Broker and messages

To reliably exchange events over the network we need a broker. Broker can receive and forward messages that are usually represented as bytes. If we can encode an event object as bytes then broker can receive and forward events.

Messages

Messages are events encoded in a particular way. You can do two things with a message:

• decode its contents
• acknowledge it

A message is never decoded into an instance of a particular event that it was produced from. The receiving side doesn't know anything about code organization of the sender. How do you know what event is represented by a message then? There is a special subject property which is derived from a class name. For example, a message that encodes a MoneyReceived event has a "money-received" subject.

Brokers

A broker can do two things: - push messages to the receiver - send messages from the sender (with a confirmation for each one)

In eventual every message is guaranteed to be sent to the broker at least once.