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HTTP SEARCH Method
Individual Submission J. Reschke
Internet-Draft A. Malhotra
Intended status: Standards Track J. Snell
Expires: March 23, 2019 September 19, 2018

HTTP SEARCH Method

draft-snell-search-method–01

Abstract

This specification updates the definition and semantics of the HTTP SEARCH request method originally defined by [RFC5323].

Status of this Memo

This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work in progress”.

This Internet-Draft will expire on March 23, 2019.

Copyright Notice

Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust’s Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

1. Introduction

This specification updates the HTTP SEARCH method originally defined in [RFC5323].

Many existing HTTP-based applications use the HTTP GET and POST methods in various ways to implement the functionality provided by SEARCH.

Using a GET request with some combination of query parameters included within the request URI (as illustrated in the example below) is arguably the most common mechanism for implementing search in web applications. With this approach, implementations are required to parse the request URI into distinct path (everything before the ‘?’) and query elements (everything after the ‘?’). The path identifies the resource processing the query (in this case ‘http://example.org/feed’) while the query identifies the specific parameters of the search operation.

A typical use of HTTP GET for requesting a search

GET /feed?q=foo&limit=10&sort=-published HTTP/1.1
Host: example.org
⧉

While there are definite advantages to using GET requests in this manner, the disadvantages should not be overlooked. Specifically:

  • Without specific knowledge of the resource and server to which the GET request is being sent, there is no way for the client to know that a search operation is being requested. Identical requests sent to two different servers can implement entirely different semantics.
  • Encoding query parameters directly into the request URI effectively casts every possible combination of query inputs as distinct resources. For instance, because mechanisms such as HTTP caching handle request URIs as opaque character sequences, queries such as ‘http://example.org/?q=foo’ and ‘http://example.org/?q=Foo’ will be treated as entirely separate resources even if they yield identical results.
  • While most modern browser and server implementations allow for long request URIs, there is no standardized minimum or maximum length for URIs in general. Many resource constrained devices enforce strict limits on the maximum number of characters that can be included in a URI. Such limits can prove impractical for large or complex query parameters.
  • Query expressions included within a request URI must either be restricted to relatively simple key value pairs or encoded such that the query can be safely represented in the limited character-set allowed by URL standards. Such encoding can add significant complexity, introduce bugs, or otherwise reduce the overall visibility of the query being requested.

As an alternative to using GET, many implementations make use of the HTTP POST method to perform queries, as illustrated in the example below. In this case, the input parameters to the search operation are passed along within the request payload as opposed to using the request URI.

A typical use of HTTP GET for requesting a search

POST /feed HTTP/1.1
Host: example.org
Content-Type: application/x-www-form-urlencoded

q=foo&limit=10&sort=-published
⧉

This variation, however, suffers from the same basic limitation as GET in that it is not readily apparent — absent specific knowledge of the resource and server to which the request is being sent — that a search operation is what is being requested. Web applications use the POST method for a wide variety of uses including the creation or modification of existing resources. Sending the request above to a different server, or even repeatedly sending the request to the same server could have dramatically different effects.

The SEARCH method provides a solution that spans the gap between the use of GET and POST. As with POST, the input to the query operation is passed along within the payload of the request rather than as part of the request URI. Unlike POST, however the semantics of the SEARCH method are specifically defined.

In this document, the key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” are to be interpreted as described in [RFC2119].

4. Examples

The non-normative examples in this section make use of a simple, hypothetical plain-text based query syntax based on SQL with results returned as comma-separated values. This is done for illustration purposes only. Implementations are free to use any format they wish on both the request and response.

4.1. Simple SEARCH with a Direct Response

A simple query with a direct response:

  SEARCH /contacts HTTP/1.1
  Host: example.org
  Content-Type: text/query
  Accept: text/csv

  select surname, givenname, email limit 10
⧉

Response:

  HTTP/1.1 200 OK
  Content-Type: text/csv

  surname, givenname, email
  Smith, John, john.smith@example.org
  Jones, Sally, sally.jones@example.com
  Dubois, Camille, camille.dubois@example.net
⧉

4.2. Simple SEARCH with indirect response (303 See Other)

A simple query with an Indirect Response (303 See Other)

  SEARCH /contacts HTTP/1.1
  Host: example.org
  Content-Type: text/query
  Accept: text/csv

  select surname, givenname, email limit 10
⧉

Response:

  HTTP/1.1 303 See Other
  Location: http://example.org/contacts/query123
⧉

Fetch Query Response:

  GET /contacts/query123 HTTP/1.1
  Host: example.org
⧉

Response:

  HTTP/1.1 200 OK
  Content-Type: text/csv

  surname, givenname, email
  Smith, John, john.smith@example.org
  Jones, Sally, sally.jones@example.com
  Dubois, Camille, camille.dubois@example.net
⧉

5. Security Considerations

The SEARCH method is subject to the same general security considerations as all HTTP methods as described in [RFC7231].

6. IANA Considerations

IANA is requested to update the registration of the SEARCH method in the permanent registry at <http://www.iana.org/assignments/http-methods> (see Section 8.1 of [RFC7231]).

Method Name Safe Idempotent Specification
SEARCH Yes Yes Section 2

Authors’ Addresses

Julian Reschke
EMail: julian.reschke@greenbytes.de
Ashok Malhotra
EMail: ashok.malhotra@oracle.com
James M Snell
EMail: jasnell@gmail.com