feat: add amqp exchange routing pattern and ref in channel operation

[timonback]

Description

In Java Spring applications, it is possible to define an application that connects to an amqp broker, defines exchanges, queues and listens to incoming message on these queues.

My current understanding of amqp:

1. A publisher connects to a broker
2. The publisher sends a message with a routing key to an exchange
3. The broker matches the message's routing key with the routing patterns of the defined exchanges and forwards the message to those queues.
4. (Bindings are used to connect an exchange with a queue, which do have a n-to-m mapping)
5. The consumer receives message from the queue

In AsyncAPI, the amqp binding supports two types of channels: routingKey (which is an exchange) and queue.
Unfortunately, there is no link between the two.

Proposal:
Add (optional) fields:

1. name to specify the actual routing pattern used (in the (topic) exchange or amqp binding)
2. channel.$ref to connect the is=routingKey channel type to the is=queue channel type.

I am looking forward to your thoughts.

Example:

asyncapi: 3.0.0
info:
  title: Springwolf example project - AMQP
  version: 1.0.0
  description: Springwolf example project to demonstrate springwolfs abilities
defaultContentType: application/json
servers:
  amqp-server:
    host: amqp:5672
    protocol: amqp
channels:
  queue-update-id_#_CRUD-topic-exchange-1-id:
    address: CRUD-topic-exchange-1
    messages:
      java.lang.String:
        $ref: "#/components/messages/java.lang.String"
    bindings:
      amqp:
        is: routingKey
        exchange:
          name: CRUD-topic-exchange-1
          type: topic
          durable: true
          autoDelete: false
          vhost: /
        bindingVersion: 0.3.0
  queue-update_id:
    address: queue-update
    bindings:
      amqp:
        is: queue
        queue:
          name: queue-update
          durable: false
          exclusive: false
          autoDelete: false
          vhost: /
        bindingVersion: 0.3.0
components:
  schemas:
    SpringRabbitListenerDefaultHeaders:
      type: object
      properties: {}
      examples:
        - {}
    java.lang.String:
      title: String
      type: string
      examples:
        - '"string"'
  messages:
    java.lang.String:
      headers:
        $ref: "#/components/schemas/SpringRabbitListenerDefaultHeaders"
      payload:
        schemaFormat: application/vnd.aai.asyncapi+json;version=3.0.0
        schema:
          $ref: "#/components/schemas/java.lang.String"
      name: java.lang.String
      title: String
      bindings:
        amqp:
          bindingVersion: 0.3.0
operations:
  queue-update-id_#_CRUD-topic-exchange-1-id_receive_bindingsUpdate:
    action: receive
    channel:
      $ref: "#/channels/queue-update-id_#_CRUD-topic-exchange-1-id"
    bindings:
      amqp:
        expiration: 0
        bindingVersion: 0.3.0
    messages:
      - $ref: "#/channels/queue-update-id_#_CRUD-topic-exchange-1-id/messages/java.lang.String"

[github-actions]

Welcome to AsyncAPI. Thanks a lot for creating your first pull request. Please check out our contributors guide useful for opening a pull request.
Keep in mind there are also other channels you can use to interact with AsyncAPI community. For more details check out this issue.

[Pakisan]

@timonback this repo is destination point

Start from creating PR in schemas repo - https://github.com/asyncapi/spec-json-schemas/tree/master/bindings/amqp

Create new version 0.4.0 and change schema

[timonback]

Thank you @Pakisan for the pointing out the correct repo. I re-created this PR as asyncapi/spec-json-schemas#555

[Pakisan]

@jonaslagoni @dalelane @smoya @GreenRover please, take a look

this PR is ready asyncapi/spec-json-schemas#555

[Pakisan]

@jonaslagoni @dalelane @smoya @GreenRover please, take a look

this PR is ready asyncapi/spec-json-schemas#555

up

@derberg @fmvilas @dalelane @smoya @char0n @GreenRover

[GreenRover]

Sorry my knowledge about amqp is very low, i am not sure if i can help.

[derberg]

Sorry for the late review @timonback
I love the work you're doing with Springwolf!

I have some general comments except for the inline ones I left in a PR:

• would be good if you could update the example from PR description with the new binding (adding some inline comment about the new addition) to visualize the added change
• since new fields are added to the binding, it also means you need to update the version value in the README.md - same to do in json schema
• for the sake of consistency, please have a look on how exchange object is defined. First the Map is described and then specific properties, like name and type. Please follow the same approach with new channel option. Although in your case it is even easier as channel will be of type Reference Object like in https://github.com/asyncapi/spec/blob/master/spec/asyncapi.md#operation-reply-object
• make it clear in description that we are talking about AsyncAPI channel only, and $ref only. Have a look at how we do it in case of channel reference in reply object.

also cc @jonaslagoni that did a migration of the binding to v3, maybe he also have something to add

[derberg]

technically shouldn't there be something matching this name in the userSignup to make this example make sense?

[jonaslagoni]

@derberg did not go into specifics of whether something made sense for AMQP, so I will stay out of the specifics :) Already reviewed asyncapi/spec-json-schemas#555