Coming from a Java background, BlazeDS really interests me. Basically it’s Adobe’s open source version of it’s LiveCycle Data Services (LCDS). Basically they’re a set of JAR files deployed on your server to improve the comunication between a Java backend and a Flex presentation layer by comunicating via AMF (Action Message Format). You can always comunicate out of Flex using http services and consuming XML but that’s not the fastest way to work.
James Ward’s site has some benchmarks for comunicating via AMF with BlazeDS.
Chirstophe Coenraets has lots of great stuff on his blog including plenty of BlazeDS stuff. This post he wrote for Adobe Devnet has everything to get you started using BlazeDS including a download of a pre-configured Tomcat server and examples to work through.
One thing to note – if you can’t get the database update exercise to work, that’s because the example has the update statement created but never executes it.
Adobe doesn’t go out of it’s way to outline the differences between BlazeDS and LCDS but Sujit has a nice clear post here that does a good job explaining it.
With the different channel choices available, I think this post from Damon Cooper’s blog does a good job of exploring the pros and cons of each.