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# AsyncAPI Specification
#### Disclaimer
Part of this content has been taken from the great work done by the folks at the [OpenAPI Initiative](https://openapis.org). Mainly because **it's a great work** and we want to keep as much compatibility as possible with the [OpenAPI Specification](https://github.com/OAI/OpenAPI-Specification).
#### Version 2.1.0
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC 2119](http://www.ietf.org/rfc/rfc2119.txt).
The AsyncAPI Specification is licensed under [The Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.html).
## Introduction
The AsyncAPI Specification is a project used to describe and document message-driven APIs in a machine-readable format. It’s protocol-agnostic, so you can use it for APIs that work over any protocol (e.g., AMQP, MQTT, WebSockets, Kafka, STOMP, HTTP, Mercure, etc).
The AsyncAPI Specification defines a set of files required to describe such an API.
These files can then be used to create utilities, such as documentation, integration and/or testing tools.
The file(s) MUST describe the operations an [application](#definitionsApplication) accepts. For instance, consider the following AsyncAPI definition snippet:
```yaml
user/signedup:
subscribe:
$ref: "#/components/messages/userSignUp"
```
It means that the [application](#definitionsApplication) allows [consumers](#definitionsConsumer) to subscribe to the `user/signedup` [channel](#definitionsChannel) to receive userSignUp [messages](#definitionsMessage) produced by the application.
**The AsyncAPI specification does not assume any kind of software topology, architecture or pattern.** Therefore, a server MAY be a message broker, a web server or any other kind of computer program capable of sending and/or receiving data. However, AsyncAPI offers a mechanism called "bindings" that aims to help with more specific information about the protocol.
## Table of Contents
<!-- TOC depthFrom:2 depthTo:4 withLinks:1 updateOnSave:0 orderedList:0 -->
- [Definitions](#definitions)
- [Application](#definitionsApplication)
- [Producer](#definitionsProducer)
- [Consumer](#definitionsConsumer)
- [Message](#definitionsMessage)
- [Channel](#definitionsChannel)
- [Protocol](#definitionsProtocol)
- [Specification](#specification)
- [Format](#format)
- [File Structure](#file-structure)
- [Schema](#schema)
- [AsyncAPI Object](#A2SObject)
- [AsyncAPI Version String](#A2SVersionString)
- [Identifier](#A2SIdString)
- [Info Object](#infoObject)
- [Contact Object](#contactObject)
- [License Object](#licenseObject)
- [Servers Object](#serversObject)
- [Server Object](#serverObject)
- [Server Variable Object](#serverVariableObject)
- [Default Content Type](#defaultContentTypeString)
- [Channels Object](#channelsObject)
- [Channel Item Object](#channelItemObject)
- [Operation Object](#operationObject)
- [Operation Trait Object](#operationTraitObject)
- [Message Object](#messageObject)
- [Message Trait Object](#messageTraitObject)
- [Tags Object](#tagsObject)
- [Tag Object](#tag-object)
- [External Documentation Object](#externalDocumentationObject)
- [Components Object](#componentsObject)
- [Reference Object](#referenceObject)
- [Schema Object](#schemaObject)
- [Security Scheme Object](#securitySchemeObject)
- [Security Requirement Object](#security-requirement-object)
- [OAuth Flows Object](#oauth-flows-object)
- [OAuth Flow Object](#oauth-flow-object)
- [Server Bindings Object](#serverBindingsObject)
- [Parameters Object](#parametersObject)
- [Parameter Object](#parameterObject)
- [Channel Bindings Object](#channelBindingsObject)
- [Operation Bindings Object](#operationBindingsObject)
- [Message Bindings Object](#messageBindingsObject)
- [Correlation ID Object](#correlationIdObject)
- [Specification Extensions](#specificationExtensions)
<!-- /TOC -->
## <a name="definitions"></a>Definitions
#### <a name="definitionsApplication"></a>Application
An application is any kind of computer program or a group of them. It MUST be a [producer](#definitionsProducer), a [consumer](#definitionsConsumer) or both. An application MAY be a microservice, IoT device (sensor), mainframe process, etc. An application MAY be written in any number of different programming languages as long as they support the selected [protocol](#definitionsProtocol). An application MUST also use a protocol supported by the server in order to connect and exchange [messages](#definitionsMessage).
#### <a name="definitionsProducer"></a>Producer
A producer is a type of application, connected to a server, that is creating [messages](#definitionsMessage) and addressing them to [channels](#definitionsChannel). A producer MAY be publishing to multiple channels depending on the server, protocol, and use-case pattern.
#### <a name="definitionsConsumer"></a>Consumer
A consumer is a type of application, connected to a server via a supported [protocol](#definitionsProtocol), that is consuming [messages](#definitionsMessage) from [channels](#definitionsChannel). A consumer MAY be consuming from multiple channels depending on the server, protocol, and the use-case pattern.
#### <a name="definitionsMessage"></a>Message
A message is the mechanism by which information is exchanged via a channel between servers and applications. A message MUST contain a payload and MAY also contain headers. The headers MAY be subdivided into [protocol](#definitionsProtocol)-defined headers and header properties defined by the application which can act as supporting metadata. The payload contains the data, defined by the application, which MUST be serialized into a format (JSON, XML, Avro, binary, etc.). Since a message is a generic mechanism, it can support multiple interaction patterns such as event, command, request, or response.
#### <a name="definitionsChannel"></a>Channel
A channel is an addressable component, made available by the server, for the organization of [messages](#definitionsMessage). [Producer](#definitionsProducer) applications send messages to channels and [consumer](#definitionsConsumer) applications consume messages from channels. Servers MAY support many channel instances, allowing messages with different content to be addressed to different channels. Depending on the server implementation, the channel MAY be included in the message via protocol-defined headers.
