Add your business code with your implementation of inercept().
You may manipulate the content of the message, but not the key and qos or other attributes of the MsgUnit object.
@param publisher The subject object describing the publisher
@param msgUnit The message to check
@return "" or "OK": The message is accepted
Any other string: The message is rejected and your string is passed back to the publisher.
@exception XmlBlasterException Is thrown on problems, for example if the MIME typedoes not fit to message content.
Take care throwing an exception, as the exception is routed back to the publisher. If the publish() had many messages (a MsgUnit[]), all other messages are lost as well. Probably it is best to return 'ERROR' instead and log the situation.