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Working draft of "GraphQL over HTTP" specification
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README.md

Stage 1: Proposal

This spec is under active development. For more information, please see the Roadmap or how to get involved.


GraphQL over HTTP

Introduction

HTTP is the most common choice as the client-server protocol when using GraphQL because of its ubiquity. However the GraphQL specification deliberately does not specify the transport layer.

The closest thing to an official specification is the article Serving over HTTP. Leading implementations on both client and server have mostly upheld those best practices and thus established a de-facto standard that is commonly used throughout the ecosystem.

This specification is intended to fill this gap by specifying how GraphQL should be served over HTTP. The main intention of this specification is to provide interoperability between different client libraries, tools and server implementations.

Copyright notice

TBD

Conformance

A conforming implementation of GraphQL over HTTP must fulfill all normative requirements. Conformance requirements are described in this document via both descriptive assertions and key words with clearly defined meanings.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the normative portions of this document are to be interpreted as described in IETF RFC 2119. These key words may appear in lowercase and still retain their meaning unless explicitly declared as non-normative.

A conforming implementation of GraphQL over HTTP may provide additional functionality, but must not where explicitly disallowed or it would otherwise result in non-conformance.

Non-Normative Portions

All contents of this document are normative except portions explicitly declared as non-normative.

Examples in this document are non-normative, and are presented to aid understanding of introduced concepts and the behavior of normative portions of the specification. Examples are either introduced explicitly in prose (e.g. "for example") or are set apart in example or counter-example blocks, like this:

This is an example of a non-normative example.
This is an example of a non-normative counter-example.

Notes in this document are non-normative, and are presented to clarify intent, draw attention to potential edge-cases and pit-falls, and answer common questions that arise during implementation. Notes are either introduced explicitly in prose (e.g. "Note: ") or are set apart in a note block, like this:

Note: This is an example of a non-normative note.

Overview

Serving GraphQL over HTTP provides the ability to use the full advantages of GraphQL with the rich feature set of HTTP. Carrying GraphQL in HTTP does not mean that GraphQL overrides existing semantics of HTTP but rather that the semantics of GraphQL over HTTP map naturally to HTTP semantics.

GraphQL naturally follows the HTTP request/response message model providing a GraphQL request in an HTTP request and GraphQL response in an HTTP response.

URL

A GraphQL server operates on a single URL and all GraphQL requests for a given service should be directed at this URL. Other protocols may also use that URL.

It is recommended to end the path component of the URL with /graphql, for example: http://example.com/graphql or http://example.com/product/graphql.

Serialization Format

Similar to the GraphQL specification this specification does not require a specific serialization format. For consistency and ease of notation, examples of the response are given in JSON throughout the spec.

Request

The GraphQL HTTP server SHOULD handle the HTTP GET and POST methods. Additionally, GraphQL MAY be used in combination with other HTTP request methods.

Request Parameters

A request for execution should contain the following request parameters:

  • query - A Document containing GraphQL Operations and Fragments to execute.
  • operationName - [Optional]: The name of the Operation in the Document to execute.
  • variables - [Optional]: Values for any Variables defined by the Operation.

Note: depending on the serialization format used, values of the aforementioned parameters can be encoded differently but their names and semantics must stay the same.

Note: specifying null in JSON (or equivalent values in other formats) as values for optional request parameters is equivalent to not specifying them at all.

GET

For HTTP GET requests, the query parameters should be provided in the query component of the request URL in the form of key=value pairs with & symbol as a separator and both the key and value should have their "reserved" characters percent-encoded as specified in section 2 of RFC3986. The unencoded value of the variables parameter should be represented as a JSON-encoded string.

GET requests can be used for executing ONLY queries. If the values of query and operationName indicates that a non-query operation is to be executed, the server should immediately respond with an error status code, and halt execution.

For example, if we wanted to execute the following GraphQL query:

query ($id: ID!) {
  user(id:$id) {
    name
  }
}

With the following query variables:

{
  id:"QVBJcy5ndXJ1"
}

This request could be sent via an HTTP GET as follows:

http://example.com/graphql?query=query(%24id%3A%20ID!)%7Buser(id%3A%24id)%7Bname%7D%7D&variables=%7B%22id%22%3A%22QVBJcy5ndXJ1%22%7D

Note: query and operationName parameters are encoded as raw strings in the query component. Therefore if the query string contained operationName=null then it should be interpreted as the operationName being the string "null". If a literal null is desired, the parameter (e.g. operationName) should be omitted.

POST

A standard GraphQL POST request should have a body which contains values of the request parameters encoded according to the value of Content-Type header.

For example if the Content-Type is application/json then the request body may be:

{
  "query": "query($id: ID!){user(id:$id){name}}",
  "variables": { "id": "QVBJcy5ndXJ1" }
}

Note: both query and mutation operations can be sent over POST requests.

Response

When a GraphQL server receives a request, it must return a well‐formed response. The server’s response describes the result of executing the requested operation if successful, and describes any errors encountered during the request.

Body

If the server's response contains a body it should follow the requirements for GraphQL response.

Note: For any non-2XX response, the client should not rely on the body to be in GraphQL format since the source of the response may not be the GraphQL server but instead some intermediary such as API gateways, firewalls, etc.

Status Codes

If the data entry in the response has any value other than null (when the operation has successfully executed without error) then the response should use the 200 (OK) status code. If the operation failed before or during execution, due to a syntax error, missing information, validation error or any other reason, then response should use the 4XX or 5XX status codes. It is recommended to use the same error codes as the reference implementation.

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