#### <a name="definitionsProtocol"></a>Protocol
A protocol is the mechanism (wireline protocol or API) by which [messages](#definitionsMessage) are exchanged between the application and the [channel](#definitionsChannel). Example protocols include, but are not limited to, AMQP, HTTP, JMS, Kafka, MQTT, STOMP, Mercure, WebSocket.
#### <a name="definitionsBindings"></a>Bindings
A "binding" (or "protocol binding") is a mechanism to define protocol-specific information. Therefore, a protocol binding MUST define protocol-specific information only.
## <a name="specification"></a>Specification
### <a name="format"></a>Format
The files describing the message-driven API in accordance with the AsyncAPI Specification are represented as JSON objects and conform to the JSON standards.
YAML, being a superset of JSON, can be used as well to represent a A2S (AsyncAPI Specification) file.
For example, if a field is said to have an array value, the JSON array representation will be used:
```yaml
{
"field" : [...]
}
```
While the API is described using JSON it does not impose a JSON input/output to the API itself.
All field names in the specification are **case sensitive**.
The schema exposes two types of fields.
Fixed fields, which have a declared name, and Patterned fields, which declare a regex pattern for the field name.
Patterned fields can have multiple occurrences as long as each has a unique name.
In order to preserve the ability to round-trip between YAML and JSON formats, YAML version [1.2](http://www.yaml.org/spec/1.2/spec.html) is recommended along with some additional constraints:
- Tags MUST be limited to those allowed by the [JSON Schema ruleset](http://www.yaml.org/spec/1.2/spec.html#id2803231)
- Keys used in YAML maps MUST be limited to a scalar string, as defined by the YAML Failsafe schema ruleset
### <a name="file-structure"></a>File Structure
The A2S representation of the API is made of a single file.
However, parts of the definitions can be split into separate files, at the discretion of the user.
This is applicable for `$ref` fields in the specification as follows from the [JSON Schema](https://json-schema.org/understanding-json-schema/structuring.html) definitions.
By convention, the AsyncAPI Specification (A2S) file is named `asyncapi.json` or `asyncapi.yaml`.
### <a name="schema"></a>Schema
#### <a name="A2SObject"></a>AsyncAPI Object
This is the root document object for the API specification.
It combines resource listing and API declaration together into one document.
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="A2SAsyncAPI"></a>asyncapi | [AsyncAPI Version String](#A2SVersionString) | **Required.** Specifies the AsyncAPI Specification version being used. It can be used by tooling Specifications and clients to interpret the version. The structure shall be `major`.`minor`.`patch`, where `patch` versions _must_ be compatible with the existing `major`.`minor` tooling. Typically patch versions will be introduced to address errors in the documentation, and tooling should typically be compatible with the corresponding `major`.`minor` (1.0.*). Patch versions will correspond to patches of this document.
<a name="A2SId"></a>id | [Identifier](#A2SIdString) | Identifier of the [application](#definitionsApplication) the AsyncAPI document is defining.
<a name="A2SInfo"></a>info | [Info Object](#infoObject) | **Required.** Provides metadata about the API. The metadata can be used by the clients if needed.
<a name="A2SServers"></a>servers | [Servers Object](#serversObject) | Provides connection details of servers.
<a name="A2SDefaultContentType"></a>defaultContentType | [Default Content Type](#defaultContentTypeString) | Default content type to use when encoding/decoding a message's payload.
<a name="A2SChannels"></a>channels | [Channels Object](#channelsObject) | **Required** The available channels and messages for the API.
<a name="A2SComponents"></a>components | [Components Object](#componentsObject) | An element to hold various schemas for the specification.
<a name="A2STags"></a>tags | [Tags Object](#tagsObject) | A list of tags used by the specification with additional metadata. Each tag name in the list MUST be unique.
<a name="A2SExternalDocs"></a>externalDocs | [External Documentation Object](#externalDocumentationObject) | Additional external documentation.
This object can be extended with [Specification Extensions](#specificationExtensions).
#### <a name="A2SVersionString"></a>AsyncAPI Version String
The version string signifies the version of the AsyncAPI Specification that the document complies to.
The format for this string _must_ be `major`.`minor`.`patch`. The `patch` _may_ be suffixed by a hyphen and extra alphanumeric characters.
A `major`.`minor` shall be used to designate the AsyncAPI Specification version, and will be considered compatible with the AsyncAPI Specification specified by that `major`.`minor` version.
The patch version will not be considered by tooling, making no distinction between `1.0.0` and `1.0.1`.
In subsequent versions of the AsyncAPI Specification, care will be given such that increments of the `minor` version should not interfere with operations of tooling developed to a lower minor version. Thus a hypothetical `1.1.0` specification should be usable with tooling designed for `1.0.0`.
#### <a name="A2SIdString"></a>Identifier
This field represents a unique universal identifier of the [application](#definitionsApplication) the AsyncAPI document is defining. It must conform to the URI format, according to [RFC3986](http://tools.ietf.org/html/rfc3986).
It is RECOMMENDED to use a [URN](https://tools.ietf.org/html/rfc8141) to globally and uniquely identify the application during long periods of time, even after it becomes unavailable or ceases to exist.
###### Examples
```json
{
"id": "urn:com:smartylighting:streetlights:server"
}
```
```yaml
id: 'urn:com:smartylighting:streetlights:server'
```
```json
{
"id": "https://github.com/smartylighting/streetlights-server"
}
```
```yaml
id: 'https://github.com/smartylighting/streetlights-server'
```
#### <a name="infoObject"></a>Info Object
The object provides metadata about the API.
