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1、<p> Designing and developing applications for z/OS</p><p> 8.1 Application designers and programmers</p><p> The tasks of designing an application and developing one are distinct enough
2、 to treat each in a separate textbook. In larger z/OS sites, separate departments might be used to carry out each task. This chapter provides an overview of these job roles and shows how each skill fits into the overall
3、view of a typical application development life cycle on z/OS. The application designer is responsible for determining the best programming solution for an important business requirement. The success of an</p><
4、p> The application programmer is responsible for developing and maintaining application programs. That is, the programmer builds, tests, and delivers the application programs that run on the mainframe for the end use
5、rs. Based on the application designer’s specifications, the programmer constructs an application program using a variety of tools. The build process includes many iterations of code changes and compiles, application buil
6、ds, and unit testing. During the development process, the designer </p><p> 8.2 Designing an application for z/OS</p><p> During the early design phases, the application designer makes decisio
7、ns regarding the characteristics of the application. These decisions are based on many criteria, which must be gathered and examined in detail to arrive at a solution that is acceptable to the user. The decisions are not
8、 independent of each other, in that one decision will have an impact on others and all decisions must be made taking into account the scope of the project and its constraints. Designing an application to run on</p>
9、<p> _ “Designing for z/OS: Batch or online?” on page 258</p><p> _ “Designing for z/OS: Data sources and access methods” on page 258</p><p> _ “Designing for z/OS: Availability and wo
10、rkload requirements” on page 258</p><p> _ “Designing for z/OS: Exception handling” on page 259 </p><p> Beyond these decisions, other factors that might influence the design of a z/OS applica
11、tion might include the choice of one or more programming languages and development environments. Other considerations discussed in this chapter include the following: </p><p> _ Using mainframe character se
12、ts in “Using the EBCDIC character set” on page 265. </p><p> _ Use of an interactive development environment (IDE) in “Using application development tools” on page 267. </p><p> _ We discuss d
13、ifferences between the various programming languages in Chapter 9, “Using programming languages on z/OS” on page 275. Keep in mind that the best designs are those that start with the end result in mind. We must know what
14、 it is that we are striving for before we start to design.</p><p> 8.2.1 Designing for z/OS: Batch or online?</p><p> When designing an application for z/OS and the mainframe, a key considerat
15、ion is whether the application will run as a batch program or an online program. In some cases, the decision is obvious, but most applications can be designed to fit either paradigm. How, then, does the designer decide w
16、hich approach to use?</p><p> Reasons for using batch or online:</p><p> _ Reasons for using batch</p><p> – Data is stored on tape.</p><p> – Transactions are subm
17、itted for overnight processing.</p><p> – User does not require online access to data.</p><p> _ Reasons for using online:</p><p> – User requires online access to data.</p>
