網(wǎng)上書(shū)店網(wǎng)站設(shè)計(jì)chapter18-19 chapter09p8

1、Chapter 9Process ModelingObjectivesDefine systems modeling and differentiate logical and physical models.Define process modeling and explain its benefits.Recognize and understand basic concepts and constructs of a process model.Read and interpret a data flow diagram.Explain when to construct process

2、 models and where to store them.Construct a context diagram to illustrate a systems interfaces with its environment.Identify use cases, external and temporal business events.Perform event partitioning and organize events in a functional position diagram.Draw event diagrams and merge them into a syst

3、em diagram.Draw primitive data flow diagrams and describe the elementary data flows in terms of data structures and procedural logic.Document the distribution of processes to locations.Synchronize data and process models using a CRUD matrix.9-39-4Models: Logical and PhysicalLogical model a nontechni

4、cal pictorial representation that depicts what a system is or does. Synonyms or essential model, conceptual model, and business model.Physical model a technical pictorial representation that depicts what a system is or does and how the system is implemented. Synonyms are implementation model and tec

5、hnical model.Model a pictorial representation of reality. Just as a picture is worth a thousand words, most models are pictorial representations of reality.9-5Why Logical System ModelsLogical models remove biases that are the result of the way the system is currently implemented, or the way that any

6、 one person thinks the system might be implemented.Logical models reduce the risk of missing business requirements because we are too preoccupied with technical results.Logical models allow us to communicate with end-users in nontechnical or less technical languages.9-6Process Modeling and DFDsProce

7、ss modeling a technique used to organize and document a systems processes.Flow of data through processesLogicPoliciesProceduresData flow diagram (DFD) a process model used to depict the flow of data through a system and the work or processing performed by the system. Synonyms are bubble chart, trans

8、formation graph, and process model. The DFD has also e a popular tool for business process redesign.9-7Simple Data Flow Diagram9-8DFD和流程圖的區(qū)別DFD中的過(guò)程可以并行操作 (at-the-same-time)流程圖（ flowcharts ）中的過(guò)程一次只能執(zhí)行一步（ one at a time ）。DFD顯示了數(shù)據(jù)通過(guò)系統(tǒng)的流程流程圖顯示了控制的順序和轉(zhuǎn)移的流程。DFD可以展示具有不同定時(shí)的動(dòng)態(tài)過(guò)程（不同的定時(shí)標(biāo)準(zhǔn)并存）流程圖是一個(gè)具有一致定時(shí)的單一程序的一

9、部分過(guò)程建模的系統(tǒng)概念9-99-10外部代理外部代理（External agent）是與系統(tǒng)交互的外部的人員、組織部門(mén)、其他系統(tǒng)或其他組織，又稱為外部實(shí)體。 外部代理定義了要建模系統(tǒng)的“邊界”或范圍隨著項(xiàng)目范圍和目標(biāo)的變化，外部代理可以變成過(guò)程，反之亦然.外部代理一般為以下之一:辦公室、部門(mén)、分部.一個(gè)外部組織或代理.另外的企業(yè)或者信息系統(tǒng).系統(tǒng)的最終用戶或者管理人員之一用描述性的單數(shù)名詞命名Gane 和 Sarson 形狀DeMarco/Yourdon 形狀9-11數(shù)據(jù)存儲(chǔ)數(shù)據(jù)存儲(chǔ)（Data store）存儲(chǔ)數(shù)據(jù)供日后使用。同義詞包括文件和數(shù)據(jù)庫(kù). 經(jīng)常由文件或數(shù)據(jù)庫(kù)實(shí)現(xiàn).如果說(shuō)數(shù)據(jù)流是運(yùn)動(dòng)

