HTTP                                                          J. Reschke
Internet-Draft                                                greenbytes
Updates: 5323 (if approved)                                  A. Malhotra
Intended status: Standards Track                             A. Malhotra
Expires: 10 December 2021 13 May 2022
                                                              J.M. Snell
                                                             8 June
                                                         9 November 2021

                         The HTTP SEARCH QUERY Method


   This specification updates the definition and semantics of the defines a new HTTP
   SEARCH method, QUERY, as a safe,
   idempotent request method originally defined by RFC 5323. that can carry request content.

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. A.2.

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   provisions of BCP 78 and BCP 79.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  SEARCH  QUERY . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Caching . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  The "Accept-Search" "Accept-Query" Header Field . . . . . . . . . . . . . . .   5
   4.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   6   5
     4.1.  Simple SEARCH QUERY with a Direct Response . . . . . . . . . .   6 .   5
     4.2.  Simple SEARCH QUERY with indirect response (303 See Other) . . .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .   8   7
     A.1.  Since draft-ietf-httpbis-safe-method-w-body-00  . . . . .   8
     A.2.  Since draft-ietf-httpbis-safe-method-w-body-01  . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9   8

1.  Introduction

   This specification updates defines the HTTP SEARCH QUERY request 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

   Using as a GET request with some combination means
   of query parameters
   included within the making a safe, idempotent request URI (as illustrated in the example below) that contains content.

   Most often, this is arguably desirable when the most common mechanism for implementing search data conveyed in web
   applications.  With this approach, implementations are required to
   parse the a request URI is
   too voluminous to be encoded into distinct path (everything before the '?')
   and query elements (everything after the '?').  The path identifies
   the resource processing the query (in this case '
   feed') request's URI.  For example,
   while the query identifies the specific parameters of the
   search operation.

   A typical use of HTTP GET for requesting a search this is an common and interoperable query:

   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
   if the client to know
      that a search operation is being requested.  Identical requests
      sent to two different servers can implement entirely different

   *  Encoding query parameters directly into the request URI
      effectively casts every possible combination extend to several kilobytes or more of query inputs as
      distinct resources.  For instance, data
   it may not be, 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 many implementations allow for
      long request URIs, there is no standardized minimum or maximum
      length for URIs in general.  Many resource constrained devices
      enforce strict place limits on the maximum number of characters that can
      be included in a URI.  Such their
   size.  Often these limits can prove impractical for large are not known or complex query parameters.

   *  Query expressions included within discoverable ahead of
   time, because a request can pass through many uncoordinated systems.
   Additionally, expressing some data in the target URI must either be
      restricted is inefficient,
   because it needs to relatively simple key value pairs or be encoded such
      that the query can to be safely represented in the limited character-
      set allowed by URL standards.  Such encoding can add significant
      complexity, introduce bugs, or otherwise reduce a valid URI.

   Encoding query parameters directly into the overall
      visibility request URI also
   effectively casts every possible combination of the query being requested. inputs as
   distinct resources.  Depending on the application, that may not be

   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 safe, idempotent query 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. performed.

   The SEARCH QUERY 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 however, the SEARCH method are specifically defined. is explicitly
   safe and idempotent, allowing functions like caching and automatic
   retries to operate.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "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.


   The SEARCH QUERY method is used to initiate a server-side search. query.  Unlike the
   HTTP GET method, which requests that a server return a representation
   of the resource identified by the target URI (as defined by
   Section 7.1 of [RFCHTTP]), the SEARCH QUERY method is used to ask the server
   to perform a query operation (described by the request payload) over
   some set of data scoped to the effective request URI.  The payload
   returned in response to a SEARCH QUERY cannot be assumed to be a
   representation of the resource identified by the effective request

   The body payload of the request defines the query.  Implementations
   MAY use a request body of any content type with the SEARCH method;
   however, for backwards compatibility with existing WebDAV
   implementations, SEARCH requests QUERY method,
   provided that use the text/xml or
   application/xml media types with a root element (Section 2.1 of
   [XML]) in the "DAV:" XML namespace ([XMLNS]) MUST be processed per
   the requirements established by [RFC5323].

   SEARCH it has appropriate query semantics.

   QUERY requests are both safe and idempotent with regards to the
   resource identified by the request URI.  That is, SEARCH QUERY requests do
   not alter the state of the targeted resource.  However, while
   processing a search QUERY request, a server can be expected to allocate
   computing and memory resources or even create additional HTTP
   resources through which the response can be retrieved.

