Hi Niraj,
If you do not want to execute service A in the same context as service B you can think of publish-subscribe scenario.
This means that you publish a document from the catch clause of the service B.
A trigger that waits for that kind of document will execute service A.
In this way service B can evolve separately of service A.
Is this what were you looking for?
Vlad Turian
#webMethods#Integration-Server-and-ESB