As I mentioned in the previous blog, the Portal Runtime(PRT) is sitting beneath the J2EE Engine, while the J2EE Engine is part of the SAP Web Application Server.
Now, let's have a close look on the SAP Web Application Server( refer as WAS) architeture. Note that this is the latest Netweaver WAS Service Pack 15 architeture. (The WAS architeture has some major change from SP2 onwards, since SAP start using the Netweaver framework.)
You may wonder why the "Browser/Portal" box sitting outside the J2EE, since I mentioned that the PRT is located beneath the J2EE Engine. The "Browser/Portal" box is actually the front-end client browser.
As you may notice, the WAS can also connect to other 3rd party web applications or using web services through the SAP Exchange Infrastruture.
All the communications are managed by a component called "Internet Communication Manager",basically it conatains a dispatcher/servlet to forward the request and response.
So, what is the Web Dynpro component? As I mentioned in my previous blog, Web Dynpro technology is the latest technolohy invented by SAP to provide a fast bulding UI framework for business applications. Web Dynpro using a declarative concept (metadata modelling approach) where the programming tasks have been minimized to 20% , and almost 80% of the tasks can be done by modelling the metadata (with tables and diagarms - Web Dynpro toools).
In the persistance layer, here will be all the database abstracts including all the backend systems like database, SAP Systems and etc that provides the storage of persistant data.
In the future, I will future explain the pros and cons of the Web Dynpro technology, compare the the custom Java iViews/portal components development(J2EE) technology.