WebDynpro ABAP - inter session events possible?

Question

Hi Experts,
I have a ABAP-WebDynpro application with various tabstrips to show and maintain process data within a production process. Each tabstrip contains several data of a specific process step. At the beginning, very few data are already present. While production progresses, chemical analysis is being taken and machine data is gathered. Assoon as new data for the process step is available, a refresh should be performed.
Though not perfect in every aspect, we made this scenario work in a similar way in ABAP Dynpro by using inter session eventing (ISE). Is there a possibility to trigger events in WebDynpro cross-session - for example after adding data to the database?
Best regards
Jens

Answer 1

There is no real cross session eventing available in Web Dynpro.  The problem is two fold. First, UI updates can't be initiated by the server in HTTP (unlike the SAPGUI which does have a push mechanism to the client).  This is a current limitaiton of HTTP itself and not something Web Dynpro related.  So to trigger the phase model of Web Dynpro, something must occur on the client to trigger the server event.  In NetWeaver 7.0 and 7.01 you have to use the timedTrigger UI element to acomplish this:
http://help.sap.com/saphelp_nw70ehp1/helpdata/en/da/a6884121a41c09e10000000a155106/frameset.htm
You then generally used a shared memory object (or even temporary database entries) to communicate data or events between to different processes.  For instance a background job is running and places it status in a shared memory object attribute.  The Web Dynpro can then fire a TimedTrigger every minute to check the value of this shared memory object attribute.
In NetWeaver 7.02 we improve this process with a new capability called the Web Dynpro Notification Service.  Instead of the timedTrigger, we can simulate a push of data/events to the client using AJAX.  We open an secondary server request to the ICM to check the status of an event. That way we don't have to disrupt the client side activity or incurre the full Web Dynpro Phase Model until we know a change in the status of our event has occured.  Also since the status info is stored in the ICM Cache, you don't even have to fall into an ABAP Workprocess to check the status.