How best 2 use Shared AM in taskflow -new transaction/isolated data control

Question

Hi all
I have nearly 800 screens in my app (under 20 or so different AMs), in which I access some Common VOs to work with by applying filtering (on Secondary Rowset, on Default Rowset using View criteria) on that, Used as View Accessor VO (List of Values) & Sorting. These common VOs are not DB driven but custom java datasource implemented and once it is loaded with data, data will not change. I use Dynamic tab shell to load the screens as separate task-flows. These task-flows are defined to be opened with New Tansaction/Isolated Datacontrol. Right now these Common VOs are shuttled in a default scoped AM (Say 'LookupAM') and attached the same as nested AM for the other AMs.
With the above design, the current behavior is whenever I load a task-flow in Dynamic tab shell, it creates a fresh instance for Shreen AM as well as LookUpAM (I tested by including println inside prepareSession() API of AM Implementation class).
I feel I'll get benefitted in terms of memory saving/performance when I use only one instance of LookupAM for all the screens. I prepared a sample app that mimic our actual application, but made the LookupAM to be a Application scoped shared AM (lets say SharedLookupAM). I've also made all the LOV View accessors comes from this Shared AM. When I run this sample, the behavior is every time I load the task-flow, still the framework creates Am instance for both screen AM and SharedLookupAM! Why so?
Question:
1. Considering my application design (i.e. consuming Shared AM instance from inside the task-flow which are desinged to be opened with new transaction/isolated datacontrol), will I get benefitted in any way If i use Shared AM. If so, what are all the possible type of usages of shared AM for my design?
2. Why framework creates instance of Shared AM everytime I load the task-flow. Does it meant task-flow settings takes the precedence over the Shared AM configuration and it overrides that?
Thanks in advance.
Raghu
Edited by: Raguraman on Apr 9, 2013 3:25 AM

Answer 1

Hi,
+1. Considering my application design (i.e. consuming Shared AM instance from inside the task-flow which are desinged to be opened with new transaction/isolated datacontrol), will I get benefitted in any way If i use Shared AM. If so, what are all the possible type of usages of shared AM for my design?+
Isolated data control settings are the most expensive settings you can have in ADF. They should be used only if the requirement for the task flow is to be atomic in that it can be committed or rolled back independently. If this is not the case for your use cases, then using shared data control is a better option to use. Note that my expectation to application scope AM is that the AM instance is created per user but that the data cache is only queried once.
+2. Why framework creates instance of Shared AM everytime I load the task-flow. Does it meant task-flow settings takes the precedence over the Shared AM configuration and it overrides that?+
Well, you tell it to do so. With the setting of isolated to the Data Control you explicitly tell it to open a new transaction in which case a new instance is created.
Frank