How can I send a large message to WebSphere MQ through JMS?

There is a built in limitation of 2 MB for the IBM WebSphere MQ JMS interface.

http://www-01.ibm.开发者_如何学编程com/support/docview.wss?uid=swg21221260

Is there a way to bypass that limitation?

The limitation applied to WMQ versions distributed with WAS back at V5.1.1 many years ago. If this is the problem, upgrading to current version of WMQ will resolve it. The current version of WMQ is V7.0.1. V6.0.2 is also still current but will be out of service in September of 2012. V6 & V7 can send and receive messages up to 100MB but WMQ itself defaults to 4MB out of the box. It is necessary to tune parameters of the QMgr, queues and channels if messages larger than 4MB are required but JMS is not a limitation at modern versions.

The WMQ Java/JMS manuals do not specifically mention a maximum size because it is the same as the native WMQ max length of 100MB. However, the WMQ V6 Performance Report provides benchmarks for JMS messages up to 64MB.

Whatever is preventing you from putting a 3MB message isn't a limitation of WMQ's JMS implementation as regards message size. If you have checked MAXMSGL on all of the channels and queues and the QMgr then it's something less obvious but it is configuration.

This might sound arduous, but it is a solution:

1. Take your message content, convert it into a byte array.
2. Split the byte array into n sub arrays that are ~< 1.9 MB each.
3. Start a JMS transaction and send each sub array in a ByteMessage, incrementing the group count:

e.g.

   message.setStringProperty("JMSXGroupID", groupId);
   message.setIntProperty("JMSXGroupSeq", i);

On the receiver side, you implement a selector to get all the messages in the group as soon as you receive the first message. Retrieve all the messages in the group (hopefully you get them all), sort them correctly, re-create the big byte array, unmarshall it, and you're done.

Trivial really.....

Here's a better example.