The metadata can be used by the clients if needed.
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="infoObjectTitle"></a>title | `string` | **Required.** The title of the application.
<a name="infoObjectVersion"></a>version | `string` | **Required** Provides the version of the application API (not to be confused with the specification version).
<a name="infoObjectDescription"></a>description | `string` | A short description of the application. [CommonMark syntax](http://spec.commonmark.org/) can be used for rich text representation.
<a name="infoObjectTermsOfService"></a>termsOfService | `string` | A URL to the Terms of Service for the API. MUST be in the format of a URL.
<a name="infoObjectContact"></a>contact | [Contact Object](#contactObject) | The contact information for the exposed API.
<a name="infoObjectLicense"></a>license | [License Object](#licenseObject) | The license information for the exposed API.
This object can be extended with [Specification Extensions](#specificationExtensions).
##### Info Object Example:
```json
{
"title": "AsyncAPI Sample App",
"description": "This is a sample server.",
"termsOfService": "http://asyncapi.org/terms/",
"contact": {
"name": "API Support",
"url": "http://www.asyncapi.org/support",
"email": "support@asyncapi.org"
},
"license": {
"name": "Apache 2.0",
"url": "http://www.apache.org/licenses/LICENSE-2.0.html"
},
"version": "1.0.1"
}
```
```yaml
title: AsyncAPI Sample App
description: This is a sample server.
termsOfService: http://asyncapi.org/terms/
contact:
name: API Support
url: http://www.asyncapi.org/support
email: support@asyncapi.org
license:
name: Apache 2.0
url: http://www.apache.org/licenses/LICENSE-2.0.html
version: 1.0.1
```
#### <a name="contactObject"></a>Contact Object
Contact information for the exposed API.
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="contactObjectName"></a>name | `string` | The identifying name of the contact person/organization.
<a name="contactObjectUrl"></a>url | `string` | The URL pointing to the contact information. MUST be in the format of a URL.
<a name="contactObjectEmail"></a>email | `string` | The email address of the contact person/organization. MUST be in the format of an email address.
This object can be extended with [Specification Extensions](#specificationExtensions).
##### Contact Object Example:
```json
{
"name": "API Support",
"url": "http://www.example.com/support",
"email": "support@example.com"
}
```
```yaml
name: API Support
url: http://www.example.com/support
email: support@example.com
```
#### <a name="licenseObject"></a>License Object
License information for the exposed API.
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="licenseObjectName"></a>name | `string` | **Required.** The license name used for the API.
<a name="licenseObjectUrl"></a>url | `string` | A URL to the license used for the API. MUST be in the format of a URL.
This object can be extended with [Specification Extensions](#specificationExtensions).
##### License Object Example:
```json
{
"name": "Apache 2.0",
"url": "http://www.apache.org/licenses/LICENSE-2.0.html"
}
```
```yaml
name: Apache 2.0
url: http://www.apache.org/licenses/LICENSE-2.0.html
```
#### <a name="serversObject"></a>Servers Object
The Servers Object is a map of [Server Objects](#serverObject).
##### Patterned Fields
Field Pattern | Type | Description
---|:---:|---
<a name="serversObjectServer"></a>`^[A-Za-z0-9_\-]+$` | [Server Object](#serverObject) | The definition of a server this application MAY connect to.
##### Servers Object Example
```json
{
"production": {
"url": "development.gigantic-server.com",
"description": "Development server",
"protocol": "kafka",
"protocolVersion": "1.0.0"
}
}
```
```yaml
production:
url: development.gigantic-server.com
description: Development server
protocol: kafka
protocolVersion: '1.0.0'
```
#### <a name="serverObject"></a>Server Object
An object representing a message broker, a server or any other kind of computer program capable of sending and/or receiving data. This object is used to capture details such as URIs, protocols and security configuration. Variable substitution can be used so that some details, for example usernames and passwords, can be injected by code generation tools.
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="serverObjectUrl"></a>url | `string` | **REQUIRED**. A URL to the target host. This URL supports Server Variables and MAY be relative, to indicate that the host location is relative to the location where the AsyncAPI document is being served. Variable substitutions will be made when a variable is named in `{`brackets`}`.
<a name="serverObjectProtocol"></a>protocol | `string` | **REQUIRED**. The protocol this URL supports for connection. Supported protocol include, but are not limited to: `amqp`, `amqps`, `http`, `https`, `ibmmq`, `jms`, `kafka`, `kafka-secure`, `mqtt`, `secure-mqtt`, `stomp`, `stomps`, `ws`, `wss`, `mercure`.
<a name="serverObjectProtocolVersion"></a>protocolVersion | `string` | The version of the protocol used for connection. For instance: AMQP `0.9.1`, HTTP `2.0`, Kafka `1.0.0`, etc.
<a name="serverObjectDescription"></a>description | `string` | An optional string describing the host designated by the URL. [CommonMark syntax](http://spec.commonmark.org/) MAY be used for rich text representation.
<a name="serverObjectVariables"></a>variables | Map[`string`, [Server Variable Object](#serverVariableObject)] | A map between a variable name and its value. The value is used for substitution in the server's URL template.
<a name="serverObjectSecurity"></a>security | [[Security Requirement Object](#securityRequirementObject)] | A declaration of which security mechanisms can be used with this server. The list of values includes alternative security requirement objects that can be used. Only one of the security requirement objects need to be satisfied to authorize a connection or operation.
