RabbitMQ talk at LShift Last Night

I attended the AMQP+RabbitMQ talk last night at LShift, and it was a pretty good time. Apparently the talk was largely a rehash of the talk that Alexis & company did at Google UK a few weeks ago, and was pretty interesting.

The basic pattern was:

• Talk about MOM (messaging is good) and AMQP (AMQP is also good)
• Talk about RabbitMQ (RabbitMQ is good) and Erlang/OTP (they're also good and ideal for implementation of an AMQP broker)
• Demonstration of some cool stuff you can do tying it all together

To me the biggest parts that were new and quite interesting and well worth the time was the latter half, where they showed how a lot of the features in Erlang are ideally suited to developing an AMQP broker in under 5000 lines of human-written code (a little more is auto-generated from the AMQP spec itself), and some of the neat things that Erlang gives you as a platform for maintenance and monitoring.

Specifically, in case you haven't been looking at it yet, Erlang gives you a natural model to represent a lot of concepts in building large asynchronous systems. Since there's a lot of processing that goes on in message-oriented systems which is by its very nature asynchronous, it's pretty easy to map that onto Erlang in a pretty trivial way, which drastically reduces the amount of code that you need to write yourself.

Since the major concepts you're working with (Exchanges, Queues, Sockets) map directly to low-level Erlang actors^H^H^H^H^H^Hprocesses, Erlang gives you a really easy way to automatically introspect the state of those things, since they're being mapped to processes. This for a Java guy was pretty cool, because essentially you can introspect into the state of a running Erlang system and see in one fell swoop a snapshot of a process which shows you the equivalent of (for Java):

• The stack trace
• Values of all local variables across the stack
• Values of all elements in the heap directly addressible from the bound variables

Doing that even with the new tools available in Java 6 and Terracotta is nowhere near as easy to do, and it was pretty darn powerful to witness.

And then, down t' pub.

One of the most interesting things to me was that quite a few of the people there really weren't part of the converted trying to hear things to make them feel all happy about themselves. Rather, there were a lot of people who aren't currently using MOM systems (or have basically done stuff that's core to MOM themselves, because the basic concepts are so intuitive that if you don't know what's out there, you'll end up writing your own half-baked MOM implementation yourself to do almost any non-trivial asynchronous system) who are eager to look into them now.

That's pretty nice to hear, and I think is one of the major medium-term benefits of AMQP: expansion of the overall MOM space from one dominated by MQSeries which people use because they have to, not because they want to, to one where people actively choose to use MOM because it's seen as a benefit rather than a hurdle. So AMQP really will involve growing the space, rather than cannibalizing it. And that to me is a great thing.