[brassybadger]

This is the old debate whether applications should be tightly or loosely coupled. As the article concludes, there are tradeoffs to consider - the broker is a SPOF indeed, but on the other hand it'll take care of all the queueing logic (which is not that simple as it seems - acknowledgements, backpressure, redelivery, timeouts etc etc). It's also much easier to scale the system out if applications are loosely coupled.

Furthermore, a good broker supports some kind of failover. We run a RabbitMQ cluster behind a load balancer, and it works great - once e.g. we had a hardware failure, and the applications did not notice anything from it. Of course we also have to monitor the queues on the broker (one of the few ways to bring down Rabbit is to fill up its disk). But having a central broker for connecting apps also means you have a central point you can keep an eye on to check where your bottlenecks are (which queues build up).

Loosely coupled applications are also much more unix-like in the sense that you can make them do one thing instead of baking in your custom restart logic (over a network? please don't).

[HeyImAlex]

I feel like it's an endless battle, trying to move away from a SPOF; even in your rabbitMQ cluster your load balancer is a SPOF. Who watches the watchmen? At a certain point you just have to accept that you're not gaining a whole lot by adding more complexity. Process supervision over a network (a la something like fleet or flynn or mesos) is a pretty neat solution. I've been playing around with this stuff the past week and I'm having a lot of trouble coming up with the perfect setup haha

[vidarh]

A load balancer need (should) not be SPOF: You run two (or more) of them, with IP takeover (e.g. via keepalived or similar, that continuously vote on the master), or you make the clients try to connect to two or more IP's. Or both.

It's really quite trivial to ensure your load balancer is not SPOF if you're ok with clients having to reconnect on failure, and only slightly more hassle if you want to allow connections to survive one of your load balancer boxes failing.