<a name="serverObjectBindings"></a>bindings | [Server Bindings Object](#serverBindingsObject) \| [Reference Object](#referenceObject) | A map where the keys describe the name of the protocol and the values describe protocol-specific definitions for the server.
This object MAY be extended with [Specification Extensions](#specificationExtensions).
##### Server Object Example
A single server would be described as:
```json
{
"url": "development.gigantic-server.com",
"description": "Development server",
"protocol": "kafka",
"protocolVersion": "1.0.0"
}
```
```yaml
url: development.gigantic-server.com
description: Development server
protocol: kafka
protocolVersion: '1.0.0'
```
The following shows how multiple servers can be described, for example, at the AsyncAPI Object's [`servers`](#A2SServers):
```json
{
"servers": {
"development": {
"url": "development.gigantic-server.com",
"description": "Development server",
"protocol": "amqp",
"protocolVersion": "0.9.1"
},
"staging": {
"url": "staging.gigantic-server.com",
"description": "Staging server",
"protocol": "amqp",
"protocolVersion": "0.9.1"
},
"production": {
"url": "api.gigantic-server.com",
"description": "Production server",
"protocol": "amqp",
"protocolVersion": "0.9.1"
}
}
}
```
```yaml
servers:
development:
url: development.gigantic-server.com
description: Development server
protocol: amqp
protocolVersion: 0.9.1
staging:
url: staging.gigantic-server.com
description: Staging server
protocol: amqp
protocolVersion: 0.9.1
production:
url: api.gigantic-server.com
description: Production server
protocol: amqp
protocolVersion: 0.9.1
```
The following shows how variables can be used for a server configuration:
```json
{
"servers": {
"production": {
"url": "{username}.gigantic-server.com:{port}/{basePath}",
"description": "The production API server",
"protocol": "secure-mqtt",
"variables": {
"username": {
"default": "demo",
"description": "This value is assigned by the service provider, in this example `gigantic-server.com`"
},
"port": {
"enum": [
"8883",
"8884"
],
"default": "8883"
}
}
}
}
}
```
```yaml
servers:
production:
url: '{username}.gigantic-server.com:{port}/{basePath}'
description: The production API server
protocol: secure-mqtt
variables:
username:
# note! no enum here means it is an open value
default: demo
description: This value is assigned by the service provider, in this example `gigantic-server.com`
port:
enum:
- '8883'
- '8884'
default: '8883'
```
#### <a name="serverVariableObject"></a>Server Variable Object
An object representing a Server Variable for server URL template substitution.
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="serverVariableObjectEnum"></a>enum | [`string`] | An enumeration of string values to be used if the substitution options are from a limited set.
<a name="serverVariableObjectDefault"></a>default | `string` | The default value to use for substitution, and to send, if an alternate value is _not_ supplied.
<a name="serverVariableObjectDescription"></a>description | `string` | An optional description for the server variable. [CommonMark syntax](http://spec.commonmark.org/) MAY be used for rich text representation.
<a name="serverVariableObjectExamples"></a>examples | [`string`] | An array of examples of the server variable.
This object MAY be extended with [Specification Extensions](#specificationExtensions).
#### <a name="defaultContentTypeString"></a>Default Content Type
A string representing the default content type to use when encoding/decoding a message's payload. The value MUST be a specific media type (e.g. `application/json`). This value MUST be used by schema parsers when the [contentType](#messageObjectContentType) property is omitted.
In case a message can't be encoded/decoded using this value, schema parsers MUST use their default content type.
##### Default Content Type Example
```json
{
"defaultContentType": "application/json"
}
```
```yaml
defaultContentType: application/json
```
#### <a name="channelsObject"></a>Channels Object
Holds the relative paths to the individual channel and their operations. Channel paths are relative to servers.
Channels are also known as "topics", "routing keys", "event types" or "paths".
##### Patterned Fields
Field Pattern | Type | Description
---|:---:|---
<a name="channelsObjectChannel"></a>{channel} | [Channel Item Object](#channelItemObject) | A relative path to an individual channel. The field name MUST be in the form of a [RFC 6570 URI template](https://tools.ietf.org/html/rfc6570). Query parameters and fragments SHALL NOT be used, instead use [bindings](#channelBindingsObject) to define them.
##### Channels Object Example
```json
{
"user/signedup": {
"subscribe": {
"$ref": "#/components/messages/userSignedUp"
}
}
}
```
```yaml
user/signedup:
subscribe:
$ref: "#/components/messages/userSignedUp"
```
#### <a name="channelItemObject"></a>Channel Item Object
Describes the operations available on a single channel.
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="channelItemObjectRef"></a>$ref | `string` | Allows for an external definition of this channel item. The referenced structure MUST be in the format of a [Channel Item Object](#channelItemObject). If there are conflicts between the referenced definition and this Channel Item's definition, the behavior is *undefined*.
<a name="channelItemObjectDescription"></a>description | `string` | An optional description of this channel item. [CommonMark syntax](http://spec.commonmark.org/) can be used for rich text representation.
<a name="channelItemObjectSubscribe"></a>subscribe | [Operation Object](#operationObject) | A definition of the SUBSCRIBE operation, which defines the messages produced by the application and sent to the channel.
<a name="channelItemObjectPublish"></a>publish | [Operation Object](#operationObject) | A definition of the PUBLISH operation, which defines the messages consumed by the application from the channel.
<a name="channelItemObjectParameters"></a>parameters | [Parameters Object](#parametersObject) | A map of the parameters included in the channel name. It SHOULD be present only when using channels with expressions (as defined by [RFC 6570 section 2.2](https://tools.ietf.org/html/rfc6570#section-2.2)).
