安徽工業(yè)大學 軟件工程 方木云 ch7

1、Notice通知,實驗內容：科研管理系統(tǒng)架構要求：B/S模式語言要求：Java, C#數據庫：SQL Server2005以上進度要求：第10周檢查人員要求：一人獨立完成 可以下載框架進行二次開發(fā),Requirement Engineering,1.What is requirement2.How to do requirement3.How to describe

2、 requirement軟件利潤=需求-設計人生利潤=？需海無涯,Requirement pre contract合同前需求方法,Through Networks 網絡上Through Books書籍上Interview with endusers 現(xiàn)場了解,Requirement after contract合同后需求,現(xiàn)場詳細需求分析利用原型生成中使用的所有單據都要收集1.橫向單據2.縱向單據3.入庫單據

3、4.出庫單據,How to express Requirements需求后整理表達方法,分類整理的能力流程整理數據單據的整理兩種方法：面向數據流面向對象,Who act the role誰承擔需求分析,系統(tǒng)分析員,系統(tǒng)分析員的作用：,developers,users,managers,analyst,prototype,Requirement specification,planning,兩類需求建模：面向數據流；面向對

4、象,To explain why Entity-Relationship Diagram(ERD) is used? ER圖To describe Data Flow Diagram(DFD) 數據流圖To introduce some of the notations used in the Unified Modelling Language (UML) 統(tǒng)一建模語言面向過程設計： ER圖+數據流圖+詳細

5、設計面向對象設計：統(tǒng)一建模語言+RUP,面向數據流和面向對象,Entity-Relationship Diagram （ERD）設計數據庫Data Flow Diagram（DFD）描述系統(tǒng)數據流the Unified Modelling Language (UML)采用統(tǒng)一建模語言,Model types模型類型,Entity-Relationship Diagram （ERD）在數據庫課程中已講Data Flow

6、Diagram（DFD）主要介紹，實驗報告中要采用the Unified Modelling Language (UML)新的內容，逐漸取代DFD，其內容繁多，不是一兩次能講完，因此只介紹框架,Data flow diagrams數據流圖,DFDs model the system from a functional perspectiveTracking and documenting how the data associ

7、ated with a process is helpful to develop an overall understanding of the systemData flow diagrams may also be used in showing the data exchange between a system and other systems in its environment,,Process 數據加工 (數據變

8、換),,Data source or destination 數據源點或終點 (外部實體),,Data flow 數據流,Data Store 數據存儲文件,數據流圖中的主要圖形元素,Example 1 描述銀行取款過程的數據流圖,分層的數據流圖,在多層數據流圖中，頂層流圖僅包含一個加工，它代表被開發(fā)系統(tǒng)。它的輸入流是該系統(tǒng)的輸入數據，輸出流是系統(tǒng)所輸出數據底層流圖是指其加工不需再做分解的數據流圖，它處在最底層中間層流圖則表示對

9、其上層父圖的細化。它的每一加工可能繼續(xù)細化，形成子圖。,Example 2商店業(yè)務處理系統(tǒng),這個數據流圖只是一個高層的系統(tǒng)邏輯模型，它反映了目標系統(tǒng)要實現(xiàn)的功能數據流圖繪制步驟 首先確定系統(tǒng)的輸入和輸出 根據商店業(yè)務，畫出頂層數據流圖，以反映最主要業(yè)務處理流程,Analysis,經過分析，商店業(yè)務處理的主要功能應當有銷售、采購、會計三大項。主要數據流輸入的源點和輸出終點是顧客和供應商。 然后從輸入端開始，根據商店業(yè)務工作流程，

10、畫出數據流流經的各加工框，逐步畫到輸出端，得到第一層數據流圖,Analysis,0層數據流圖,1層子數據流圖 銷售細化,1層子數據流圖 采購細化,檢查和修改數據流圖的原則,數據流圖上所有圖形符號只限于前述四種基本圖形元素數據流圖的主圖必須包括前述四種基本元素，缺一不可數據流圖的主圖上的數據流必須封閉在外部實體之間每個加工至少有一個輸入數據流和一個輸出數據流,在數據流圖中

