To: Chris Maresca
Posted on Tuesday, February 26th, 2002 5:42 PM
To: Chris Maresca
From: Russell Beattie
Subject: EventEngine
Okay,
So it looks like a J2EE server isn't the best place to put a C&S application per se - J2EE servers are really only transaction containers for Java objects. They do some DB stuff to help out, but basically everything else is just finding, providing and pooling object resources.
Here's an article about integrating a scheduler into a J2EE app: http://www.theserverside.com/resources/article.jsp?l=Job-Scheduling-In-J2EE-Applications
You can see that they are talking about integrating the scheduler as a separate service which has RMI, CORBA or SOAP links to the J2EE server. This makes a lot of sense.
Okay - so EventEngine can be based on Avalon:
http://jakarta.apache.org/avalon/developing/introduction.html
And do EXACTLY what this article is talking about - provide hooks into J2EE servers. This will allow the EventEngine to be more of an "engine" which makes it much nicer in my mind.
You can also see this article about integrating SOAP into J2EE:
http://www.theserverside.com/resources/article.jsp?l=Systinet-web-services-part-4
I'm not J2EE's biggest fan because of how manual everything is: You have to create the initial EJBeans with the functionality you want, then YOU have to write all the RMI code to access this from external clients. CMP (Container Managed Persistance) database access is contrived and useless (and mostly not recommended by anyone on the net) so YOU have to write all the DB access code yourself also... Nothing is done for you, unlike in .NET where everything is point and click.
The only GOOD thing about this is that because it's a relatively low-level spec, switching all that crappy RMI or local access code for SOAP code will be relatively straight forward it seems, though the J2EE servers will need to support that feature (I think). Otherwise you end up doing everything twice in a 3-tier system (client calls server via SOAP, server calls EJB server via RMI...)
There doesn't seem to be many scheduling servers out there (free or otherwise) that integrates seamlessly with J2EE, so this looks like a great project. Basic scheduling server + J2EE based Calendering application and it'll be pretty cool.
So Avalon is pretty nice and there's already some cool projects that use it like JAMES and the JabaServer (a Java based Jabber Server). I'm also interested in making a Jabber Agent Server using Avalon too... Imagine integrating the C&S app with Jabber (or whatever other IM). Pretty neato.
That is all for now.
-Russ