<a name="channelItemObjectBindings"></a>bindings | [Channel Bindings Object](#channelBindingsObject) \| [Reference Object](#referenceObject) | A map where the keys describe the name of the protocol and the values describe protocol-specific definitions for the channel.
This object can be extended with [Specification Extensions](#specificationExtensions).
##### Channel Item Object Example
```json
{
"description": "This channel is used to exchange messages about users signing up",
"subscribe": {
"summary": "A user signed up.",
"message": {
"description": "A longer description of the message",
"payload": {
"type": "object",
"properties": {
"user": {
"$ref": "#/components/schemas/user"
},
"signup": {
"$ref": "#/components/schemas/signup"
}
}
}
}
},
"bindings": {
"amqp": {
"is": "queue",
"queue": {
"exclusive": true
}
}
}
}
```
```yaml
description: This channel is used to exchange messages about users signing up
subscribe:
summary: A user signed up.
message:
description: A longer description of the message
payload:
type: object
properties:
user:
$ref: "#/components/schemas/user"
signup:
bindings:
amqp:
is: queue
queue:
exclusive: true
```
Using `oneOf` to specify multiple messages per operation:
```json
{
"subscribe": {
"message": {
"oneOf": [
{ "$ref": "#/components/messages/signup" },
{ "$ref": "#/components/messages/login" }
]
}
}
}
```
```yaml
subscribe:
message:
oneOf:
- $ref: '#/components/messages/signup'
- $ref: '#/components/messages/login'
```
#### <a name="operationObject"></a>Operation Object
Describes a publish or a subscribe operation. This provides a place to document how and why messages are sent and received.
For example, an operation might describe a chat application use case where a user sends a text message to a group. A publish operation describes messages that are received by the chat application, whereas a subscribe operation describes messages that are sent by the chat application.
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="operationObjectOperationId"></a>operationId | `string` | Unique string used to identify the operation. The id MUST be unique among all operations described in the API. The operationId value is **case-sensitive**. Tools and libraries MAY use the operationId to uniquely identify an operation, therefore, it is RECOMMENDED to follow common programming naming conventions.
<a name="operationObjectSummary"></a>summary | `string` | A short summary of what the operation is about.
<a name="operationObjectDescription"></a>description | `string` | A verbose explanation of the operation. [CommonMark syntax](http://spec.commonmark.org/) can be used for rich text representation.
<a name="operationObjectTags"></a>tags | [Tags Object](#tagsObject) | A list of tags for API documentation control. Tags can be used for logical grouping of operations.
<a name="operationObjectExternalDocs"></a>externalDocs | [External Documentation Object](#externalDocumentationObject) | Additional external documentation for this operation.
<a name="operationObjectBindings"></a>bindings | [Operation Bindings Object](#operationBindingsObject) \| [Reference Object](#referenceObject) | A map where the keys describe the name of the protocol and the values describe protocol-specific definitions for the operation.
<a name="operationObjectTraits"></a>traits | [[Operation Trait Object](#operationTraitObject) | [Reference Object](#referenceObject) ] | A list of traits to apply to the operation object. Traits MUST be merged into the operation object using the [JSON Merge Patch](https://tools.ietf.org/html/rfc7386) algorithm in the same order they are defined here.
<a name="operationObjectMessage"></a>message | [[Message Object](#messageObject) | [Reference Object](#referenceObject)] | A definition of the message that will be published or received on this channel. `oneOf` is allowed here to specify multiple messages, however, **a message MUST be valid only against one of the referenced message objects.**
This object can be extended with [Specification Extensions](#specificationExtensions).
##### Operation Object Example
```json
{
"operationId": "registerUser",
"summary": "Action to sign a user up.",
"description": "A longer description",
"tags": [
{ "name": "user" },
{ "name": "signup" },
{ "name": "register" }
],
"message": {
"headers": {
"type": "object",
"properties": {
"applicationInstanceId": {
"description": "Unique identifier for a given instance of the publishing application",
"type": "string"
}
}
},
"payload": {
"type": "object",
"properties": {
"user": {
"$ref": "#/components/schemas/userCreate"
},
"signup": {
"$ref": "#/components/schemas/signup"
}
}
}
},
"bindings": {
"amqp": {
"ack": false
},
},
"traits": [
{ "$ref": "#/components/operationTraits/kafka" }
]
}
```
```yaml
operationId: registerUser
summary: Action to sign a user up.
description: A longer description
tags:
- name: user
- name: signup
- name: register
message:
headers:
type: object
properties:
applicationInstanceId:
description: Unique identifier for a given instance of the publishing application
type: string
payload:
type: object
properties:
user:
$ref: "#/components/schemas/userCreate"
signup:
$ref: "#/components/schemas/signup"
bindings:
amqp:
ack: false
traits:
- $ref: "#/components/operationTraits/kafka"
```
#### <a name="operationTraitObject"></a>Operation Trait Object
Describes a trait that MAY be applied to an [Operation Object](#operationObject). This object MAY contain any property from the [Operation Object](#operationObject), except `message` and `traits`.
If you're looking to apply traits to a message, see the [Message Trait Object](#messageTraitObject).
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="operationTraitObjectOperationId"></a>operationId | `string` | Unique string used to identify the operation. The id MUST be unique among all operations described in the API. The operationId value is **case-sensitive**. Tools and libraries MAY use the operationId to uniquely identify an operation, therefore, it is RECOMMENDED to follow common programming naming conventions.
<a name="operationTraitObjectSummary"></a>summary | `string` | A short summary of what the operation is about.
<a name="operationTraitObjectDescription"></a>description | `string` | A verbose explanation of the operation. [CommonMark syntax](http://spec.commonmark.org/) can be used for rich text representation.