18、;<p> – High response time requirements.</p><p> 8.2.2 Designing for z/OS: Data sources and access methods</p><p> Here, the designer’s considerations typically include the following:&
19、lt;/p><p> _ What data must be stored?</p><p> _ How will the data be accessed? This includes a choice of access method.</p><p> _ Are the requests ad hoc or predictable?</p>
20、<p> _ Will we choose PDS, VSAM, or a database management system (DBMS) such as DB2?</p><p> 8.2.3 Designing for z/OS: Availability and workload requirements</p><p> For an application
21、that will run on z/OS, the designer must be able to answer the following questions:</p><p> _ What is the quantity of data to store and access?</p><p> _ Is there a need to share the data?<
22、/p><p> _ What are the response time requirements?</p><p> _ What are the cost constraints of the project?</p><p> _ How many users will access the application at once?</p>&
23、lt;p> What is the availability requirement of the application (24 hours a day 7 days a week or 8:00 AM to 5:00 PM weekdays, and so on)?</p><p> 8.2.4 Designing for z/OS: Exception handling</p>&l
24、t;p> Are there any unusual conditions that might occur? If so, we need to incorporate these in our design in order to prevent failures in the final application. We cannot always assume, for example, that input will a
25、lways be entered as expected.</p><p> 8.3 Application development life cycle: An overview</p><p> An application is a collection of programs that satisfies certain specific requirements (resol
26、ves certain problems). The solution could reside on any platform or combination of platforms, from a hardware or operating system point of view. As with other operating systems, application development on z/OS is usually
27、 composed of the following phases: </p><p> _ Design phase</p><p> – Gather requirements. User, hardware and software requirements</p><p> – Perform analysis.</p><p>
28、; – Develop the design in its various iterations:</p><p> –High-level design</p><p> –Detailed design</p><p> – Hand over the design to application programmers.</p><p
29、> _ Code and test application.</p><p> _ Perform user tests.</p><p> User tests application for functionality and usability.</p><p> _ Perform system tests.</p><p&
30、gt; – Perform integration test (test application with other programs to verify that</p><p> all programs continue to function as expected).</p><p> – Perform performance (volume) test using p
31、roduction data.</p><p> _ Go production—hand off to operations.</p><p> Ensure that all documentation is in place (user training, operation procedures).</p><p> _ Maintenance pha
32、se—ongoing day-to-day changes and enhancements to application.</p><p> Figure 8-1 shows the process flow during the various phases of the application development life cycle.Figure 8-2 depicts the design pha
33、se up to the point of starting development.</p><p> Once all of the requirements have been gathered, analyzed, verified, and a design has been produced, we are ready to pass on the programming The programme
34、rs take the design documents (programming requirements) and then proceed with the iterative process of coding, testing, revising, and testing again, as we see in Figure 8-3. After the programs have been tested by the pro
35、grammers, they will be part of a series of formal user and system tests. These are used to verify usability and functionality </p><p> The operational procedures documentation enables Operations to take ove
