I'm trying to create a router to integrate a number of JMS topics & Queues. I am constrained by the fact the client I am working for can't change the JMS implementation (TibCo EMS with some custom client libraries) and the fact that they have written their own XA transaction manager which doesn't quite conform with the JTA spec. It is very important that message delivery is guaranteed.
I've done a lot of reading and experimenting with Camel and I've realised that I probably need to write my own JMS component, as the standard JMS component is not going to integrate with the JMS client libraries or TM I have.
I need to be able to put hooks into the route lifecycle at the following points:
During the route startup, I need to identify all JMS connections and enlist them as XA resources with the TM implementation
When a message is received at the consumer, I need to start a transaction including all the JMS connections in the route
When a routing decision is made, I need to send the message to the producer and commit the transaction
Given the above, I think I can implement a very simplified version of the camel-jms component which strips out all the Spring parts and only contains the bare minimum required to interact with my JMS libraries.
Where would be the best place to initialise the transaction manager? I've been looking at DefaultCamelContext, RoutePolicy and RouteContext but I can't find a place where all the endpoints are resolved and initialised.
I solved this problem by implementing the UserTransaction and TransactionManager interfaces and creating a PlatformTransactionManager which the Camel JMS component uses to create the DefaultMessageListenerContainer.
One important point to note is that the transacted property on the Camel JMSComponent refers to local transactions, not XA transactions. If you set this property to true after passing a PlatformTransactionManager to the component, the DMLC will effectively try to commit your transaction twice, which won't work.
This leaves me with a nice working example consuming from one JMS broker and producing to another, but it is very slow - ~5 messages per second. Unfortunately Spring JMS does not support batching so it seems the best solution here is to adjust the JMS topic configurations such that routing only takes place between topics on the same broker.