<a name="operationTraitObjectTags"></a>tags | [Tags Object](#tagsObject) | A list of tags for API documentation control. Tags can be used for logical grouping of operations.
<a name="operationTraitObjectExternalDocs"></a>externalDocs | [External Documentation Object](#externalDocumentationObject) | Additional external documentation for this operation.
<a name="operationTraitObjectBindings"></a>bindings | [Operation Bindings Object](#operationBindingsObject) \| [Reference Object](#referenceObject) | A map where the keys describe the name of the protocol and the values describe protocol-specific definitions for the operation.
This object can be extended with [Specification Extensions](#specificationExtensions).
##### Operation Trait Object Example
```json
{
"bindings": {
"amqp": {
"ack": false
}
}
}
```
```yaml
bindings:
amqp:
ack: false
```
#### <a name="parametersObject"></a>Parameters Object
Describes a map of parameters included in a channel name.
This map MUST contain all the parameters used in the parent channel name.
##### Patterned Fields
Field Pattern | Type | Description
---|:---:|---
<a name="parametersObjectName"></a>`^[A-Za-z0-9_\-]+$` | [Parameter Object](#parameterObject) | [Reference Object](#referenceObject) | The key represents the name of the parameter. It MUST match the parameter name used in the parent channel name.
##### Parameters Object Example
```json
{
"user/{userId}/signup": {
"parameters": {
"userId": {
"description": "Id of the user.",
"schema": {
"type": "string"
}
}
},
"subscribe": {
"$ref": "#/components/messages/userSignedUp"
}
}
}
```
```yaml
user/{userId}/signup:
parameters:
userId:
description: Id of the user.
schema:
type: string
subscribe:
$ref: "#/components/messages/userSignedUp"
```
#### <a name="parameterObject"></a>Parameter Object
Describes a parameter included in a channel name.
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="parameterObjectDescription"></a>description | `string` | A verbose explanation of the parameter. [CommonMark syntax](http://spec.commonmark.org/) can be used for rich text representation.
<a name="parameterObjectSchema"></a>schema | [Schema Object](#schemaObject) \| [Reference Object](#referenceObject) | Definition of the parameter.
location | `string` | A [runtime expression](#runtimeExpression) that specifies the location of the parameter value. Even when a definition for the target field exists, it MUST NOT be used to validate this parameter but, instead, the `schema` property MUST be used.
This object can be extended with [Specification Extensions](#specificationExtensions).
##### Parameter Object Example
```json
{
"user/{userId}/signup": {
"parameters": {
"userId": {
"description": "Id of the user.",
"schema": {
"type": "string"
},
"location": "$message.payload#/user/id"
}
},
"subscribe": {
"$ref": "#/components/messages/userSignedUp"
}
}
}
```
```yaml
user/{userId}/signup:
parameters:
userId:
description: Id of the user.
schema:
type: string
location: $message.payload#/user/id
subscribe:
$ref: "#/components/messages/userSignedUp"
```
#### <a name="serverBindingsObject"></a>Server Bindings Object
Map describing protocol-specific definitions for a server.
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="serverBindingsObjectHTTP"></a>`http` | [HTTP Server Binding](https://github.com/asyncapi/bindings/blob/master/http#server) | Protocol-specific information for an HTTP server.
<a name="serverBindingsObjectWebSockets"></a>`ws` | [WebSockets Server Binding](https://github.com/asyncapi/bindings/blob/master/websockets#server) | Protocol-specific information for a WebSockets server.
<a name="serverBindingsObjectKafka"></a>`kafka` | [Kafka Server Binding](https://github.com/asyncapi/bindings/blob/master/kafka#server) | Protocol-specific information for a Kafka server.
<a name="serverBindingsObjectAMQP"></a>`amqp` | [AMQP Server Binding](https://github.com/asyncapi/bindings/blob/master/amqp#server) | Protocol-specific information for an AMQP 0-9-1 server.
<a name="serverBindingsObjectAMQP1"></a>`amqp1` | [AMQP 1.0 Server Binding](https://github.com/asyncapi/bindings/blob/master/amqp1#server) | Protocol-specific information for an AMQP 1.0 server.
<a name="serverBindingsObjectMQTT"></a>`mqtt` | [MQTT Server Binding](https://github.com/asyncapi/bindings/blob/master/mqtt#server) | Protocol-specific information for an MQTT server.
<a name="serverBindingsObjectMQTT5"></a>`mqtt5` | [MQTT 5 Server Binding](https://github.com/asyncapi/bindings/blob/master/mqtt5#server) | Protocol-specific information for an MQTT 5 server.
<a name="serverBindingsObjectNATS"></a>`nats` | [NATS Server Binding](https://github.com/asyncapi/bindings/blob/master/nats#server) | Protocol-specific information for a NATS server.
<a name="serverBindingsObjectJMS"></a>`jms` | [JMS Server Binding](https://github.com/asyncapi/bindings/blob/master/jms#server) | Protocol-specific information for a JMS server.
<a name="serverBindingsObjectSNS"></a>`sns` | [SNS Server Binding](https://github.com/asyncapi/bindings/blob/master/sns#server) | Protocol-specific information for an SNS server.
<a name="serverBindingsObjectSQS"></a>`sqs` | [SQS Server Binding](https://github.com/asyncapi/bindings/blob/master/sqs#server) | Protocol-specific information for an SQS server.
<a name="serverBindingsObjectSTOMP"></a>`stomp` | [STOMP Server Binding](https://github.com/asyncapi/bindings/blob/master/stomp#server) | Protocol-specific information for a STOMP server.
