Web Dynpro for Java.doc

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1、WEB DYNPRO GUIDE41PREFACE42WHAT IS WEB DYNPRO43PREREQUISITES6Installation6Technical prerequisites7NetWeaver und NetWeaver Developer Studio7NetWeaver Developer Studio settings8Useful Tools8SDM8Visual Administrator8Other tools94NETWEAVER DEVELOPER STUDIO9Perspectives, Views and Editors9Web Dynpro Pers

2、pective considering “Exchange Profile10Web Dynpro Explorer11Diagram View11Outline13Editor Window13“Properties Window155PRINCIPLES16MVC16Model16View17Controller176STARTING POINT OF LEARNING17Web Dynpro introduction JA31017Tutorial from SAP intranet18Virtual class room19Help provided by the NWDS19SDN

3、SAP Developer Network20Inside Web Dynpro for Java20Web Dynpro Developers20Links in the SAP Intranet207ARCHITECTURE OF A WD PROJECT AND NAMING CONVENTION21Root node21Web Dynpro Project22Dictionary22Source Folder22Applications22Web Dynpro Components23component usage24Component Interface29View Assembly

4、24Windows25Interface View30ViewSet25View Area 25Views25Inbound Plug 26Outbound Plug 26Navigation Link 26Controller26Custom Controllers28Component Controller as a special custom controller28View Controller29Component Interface Controller30Model30message pool31model usage308PROCESS FLOW31Visual31Decla

5、rative31Programmatic31Deploying329REBUILD, DEPLOY, CREATE NEW ARCHIVE AND RUNS3210API32IWDMessageManager3211CONTEXT32Context mapping 32Data Binding3312LAYOUT34List of elements343413SPECIAL TOPICS34Debugging34Authentification34Accessibility (siehe Script)34Tree34Table3414ABKRZUNGSVERZEICHNIS35LITERAT

6、URNACHWEIS37LITERATURNACHWEIS37Web Dynpro for JavaManuela Berg1 June 2005Web Dynpro Guide1 PrefaceI tried to make it clear between all of these topics listed in the index of contents. This is for affording the entrance into this lecture at any arbitrary point that is required by any person who start

7、s or improves developing web applications with Web Dynpro.Some terms like “components, “elements, “context, “interface and “view may have different meanings according to the context. I try to emphasize whether the term is used for eclipse or Web Dynpro. Additionally I will make the Web Dynpro term i

8、n bold to avoid ambiguity.There are some Screenshots in this text that do not have the originally size you will find on your screen. Screenshots are usually cropped or resized.Paths or sequences of actions are italic.2 What is Web DynproWeb Dynpro is a GUI technology invented by SAP that delivers es

9、pecially graphical tools for developing web-based applications. It is integrated in the NWDI NetWeaver Developer Infrastructure. Because of Web Dynpros amount of advantages for end-users, developers and even administrators, Web Dynpro will become SAPs GUI technology in the future. Now there exist ma

10、ny mission-critical applications which were programmed with this long-term strategy technology that was firstly introduced to customers and partners of SAP at SAP TechEd 2002. WD provides good support for building ERP applications.Formerly used browser-based technologies at SAP are ABAP/ Dynpro, ITS

11、 Internet Transaction Server, BSP Business Server Pages or JSP Java Server Pages. In certain areas they are still used, but because of their disadvantages they will be replaced by Web Dynpro in the future. JSP is strictly bound to the Java/J2EE platform whereas ABAP Dynpro can not separate between b

12、ackend and frontend. The ITS technology is not as flexible as it is demanded by modern UI design. Web Dynpro has all of these advantages.Figure 1 - Web Dynpro is a GUI technology that separates from arbitrary backend.As for the architectural advantages of Web Dynpro, users and developers benefits fr

13、om the platform and browser independence. Web Dynpro is also independent from the database and the client technology (see Figure 1).Concerning the platform, the application can be created with Java or ABAP, as the developer prefers. According to this decoupling of JSP and Java, this is only possible

14、 inside a homogeneous Java world. The platform for .NET is planned, too.As for the client-technology, HTML, XML and WML-enabled devices are able to act as front-end. Furthermore WD can be rendered with HTML, SWING or mobile technologies (see Figure 2). Only those parts of the screen that has been ch