   A successful response to a SEARCH QUERY request is expected to provide some
   indication as to the final disposition of the search operation.  For
   instance, a successful search query that yields no results can be
   represented by a 204 No Content response.  If the response includes a
   content, it is expected to describe the results of the search operation.  In
   some cases, the server may choose to respond indirectly to the SEARCH QUERY
   request by returning a 3xx Redirection with a Location header field
   specifying an alternate Request URI from which the search results can be
   retrieved using an HTTP GET request.  Various non-normative examples
   of successful SEARCH QUERY responses are illustrated in Section 4.

   The response to a SEARCH request is not cacheable.  It ought to be
   noted, however, that because SEARCH requests are safe and idempotent,
   responses to a SEARCH MUST NOT invalidate previously cached responses
   to other requests directed at the same effective request URI.
   // By default, that is.  We need to figure out under which conditions
   // we can make the result cacheable.

   The semantics of the SEARCH QUERY method change to a "conditional SEARCH" QUERY" if
   the request message includes an If-Modified-Since, If-Unmodified-
   Since, If-Match, If-None-Match, or If-Range header field ([RFCHTTP],
   Section 13).  A conditional SEARCH QUERY requests that the query be
   performed only under the circumstances described by the conditional
   header field(s).  It is important to note, however, that such
   conditions are evaluated against the state of the target resource
   itself as opposed to the collected results of the search operation.

2.1.  Caching

   The response to a QUERY method is cacheable; a cache MAY use it to
   satisfy subsequent QUERY requests as per Section 4 of

   The cache key for a query (see Section 2 of [HTTP-CACHING]) MUST
   incorporate the request content.  When doing so, caches SHOULD first
   normalize request content to remove semantically insignificant
   differences, thereby improving cache efficiency, by:

   *  Removing content encoding(s)

   *  Normalizing based upon knowledge of format conventions, as
      indicated by the any media type suffix in the request's Content-
      Type field (e.g., "+json")

   *  Normalizing based upon knowledge of the semantics of the content
      itself, as indicated by the request's Content-Type field.

   Note that any such normalization is performed solely for the purpose
   of generating a cache key; it does not change the request itself.

3.  The "Accept-Search" "Accept-Query" Header Field

   The "Accept-Search" "Accept-Query" response header field MAY be used by a server to
   directly signal support for the SEARCH QUERY method while identifying the
   specific query format media types type(s) that may be used.


   Accept-Query = 1#media-type

   The Accept-Search Accept-Query header field specifies a comma-separated listing of
   media types (with optional parameters) as defined by Section 8.3.1 of

   The order of types listed by the Accept-Search Accept-Query header field is

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 QUERY with a Direct Response

   A simple query with a direct response:


   QUERY /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 QUERY with indirect response (303 See Other)

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


   QUERY /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 QUERY 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 add QUERY method in the permanent registry at <
   <> (see Section 16.1.1 of

            | Method Name | Safe | Idempotent | Specification |
            | SEARCH QUERY       | Yes  | Yes        | Section 2     |

                                  Table 1

7.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC5323]  Reschke, J., Ed., Reddy, S., Davis, J., and A. Babich,
              "Web Distributed Authoring and Versioning (WebDAV)
              SEARCH", RFC 5323, DOI 10.17487/RFC5323, November 2008,

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <>.

   [RFCHTTP]  Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "HTTP Semantics", Work in Progress, Internet-Draft,
              draft-ietf-httpbis-semantics-16, 27 May
              draft-ietf-httpbis-semantics-19, 10 September 2021,

   [XML]      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, 26
              November 2008,
              <>.  Latest
              version available at

   [XMLNS]    Bray, T., Hollander, D., Layman, A., Tobin,

              Fielding, R., Ed., Nottingham, M., Ed., and H.
              Thompson, "Namespaces J. Reschke,
              Ed., "HTTP Semantics", Work in XML 1.0 (Third Edition)", W3C
              Recommendation REC-xml-names-20091208, 8 December 2009,
              Latest version available at
              names/. Progress, Internet-Draft,
              draft-ietf-httpbis-cache-19, 10 September 2021,

Appendix A.  Change Log

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

   // (see

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

   *  Use "example/query" media type instead of undefined "text/query"

   *  In Section 3, adjust the grammar to just define the field value

   *  Update to latest HTTP core spec, and adjust terminology
      accordingly (

   *  Reference RFC 8174 and markup bcp14 terms

   *  Update HTTP reference (

   *  Relax restriction of generic XML media type in request body

A.2.  Since draft-ietf-httpbis-safe-method-w-body-01

   *  Add minimal description of cacheability

   *  Use "QUERY" as method name (

   *  Update HTTP reference (

Authors' Addresses

   Julian Reschke
   greenbytes GmbH
   Hafenweg 16
   48155 M√ľnster


   Ashok Malhotra

   James M Snell