1. A system to support session management in a distributed transactional service system, comprising: a distributed transactional server that provides at least one distributed transactional service; and an affinity client that operates to receive a service request from a user application and invoke the at least one distributed transactional service provided by the distributed transactional server, wherein the distributed transactional server operates to create and maintain a session for the user application when the at least one distributed transactional service is invoked, and wherein the distributed transactional server operates to determine an affinity scope associated with the session, wherein the affinity scope defines a routing scope within the distributed transactional service system, into which consequent requests in the session from the user application are dispatched, and wherein the affinity client operates to maintain the affinity scope associated with the session.