15、anged, will be rendered again. That avoids a full page reloaded and enables a flicker-free web UI. This is in addition to a performance optimized protocol between client and server also good for a significant performance. Better utilization of network bandwidth, minimal refreshes and caches provides

16、 faster response times and therefore there is a better user experience.If the user installs a standard browser which is Internet Explorer (as of Windows 5.5) or Netscape Navigator (from Windows, Mac OS or Linux), the Web Dynpro application Figure 2 - Web Dynpro Applications can be rendered on differ

17、ent device types.would be implemented in HTML and JavaScript is used for making the client-server application interactive. The user can work with Smart Client or Mobile Device, too. In addition the user benefits from the advantages of internet innovations like zero installation, worldwide access, in

18、tegration of arbitrary content via hyperlink, zero-footprint and client-side dynamics.Web Dynpro integrates open non-J2EE standards. A great benefit for SAP is that Web Dynpro can be easily integrated in the Java development infrastructure and the software development logistic of SAP. WD supports mu

19、lti-user development like the R/3 system because WD is built on the top of the SAP Web AS. Beside WD provides a DTR for centralized version control and a Component Build Service for automated builds.One of the biggest advantages of the GUI technology that was invented by SAP is the MVC Model View Co

20、ntroller paradigm approach. That means that Web Dynpro is model-driven. Furthermore this paradigm makes it possible to separate the business logic in the WD model from the layout logic in the WD view. That allows developers to concentrate on the presentation and interaction without knowing anything

21、about the backend with the business data. Moreover the backend is reusable in a certain degrees for other graphical user interfaces, if it is needed for instance for another platform. The developer can use Web Services, ESI Services, Java and ABAP backend as a model.Web Dynpro provides some more adv

22、antages that can not be provided by the above mentioned web-based technologies, except the original ABAP/ Dynpro. The application developer may utilize useful helps and tools to create input checks, input helps, easy to use error handling and support for multiple languages, which is supported by the

23、 Web Dynpro framework. Web Dynpro also offers a dictionary and that enables field validation and Data Dictionary integration (automatic value help, type support, reuse of central, localization-dependent texts, short-texts, table headings and so on).WD was also designed to have a high reusability amo

24、ng the projects. Therefore, you can easily reuse and modify WD components. The developer therewith can create cost-effective, reactive and maintainable applications. Some more features of Web Dynpro are personalization, customization and portability. The declarative approach of WD concerning the lay

25、out, methods and actions, screen usage, navigation (interaction) and data binding demand less skills from the programmer and deliver more efficiency for creating web applications (see Figure 3). Even if some programming e.g. for event or error handling at a late phase of development is necessary, WD

26、 has the principle of “minimized coding and maximized design. These advantages and the abstract modeling with the graphical tools make it possible to easily how learn developing using WD. Thus the developer can concentrate on the business data flow and the user interaction because specifying the UI

27、elements and the data origin are not too complicate. Figure 3 - Development layers: some advantages and examplesWD features generic services that generate code from the declarative meta-model in standard runtime framework. That reduces repetitive coding tasks like writing HTML and making it interact

28、ive with JavaScript. Web Dynpro is form-based and provides wizards and templates. Wizards are used for instance for creating models or adding UI elements. Wizards are applied for creating buttons including the creation of the appropriate action and firing the outbound plug within the action. An exam

29、ples for templates are the creation of a table and a form of an existing context. WD is the base of the Visual Composer which provides a lot of patterns. Patterns are one kind of plans that provide a certain special type of structure for business applications that are often used and therefore they m

30、ake programs easily reusable.Most of the accessibility features like full keyboard support are delivered directly by the framework and support of the section 508 compliance. The developers only have few efforts improving the accessibility for instance with maintaining the tool tips.The end-user will

31、 benefit from improved accessibility and the portal integration, including client-side eventing and adaptation to portal styles. The user will notice a consistent look and feel across all SAP applications. WD applications are considered as having a good usability and a consistent user-friendly user

32、interface.The Client side framework offers a user an experience similar to the fat-client approach and avoids specific installation task on client. Another advantage for the administrator is that one only needs to administrate the Web AS and the browser-based clients. The comprehensive developing en

