Enterprise level events

[adepue]

I have need for an enterprise level event mechanism. Basically, a way for one service, client, or enterprise object to send events to other services, clients, or enterprise objects. Some of these services will be clustered. Of course, JMS is the logical solution to my need, but I would really like something more abstract than JMS (of course, the abstraction would most likely sit on top of JMS). An abstraction along these lines:
1. Simple way to register event listeners and publish events. At least, something simpler than JMS - something as close as possible to Swing's model.
2. Events that cross remote boundaries.
3. Events that can be "pulled" by a client. Most of our clients will be internet based and behind firewalls, so we will have no way to connect to them in order to send an event/message. The client will need to connect on a periodic basis (or stay connected) and poll for events.
4. Related to #3, an HTTP based protocol.
5. Easily configured via Spring.

Is there an open source solution that matches this description? What do people here use for enterprise level events? How do you integrate it with your Spring project?

[sethladd]

Have you looked into JavaSpaces, or tuple spaces in general? Seems like it would be a good fit. There are commercial implementations of JavaSpaces, but there is at least one open source implementation. I've had experience with both the offical JavaSpaces, and GigaSpaces, but not the open source one (I forget its name).

They are great, but don't put objects into them. Class versioning is near impossible. The same applies to JMS, though. If you are dumping simple types into the Space, I think you'll like it.

[jeje]

Have a look at Mule (http://muleumo.org) too.

[adepue]

JavaSpaces is one of those technologies that I get really excited about. However, I've only ever had access to open source/free versions and when I last looked into it, they were either immature or had too many dependencies on Jini. Maybe things are different now?

- Andy

Have you looked into JavaSpaces, or tuple spaces in general? Seems like it would be a good fit. There are commercial implementations of JavaSpaces, but there is at least one open source implementation. I've had experience with both the offical JavaSpaces, and GigaSpaces, but not the open source one (I forget its name).

They are great, but don't put objects into them. Class versioning is near impossible. The same applies to JMS, though. If you are dumping simple types into the Space, I think you'll like it.

[adepue]

Thanks for the link! Mule didn't show up when I was googling around, but from the description on the home page, it sure seems to "hit the spot".

Have a look at Mule (http://muleumo.org) too.

[skroah]

We ended up just rolling our own ESB like layer on top of JMS. It's a very lightweight Mule basically if you've looked at Mule.So now we can throw a payload into a enterprise event object, add some routing info and then dispatch it, either adding the dispather at runtime or statically via a config. file. We also have some primitive support for message transformers and channel adapters. Our event listeners are a diverse bunch, consisting of HTTP Pollers, RMI Callbackees, JMS listeners, and Spring event listeners.

Spring is used on the server side to pin up all of the resources at boot time. These include the JMS components, the RMI services and the web applications. We also use Spring events to propogate some events. This is nice in that these event listeners don't need to be aware of messaging at all. Other then that that's all we need.

ESB seems to be gaining momentum I see a lot more vendors out there now. The book you want is enterprise integration patterns by Hohpe. It includes some nice visio stencils for your documentation as well.

http://www.enterpriseintegrationpatterns.com

[henk]

Thanks for the link! Mule didn't show up when I was googling around, but from the description on the home page, it sure seems to "hit the spot".

Have a look at Mule (http://muleumo.org) too.

Do you think Mule is ready for production ?

Henk

[rossmason]

Mule is is already being used in production. Also, the latest release (http://wiki.muleumo.org/display/MULE/Release+Notes) sees a more robust and better tested server. It's definitely worth a look