Initially when developing Alchemy we had a look at NSQ http://nsq.io and found it a little difficult (that was a year or so ago, so might be better now). Then we started looking at RabbitMQ and thought it fit our requirements better. I have not heard of NATS but will definitely have a look see. At the moment Alchemy is tied to RabbitMQ pretty tightly, but abstracting and supporting many queue solutions would be good.

I don't like pushing the retry into the client side. Since microservice by necessity have lots of communication between them that can be quite a bit of code across all the services. I would rather the architecture deal with it and just ensure that endpoints are idempotent so calls can be retried without adding client complexity. This is a personal preference, and in some cases clients do need to deal with retires, but I just like it not to be the default.

In the services folder there is this https://github.com/LoyaltyNZ/alchemy-framework/blob/master/s... pretty good RabbitMQ HA setup, with:

1. cluster_partition_handling set to autoheal so that it will do its best to recover (a few lost messages is infinitely better than a broken system) 2. queue_master_locator is min-master, so queues are mastered on nodes where the least amount of other queues are mastered. This will balance the queues across the clusters meaning if a node goes down then there will be minimal amount of queues to recreate 3. A mirror policy to mirror every queue (this will only mirror service queues because response queues are exclusive) , this will make the system a bit slower, but makes it much more robust.

This is enough to handle split brain (although this is difficult to test) and nodes going down and coming back (much easier to test).

Cheers for the comment :)