10、中的數(shù)據(jù)，那么數(shù)據(jù)存儲(chǔ)就是靜止的數(shù)據(jù).數(shù)據(jù)存儲(chǔ)一般為以下之一:人（或小組）地點(diǎn)對(duì)象時(shí)間 (有關(guān)哪些數(shù)據(jù)被捕獲)概念 (有關(guān)哪些數(shù)據(jù)是重要的)在DFD上數(shù)據(jù)存儲(chǔ)表示了所有數(shù)據(jù)實(shí)體的實(shí)例。用復(fù)數(shù)名詞命名Gane and Sarson 形狀DeMarco/Yourdon 形狀9-12過(guò)程概念過(guò)程（Process） 是在輸入數(shù)據(jù)流或條件上執(zhí)行，或者對(duì)輸入數(shù)據(jù)流或條件作出響應(yīng)的工作，同義詞是轉(zhuǎn)換. 所有信息系統(tǒng)都包含過(guò)程，通常有很多。過(guò)程響應(yīng)業(yè)務(wù)事件和條件并數(shù)據(jù)轉(zhuǎn)換城有用信息。建模過(guò)程有助于我們理解過(guò)程與系統(tǒng)環(huán)境、其他系統(tǒng)以及其他過(guò)程如何交互.用一個(gè)強(qiáng)動(dòng)作動(dòng)詞跟一個(gè)描述需要完成工作的賓語(yǔ)從句.Gane

11、和 Sarson 形狀9-13一個(gè)系統(tǒng)的傳統(tǒng)過(guò)程建模一個(gè)系統(tǒng)最簡(jiǎn)單的過(guò)程模型是基于輸入、輸出和系統(tǒng)本身的-被看做是一個(gè)過(guò)程。9-14過(guò)程分解分解（ position）是將一個(gè)系統(tǒng)分解成它的組件子系統(tǒng)、過(guò)程和子過(guò)程的行動(dòng)。每個(gè)層次的抽象都揭示了有關(guān)整個(gè)系統(tǒng)或系統(tǒng)的某個(gè)子集的或多或少的細(xì)節(jié)。9-15分解圖分解圖（ position diagram） 是一種用來(lái)描述系統(tǒng)分解的工具，也稱為層次圖（hierarchy chart）.9-16邏輯過(guò)程的類型功能（Function）是企業(yè)的一套相關(guān)的和正在進(jìn)行的活動(dòng).一個(gè)功能沒(méi)有開(kāi)始和結(jié)束.事件（Event） 是必須作為一個(gè)整體完成的邏輯工作單位，有時(shí)被稱作

12、事務(wù)（ transaction ）.由離散的輸入觸發(fā)，當(dāng)過(guò)程與相應(yīng)的輸出響應(yīng)時(shí)事件結(jié)束.功能由響應(yīng)事件的過(guò)程組成.基本過(guò)程（Elementary process ）是為完成一個(gè)事件的響應(yīng)所需要的離散的詳細(xì)活動(dòng)或任務(wù)。也稱為原子過(guò)程（primitive process）.它們是在一個(gè)過(guò)程模型中描述的最底層的細(xì)節(jié).9-17功能過(guò)程名示例生產(chǎn)計(jì)劃生產(chǎn)調(diào)度材料管理生產(chǎn)控制質(zhì)量管理庫(kù)存控制訂單輸入銷售報(bào)告客戶關(guān)系退貨退款功能用描述整個(gè)功能的名詞命名9-18事件過(guò)程名示例處理客戶訂單處理客戶訂單修改處理客戶地址修改響應(yīng)客戶投訴響應(yīng)訂單查詢響應(yīng)產(chǎn)品價(jià)格查詢生成退單報(bào)告生成客戶賬號(hào)結(jié)算表生成發(fā)票“處理_”、“

