Parallel ABAP programming while using references

Question

Hi SCN,
first of all the context of my problem, to get to its root:
I have created a kind of Framework (object oriented), which later on will provide an easy way to set up Charts in a Dashboard.
Put simply, the framework works like this:
There is a interface for the source of the data and customizing to be shown in the chart, with the methods 'get_data' and 'get_customizing'.
You can simply implement the specific interface in a class, which therefore is a 'source object' for the chart classes later on (getting the Chart Customizing and the Chart data using the defined methods mentioned above). The chart classes use the functionality of CL_GUI_CHART_ENGINE.
This concept works fine so far.
But I added a quite important feature - every chart should be refreshed after some time. Therefore I use the class CL_GUI_TIMER, which triggers the refreshing after some time. The problem is: if there are for instance two graphs shown and the first one is refreshing it's data (so the 'get_data' method of the source object is processed, which could mean there are some select statements implemented and therefore need some time). WHILE this is processing, the time may has come for the second graph to refresh (so CL_GUI_TIMER raises the 'finished' event) - so the event will be fired, but the handler method for the won't be executed, because the first chart is currently processing the GET_DATA method. This means, nothing happens when the second chart should be refreshed.
Fine, I told myself, parallel programming could easily fix this (later on, I figured out I was horribly mistaken (comment: I had no experience in parallel programming in ABAP so far)).
My intention was to give every chart object a separate 'thread', so they wouldn't be in each others ways (and thereby, as a side effect, the whole construct would gain some performance).
Finally we got to the actual problem:
There my problems started - the only way, to do some parallel programming in ABAP seems to be function modules using RFC (event though I always want to stay on the same application server). So the 'parallel thread' has to be a RFC function module - which means, there is no possibility for me to supply some object references to the function module (in my example, this would be the graph objects). So far I tried to do some workarounds like:
- using serialization, whereby I give the serialized objects into the function module as a string and rebuild it in there, which would work fine, if there where no attributes of objects, that are not serialize-able, in the chart objects (like a instance of CL_GUI_TIMER and some more).
- using shared objects, which gives me a way to access the object from the function module as well. But - there is no way to use event-handler methods in shared objects classes. So if I mark the 'Root class' of the chart classes as shared memory-enabled in SE24, I can't activate it, because it contains some event-handler methods (for example the one that reacts on the 'finished' event of CL_GUI_TIMER).
Now I'm running out of ideas, how I could solve my problems and use parallel programming in ABAP actually using references and all the object oriented features I need (events, interfaces, inheriting and so on).
Does someone of you out there have any idea how I could fix this - if there may is another way of parallel programming in ABAP, or another way to access objects using RFC function modules, or anything else?
I really appreciate any hint you could give me.
Let me know, if you need some more information.
Thank you very very much for your help and best regards
Sebastian

Answer 1

As you said RFC Enabled function modules are the only way to enable parallel processing.
Your event handler for the 'finished' event of your timer can call an RFC FM with another method on the class being performed when it's done:
CALL FUNCTION func STARTING NEW TASK task
              [DESTINATION {dest|{IN GROUP {group|DEFAULT}}}]
              parameter list
              CALLING meth ON END OF TASK].
You can pass in what you need for the select and get back the results. Then the method you call 'on end of task' can perform the rest of the refresh. If you want to stick to mostly OO concepts then the RFC function module could just be a wrapper for a static method on your class which gathers data for your refresh...