Presentation outline and notes/references for my Traiangle Java User’s Group presentation given on April 18, 2011. The slides used during the presentation are merely an instrument for me as the presenter; they aren’t available for download. Below is the rough outline I (kinda) followed and at the bottom are references and helpful links. Feel free to leave any and all candid feedback in the comments. Thanks for attending! Continue reading
Spring and Hibernate have long been my choice of frameworks with which to construct maintainable, scalable middle-tier software. Spring promotes good OO design using loose coupling and provides excellent declarative transaction support. Hibernate is the persistence tool of choice for the open source community. Any sane person who programs this way will have given up on EJB long ago. Coarse-grained entities, tightly coupled service objects and XML deployment descripters a-plenty are enough to bring a guy to his knees.
But no more. The EJB expert group, now composed of some of the very creators of modern persistence framework, has bequeathed upon us something wonderful. The lightweight POJO programming model we have come to love is apparent everywhere in the EJB 3.0 specifiction (JSR-220), which was unanimously accepted by the JCP earlier this year. EJB 3.0 is just one goodie in the larger Java EE 5 (JSR-244) bag – but this post is going to be long enough as it is. Continue reading
This afternoon’s festivities were highlited by a characteristically colorful presentation by Gavin King. For those who don’t know, Gavin is the creator of the Hibernate persistence framework which was aquired eventually by JBoss.
Gavin & crew demonstrated quickly but effectively the lovely synergy that has been brought to EJB3 and JSF by their newest creation, Seam. Seam can hardly be called a web framework — you wouldn’t recognize it as such what with its lack of, well, just about everything that you’ve come to expect from a web framework.
Seam throws away boilerplate code a-la Rails, but does so in a way that leverages a lot of the untapped power of EJB3 and JSF. Seam is all about Don’t Repeat Yourself (DRY). As such, we throw away form beans (a-la Spring MVC) and a whole lot of XML (in favor of annotations).
The most surprising theme that emerges from all of this is the rampant use of Stateful Session beans. You read that right – I said Stateful. Seam begs the question, “why on earth would I represent state in a database (slow is an understatement) or in HTTPSession (with no dirty checking) when I can use this lovely gift called Stateful beans?” He makes a damn good point. By representing web conversations as SFSB’s (which are POJO’s in EJB3, in case you’re wondering) you eliminate many of the headaches associated with web apps. Multiple tabs open in your browser? Piece of cake – each browser tab/session/window has a unique conversation (they’re stateful, remember?). Double submit? Ha! Don’t even try! Want to have a clean client redirect after performing some action, but still pass messages across? No problemo – you’ve got a lightweight stateful conversation behind you.
By logically grouping your flows into SFSB’s, you can leverage more sophisticated failover because the container dirty-checks each instance and replicates automatically. Try that with HTTPSession.
So, I will be doing a sandbox app soon with Seam, and I’ll post more as I know it. Till then, read all you can.
You can’t really question the inertia behind enterprise development using POJO’s and lightweight frameworks. Rod Johnson (of Spring framework fame) wrote the book about this approach, effectively putting the last nail in the heavy framework’s coffin. This morning’s presentation by JBoss covered their take on this from a 5000-ft level and also described some of the new things afoot in v5 of JBoss AS.
JBoss is mutating their MicroKernel (heavily JMX based) into what they call the MicroContainer. The MicroContainer architecture could be described by reading the outline of Spring’s core container and subtituting “Spring” for “JBoss”. Indeed, they are not only building a lightweight DI framework; they are building their entire app server on it. Cool.
JBoss has always been good about letting the developer/integrater customize the footprint of the server through configuration. It looks like this is going to be even cleaner and better in v5, since the same DI engine which builds the server innerworkings can also assemble application components — all the way up through the presentation tier using Seam/JSF.