Async APIs

A message broker usually refers to a piece of infrastructure that is responsible for sending a receiving messages. Asynchronous APIs are generally message broker centric.

A subscriber or consumer manifests and interest in a certain type of message and then leaves a connection open to the message broker so that it can have messages pushed to them.

Messages

Messages are often catalogued as either events or commands.

• Events communicate that something happened
• Commands indicate to the subscribe that it should do something

Channels

Brokers generally contain a set of channels that hold different sorts of messages, one channel for user sign ups, one channel for new purchases etc. These are sometimes can topics, routing keys or event types.

Structure

The info section of the spec contains a title object. However, it’s not clear how this interacts with the broker, channels model. Is this just a convenient way of grouping different channels?

Servers

The server section of the AsyncAPI defines where and how to connect for events.

There are a range of protocol properties that describe the connection type for an event. This can be HTTP.

Channels

The operationId property defines the name of the function that should take care of the functionality of pushing events for a particular channel.