By Kavitha Srinivasan on Jun 29, 2012
When using EMS (Enterprise Message Source) as a BAM feed, the best practice is to use one EMS to write to one Data Object. There is a possibility of collisions and duplicates when multiple EMS write to the same row of a DO at the same time. This customer had 17 EMS writing to one DO at the same time. Every sensor in their BPEL process writes to one topic but the Topic was read by 1 EMS corresponding to one sensor. They then used XSL within BAM to transform the payload into the BAM DO format. And hence for a given BPEL instance, 17 sensors fired, populated 1 JMS topic, was consumed by 17 EMS which in turn wrote to 1 DataObject.(You can image what would happen for later versions of the application that needs to send more information to BAM !).
For those of you wondering about how squeaky clean this design is, you are right ! This is indeed not squeaky clean and that brings us to yet another 'inferred' best practice. (I try very hard not to state the obvious in my blogs with the hope that everytime I blog, it is very useful but this one is an exception.)
It is optimal to do transformations within an engine like BPEL. Not only does this provide modelling ease with a nice GUI XSL mapper in JDeveloper, the XSL engine in BPEL is quite efficient at runtime as well. And so, doing XSL transformations in BAM is not quite prudent.
The same is true for any non-trivial calculations as well. It is best to do all transformations,calcuations and sanitize the data in a BPEL or like layer and then send this to BAM (via JMS, WS etc.) This then delegates simply the function of report rendering and mechanics of real-time reporting to the Oracle BAM reporting tool which it is most suited to do.
Hope this helps ..