API Blueprint AST

Deprecation Notice

As of 2015-12-02 the API Blueprint AST is deprecated and should not be used for new development. The API Blueprint AST has been superseded by API Elements.

JSON & YAML face of the API Blueprint

API Blueprint AST is JSON or YAML, machine-friendly, face of API Blueprint suitable for use in tools consuming (or producing) API Blueprint.

This document defines serialization formats for API Blueprint abstract syntax tree, or AST for short.

For the definition of API Blueprint AST Source Map see the API Blueprint AST Source Map definition.

Converting API Blueprint to AST and its serialization is the task of API Blueprint Parser – Drafter or one of its bindings. Reverse process from AST (serialization) to API Blueprint is also possible thanks to the Matter Compiler.

Don't like to design APIs in JSON or YAML?

If you are looking for a way to describe your Web API without using JSON or YAML see API Blueprint.

Version

• Version: 4.0
• Created: 2013-08-30
• Updated: 2015-09-07

Future Development

As of version 3.0 the API Blueprint AST is in the interim transition period towards unified document-structure based on the concept of DOM elements (see the Element object). Please refrain from using AST elements marked as "deprecated".

Quick Links

• AST Description
• Media Types
• Keys description
• Example: JSON serialization
• Serialization in Drafter
• Serialized Parsing Result Media Types

AST Definition

Following is the definition of API Blueprint AST media types using the MSON syntax.

NOTE: Most of the keys corresponds to their counter parts in API Blueprint Specification. Where applicable, refer to the relevant entry API Blueprint Language Specification for details.

Blueprint (object)

• _version (string) - Version of the AST Serialization as defined in this document

• metadata (array) - Ordered array of API Blueprint metadata

  • (object)
    • name (string) - Name of the metadata
    • value (string) - Value of the metadata

• name (string) - Name of the API

• description (string) - Top-level description of the API in Markdown (.raw) or HTML (.html)

• resourceGroups (array[Resource Group]) - Deprecated

  Note this property is deprecated and will be removed in a future. Replaced by category elements of the content property.

• element: category (fixed, required)

• content (array[Element]) - Section elements of the blueprint

Element (object)

A component of an API description.

Properties

• element (enum[string]) - Element name
  • category - Element is a group of other elements
  • copy - Element is a human readable text
  • resource - Element is a Resource
  • dataStructure - Element is a Data Structure definition
  • asset - Element is an asset of API description
• attributes (object) - Element-specific attributes
  • name (string, optional) - Human readable name of the element
• content (enum)
  • (array[Element]) - Ordered array of nested elements (for element category)
  • (string) - Markdown-formatted text (for element copy and asset type)
  • (Resource) - Resource definiton (for element resource)
  • (Data Structure) - Data structure (for element dataStructure)

Resource Group (object)

Deprecated, replaced by the category Element.

Logical group of resources.

Properties

• name (string) - Name of the Resource Group
• description (string) - Description of the Resource Group (.raw or .html)
• resources (array[Resource]) - Ordered array of the respective resources belonging to the Resource Group

Resource (object)

Description of one resource, or a cluster of resources defined by its URI template.

Properties

• name (string) - Name of the Resource

• description (string) - Description of the Resource (.raw or .html)

• element: resource (fixed, required)

• uriTemplate (string) - URI Template as defined in RFC6570

• model (Payload) - Resource Model, a reusable payload representing the resource

• parameters (array[Parameter]) - Ordered array of URI parameters

• actions (array[Action]) - Ordered array of actions available on the resource each defining at least one complete HTTP transaction

• content (array[Data Structure]) - Array of Resource's elements

  In the interim period this may contain at maximum one element of the dataStructure type - the definition of the of the Resource attributes.

Action (object)

An HTTP transaction (a request-response transaction). Actions are specified by an HTTP request method within a resource.

Properties

• name (string) - Name of the Action

• description (string) - Description of the Action (.raw or .html)

• method (string) - HTTP request method defining the action

• parameters (array[Parameter]) - Ordered array of resource's URI parameters descriptions specific to this action

• examples (array[Transaction Example]) - Ordered array of HTTP transaction examples for the relevant HTTP request method

• attributes (object) - Action-specific attributes

  • uriTemplate (string) - URI Template as defined in RFC6570
  • relation (string) - Link relation identifier of the action as defined in Relation section

• content (array[Data Structure]) - Array of Action's elements

  In the interim period this may contain at maximum one element of the dataStructure type - the definition of the of the action input attributes.