13、響應(yīng)_”或“生成_”9-19基本過(guò)程名示例驗(yàn)證客戶身份驗(yàn)證訂購(gòu)產(chǎn)品編號(hào)檢查產(chǎn)品的可用性計(jì)算訂單費(fèi)用檢查客戶信用排序退單獲得客戶地址更新客戶地址添加新客戶刪除客戶用一個(gè)強(qiáng)動(dòng)詞后跟一個(gè)描述實(shí)施的工作的賓語(yǔ)從句命名9-20邏輯過(guò)程的特點(diǎn)邏輯過(guò)程模型忽略了那些除了移動(dòng)或路由數(shù)據(jù)（也就是保持?jǐn)?shù)據(jù)不變）而不做任何其他工作的過(guò)程.應(yīng)該僅僅保留以下邏輯過(guò)程：執(zhí)行計(jì)算（計(jì)算平均積分點(diǎn)）做出決策（決定是否可以獲得訂購(gòu)的產(chǎn)品）排序、過(guò)濾或者總結(jié)數(shù)據(jù)（確定過(guò)期的發(fā)票）組織數(shù)據(jù)成為有用的信息（生成報(bào)告或者回答問(wèn)題）觸發(fā)其他過(guò)程（打開(kāi)抽屜或者指揮一個(gè)機(jī)器人）使用存儲(chǔ)數(shù)據(jù)（創(chuàng)建、讀取、修改或者刪除記錄）9-21DFD中的常

14、見(jiàn)錯(cuò)誤黑洞無(wú)輸入灰洞9-22數(shù)據(jù)流（Data flow ）是一個(gè)過(guò)程的數(shù)據(jù)輸入，或者來(lái)自一個(gè)過(guò)程的數(shù)據(jù)（或信息）輸入.數(shù)據(jù)流是運(yùn)動(dòng)中的數(shù)據(jù)數(shù)據(jù)流也可能被用于表示在文件或數(shù)據(jù)庫(kù)（在DFD中稱為數(shù)據(jù)存儲(chǔ)）中創(chuàng)建、讀取、刪除或修改數(shù)據(jù)。組合數(shù)據(jù)流（Composite data flow） 由其他數(shù)據(jù)流構(gòu)成的數(shù)據(jù)流?？刂屏鳎–ontrol flow ）表示觸發(fā)一個(gè)過(guò)程的條件或非數(shù)據(jù)事件。保守地用于DFD.數(shù)據(jù)流和控制流數(shù)據(jù)流名稱控制流名稱9-23數(shù)據(jù)流報(bào)文概念一起旅行的數(shù)據(jù)應(yīng)該被表示為一個(gè)單一的數(shù)據(jù)流，無(wú)論其中可能包含多少物理文檔.9-24組合數(shù)據(jù)流和基本數(shù)據(jù)流交合點(diǎn)（Junction）指任何給定的“

15、訂單”僅僅是某種訂單的一個(gè)實(shí)例.基本數(shù)據(jù)流組合數(shù)據(jù)流9-25往返于數(shù)據(jù)存儲(chǔ)的數(shù)據(jù)流9-26邏輯數(shù)據(jù)流規(guī)則所有數(shù)據(jù)流都應(yīng)該命名.在邏輯模型中，數(shù)據(jù)流名稱應(yīng)該描述數(shù)據(jù)流，而非如何或者可以如何實(shí)現(xiàn)所有的數(shù)據(jù)流必須以一個(gè)過(guò)程開(kāi)始和/或結(jié)束.例9-27例9-28D1 doesnt begin or end at a process.D4 doesnt begin or end at a process.unnamedMiracleBlack HoleProcess2 simply forwards D6.9-29數(shù)據(jù)守恒數(shù)據(jù)守恒（Data conservation ）是確保一個(gè)數(shù)據(jù)流只包含接收數(shù)據(jù)的過(guò)程

16、真正需要的數(shù)據(jù)的實(shí)踐.有時(shí)被稱為“饑餓過(guò)程”（starving the processes）重新對(duì)業(yè)務(wù)過(guò)程重構(gòu)的強(qiáng)調(diào)鼓勵(lì)管理人員、用戶和系統(tǒng)分析員在設(shè)計(jì)任何信息系統(tǒng)之前確定并消除低效率因素.簡(jiǎn)化了過(guò)程之間的接口.必須精確地定義每個(gè)（非組合）數(shù)據(jù)流的數(shù)據(jù)成分。數(shù)據(jù)成分以數(shù)據(jù)結(jié)構(gòu)（data structures）的形式表示.9-30數(shù)據(jù)結(jié)構(gòu)數(shù)據(jù)流可以按照下列類型的數(shù)據(jù)結(jié)構(gòu)描述:一個(gè)序列（sequence） 或者一組依次出現(xiàn)的數(shù)據(jù)屬性.從一組屬性中選擇（selection） 一個(gè)或多個(gè)屬性.一個(gè)或多個(gè)屬性的重復(fù)（repetition）.數(shù)據(jù)流可以被定義為數(shù)據(jù)結(jié)構(gòu)。數(shù)據(jù)結(jié)構(gòu)（ Data structu

