Multple Transactions in One OAF Page

Date: 20-May-2010  (I am little late for posting this article)

Background:

One very respected gentleman (who's blog we all would have visited while working on OAF.. keep guessing !!) asked a question in interview to a dear friend of mine.

How can we have two regions in a page in such a way that if you commit data in one region it shouldn't commit the data in other regions of the page?

In other words the requirement is to have two transactions in one OAF page.

First Reaction:

Shock!!

Root Application Module provides transaction context.

We can have only one Root Application Module in a page, then how can we have two transactions?

Why we need it?

I don't think we need it at all.

We can handle scenarios like this using combinations of Read-Only and Updatable VOs.

My strict recommendation is you try this only at home and never at work. You'll not be always available for your code's maintenance.

An observation that led to answer:

Application Behavior:

After some brainstorming, I remembered an observation while navigating between pages with retainAM=Y and with different Root AM, state of the page is getting retained.

Learning:

Somewhere system was retaining both Root AMs.

Two Root AMs means two transactions.

Test Case Tried:

On a relatively free day at work. I discussed this testcase with my colleague, one of the better technical resources I have ever worked with.

Tried passing AM object of one page to next page using Request and Session scope. Tried out things with both AMs in second page. 

It worked like magic.

Snippet:
------------

Page 1: Empty Page

Controller 1:

pageContext.putSessionValueDirect("xxfirstAM", pageContext.getApplicationModule(webBean));

//You can try passing it in Request also.

//We'll get this value in second CO and update data in VO's in this AM, call APIs by getting OADBTransaction

pageContext.forwardImmediately(<url of second page>);

Page 2: Transaction Page

Controller 2:

OAApplicationModule secondPageAM = pageContext.getRootApplicationModule();

OAApplicationModule firstPageAM =             (OAApplicationModule)pageContext.getSessionValueDirect("xxfirstAM");

// This way we'll be having two AMs in our Controller.

// Both these AMs will have their own transactions.

// Changes commited from one of them will not commit changes in other.