Cap Concurrent Instances From Receive Activity

Question

Hi,
I am polling a table using a DB adapter and instantiating BPEL instances through receive activity for a batch of around 100 records. At runtime, there may be a few hundred or sometimes a few thousands of records that are present in a table for processing.
I would like to be able to limit the number of concurrent instances so that the server would not get overloaded. Any ideas on how to do this properly?
Regards,
Anand.

Answer 1

There are two ways to handle this scenario:
<li>The preferred way would be: In a domain where your poller is, decrease the dspInvokeThreads to the max number of concurrent instances you want to be invoked. Please note that this would only control the number of instances instantiated at a point in time. This solution would work for [10.1.3.4|"http://download.oracle.com/docs/cd/E12524_01/relnotes.1013/e12523/bpelrn.htm#BABHCGEI"] </li>
<li>This is could also be handled in the database layer by using a TopN toplink query or by using a wrapper view like
select * from (select a,b,c,rownum "rn" from polling_table) where rn<maxRowsThis approach would ensure that you expose only a fixed number of rows to BPEL for process instantiation
Please note that this would have other cruft in terms of using a database trigger for logical deletes etc.
This thread has more information:{thread:id=994481}
Hope this helps,
Regards,
Shanmu.