17、re ）是數(shù)據(jù)屬性的特別排列，它定義了數(shù)據(jù)流的一個(gè)實(shí)例。數(shù)據(jù)屬性（Data attribute ） 是對(duì)最終用戶和業(yè)務(wù)有意義的最小數(shù)據(jù)塊構(gòu)成一個(gè)數(shù)據(jù)流的數(shù)據(jù)屬性被組織成數(shù)據(jù)結(jié)構(gòu)。9-31一個(gè)數(shù)據(jù)流的數(shù)據(jù)結(jié)構(gòu)的符號(hào)9-32一個(gè)數(shù)據(jù)流的數(shù)據(jù)結(jié)構(gòu)DATA STRUCTUREORDER=ORDER NUMBER +ORDER DATE+ PERSONAL CUSTOMER NUMBER, CORPORATE ACCOUNT NUMBER+SHIPPING ADDRESS=ADDRESS+(BILLING ADDRESS=ADDRESS)+1 PRODUCT NUMBER+ PRODUCT DESCRI

18、PTION+ QUANTITY ORDERED+ PRODUCT PRICE+ PRODUCT PRICE SOURCE+ EXTENDED PRICE N+SUM OF EXTENDED PRICES+PREPAID AMOUNT+(CREDIT CARD NUMBER+EXPIRATION DATE)(QUOTE NUMBER)ADDRESS=(POST OFFICE BOX NUMBER)+STREET ADDRESS+CITY+STATE, MUNICIPALITY+(COUNTRY)+POSTAL CODEENGLISH ENTERPRETATIONAn instance of OR

19、DER consists of:ORDER NUMBER andORDER DATE andEither PERSONAL CUSTOMER NUMBERor CORPORATE ACCOUNT NUMBERand SHIPPING ADDRESS (which is equivalent to ADDRESS)and optionally: BILLING ADDRESS (which is equivalent to ADDRESS)and one or more instances of:PRODUCT NUMBER andPRODUCT DESCRIPTION andQUANTITY

20、ORDERED andPRODUCT PRICE andPRODUCT PRICE SOURCE andEXTENDED PRICEand SUM OF EXTENDED PRICES andPREPAID AMOUNT andoptionally: both CREDIT CARD NUMBER and EXPIRATION DATEAn instance of ADDRESS consists of:optionally: POST OFFICE BOX NUMBER andSTREET ADDRESS andCITY andEither STATE or MUNICIPALITYand

21、optionally: COUNTRYand POSTAL CODE9-33數(shù)據(jù)結(jié)構(gòu)的構(gòu)建（1/3）Data StructureFormat by Example(relevant portion is boldfacedEnglish Interpretation(relevant portion is boldfaced)Sequence of Attributes - The sequence data structure indicates one or more attributes that may (or must) be included in a data flow.WAGE

22、 AND TAX STATEMENT= TAXPAYER IDENTIFICATION NUMBER+ TAXPAYER NAME+ TAXPAYER ADDRESS+ WAGES, TIPS, AND COMPENSATION+ FEDERAL TAX WITHHELD+An instance of WAGE AND TAX STATEMENTS consists of: TAXPAYER IDENTIFICATION NUMBER and TAXPAYER NAME and TAXPAYER ADDRESS and WAGES, TIPS AND COMPENSATION and FEDE