33、vironment and runtime environment facilitates the integration in the software lifecycle and distribution infrastructure to handle installation, upgrade, administration and monitoring task.3 Prerequisites3.1 InstallationFor developing applications with Web Dynpro with Java you need knowledge of the J

34、ava programming language, of course, as well as a JDK Java Development Kit as a foundation. At least you will need to have JDK 1.4.2. and you can download it from Sun homepage: .Secondly you will need the SAP NWDS NetWeaver Developer Studio (formerly called SAP Java IDE Integrated Development Enviro

35、nment) as your developing environment.The third important thing for developing Web Dynpro applications is the testing environment in this case would be the J2EE engine as a part of the SAP Web AS Application Server. You probably need to install a local J2EE engine, and you will have a central server

36、 for testing.The developing environment and the testing environment at SAP are called SAP NetWeaver Developer Workplace. If you have not installed everything you need, you could install it from the following link: .After installing, you would need to adjust some settings (see chapter 3.4) and get fa

37、miliar with some useful tools.You also need a browser. You could install Internet Explorer 6.0 or higher or Netscape Navigator or higher.3.2 Technical prerequisitesThe full installation with the SAP DB, the J2EE engine and the Java tool requires about 800 MB RAM memory (to drive the engine and the N

38、WDS), 1.5 GB free hard-disk space and Pentium 4 Processor and 1.5 GHz processor power. If you do not fulfill these requirements you will not be able to perform properly.You would probably need this much hard-disk place, because if you install the J2EE engine an instance of the SAP database will be i

39、nstalled too. That is needed as a persistence layer for the engine.3.3 NetWeaver und NetWeaver Developer StudioIf you are not familiar with NetWeaver I yould give a short introduction here.Developers at SAP usually work in larger teams. Therefore the most common approach for our Java developers is t

40、o have a local developing environment and a local testing environment as well as a central test environment. As you probably know this approach delivers benefits, which are having a shorter correction cycle and for avoiding inconsistencies between local developers. Therefore, you would have to devel

41、op a project locally.Figure 4 - SAP Web AS within SAP NetWeaverThe central testing environment checks if the components work together. A component should work as if it is expected according to its interface. If components do not work together, you will receive warnings or errors. If you prevent to a

42、ccess on changed codes locally and guarantee that your codes work with the existing interfaces and components, you will not have problems running this changed code in the complete testing environment. Therefore you integrate the changing codes after proving into the central testing environment.1) Th

43、e developing environment is provided by the SAP NWDS NetWeaver Developer Studio. It provides the designing time environment for Web Dynpro Applications. Web Dynpro tools are plug-ins of the Open-Source Project Eclipse. NWDS is usually installed at C:Program FilesSAPJDTeclipse at SAP. 2) The testing

44、environment is the Web Dynpro runtime environment that is one part of the SAP J2EE engine in the SAP Web AS Application Server or Application Platform in the SAP NetWeaver. J2EE engine is sometimes called Java stack or SAP Web AS stack (see Figure 4).3) In most cases, your central testing environmen

45、t has already existed. For IB these are for example SAP systems like BXI or BXT3.4 NetWeaver Developer Studio settingsIn general you can configure a plug-in if it is required through Window Preferences “relevant selction in the tree.If you have installed everything correctly you still have to select

46、 the J2EE server in the NWDS (Windows Preferences SAP J2EE engine select SAP J2EE engine is installed on local host.)Next thing you have to know is that your default workspace is saved under C:Documents and SettingsAll UsersDocumentsSAPWorkspace. That is where your project will be saved.If you will

47、use perforce and develop within IB Integration Builder then you must change the workspace into C:p4tcaiidevDevWorkplaceECSetupworkspace.In general you have to be careful with giving names of elements that generate files. WD may generate files with longer names. Length should not exceed 255 character

48、s, which are the limit of Windows. Be aware that the length can only be checked during design time, but not during deploy time.3.5 Useful ToolsSAP J2EE engine offers some useful tools for managing your engine.3.5.1 SDMThe most needed tool is the SDM Software Deployment Manager. SDM is a client/server application that enables you managing the (un-)de