Pub/sub, as the name suggests, is where a software agent publishes a message onto a queue, and other agents can subscribe to that type of message to receive it. When a message is published, all subscribers receive it, but crucially the publisher does not require any knowledge of the subscribers or even need to know how many there are (or even if there are any at all).
Pub/sub is best done with the broker style of message queuing architecture. It can be done without a broker, but it is not particularly reliable. If your use case can tolerate message loss, then you may be able to get away without a broker. But, if you require guaranteed delivery, then you should use one. Using the RabbitMQ broker also allows you to take advantage of ...
