One document matched: draft-snell-search-method-00.xml

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<rfc category="std" ipr="trust200811" docName="draft-snell-search-method-00">
  <front>
    <title abbrev="HTTP SEARCH Method">
      HTTP SEARCH Method
    </title>

    <author initials="J." surname="Reschke" fullname="Julian Reschke">
      <address>
        <email>julian.reschke@greenbytes.de</email>
      </address>
    </author>
    <author initials="A." surname="Malhotra" fullname="Ashok Malhotra">
      <address>
        <email>ashok.malhotra@oracle.com</email>
      </address>
    </author>
     <author initials="J.M." surname="Snell" fullname="James M Snell">
      <address>
        <email>jasnell@gmail.com</email>
      </address>
    </author>

    <date month="April" year="2015" />

    <area>Applications</area>
    <workgroup>Individual Submission</workgroup>
    <keyword>I-D</keyword>
    <keyword>http</keyword>
    <keyword>search</keyword>
    <keyword>method</keyword>

    <abstract>
      <t>
        This specification updates the definition and semantics of the
        HTTP SEARCH request method previously defined by <xref target="RFC5323" />.
      </t>
    </abstract>

  </front>

  <middle>

  <section anchor="intro" title="Introduction">

    <t>
      This specification updates the HTTP SEARCH method originally
      defined in <xref target="RFC5323"/>.
    </t>

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

    <t>
      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.
    </t>

<figure><preamble>A typical use of HTTP GET for requesting a search</preamble>
<artwork><![CDATA[
GET /feed?q=foo&limit=10&sort=-published HTTP/1.1
Host: example.org
]]></artwork></figure>

    <t>
      While there are definite advantages to using GET requests in this manner,
      the disadvantages should not be overlooked. Specifically:
      <list style="symbols">
        <t>
          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.
        </t>
        <t>
          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.
        </t>
        <t>
          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.
        </t>
        <t>
          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.
        </t>
      </list>
    </t>

    <t>
      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.
    </t>

<figure><preamble>A typical use of HTTP GET for requesting a search</preamble>
<artwork><![CDATA[
POST /feed HTTP/1.1
Host: example.org
Content-Type: application/x-www-form-urlencoded

q=foo&limit=10&sort=-published
]]></artwork></figure>

    <t>
      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.
    </t>

    <t>
      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.
    </t>

    <t>
      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 <xref target="RFC2119" />.
    </t>

  </section>

  <section title="SEARCH" anchor="search">

    <t>
      The SEARCH method is used to initiate a server-side search. Unlike
      the HTTP GET method, which requests that a server return a
      representation of the resource identified by the effective
      request URI (as defined by <xref target="RFC7230"/>), the SEARCH
      method is used by a client 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 cannot be assumed to be a representation of the resource
      identified by the effective request URI.
    </t>

    <t>
      The body 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 that use the text/xml or application/xml content types
      MUST be processed in exact accordance with the requirements established by
      <xref target="RFC5323" />.
    </t>

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

    <t>
      A successful response to a SEARCH request is expected to provide some
      indication as to the final disposition of the search operation. For instance,
      a successful search that yields no results can be represented by a 204 No Content
      response. If the response includes a body payload, the payload is expected
      to describe the results of the search operation. In some cases, the search
      arbiter might choose to respond indirectly to the SEARCH request by returning
      a 3xx Redirection with a Location header specifying an alternate Request URI
      from which the search results can be retrieved by using an HTTP GET request.
      Various non-normative examples of successful SEARCH responses are illustrated
      in <xref target="examples" />.
    </t>

    <t>
      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.
    </t>

    <t>
      The semantics of the SEARCH method change to a "conditional SEARCH" if
      the request message includes an If-Modified-Since, If-Unmodified-
      Since, If-Match, If-None-Match, or If-Range header field
      (<xref target="RFC7232"/>).  A conditional
      SEARCH 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.
    </t>

  </section>

  <section title="The "Accept-Search" Header Field" anchor="accept-search">
    <t>
      The "Accept-Search" response header field MAY be used by servers to
      directly signal support for the SEARCH method while identifying
      the specific query format Content-Type's that can be used.
    </t>

<figure><preamble></preamble><artwork><![CDATA[
Accept-Search = "Accept-Search" ":" 1#media-type
]]></artwork></figure>

    <t>
      The Accept-Search header specifies a comma-separated listing of media
      types (with optional parameters) as defined by <xref target="RFC7231"/>,
      Section 3.1.1.1.
    </t>

  </section>

  <section title="Examples" anchor="examples">

    <t>
      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.
    </t>

    <section title="Simple SEARCH with a Direct Response">
<figure><preamble>A simple SPAQRL query with a Direct Response:</preamble><artwork><![CDATA[
  SEARCH /contacts HTTP/1.1
  Host: example.org
  Content-Type: text/query
  Accept: text/csv

  select surname, givenname, email limit 10
]]></artwork></figure>

<figure><preamble>Response:</preamble><artwork><![CDATA[
  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
]]></artwork></figure>

    </section>

    <section title="Simple SEARCH with Indirect Response (303 See Other)">
<figure><preamble>A simple SPAQRL query with an Indirect Response (303 See Other)</preamble><artwork><![CDATA[
  SEARCH /contacts HTTP/1.1
  Host: example.org
  Content-Type: text/query
  Accept: text/csv

  select surname, givenname, email limit 10
]]></artwork></figure>

<figure><preamble>Response:</preamble><artwork><![CDATA[
  HTTP/1.1 303 See Other
  Location: http://example.org/contacts/query123
]]></artwork></figure>

<figure><preamble>Fetch Query Response:</preamble><artwork><![CDATA[
  GET /contacts/query123 HTTP/1.1
  Host: example.org
]]></artwork></figure>

<figure><preamble>Response:</preamble><artwork><![CDATA[
  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
]]></artwork></figure>

    </section>

  </section>

  <section title="Security Considerations">
    <t>
      The SEARCH method is subject to the same general security
      considerations as all HTTP methods as described in
      <xref target="RFC7231"/>.
    </t>
  </section>

  <section title="IANA Considerations">

    <t>
      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 <xref target="RFC7231" />).
    </t>

    <texttable>
      <ttcol>Method Name</ttcol>
      <ttcol>Safe</ttcol>
      <ttcol>Idempotent</ttcol>
      <ttcol>Specification</ttcol>

      <c>SEARCH</c>
      <c>Yes</c>
      <c>Yes</c>
      <c><xref target="search"/></c>

    </texttable>

  </section>

</middle>
<back>
  <references title="Normative References">
    &rfc2119;
    &rfc5323;
    &rfc4918;
    &part1;
    &part2;
    &part4;
    &part6;
  </references>
</back>
</rfc>