I generally find it is best to have exchanges grouped by object type / exchange type combinations. in you example of user events, you could do a number of different things depending on what your system needs. in one scenario, it might make sense to have an exchange per event as you’ve listed. you could … Read more
I’m confused by your choice of three terms to compare. Within RabbitMQ, Fanout and Direct are exchange types. Pub-Sub is a generic messaging pattern but not an exchange type. And you didn’t even mention the 3rd and most important Exchange type, namely Topic. In fact, you can implement Fanout behavior on a Topic exchange just … Read more
RabbitMQ is an AMQP broker, while ActiveMQ is a JMS one. I suggest you read the AMQP wikipedia article to get an idea of the concepts used in AMQP, which are different than the ones you’re familiar in JMS. One of the main difference is that in AMQP a producer sends to an exchange without … Read more
Unacknowledged messages are those which have been delivered across the network to a consumer but have not yet been ack’ed or rejected — but that consumer hasn’t yet closed the channel or connection over which it originally received them. Therefore the broker can’t figure out if the consumer is just taking a long time to … Read more
This is a great question. The main uses of messaging are: scaling, offloading work, integration, monitoring, event handling, routing, networking, push, mobility, buffering, queueing, task sharing, alerts, management, logging, batch, data delivery, pubsub, multicast, audit, scheduling, … and more. Basically: anything where you need data but don’t want to make a database request. (Caching is … Read more
You can actually retrieve this via the client. When you perform a queue_declare operation, RabbitMQ returns a tuple with three values: (<queue name>, <message count>, <consumer count>). The passive argument to queue_declare allows you to check whether a queue exists without modifying the server state, so you can use queue_declare with the passive option to … Read more
It turns out that it is related to permissions. Somehow my rabbitmq server was started with user ‘rabbitmq’ (which is strange), so that I had to do sudo -u rabbitmq rabbitmqctl stop
The immediate and mandatory fields are part of the AMQP specification, and are also covered in the RabbitMQ FAQ to clarify how its implementers interpreted their meaning: Mandatory This flag tells the server how to react if a message cannot be routed to a queue. Specifically, if mandatory is set and after running the bindings … Read more
At first, REST, RPC – architecture patterns, AMQP – wire-level and HTTP – application protocol which run on top of TCP/IP AMQP is a specific protocol when HTTP – general-purpose protocol, thus, HTTP has damn high overhead comparing to AMQP AMQP nature is asynchronous where HTTP nature is synchronous both REST and RPC use data … Read more
There are not any hard-coded limits inside RabbitMQ broker. The broker will utilize all available resources (unless you set limits on some of them, they are called watermarks in RabbitMQ terminology). There are some limitations put by Erlang itself, like maximum number of concurrent processes, but if you theoretically can reach them on single node … Read more