<a name="serverBindingsObjectRedis"></a>`redis` | [Redis Server Binding](https://github.com/asyncapi/bindings/blob/master/redis#server) | Protocol-specific information for a Redis server.
<a name="serverBindingsObjectMercure"></a>`mercure` | [Mercure Server Binding](https://github.com/asyncapi/bindings/blob/master/mercure#server) | Protocol-specific information for a Mercure server.
<a name="serverBindingsObjectIBMMQ"></a>`ibmmq` | [IBM MQ Server Binding](https://github.com/asyncapi/bindings/blob/master/ibmmq#server-binding-object) | Protocol-specific information for an IBM MQ server.
This object can be extended with [Specification Extensions](#specificationExtensions).
#### <a name="channelBindingsObject"></a>Channel Bindings Object
Map describing protocol-specific definitions for a channel.
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="channelBindingsObjectHTTP"></a>`http` | [HTTP Channel Binding](https://github.com/asyncapi/bindings/blob/master/http/README.md#channel) | Protocol-specific information for an HTTP channel.
<a name="channelBindingsObjectWebSockets"></a>`ws` | [WebSockets Channel Binding](https://github.com/asyncapi/bindings/blob/master/websockets/README.md#channel) | Protocol-specific information for a WebSockets channel.
<a name="channelBindingsObjectKafka"></a>`kafka` | [Kafka Channel Binding](https://github.com/asyncapi/bindings/blob/master/kafka/README.md#channel) | Protocol-specific information for a Kafka channel.
<a name="channelBindingsObjectAMQP"></a>`amqp` | [AMQP Channel Binding](https://github.com/asyncapi/bindings/blob/master/amqp/README.md#channel) | Protocol-specific information for an AMQP 0-9-1 channel.
<a name="channelBindingsObjectAMQP1"></a>`amqp1` | [AMQP 1.0 Channel Binding](https://github.com/asyncapi/bindings/blob/master/amqp1/README.md#channel) | Protocol-specific information for an AMQP 1.0 channel.
<a name="channelBindingsObjectMQTT"></a>`mqtt` | [MQTT Channel Binding](https://github.com/asyncapi/bindings/blob/master/mqtt/README.md#channel) | Protocol-specific information for an MQTT channel.
<a name="channelBindingsObjectMQTT5"></a>`mqtt5` | [MQTT 5 Channel Binding](https://github.com/asyncapi/bindings/blob/master/mqtt5#channel) | Protocol-specific information for an MQTT 5 channel.
<a name="channelBindingsObjectNATS"></a>`nats` | [NATS Channel Binding](https://github.com/asyncapi/bindings/blob/master/nats/README.md#channel) | Protocol-specific information for a NATS channel.
<a name="channelBindingsObjectJMS"></a>`jms` | [JMS Channel Binding](https://github.com/asyncapi/bindings/blob/master/jms/README.md#channel) | Protocol-specific information for a JMS channel.
<a name="channelBindingsObjectSNS"></a>`sns` | [SNS Channel Binding](https://github.com/asyncapi/bindings/blob/master/sns/README.md#channel) | Protocol-specific information for an SNS channel.
<a name="channelBindingsObjectSQS"></a>`sqs` | [SQS Channel Binding](https://github.com/asyncapi/bindings/blob/master/sqs/README.md#channel) | Protocol-specific information for an SQS channel.
<a name="channelBindingsObjectSTOMP"></a>`stomp` | [STOMP Channel Binding](https://github.com/asyncapi/bindings/blob/master/stomp/README.md#channel) | Protocol-specific information for a STOMP channel.
<a name="channelBindingsObjectRedis"></a>`redis` | [Redis Channel Binding](https://github.com/asyncapi/bindings/blob/master/redis#channel) | Protocol-specific information for a Redis channel.
<a name="channelBindingsObjectMercure"></a>`mercure` | [Mercure Channel Binding](https://github.com/asyncapi/bindings/blob/master/mercure#channel) | Protocol-specific information for a Mercure channel.
<a name="channelBindingsObjectIBMMQ"></a>`ibmmq` | [IBM MQ Channel Binding](https://github.com/asyncapi/bindings/tree/master/ibmmq#channel-binding-object) | Protocol-specific information for an IBM MQ channel.
This object can be extended with [Specification Extensions](#specificationExtensions).
#### <a name="operationBindingsObject"></a>Operation Bindings Object
Map describing protocol-specific definitions for an operation.
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="operationBindingsObjectHTTP"></a>`http` | [HTTP Operation Binding](https://github.com/asyncapi/bindings/blob/master/http/README.md#operation) | Protocol-specific information for an HTTP operation.
<a name="operationBindingsObjectWebSockets"></a>`ws` | [WebSockets Operation Binding](https://github.com/asyncapi/bindings/blob/master/websockets/README.md#operation) | Protocol-specific information for a WebSockets operation.
<a name="operationBindingsObjectKafka"></a>`kafka` | [Kafka Operation Binding](https://github.com/asyncapi/bindings/blob/master/kafka/README.md#operation) | Protocol-specific information for a Kafka operation.
<a name="operationBindingsObjectAMQP"></a>`amqp` | [AMQP Operation Binding](https://github.com/asyncapi/bindings/blob/master/amqp/README.md#operation) | Protocol-specific information for an AMQP 0-9-1 operation.
<a name="operationBindingsObjectAMQP1"></a>`amqp1` | [AMQP 1.0 Operation Binding](https://github.com/asyncapi/bindings/blob/master/amqp1/README.md#operation) | Protocol-specific information for an AMQP 1.0 operation.