Payload (object)

An API Blueprint payload.

Properties

• name (string) - Name of the payload

  The content of this key depends on the type of payload:

  • model payload: name of the resource, if any
  • request payload: name of the request, if any
  • response payload: HTTP status code

• reference (Reference) - Present if and only if a reference to a Resource Model is present in the payload and it has been resolved correctly

• description (string) - Description of the payload (.raw or .html)

• headers (array[[Header][]]) - Ordered array of HTTP headers that are expected to be transferred with HTTP message represented by this payload

• body (string) - Deprecated

  An entity body to be transferred with HTTP message represented by this payload

  Note this property is deprecated and will be removed in a future. Replaced by bodyExample Asset element.

• schema (string) - Deprecated

  A validation schema for the entity body as defined in body.

  Note this property is deprecated and will be removed in a future. Replaced by bodySchema asset element.

• content (array) - Array of Payloads's elements

  In the interim period this may contain only:

  • At maximum one element of the dataStructure type - the definition of the message-body attributes

  • Up to two asset elements one for body example other for body schema

  • Items

    • (Data Structure)
    • (Asset)

Header

A HTTP header that are expected to be transferred with an HTTP message.

Properties

• name (string, required) - The name of the header
• value (string, required) - The value of the header

Asset (Element)

An API Blueprint asset. The content is an Asset in its textual representation as written in the source API Blueprint.

Properties

• element: asset (fixed, required)
• attributes
  • role - Role of the asset
    • bodyExample - Asset is an example of message-body
    • bodySchema - Asset is an schema for message-body

Parameter (object)

Description of one URI template parameter.

Properties

• name (string) - Name of the parameter
• description (string) - Description of the parameter (.raw or .html)
• type (string) - An arbitrary type of the parameter (a string)
• required (boolean) - Boolean flag denoting whether the parameter is required (true) or not (false)
• default (string) - A default value of the parameter (a value assumed when the parameter is not specified)
• example (string) - An example value of the parameter
• values (array) - An array enumerating possible parameter values
  • (object)
    • value (string) - Value choice of for the parameter

Transaction Example (object)

An HTTP transaction example with expected HTTP message request and response payload(s).

Properties

• name (string) - Name of the Transaction Example
• description (string) - Description of the Transaction Example (.raw or .html)
• requests (array[Payload]) - Ordered array of example transaction request payloads
• responses (array[Payload]) - Ordered array of example transaction response payloads

Reference (object)

A reference object which is used whenever there is a reference to a Resource Model.

Properties

• id (string) - The identifier (name) of the reference

Media Types

The application/vnd.apiblueprint.ast is the media type for API Blueprint AST. The media type serialization format is specified in the +<serialization format> appendix.

Serialization formats

Two supported, feature-equal serialization formats are JSON and YAML:

