I was looking what SLEE (Service Logic Execution Environment) or in the java world JAIN SLEE could offer in a telephony world. I am working on an open source telephony application called Svarog (http://sourceforge.net/projects/svarog/) based on Asterisk PBX (http://www.asterisk.org/) and I wanted to see how I could improve it in a next step.
Well, there is the SLEE specification and a java open source implementation sponsored by RedHat and JBoss called Mobicents (http://www.mobicents.org-a.googlepages.com/index.html). I am not an expert in telephony nor in SLEE specification, but what I understood is that this is something to do with EDA (Event Driven Architecture). We also have a reference implementation of SLEE, which is done by OpenCloud (http://www.opencloud.com/ ). And SLEE is often considered to be in telephony what EJB is in JEE.
SLEE is also "service" oriented where it has its own SBB (Service Building Blocks) which are resource adaptors. It does not seem to be specified for the telephony world only and it should be possible to inlcude any kind of services into the SLEE environment. It is specific because it offers a scalable, robust, reliable and transacted environment for "real time" applications. Probably that is why it is tight to the telephony world.
If this is not wrong, what I said till there, I see no reason why this kind of environment could not be setup using some open source projects such as ESB (Enterprise Service Bus), JMS (Java Messaging Service), rule engines and workflow engines. What I do think is that SLEE is maybe more complicated than setting up all those different projects. There is JBI (Java Business Integration) which already has several implementations in the open source community and IBM has its own standard SCA (Service Component Architecture) which seems to be adapted as well and which should not be an opponent to the JBI specification. I think that the Springframework could offer a base for writing something "ala" SLEE and to get a good support for Java Transactions and other services needed to write a scalable, robust, reliable and transacted environment. I mentioned JMS but I know it is not event based, but could be used and I think is used in some EDA. I forget to say that there is also JCA (JEE Connector Architecture) which is here in purpose to be used for resource adapters.
Well, the point is that it seems Mobicents cannot be used without the JBoss Application Server, and I think SLEE specifies that the implementation should not be tight to JEE.
We do not have specifications for ESB but we do have for JBI, which are also used in ESB such as Mule or ServiceMix. Both of them offers integrations with workflow and rule engines and are based on events ... so, how is SLEE different in it? In my opinion, SLEE could be a standard way to do ESB.
To conclude, an ESB coupled with JCA with a good support for transactions is really a god environment for a real time event based driven architecture, could be the thing that is needed for a telecom service platform.