A bad fan crippled my linux box for a few days, and hence the site was down. Sorry bout that. How will I ever make my 5-nines SLA now?!?
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.
Is the number of pairs of shoes my wife has.Â That’s really all there is to say about that.