts may be abstract and would have to be abstracted out from a specific implementation. For reuse, design concepts have to replicated in an implementation, which in turn brings us back to the problem of maintaining integrity in the course of web evolution. Maintainance of integrity would at least require a replication of modifications, and would very likely lead to a violation of integrity.
The lack of support for inheritance in web resources represents yet another key problem. In design, generalization and specialization are fundamental concepts for organization of web sites and web applications, for instance describing general page designs which can be refined to more specific designs for certain categories of pages. As more general design decisions can not be captured in abstractions, their maintenance can not be localized but requires modification of all effected specific design artifacts.

更多軟考資料請訪問:考試吧軟件水平考試欄目

希望與更多網友交流,請進入考試吧軟件水平考試論壇

1 2 3 4 下一頁
文章責編:ak47  
看了本文的網友還看了
·計算機英語因特網(中英對照)  (2007-6-21 8:35:31)
·常見網址英文縮寫的含義匯編表  (2007-6-21 11:33:47)
·計算機專業英語名詞解釋大匯總  (2007-1-25 11:39:39)
·E-mail地址中的符號@是什么意思  (2007-1-25 11:32:20)
·了解到底什么是多媒體  (2007-1-25 11:29:34)
·A range of grid-related questions  (2007-1-25 11:26:39)
文章搜索
軟件水平考試欄目導航
版權聲明:如果軟件水平考試網所轉載內容不慎侵犯了您的權益,請與我們聯系800@exam8.com,我們將會及時處理。如轉載本軟件水平考試網內容,請注明出處。
主站蜘蛛池模板: 欧美三级黄视频 | 欧美精品99久久久久久人 | 成人国产第一区在线观看 | 欧美一区二区视频三区 | 国产亚洲欧美ai在线看片 | 午夜骚 | 国产一区欧美二区 | 精品亚洲福利一区二区 | 成人在线观看网站 | 一级做a免费视频观看网站 一男一女下面一进一出性视频 | 99热热热| 日韩在线视频网 | a成人在线 | 亚洲欧美强伦一区二区另类 | 玖玖爱zh综合伊人久久 | 日本黄色一级片视频 | 亚洲国产天堂在线mv网站 | 欧美大黄| 久艾草国产成人综合在线视频 | 天天摸天天揉天天碰天天弄 | 亚洲第一成年网 | 欧美精品一区二区三区在线播放 | 一级毛片a免费播放王色 | 高清一级毛片一本到免费观看 | 国产精品99久久免费观看 | 香蕉久久av一区二区三区 | 国产小视频免费 | 深夜福利免费观看 | 99精品国产第一福利网站 | 欧美日本一区二区 | 国产青草视频 | 国产精品亚洲欧美动漫卡通 | 国产一级一片免费播放 | 亚洲黄色网址大全 | 三级伦理在线 | 丁香六月久久 | 在线免费观看a视频 | 97国产在线观看 | 日韩一级生活片 | 欧美专区日韩 | 日韩国产中文字幕 |