• application/vnd.apiblueprint.ast.json
• application/vnd.apiblueprint.ast.yaml

Example: JSON Serialization

application/vnd.apiblueprint.ast.json; version=4.0

{
  "_version": "<AST version>",
  "metadata": [
    {
      "name": "<metadata key name>",
      "value": "<metadata value>"
    }
  ],
  "name": "<API name>",
  "description": "<API description>",
  "element": "category",
  "content": [
    {
      "element": "category",
      "attributes": {
        "name": "<resource group name>"
      },
      "content": [
        {
          "element": "copy",
          "content": "<resource group description>"
        },
        {
          "name": "<resource name>",
          "description": "<resource description>",
          "element": "resource",
          "uriTemplate": "<resource URI template>",
          "model": {
            "name": "<resource model name>",
            "description": "<resource model description>",
            "headers": [
              {
                "name": "<HTTP header field name>",
                "value": "<HTTP header field value>"
              }
            ],
            "content": [
              {
                "element": "dataStructure",
                "content":{
                  "element": "object",
                  "meta": {
                    "ref": "<sub-type>"
                  },
                  "content": []
                }
              },
              {
                "element": "asset",
                "attributes":  {
                  "role": "bodyExample"
                },
                "content": "<resource model body>"
              },
              {
                "element": "asset",
                "attributes":  {
                  "role": "bodySchema"
                },
                "content": "<resource model schema>"
              }
            ]
          },
          "parameters": [
            {
              "name": "<name>",
              "description": "<description>",
              "type": "<type>",
              "required": "<required parameter flag>",
              "default": "<default value>",
              "example": "<example value>",
              "values": [
                {
                  "value": "<enum element>"
                }
              ]
            }
          ],
          "actions": [
            {
              "name": "<action name>",
              "description": "<action description>",
              "method": "<action HTTP request method>",
              "parameters": [
                {
                  "name": "<name>",
                  "description": "<description>",
                  "type": "<type>",
                  "required": "<required parameter flag>",
                  "default": "<default value>",
                  "example": "<example value>",
                  "values": [
                    {
                      "value": "<enum element>"
                    }
                  ]
                }
              ],
              "examples": [
                {
                  "name": "<transaction example name>",
                  "description": "<transaction example description>",
                  "requests": [
                    {
                      "name": "<request name>",
                      "description": "<request description>",
                      "headers": [
                        {
                          "name": "<HTTP header field name>",
                          "value": "<HTTP header field value>"
                        }
                      ],
                      "content": [
                        {
                          "element": "dataStructure",
                          "content": {
                            "element": "object",
                            "meta": {
                              "ref": "<sub-type>"
                            },
                            "content": []
                          }
                        },
                        {
                          "element": "asset",
                          "attributes": {
                            "role": "bodyExample"
                          },
                          "content": "<request body>"
                        },
                        {
                          "element": "asset",
                          "attributes": {
                            "role": "bodySchema"
                          },
                          "content": "<request schema>"
                        }
                      ]
                    }
                  ],
                  "responses": [
                    {
                      "name": "<response HTTP status code>",
                      "description": "<response description>",
                      "headers": [
                        {
                          "name": "<HTTP header field name>",
                          "value": "<HTTP header field value>"
                        }
                      ],
                      "content": [
                        {
                          "element": "dataStructure",
                          "content": {
                            "element": "object",
                            "meta": {
                              "ref": "<sub-type>"
                            },
                            "content": []
                          }
                        },
                        {
                          "element": "asset",
                          "attributes": {
                            "role": "bodyExample"
                          },
                          "content": "<request body>"
                        },
                        {
                          "element": "asset",
                          "attributes": {
                            "role": "bodySchema"
                          },
                          "content": "<request schema>"
                        }
                      ]
                    }
                  ]
                }
              ],
              "content": [
                {
                  "element": "dataStructure",
                  "content": {
                    "element": "object",
                    "meta": {
                      "ref": "<sub-type>"
                    },
                    "content": []
                  }
                }
              ]
            },
            {
              "name": "<action name>",
              "description": "<action description>",
              "method": "<action HTTP request method>",
              "parameters": [],
              "examples": [
                {
                  "name": "<transaction example name>",
                  "description": "<transaction example description>",
                  "responses": [
                    {
                      "name": "<response HTTP status code>",
                      "reference": {
                        "id": "<resource model name>"
                      },
                      "description": "<resource model description>",
                      "headers": [
                        {
                          "name": "<HTTP header field name>",
                          "value": "<HTTP header field value>"
                        }
                      ],
                      "content": [
                        {
                          "element": "asset",
                          "attributes": {
                            "role": "bodyExample"
                          },
                          "content": "<resource model body>"
                        },
                        {
                          "element": "asset",
                          "attributes": {
                            "role": "bodySchema"
                          },
                          "content": "<resource model schema>"
                        }
                      ]
                    }
                  ]
                }
              ]
            }
          ],
          "content": [
            {
              "element": "dataStructure",
              "content": {
                "element": "object",
                "meta": {
                  "id": "<resource-name>",
                  "ref": "<sub-type>"
                },
                "content": []
              }
            }
          ]
        }
      ]
    },
    {
      "element": "category",
      "content": [
        {
          "element": "dataStructure",
          "content": {
            "element": "object",
            "meta": {
              "id": "<data-structure-name>",
              "ref": "<sub-type>"
            },
            "content": []
          }
        }
      ]
    }
  ]
}

Related Media Types

• Serialized Parsing Result Media Types - Media types for the serialization of complete parsing results (including warnings and errors)

Serialization in Drafter

The drafter command-line tool supports serialization of API Blueprint AST via the --format option. Similarly, it also supports serialization of API Blueprint Source Map using the --format and --sourcemap option.

License

MIT License. See the LICENSE file.