Internet-Draft HTTP SEARCH Method June 2021
Reschke, et al. Expires 10 December 2021 [Page]
5323 (if approved)
Intended Status:
Standards Track
J. Reschke
A. Malhotra
J.M. Snell



This specification updates the definition and semantics of the HTTP SEARCH request method originally defined by RFC 5323.

Editorial Note

This note is to be removed before publishing as an RFC.

Discussion of this draft takes place on the HTTP working group mailing list (, which is archived at

Working Group information can be found at; source code and issues list for this draft can be found at

The changes in this draft are summarized in Appendix A.1.

Status of This Memo

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

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This Internet-Draft will expire on 10 December 2021.

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 '') 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

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 '' and '' 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 POST for requesting a search

POST /feed HTTP/1.1
Content-Type: application/x-www-form-urlencoded


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.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

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
Content-Type: example/query
Accept: text/csv

select surname, givenname, email limit 10


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

surname, givenname, email
Smith, John,
Jones, Sally,
Dubois, Camille,

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
Content-Type: example/query
Accept: text/csv

select surname, givenname, email limit 10


HTTP/1.1 303 See Other

Fetch Query Response:

GET /contacts/query123 HTTP/1.1


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

surname, givenname, email
Smith, John,
Jones, Sally,
Dubois, Camille,

5. Security Considerations

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

6. IANA Considerations

IANA is requested to update the registration of the SEARCH method in the permanent registry at <> (see Section 16.1.1 of [RFCHTTP]).

Table 1
Method Name Safe Idempotent Specification
SEARCH Yes Yes Section 2

7. Normative References

Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Reschke, J., Ed., Reddy, S., Davis, J., and A. Babich, "Web Distributed Authoring and Versioning (WebDAV) SEARCH", RFC 5323, DOI 10.17487/RFC5323, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.
Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., "HTTP Semantics", Work in Progress, Internet-Draft, draft-ietf-httpbis-semantics-16, , <>.
Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth Edition)", W3C Recommendation REC-xml-20081126, , <>. Latest version available at
Bray, T., Hollander, D., Layman, A., Tobin, R., and H. Thompson, "Namespaces in XML 1.0 (Third Edition)", W3C Recommendation REC-xml-names-20091208, , <>. Latest version available at

Appendix A. Change Log

This section is to be removed before publishing as an RFC.


A.1. Since draft-ietf-httpbis-safe-method-w-body-00

Authors' Addresses

Julian Reschke
greenbytes GmbH
Hafenweg 16
48155 Münster
Ashok Malhotra
James M Snell