23、RAL TAX WITHHELD andSelection of Attributes - The selection data structure allows you to show situations where different sets of attributes describe different instances of the data flow.ORDER= (PERSONAL CUSTOMER NUMBER, CORPORATE ACCOUNT NUMBER)+ ORDER DATE+An instance or ORDER consists of: Either P

24、ERSONAL CUSTOMER NUMBER or CORPORATE ACCOUNT NUMBER; and ORDER DATE and9-34數(shù)據(jù)結(jié)構(gòu)的構(gòu)建（2/3）Data StructureFormat by Example(relevant portion is boldfacedEnglish Interpretation(relevant portion is boldfaced)Repetition of Attributes - The repetition data structure is used to set off a data attribute or gro

25、up of data attributes that may (or must) repeat themselves a specific number of time for a single instance of the data flow. The minimum number of repetitions is usually zero or one. The maximum number of repetitions may be specified as “n” meaning “many” where the actual number of instances varies

26、for each instance of the data flow. POLICY NUMBER+ POLICYHOLDER NAME+ POLICY HOLDER ADDRESS+ 0 DEPENDENT NAME+ DEPENDENTS RELATIONSHIP N+ 1 EXPENSE DESCRIPTION+ SERVICE PROVIDER+ EXPENSE AMOUNT NAn instance of CLAIM consists of: POLICY NUMBER and POLICYHOLDER NAME and POLICYHOLDER ADDRESS and zero o

27、r more instance of: DEPENDENT NAME and DEPENDENTS RELATIONSHIP and one or more instances of: EXPENSE DESCRIPTION and SERVICE PROVIDER and EXPENSE ACCOUNT9-35數(shù)據(jù)結(jié)構(gòu)的構(gòu)建（3/3）Data StructureFormat by Example(relevant portion is boldfacedEnglish Interpretation(relevant portion is boldfaced)Optional Attribut

28、es - The optional notation indicates that an attribute, or group of attributes in a sequence or selection date structure may not be included in all instances of a data flow.Note: For the repetition data structure, a minimum of “zero” is the same as making the entire repeating group “optional.”CLAIM=

29、 POLICY NUMBER+ POLICYHOLDER NAME+ POLICYHOLDER ADDRESS+ ( SPOUSE NAME+ DATE OF BIRTH)+An instance of CLAIM consists of: POLICY NUMBER and POLICYHOLDER NAME and POLICYHOLDER ADDRESS and optionally, SPOUSE NAME and DATE OF BIRTH andReusable Attributes - For groups of attributes that are contained in

30、many data flows, it is desirable to create a separate data structure that can be reused in other data structures.DATE= MONTH+ DAY+ YEAR+Then, the reusable structures can be included in other data flow structures as follows: ORDER=ORDER NUMBER+DATE INVOICE=INVOICE NUMBER+DATE PAYMENT=CUSTOMER NUMBER+

31、DATE9-36數(shù)據(jù)類型和域數(shù)據(jù)屬性應(yīng)該由兩個(gè)特性來(lái)定義：數(shù)據(jù)類型和域。數(shù)據(jù)類型（Data type ）定義了一個(gè)屬性中可以存儲(chǔ)什么類型的數(shù)據(jù).Character, integers, real numbers, dates, pictures等.域（Domain） 定義了一個(gè)屬性中可以取的合法值. 9-37分支流和合并流分支的數(shù)據(jù)流（Diverging data flow ）是一個(gè)分成多個(gè)數(shù)據(jù)流的數(shù)據(jù)流.指示了開(kāi)始的一個(gè)數(shù)據(jù)流需要被路由進(jìn)行并行處理.也指示了開(kāi)始的一個(gè)數(shù)據(jù)流需要有多份拷貝路由到不同目的地.合并的數(shù)據(jù)流（Converging data flow ）是多個(gè)數(shù)據(jù)流合并成一個(gè)數(shù)據(jù)流后

