Transports and Interfaces: Siebel Enterprise Application Integration > EAI JMS Transport >
About Synchronous and Asynchronous Invocation
Like the EAI MQSeries Server Transport, the EAI JMS Transport has two modes of execution: synchronous and asynchronous. Synchronous execution involves invoking individual methods of the JMS Transport directly, just like any other business service. Because the caller waits for the method to return, such invocation is synchronous. Asynchronous execution means listening for messages arriving on a particular queue and taking action whenever one arrives. This involves the creation of a separate Siebel component, called a JMS Receiver. Like the MQ Receiver, whenever a message arrives on the queue, the JMS Receiver dispatches to a business service (or workflow) and optionally sends a reply message.
NOTE: The JMS Receiver uses the EAI JMS Transport business service but cannot dispatch to a workflow that either uses this business service as one of its steps or dispatches directly to this business service.
While in-process re-entrance is not supported, you can indirectly invoke the EAI JMS Transport as one of the steps out of process by calling the Synchronous Server Requests business service.