mqtt

MQTT Bindings

This document defines how to describe MQTT-specific information on AsyncAPI.

Version

Current version is 0.1.0.

Server Binding Object

This object contains information about the server representation in MQTT.

Fixed Fields

Field Name	Type	Description
clientId	string	The client identifier.
cleanSession	boolean	Whether to create a persistent connection or not. When false, the connection will be persistent.
lastWill	object	Last Will and Testament configuration.
lastWill.topic	string	The topic where the Last Will and Testament message will be sent.
lastWill.qos	integer	Defines how hard the broker/client will try to ensure that the Last Will and Testament message is received. Its value MUST be either 0, 1 or 2.
lastWill.message	string	Last Will message.
lastWill.retain	boolean	Whether the broker should retain the Last Will and Testament message or not.
keepAlive	integer	Interval in seconds of the longest period of time the broker and the client can endure without sending a message.
bindingVersion	string	The version of this binding. If omitted, "latest" MUST be assumed.

This object MUST contain only the properties defined above.

Example

servers:
  production:
    bindings:
      mqtt:
        clientId: guest
        cleanSession: true
        lastWill:
          topic: /last-wills
          qos: 2
          message: Guest gone offline.
          retain: false
        keepAlive: 60
        bindingVersion: 0.1.0

Channel Binding Object

This object MUST NOT contain any properties. Its name is reserved for future use.

Operation Binding Object

This object contains information about the operation representation in MQTT.

Fixed Fields

Field Name	Type	Applies To	Description
qos	integer	Publish, Subscribe	Defines the Quality of Service (QoS) levels for the message flow between client and server. Its value MUST be either 0 (At most once delivery), 1 (At least once delivery), or 2 (Exactly once delivery).
retain	boolean	Publish, Subscribe	Whether the broker should retain the message or not.
bindingVersion	string	Publish, Subscribe	The version of this binding. If omitted, "latest" MUST be assumed.

This object MUST contain only the properties defined above.

Example

channels:
  user/signup:
    publish:
      bindings:
        mqtt:
          qos: 2
          retain: true
          bindingVersion: 0.1.0

Message Binding Object

This object contains information about the message representation in MQTT.

Fixed Fields

Field Name	Type	Description
bindingVersion	string	The version of this binding. If omitted, "latest" MUST be assumed.

This object MUST contain only the properties defined above.

channels:
  user/signup:
    publish:
      message:
        bindings:
          mqtt:
            bindingVersion: 0.1.0