I came into the presentation not knowing what Comet is, exception what I heard on the internet. Kevin did a great job explaining what Comet is. The most valuable part of the presentation is the demonstrations Kevin did, which are fun and informative.
I'll let you read an article by Kevin himself to get the gist of what the subject matter is. I'll just show the words I wrote down during the talk:
Jetty
Pub/Sub
Bayeux
JASONp
script tag
XSS
Cometd
Long polling
Channel
Service channel
Meta channel
Server crash
Client auto-reconnect
JSON on the wire/HTTP
The background conversation at the JUG is also informative:
Is Scala for real? Kevin told us its the hottest thing at Silicon Valley. Mark and I still have some lingering doubts. Mark is focusing on something called persistent data structures. I'm more of a Luddite, fearing the years of learning that I have to go through to be proficient.
At the end of the session, when Brian went up the stage to run the Birthday Selector application to give away the goodies, Kevin Nilson mentioned the Wheel of Fortune application that Jim Weaver wrote for his JUG. Small world.
Ken Totton (of OCI, where I work) is still looking for top notch Java architects and developers. Send me an email at "weiqigao at speakeasy dot com" if you are interested. A couple of other places are also recruiting.
Brian asked a question about MigLayout. He's reading the OCI May Java News Brief on MigLayout. I gave him an meta-answer: "Just blog about how it doesn't work, and the MigLayout author will comment on your blog and show you the right answer."
Coming back to Cometd, I do have one reservation: It's another messaging protocol. This is the rare occasion when my Java duties intersect with my messaging protocol-watching duties. It reminds me something Paul says around the office: "You can always define a Pub/Sub protocol on top of a Request/Response protocol. And you can always define a Request/Response protocol on top of a Pub/Sub protocol."