JMS Adapter: Content Based Filtering

[spinter]

Environment: Websphere MQ 7.1 / Spring Integration 2.1.1-BUILD-SNAPSHOT

Is there a way to configure a "jms:message-driven-channel-adapter" to enable content-based filtering with publish/subscribe?

Without using Spring Integration / Websphere MQ, and relying on ZeroMQ, it is as easy as:

    byte [] messageType = { 10, 2, 81, 84 };
    subscriber.subscribe( messageType );

Would appreciate a way to do it with SI's help.

P.S. The idea is not to route messages based on the payload in the same process / JVM, but to have many processes / JVMs running listening to only their messages from a single queue.

[Mark Fisher]

You can add a MessageSelector via the "selector" attribute on a message-driven-channel-adapter element. Is that sufficient for your use-case?

[spinter]

Mark,

Thanks for the idea. Doing that is not horrible, but it also means if a source has a million messages in a queue, every subscriber would receive a million messages, and then will filter them out.

If a "message selector" is the only choice I have with SI, can I use it to inspect a JMS header as well? I have control over where publishers will place a "selection criteria", and it would be nice if I can use JMS header for that, so I don't have to peek inside the payload. (I would still like to strip out all the JMSsness from the message before it is passed down the line)

Thank you.

[Gary Russell]

I suppose it depends on your broker; a few googles for IBM MQ would indicate the selection is done on the broker. It's probably reasonable to expect that all enterprise-ready brokers will run the selection on the broker rather than the client.

[Gary Russell]

And, yes, the selection uses headers; in fact the JavaDoc for Message says...

Message selectors cannot reference message body values.

[Mark Fisher]

I actually meant that you can use a JMS MessageSelector (not a Spring Integration filter), so that happens broker-side. In terms of the supported queries, scroll down to "Message Selectors": http://docs.oracle.com/javaee/1.3/ap...s/Message.html

[spinter]

Gary, Mark,

Right, I thought you meant an SI MessageSelector at first, since it is not immediately obvious where a "selector" attribute of "jms:message-driven-channel-adapter" points to. I did a quick "Command + F" on docs, and this particular "selector" is not (yet) discussed there.

Now as I looked at it a bit closer I can see it takes a selector, passes it to JmsTemplate and:

  protected Message doReceive(Session session, Destination destination, String messageSelector) throws JMSException {

    return doReceive(session, createConsumer(session, destination, messageSelector));
  }

which goes directly to the broker.

Just to confirm:

    <jms:message-driven-channel-adapter destination="xyzQueue"
                                        channel="xyzPipe"
                                        selector="someId = '75D938E89AF18C30'"/>

Will only receive messages that have "someId" set to "75D938E89AF18C30" in JMS header?

Thank you.

[Gary Russell]

Almost; you can't add arbitrary 'headers', these are more properly called 'properties'. You can set arbitrary properties on messages that can be used in message selectors.

http://publib.boulder.ibm.com/infoce...c/ac24876_.htm

and

http://docs.oracle.com/javaee/1.4/tu...4.html#wp79281

(Scroll down the Message Headers and Message Properties).

Please open up a documentation Improvement JIRA on the reference manual here...

https://jira.springsource.org/browse/INT

There *is* brief documentation in the XSD schema...

<xsd:attribute name="selector" type="xsd:string">
	<xsd:annotation>
		<xsd:documentation>
A JMS Message Selector expression.
		</xsd:documentation>
	</xsd:annotation>
</xsd:attribute>

...but we should explain it in the reference.