11、，需按層給加工框編號。編號表明該加工所處層次及上下層的親子關系規(guī)定任何一個數據流子圖必須與它上一層的一個加工對應，兩者的輸入數據流和輸出數據流必須一致。此即父圖與子圖的平衡可以在數據流圖中加入物質流，幫助用戶理解數據流圖,基本加工邏輯說明,,對數據流圖的每一個基本加工，必須有一個基本加工邏輯說明基本加工邏輯說明必須描述基本加工如何把輸入數據流變換為輸出數據流的加工規(guī)則加工邏輯說明必須描述實現(xiàn)加工的策略而不是實現(xiàn)加工的細節(jié)加工邏

12、輯說明中包含的信息應是充足的，完備的，有用的，無冗余的,Data dictionaries數據字典,1. Data dictionaries are lists of all of the names used in the system models. Descriptions of the entities, relationships and attributes are also included2. Many CASE

13、 workbenches support data dictionaries3. 數據流圖需要數據字典來補充說明,數據詞典與數據流圖配合，能清楚地表達數據處理的要求詞條描述 —— 對于在數據流圖中每一個被命名的圖形元素，均加以定義，其內容有: 名字，別名或編號，分類，描述，定義，位置，其它，等,Data dictionaries數據字典,Description of Data flow數據流詞條描述,數據流名：說明：簡要介

14、紹作用即它產生的原因和結果數據流來源：來自何方數據流去向：去向何處數據流組成：數據結構數據量流通量：數據量，流通量Example:訂單=訂單號+日期+品種+數量+單價,Description of Data store數據文件詞條描述,數據文件名：簡述：存放的是什么數據輸入數據：輸出數據：數據文件組成：數據結構存儲方式：順序，直接，關鍵碼存取頻率：Example:待訂商品=商品號+商品名稱+品種+數量+單價,

15、Description of Process加工邏輯詞條描述,加工名：加工編號：反映該加工的層次簡要描述：加工邏輯及功能簡述輸入數據流：輸出數據流：加工邏輯：簡述加工程序，加工順序Example:1.1編輯訂單=增加+刪除+修改+查詢,Description of Data source or destination 源點及匯(終)點詞條描述,名稱：外部實體名簡要描述：什么外部實體有關數據流：數目：Exampl

16、e:顧客=顧客號+顧客名稱+聯(lián)系電話+法人代表+信譽度,領書單 進書通知,購書單 缺書單,DFD練習—售書系統(tǒng),領書單　　　　 　　　　　進書通知,進書通知,購書單　　　　　　　　　　　　　缺書單,DFD練習—售書系統(tǒng),,,,F1教材存量表,F2缺書登記表,,The Unified Modeling Language統(tǒng)一建模語言,Devis

17、ed by the developers of widely used object-oriented analysis and design methodsHas become an effective standard for object-oriented modellingNotationObject classes are rectangles with the name at the top, attributes i

18、n the middle section and operations in the bottom sectionRelationships between object classes (known as associations) are shown as lines linking objectsInheritance is referred to as generalisation and is shown ‘upwards

19、’ rather than ‘downwards’ in a hierarchy,Object aggregation,Aggregation model shows how classes which are collections are composed of other classesSimilar to the part-of relationship in semantic data models,Object aggre

20、gation,Object behaviour modelling,A behavioural model shows the interactions between objects to produce some particular system behaviour that is specified as a use-caseSequence diagrams (or collaboration diagrams) in th

21、e UML are used to model interaction between objects,Issue of electronic items,CASE workbenches,A coherent set of tools that is designed to support related software process activities such as analysis, design or testingA

22、nalysis and design workbenches support system modelling during both requirements engineering and system designThese workbenches may support a specific design method or may provide support for a creating several differen

23、t types of system model,An analysis and design workbench,Analysis workbench components,Diagram editorsModel analysis and checking toolsRepository and associated query languageData dictionaryReport definition and gene

24、ration toolsForms definition toolsImport/export translatorsCode generation tools,Key points(主要知識點),A model is an abstract system view. Complementary types of model provide different system informationContext models s

25、how the position of a system in its environment with other systems and processesData flow models may be used to model the data processing in a systemState machine models model the system’s behaviour in response to inte

26、rnal or external events,Key points,Semantic data models describe the logical structure of data which is imported to or exported by the systemsObject models describe logical system entities, their classification and aggr