32、的數(shù)據(jù)流.指示了不同來(lái)源的數(shù)據(jù)流可以（必須）合并成一個(gè)報(bào)文供后續(xù)處理.9-38分支流和合并流與互斥或包含或包含或邏輯過(guò)程建模的過(guò)程9-399-40何時(shí)構(gòu)造過(guò)程模型戰(zhàn)略系統(tǒng)規(guī)劃企業(yè)過(guò)程模型描述重要的業(yè)務(wù)功能.業(yè)務(wù)過(guò)程重構(gòu)“As is” 過(guò)程模型有助于關(guān)鍵的分析.“To be” 過(guò)程模型有助于改進(jìn).系統(tǒng)分析（主要集中在這個(gè)階段）構(gòu)造當(dāng)前系統(tǒng)的模型包括它的約束建模目標(biāo)系統(tǒng)的邏輯需求建模候選技術(shù)解決方案建模目標(biāo)技術(shù)解決方案9-41傳統(tǒng)的結(jié)構(gòu)化分析自頂向下地構(gòu)造當(dāng)前系統(tǒng)的物理DFD.把物理DFD轉(zhuǎn)換為邏輯等價(jià)模型.自頂向下地構(gòu)造邏輯DFD以表示改進(jìn)的系統(tǒng).描述所有數(shù)據(jù)流、數(shù)據(jù)存儲(chǔ)、策略以及數(shù)據(jù)字典或百科

33、全書(shū)中的規(guī)程.可選擇地標(biāo)記出邏輯DFD的拷貝以表示可替代物理解決方案的.自頂向下地構(gòu)造目標(biāo)系統(tǒng)的物理DFD.9-42現(xiàn)代的結(jié)構(gòu)化分析構(gòu)造系統(tǒng)上下文DFD，以建立初始的項(xiàng)目范圍.繪制功能分解圖（functional position diagram） ，將系統(tǒng)劃分成子系統(tǒng)和/或功能.創(chuàng)建事件響應(yīng)（event-response）或用例清單以確定并證實(shí)系統(tǒng)必須提供響應(yīng)的業(yè)務(wù)事件.對(duì)于每個(gè)事件，繪制事件圖（或事件處理器（handler）通過(guò)合并事件圖構(gòu)造一個(gè)系統(tǒng)圖（或?qū)τ谝粋€(gè)更大的系統(tǒng)來(lái)說(shuō)，子系統(tǒng)圖）對(duì)需要進(jìn)一步處理細(xì)節(jié)的事件處理器構(gòu)造基本圖.把數(shù)據(jù)流和過(guò)程在數(shù)據(jù)字典中文檔化.9-43現(xiàn)代的結(jié)構(gòu)化分析

34、上述方法學(xué)是基于事件劃分（Event Partitioning），現(xiàn)在更加適用。事件劃分（ Event Partitioning ）是一種結(jié)構(gòu)化分析策略，根據(jù)業(yè)務(wù)事件和對(duì)事件的響應(yīng)將一個(gè)系統(tǒng)劃分成子系統(tǒng)。9-44結(jié)構(gòu)化分析圖（1/3）9-45結(jié)構(gòu)化分析圖（2/3）9-46結(jié)構(gòu)化分析圖（3/3）9-47用于過(guò)程建模的CASE工具如何構(gòu)造過(guò)程模型？9-489-49現(xiàn)代的結(jié)構(gòu)化分析構(gòu)造系統(tǒng)上下文DFD，以建立初始的項(xiàng)目范圍.繪制功能分解圖（functional position diagram） ，將系統(tǒng)劃分成子系統(tǒng)和/或功能.創(chuàng)建事件響應(yīng)（event-response）或用例清單以確定并證實(shí)系統(tǒng)必

