WebSphere® MQ and WebSphere MQ Everyplace® messages include an MQMD header. You can use a JavaCompute node to refer to the fields in the MQMD, and to update them.
public void addMqmd(MbMessage msg) throws MbException
{
MbElement root = msg.getRootElement();
// create a top level 'parser' element with parser class name
MbElement mqmd = root.createElementAsFirstChild("MQHMD");
// specify next parser in chain
mqmd.createElementAsFirstChild(MbElement.TYPE_NAME_VALUE,
"Format",
"XMLNS");
}