36、r responsibility for running the application on an ongoing basis. In production, the changes and enhancements are handled by a group (possibly the same programming group) that performs the maintenance. At this point in t
37、he life cycle of the application, changes are tightly controlled and must be rigorously tested before being implemented into production (Figure 8-5). As mentioned before, to meet user requirements or solve pro</p>
38、<p> The results of these interviews should inform every subsequent stage of the life cycle of the application project. At certain stages of the project, we again call upon the users to verify that we have underst
39、ood their requirements and that our solution meets their requirements. At these milestones of the project, we also ask the users to sign off on what we have done, so that we can proceed to the next step of the project.&l
40、t;/p><p> 8.3.1 Gathering requirements for the design</p><p> When designing applications, there are many ways to classify the requirements: Functional requirements, non-functional requirements,
41、emerging requirements, system requirements, process requirements, constraints on the development and on the operation—to name a few. Computer applications operate on data, which resides somewhere and which needs to be ac
42、cessed from either a local or remote location. The applications manipulate the data, performing some kind of processing on it, and then present the</p><p> An important advantage to the zSeries approach is
43、that applications can be maintained using tools that reside on the mainframe. Some of these mainframe tools make it possible to have different platforms sharing resources and data in a coordinated and secure way accordin
44、g to workload or priority. The following is a list of the various types of requirements for an application. The list is not exclusive; some items already include others.</p><p> _ Accessibility</p>&
45、lt;p> _ Recoverability</p><p> _ Serviceability</p><p> _ Availability</p><p> _ Security</p><p> _ Connectivity</p><p> _ Performance objectives&
46、lt;/p><p> _ Resource management</p><p> _ Usability</p><p> _ Frequency of data backup</p><p> _ Portability</p><p> _ Web services</p><p>
47、 _ Changeability</p><p> _ Inter-communicable</p><p> _ Failure prevention and fault analysis</p><p><b> 外文翻譯</b></p><p> 設(shè)計和z/OS的開發(fā)應用</p><p
48、> 8.1應用程序設(shè)計者和程序員</p><p> 設(shè)計和開發(fā)一個應用程序的任務是不同的,足以對待每一個單獨的教科書。在較大的z / OS的網(wǎng)站,獨立的部門可用于落實各項任務。本章提供了這些概述工作角色并展示了如何安裝到每一個技能的一個典型應用的總體看法發(fā)展在z / OS上的生命周期。應用程序設(shè)計者是負責確定最佳方案解決方案的一個重要的業(yè)務需求。任何設(shè)計成功取決于對設(shè)計師,業(yè)務本身,知識的一部分的認識政
49、務主任在大型機組織的其他作用,如編程和數(shù)據(jù)庫設(shè)計,業(yè)務,星光大道的硬件和軟件的理解??傊?,設(shè)計師一定要對整個項目的全局視圖。在這個過程中涉及的另一個作用是商業(yè)系統(tǒng)分析師。這人與用戶在某一個部門的工作負責(會計,銷售,生產(chǎn)控制制造等)來確定業(yè)務需求的應用程序。像應用程序設(shè)計,業(yè)務系統(tǒng)分析員需要的組織,業(yè)務廣泛的了解政務主任目標,以及信息系統(tǒng)的能力。收集的應用程序設(shè)計要求,從業(yè)務系統(tǒng)分析師和最終用戶。設(shè)計者還決定將哪些IT資源用于支持應用程
50、序。應用程序設(shè)計,然后寫為應用程序員設(shè)計規(guī)范執(zhí)行。應用程序程序員負責開發(fā)和維護應用程序。也就是說,程序員構(gòu)建,測試,并提供了上運行的應用程序,為最終用戶主機?;趹贸绦蛟O(shè)計人員,政務主任規(guī)格,構(gòu)造了一個應</p><p> 8.2設(shè)計一個用于z / OS應用程序</p><p> 在早期的設(shè)計階段,應用程序設(shè)計人員作出決定關(guān)于應用程序的特點。這些決定是基于很多標準,必須收集和詳細研究
51、在到達是可以接受的解決方案給用戶。該決定是不是相互獨立,另外,在這一項決定將會對他人的影響,所有決定都必須作出考慮到該項目和它的約束范圍。設(shè)計一個應用程序運行在z / OS的股份很多遵循的步驟設(shè)計一個應用程序運行在其他平臺,包括分布式環(huán)境。 z / OS上,不過,介紹了一些特殊的考慮。這本章提供了一些例子,決定在z / OS應用程序使得設(shè)計師在給定應用程序的設(shè)計過程。這份名單是不意味著要面面俱到,而是給你一個復雜的過程的想法:</
52、p><p> “設(shè)計用于z / OS:批處理或在線?”258頁</p><p> “設(shè)計用于z / OS:數(shù)據(jù)來源和訪問方法”258頁</p><p> “設(shè)計用于z / OS:可用性和工作量要求”258頁</p><p> “設(shè)計用于z / OS:異常處理”259頁</p><p> 超越這些決定,其他因素可能