35、須提供響應(yīng)的業(yè)務(wù)事件.對(duì)于每個(gè)事件，繪制事件圖（或事件處理器（handler）通過(guò)合并事件圖構(gòu)造一個(gè)系統(tǒng)圖（或?qū)τ谝粋€(gè)更大的系統(tǒng)來(lái)說(shuō)，子系統(tǒng)圖）對(duì)需要進(jìn)一步處理細(xì)節(jié)的事件處理器構(gòu)造基本圖.把數(shù)據(jù)流和過(guò)程在數(shù)據(jù)字典中文檔化.9-50上下文數(shù)據(jù)流圖上下文數(shù)據(jù)流圖（Context data flow diagram） -是用來(lái)記錄系統(tǒng)的范圍的過(guò)程模型，也稱為環(huán)境模型（environmental model）。記錄系統(tǒng)邊界和范圍的策略：把系統(tǒng)看作“黑盒子”（black box）.詢問(wèn)最終用戶系統(tǒng)需要響應(yīng)什么業(yè)務(wù)事務(wù)，這些業(yè)務(wù)事務(wù)就是系統(tǒng)的凈出入，而來(lái)源則為外部代理.詢問(wèn)最終用戶系統(tǒng)必須產(chǎn)生什么響應(yīng)，這

36、些響應(yīng)就是凈輸出，而目的地也將成為外部代理.確定外部數(shù)據(jù)存儲(chǔ)。繪制上下文數(shù)據(jù)流圖.9-51SoundStage 上下文數(shù)據(jù)流圖過(guò)程外部代理9-52SoundStage Functional position DiagramBreak system into ponents to reveal more detail.Every process to be factored should be factored into at least two child processes.Larger systems might be factored into subsystems and functi

37、ons.9-53Events and Use CasesExternal events are initiated by external agents. They result in an input transaction or data flow.Temporal events are triggered on the basis of time, or something that merely happens. They are indicated by a control flow.State events trigger processes based on a systems

38、change from one state or condition to another. They are indicated by a control flow.Use case an analysis tool for finding and identifying business events and responses.Actor anything that interacts with a system.9-54SoundStage Partial Use Case ListActor/External AgentEvent (or Use Case)TriggerRespon

39、seMarketingEstablishes a new membership subscription plan to entice new members.New Member Subscription ProgramGenerate Subscription Plan Confirmation.Create Agreement in the database.MarketingEstablishes a new membership resubscription plan to lure back former members.Past Member Resubscription Pro

40、gramGenerate Subscription Plan Confirmation.Create Agreement in the database.(time)A subscription plan expires.(current date)Generate Agreement Change Confirmation.Logically delete Agreement in database.MemberJoins club by subscribing.New SubscriptionGenerate Member Directory Update Confirmation.Cre

41、ate Member in database.Create first Member Order and Member Ordered Products in database.9-55SoundStage PartialEvent position Diagram9-56Event DiagramsEvent diagram data flow diagram that depicts the context for a single event.One diagram for each event processDepictsInputs from external agentsOutpu

42、ts to external agentsData stores from which records must be read. Data flows should be added and named to reflect the data that is read.Data stores in which records must be created, deleted, or updated. Data flows should be named to reflect the update.9-57Simple Event Diagram9-58Event Diagram (more

43、complex)9-59Temporal Event Diagram9-60System DFD9-61System DFD (concluded)9-62BalancingBalancing - a concept that requires that data flow diagrams at different levels of detail reflect consistency and completenessQuality assurance techniqueRequires that if you explode a process to another DFD to rev

44、eal more detail, you must include the same dta flows and data stores9-63Primitive DiagramsSome (not necessarily all) event processes may be exploded into primitive diagrams to reveal more detail.Complex business transaction processesProcess posed into multiple elementary processesEach elementary pro

45、cess is cohesive - it does only one thingFlow similar to computer program structure9-64Primitive DFD (see book for more readable copy)9-65Specifying a Data Flow Using a CASE Tool9-66Process LogicData Flow Diagrams good for identifying and describing processesNot good at showing logic inside processe

46、sNeed to specify detailed instructions for elementary processesHow to do it?Flowcharts & Pseudocode - most end users do not understand themNatural English - imprecise and subject to interpretation 9-67 Source: Adapted from Matthies, Leslie, The New Playscript Procedure, (Stamford, CT: Office Publications, Inc. 1977)Problems with Natural EnglishMany do not write well and d