E-Learning for Web Dynpro Java Developers
Sometimes the best way to communicate programming topics is not by writing lengthy articles or how-to guides or cookbooks, but to create short web presentations that use narration and animation.
These two web presentations have been designed to give you an insight into two key areas of Web Dynpro Java development: Navigation and Error Handling, and the Web Dynpro Phase Model.
Both of these presentations are built on the NetWeaver 7.0 version of Web Dynpro Java and can also be accessed through the updated The Web Dynpro for Java Mind Map.
Navigation and Error handling
This topic is one that can become awkward in WD applications that grow beyond three or four components. When you have a large hierarchy of WD components that all have to function together in a single business process, then handling errors is often something that is best done in a centralised manner. In addition to this, when errors occur during a round trip from the client, those errors frequently interfere with screen navigation (in other words, you have to decide how the error should be handled before allowing screen navigation to continue).
Therefore, the two topics of error handling and screen navigation should be treated as a single unit of processing in large WD component hierarchies. This web presentation lays down some principles on how this topic can be handled.
Understanding the Web Dynpro Phase Model
This is a topic of fundamental importance to any serious Web Dynpro Java developer!
Every time there is a round trip from the client to the SAP Java Server, a fixed sequence of processing steps is performed by the Web Dynpro Framework known as the “Phase Model”.
The interface between your business application and the Web Dynpro Framework is achieved through the standard hook methods found in Web Dynpro controllers such as wdDoInit() or wdDoBeforeNavigation().
However, if you don’t understand why these methods exist, or when they are called, you will end up writing very inefficient coding, and generally abusing the Web Dynpro programming model!
This presentation will show you exactly what happens every time there is a server round trip. Then you will understand what type of coding should be put inside each standard hook method, and from this understanding, you will then be able to write very efficient Web Dynpro applications.