53、會影響排列設(shè)計/操作系統(tǒng)應用程序可能包括一個選擇或多種編程語言和開發(fā)環(huán)境。其他考慮在本章討論包括以下內(nèi)容:式開發(fā)環(huán)境(IDE)在“使用應用程序開發(fā)工具“頁267。_我們討論不同的編程語言之間的差異第9章,“使用在z / OS的編程語言”頁275。請記住,最好的設(shè)計是那些與最終導致啟動頭腦。我們必須知道它是什么,我們正在努力爭取,才開始設(shè)計。</p><p> 8.2.1設(shè)計用于z/OS:批處理或在線</p
54、><p> 當設(shè)計一個應用程序的z / OS和大型機,一個重要的考慮因素是,應用程序?qū)⑦\行批處理程序或在線方案。在某些情況下,決定是顯而易見的,但大多數(shù)應用程序可以被設(shè)計為無論是典范。那么,如何決定是否設(shè)計者使用哪種方法?原因使用批處理或在線:</p><p><b> 使用批處理的原因:</b></p><p><b> 數(shù)據(jù)存儲
55、在磁帶上。</b></p><p><b> 交易提交過夜處理。</b></p><p> 用戶不需要在線訪問數(shù)據(jù)。</p><p><b> 使用在線的原因:</b></p><p> 用戶需要在線訪問數(shù)據(jù)。</p><p><b> 高響應
56、時間要求。</b></p><p> 8.2.2用于z / OS的設(shè)計:數(shù)據(jù)來源和訪問方法</p><p> 在這里,設(shè)計師的考慮,一般包括以下內(nèi)容:</p><p> 什么樣的數(shù)據(jù)必須存儲?</p><p> 數(shù)據(jù)如何被訪問?這包括訪問方法的選擇。</p><p> 的要求是臨時或預測的嗎?&l
57、t;/p><p> 我們會選擇綜合布線,VSAM的,或數(shù)據(jù)庫管理系統(tǒng)(DBMS)如DB2?</p><p> 8.2.3設(shè)計用于z / OS:可用性和工作量需求</p><p> 對于一個應用程序,將運行在z / OS上,設(shè)計者必須能夠回答下列問題:</p><p> 什么是存儲和訪問的數(shù)據(jù)量?</p><p>
58、 什么是有需要共享數(shù)據(jù)?</p><p> 什么是響應時間要求?</p><p> 什么是該項目的成本限制?</p><p> 將有多少用戶訪問該應用程序在一次?</p><p> 什么是應用程序的可用性需求24小時7天一周或上午08點到下午5:00周一至周五等 </p><p> 8.2.4設(shè)計用于z /
59、OS:異常處理</p><p> 是否有任何異常情況可能發(fā)生?如果是這樣,我們必須結(jié)合我們在設(shè)計這些為了防止在最后的應用程序失敗。我們不能總是假定,例如,輸入將永遠是進入預期。</p><p> 8.3應用開發(fā)生命周期:概述</p><p> 一個應用程序的集合是一個滿足某些特定要求(解決一些問題)。該解決方案可以駐留在任何平臺或平臺的組合,從硬件或操作統(tǒng)點的
60、觀點。與其他的操作系統(tǒng),應用程序開發(fā)在z / OS是通常由以下幾個階段:</p><p><b> 設(shè)計階段</b></p><p><b> 收集需求。</b></p><p> 用戶,硬件和軟件要求</p><p><b> 進行分析。</b></p>
61、<p> 發(fā)展中的各種迭代設(shè)計:</p><p><b> 高層次設(shè)計</b></p><p><b> 詳細設(shè)計</b></p><p> 移交到應用程式設(shè)計。</p><p> 代碼和測試應用程序。</p><p> 執(zhí)行用戶測試。用戶測試的應用功
62、能和可用性。</p><p><b> 進行系統(tǒng)測試。</b></p><p> 進行集成測試(測試應用程序與其他程序,以驗證所有方案繼續(xù)如預期般運作)。</p><p> 執(zhí)行性能(量)測試使用的生產(chǎn)數(shù)據(jù)。</p><p> 轉(zhuǎn)到生產(chǎn)交班到運營。確保所有文件是(用戶培訓,操作到位程序)。</p>
63、<p> 維護階段,持續(xù)一天到一天的變化和增強申請。</p><p> 圖8-1顯示了在應用程序流程的各個階段開發(fā)生命周期。圖8-2描述了設(shè)計階段到發(fā)展階段的開始。一旦所有的要求都被收集,分析,核實,并一設(shè)計已經(jīng)產(chǎn)生,我們準備通過在編程程序員需要的設(shè)計文件(編程要求)和然后繼續(xù)進行編碼,測試,修改和測試迭代過程再次,因為我們看到在圖8-3。之后,這個項目是由程序員測試,他們將成為一個組成部分系列正式
64、用戶和系統(tǒng)測試。這些是用來驗證的可用性和功能用戶的角度來看,以及以驗證功能在一個較大的應用程序框架(圖8-4)。在開發(fā)生命周期的最后階段是到生產(chǎn),并成為穩(wěn)定狀態(tài)。作為一個先決條件去生產(chǎn),開發(fā)團隊需要提供的文件。這通常包括與用戶培訓運作程序。用戶培訓,陌生的新用戶申請。該文件運行程序使行動部接管持續(xù)運行應用程序的責任。在生產(chǎn),更改和增強處理一組(可能相同的編程組),執(zhí)行維護。在這個點生活中的申請周期,嚴格控制改變的,必須嚴格投入生產(chǎn)前測試
65、(圖8-5)執(zhí)行。如前所述,以滿足用戶的要求或解決問題,一應用解決方案的設(shè)計可能駐留在任何平臺或組合平臺。如圖8-6所示,我們的具體應用,可位于任何三種環(huán)境:互聯(lián)網(wǎng),企業(yè)網(wǎng),或中央站點。該操作系統(tǒng)必須提供訪問這些環(huán)境的。要開始設(shè)計</p><p> 8.3.1收集需求的設(shè)計</p><p> 在設(shè)計應用中,有許多方法來分類的要求:功能需求,非功能性需求,新出現(xiàn)的要求,系統(tǒng)要求,工藝要求
66、,對發(fā)展的制約因素操作上,僅舉幾例。計算機應用的數(shù)據(jù)進行操作,并駐留在某處需要訪問,無論是從本地或遠程位置。中的應用處理數(shù)據(jù),進一些關(guān)于它的加工類,然后提出結(jié)果是對任何人要求擺在首位。這個簡單的描述涉及到許多進程和有許多操作許多不同的要求,從電腦到軟件產(chǎn)品。雖然每個應用程序的設(shè)計是一個單獨的案件,可以有許多獨特的要求,其中有些是適用于所有的應用程序的一部分同一系統(tǒng)。這不僅是因為它們是同一套應用程序的那部分。包括給定的信息系統(tǒng),而且還因為
67、它們是同一部分安裝,這是連接到同一個外部系統(tǒng)。由作為一個整體系統(tǒng)面臨的問題之一是,組件傳播在不同的機器,不同的平臺,等等,每一個表演,其工作在服務器場環(huán)境。一個重要的優(yōu)勢到zSeries的做法是,應用程序可以堅持使用工具駐留在主機上。其中一些大型主機工具,使人們有可能有一個資源共享平臺和數(shù)據(jù)不同協(xié)調(diào)和安全的方式,根據(jù)工作負荷或優(yōu)先級。以下是對一個應用程序要求的不同類型的列表。該名單不是排他性的,有的項目已經(jīng)包括了其他人。</p&g
68、t;<p><b> 無障礙</b></p><p><b> 可恢復</b></p><p><b> 適用性</b></p><p><b> 可用性</b></p><p><b> 安全</b><
69、/p><p><b> 連接</b></p><p><b> 績效目標</b></p><p><b> 資源管理</b></p><p><b> 可用性</b></p><p><b> 數(shù)據(jù)備份頻率</
70、b></p><p><b> 可移植性</b></p><p><b> 網(wǎng)絡服務</b></p><p><b> 易變性</b></p><p><b> 間傳染</b></p><p><b> 失
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