<a name="operationBindingsObjectMQTT"></a>`mqtt` | [MQTT Operation Binding](https://github.com/asyncapi/bindings/blob/master/mqtt/README.md#operation) | Protocol-specific information for an MQTT operation.
<a name="operationBindingsObjectMQTT5"></a>`mqtt5` | [MQTT 5 Operation Binding](https://github.com/asyncapi/bindings/blob/master/mqtt5/README.md#operation) | Protocol-specific information for an MQTT 5 operation.
<a name="operationBindingsObjectNATS"></a>`nats` | [NATS Operation Binding](https://github.com/asyncapi/bindings/blob/master/nats/README.md#operation) | Protocol-specific information for a NATS operation.
<a name="operationBindingsObjectJMS"></a>`jms` | [JMS Operation Binding](https://github.com/asyncapi/bindings/blob/master/jms/README.md#operation) | Protocol-specific information for a JMS operation.
<a name="operationBindingsObjectSNS"></a>`sns` | [SNS Operation Binding](https://github.com/asyncapi/bindings/blob/master/sns/README.md#operation) | Protocol-specific information for an SNS operation.
<a name="operationBindingsObjectSQS"></a>`sqs` | [SQS Operation Binding](https://github.com/asyncapi/bindings/blob/master/sqs/README.md#operation) | Protocol-specific information for an SQS operation.
<a name="operationBindingsObjectSTOMP"></a>`stomp` | [STOMP Operation Binding](https://github.com/asyncapi/bindings/blob/master/stomp/README.md#operation) | Protocol-specific information for a STOMP operation.
<a name="operationBindingsObjectRedis"></a>`redis` | [Redis Operation Binding](https://github.com/asyncapi/bindings/blob/master/redis#operation) | Protocol-specific information for a Redis operation.
<a name="operationBindingsObjectMercure"></a>`mercure` | [Mercure Operation Binding](https://github.com/asyncapi/bindings/blob/master/mercure#operation) | Protocol-specific information for a Mercure operation.
This object can be extended with [Specification Extensions](#specificationExtensions).
#### <a name="messageBindingsObject"></a>Message Bindings Object
Map describing protocol-specific definitions for a message.
##### Fixed Fields
Field Name | Type | Description
---|:---:|---
<a name="messageBindingsObjectHTTP"></a>`http` | [HTTP Message Binding](https://github.com/asyncapi/bindings/blob/master/http/README.md#message) | Protocol-specific information for an HTTP message, i.e., a request or a response.
<a name="messageBindingsObjectWebSockets"></a>`ws` | [WebSockets Message Binding](https://github.com/asyncapi/bindings/blob/master/websockets/README.md#message) | Protocol-specific information for a WebSockets message.
<a name="messageBindingsObjectKafka"></a>`kafka` | [Kafka Message Binding](https://github.com/asyncapi/bindings/blob/master/kafka/README.md#message) | Protocol-specific information for a Kafka message.
<a name="messageBindingsObjectAMQP"></a>`amqp` | [AMQP Message Binding](https://github.com/asyncapi/bindings/blob/master/amqp/README.md#message) | Protocol-specific information for an AMQP 0-9-1 message.
<a name="messageBindingsObjectAMQP1"></a>`amqp1` | [AMQP 1.0 Message Binding](https://github.com/asyncapi/bindings/blob/master/amqp1/README.md#message) | Protocol-specific information for an AMQP 1.0 message.
<a name="messageBindingsObjectMQTT"></a>`mqtt` | [MQTT Message Binding](https://github.com/asyncapi/bindings/blob/master/mqtt/README.md#message) | Protocol-specific information for an MQTT message.
<a name="messageBindingsObjectMQTT5"></a>`mqtt5` | [MQTT 5 Message Binding](https://github.com/asyncapi/bindings/blob/master/mqtt5/README.md#message) | Protocol-specific information for an MQTT 5 message.
<a name="messageBindingsObjectNATS"></a>`nats` | [NATS Message Binding](https://github.com/asyncapi/bindings/blob/master/nats/README.md#message) | Protocol-specific information for a NATS message.
<a name="messageBindingsObjectJMS"></a>`jms` | [JMS Message Binding](https://github.com/asyncapi/bindings/blob/master/jms/README.md#message) | Protocol-specific information for a JMS message.
<a name="messageBindingsObjectSNS"></a>`sns` | [SNS Message Binding](https://github.com/asyncapi/bindings/blob/master/sns/README.md#message) | Protocol-specific information for an SNS message.
<a name="messageBindingsObjectSQS"></a>`sqs` | [SQS Message Binding](https://github.com/asyncapi/bindings/blob/master/sqs/README.md#message) | Protocol-specific information for an SQS message.
<a name="messageBindingsObjectSTOMP"></a>`stomp` | [STOMP Message Binding](https://github.com/asyncapi/bindings/blob/master/stomp/README.md#message) | Protocol-specific information for a STOMP message.
<a name="messageBindingsObjectRedis"></a>`redis` | [Redis Message Binding](https://github.com/asyncapi/bindings/blob/master/redis#message) | Protocol-specific information for a Redis message.
<a name="messageBindingsObjectMercure"></a>`mercure` | [Mercure Message Binding](https://github.com/asyncapi/bindings/blob/master/mercure#message) | Protocol-specific information for a Mercure message.
<a name="messageBindingsObjectIBMMQ"></a>`ibmmq` | [IBM MQ Message Binding](https://github.com/asyncapi/bindings/tree/master/ibmmq#message-binding-object) | Protocol-specific information for an IBM MQ message.
This object can be extended with [Specification Extensions](#specificationExtensions).
#### <a name="messageObject"></a>Message Object