Internet DRAFT - draft-ietf-httpbis-safe-method-w-body
draft-ietf-httpbis-safe-method-w-body
HTTP J. Reschke
Internet-Draft greenbytes
Intended status: Standards Track A. Malhotra
Expires: 5 January 2023
J.M. Snell
4 July 2022
The HTTP QUERY Method
draft-ietf-httpbis-safe-method-w-body-03
Abstract
This specification defines a new HTTP method, QUERY, as a safe,
idempotent request method 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 (ietf-http-wg@w3.org), which is archived at
https://lists.w3.org/Archives/Public/ietf-http-wg/.
Working Group information can be found at https://httpwg.org/; source
code and issues list for this draft can be found at
https://github.com/httpwg/http-extensions/labels/safe-method-w-body.
The changes in this draft are summarized in Appendix A.3.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on 5 January 2023.
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Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. QUERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Caching . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. The "Accept-Query" Header Field . . . . . . . . . . . . . . . 5
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Simple QUERY with a Direct Response . . . . . . . . . . . 5
4.2. Simple QUERY with indirect response (303 See Other) . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Normative References . . . . . . . . . . . . . . . . . . . . 7
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 7
A.1. Since draft-ietf-httpbis-safe-method-w-body-00 . . . . . 7
A.2. Since draft-ietf-httpbis-safe-method-w-body-01 . . . . . 8
A.3. Since draft-ietf-httpbis-safe-method-w-body-02 . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
This specification defines the HTTP QUERY request method as a means
of making a safe, idempotent request that contains content.
Most often, this is desirable when the data conveyed in a request is
too voluminous to be encoded into the request's URI. For example,
while this is an common and interoperable query:
GET /feed?q=foo&limit=10&sort=-published HTTP/1.1
Host: example.org
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if the query parameters extend to several kilobytes or more of data
it may not be, because many implementations place limits on their
size. Often these limits are not known or discoverable ahead of
time, because a request can pass through many uncoordinated systems.
Additionally, expressing some data in the target URI is inefficient,
because it needs to be encoded to be a valid URI.
Encoding query parameters directly into the request URI also
effectively casts every possible combination of query inputs as
distinct resources. Depending on the application, that may not be
desirable.
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 content as opposed to using the
request URI.
A typical use of HTTP POST 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 safe, idempotent query is being performed.
The 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 content of the request rather than as part
of the request URI. Unlike POST, however, the method is explicitly
safe and idempotent, allowing functions like caching and automatic
retries to operate.
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.
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2. QUERY
The QUERY method is used to initiate a server-side 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 [HTTP]), the QUERY method is used to ask the server to
perform a query operation (described by the request content) over
some set of data scoped to the effective request URI. The content
returned in response to a QUERY cannot be assumed to be a
representation of the resource identified by the effective request
URI.
The content of the request defines the query. Implementations MAY
use a request content of any media type with the QUERY method,
provided that it has appropriate query semantics.
QUERY requests are both safe and idempotent with regards to the
resource identified by the request URI. That is, QUERY requests do
not alter the state of the targeted resource. However, while
processing a 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 QUERY request is expected to provide some
indication as to the final disposition of the operation. For
instance, a successful query that yields no results can be
represented by a 204 No Content response. If the response includes
content, it is expected to describe the results of the operation. In
some cases, the server may choose to respond indirectly to the QUERY
request by returning a 3xx Redirection with a Location header field
specifying an alternate Request URI from which the results can be
retrieved using an HTTP GET request. Various non-normative examples
of successful QUERY responses are illustrated in Section 4.
The semantics of the QUERY method change to a "conditional QUERY" if
the request message includes an If-Modified-Since, If-Unmodified-
Since, If-Match, If-None-Match, or If-Range header field ([HTTP],
Section 13). A conditional 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
[HTTP-CACHING]).
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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-Query" Header Field
The "Accept-Query" response header field MAY be used by a server to
directly signal support for the QUERY method while identifying the
specific query format media type(s) that may be used.
Accept-Query = 1#media-type
The Accept-Query header field specifies a comma-separated listing of
media types (with optional parameters) as defined by Section 8.3.1 of
[HTTP].
The order of types listed by the Accept-Query header field is not
significant.
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 QUERY with a Direct Response
A simple query with a direct response:
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QUERY /contacts HTTP/1.1
Host: example.org
Content-Type: example/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 QUERY with indirect response (303 See Other)
A simple query with an Indirect Response (303 See Other):
QUERY /contacts HTTP/1.1
Host: example.org
Content-Type: example/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
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5. Security Considerations
The QUERY method is subject to the same general security
considerations as all HTTP methods as described in [HTTP].
6. IANA Considerations
IANA is requested to add QUERY method in the permanent registry at
<http://www.iana.org/assignments/http-methods> (see Section 16.1.1 of
[HTTP]).
+=============+======+============+===============+
| Method Name | Safe | Idempotent | Specification |
+=============+======+============+===============+
| 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,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[HTTP] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110, June 2022,
<https://www.rfc-editor.org/rfc/rfc9110>.
[HTTP-CACHING]
Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Caching", STD 98, RFC 9111, June 2022,
<https://www.rfc-editor.org/rfc/rfc9111>.
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
* Use "example/query" media type instead of undefined "text/query"
(https://github.com/httpwg/http-extensions/issues/1450)
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* In Section 3, adjust the grammar to just define the field value
(https://github.com/httpwg/http-extensions/issues/1470)
* Update to latest HTTP core spec, and adjust terminology
accordingly (https://github.com/httpwg/http-extensions/
issues/1473)
* Reference RFC 8174 and markup bcp14 terms
(https://github.com/httpwg/http-extensions/issues/1497)
* Update HTTP reference (https://github.com/httpwg/http-extensions/
issues/1524)
* Relax restriction of generic XML media type in request content
(https://github.com/httpwg/http-extensions/issues/1535)
A.2. Since draft-ietf-httpbis-safe-method-w-body-01
* Add minimal description of cacheability
(https://github.com/httpwg/http-extensions/issues/1552)
* Use "QUERY" as method name (https://github.com/httpwg/http-
extensions/issues/1614)
* Update HTTP reference (https://github.com/httpwg/http-extensions/
issues/1669)
A.3. Since draft-ietf-httpbis-safe-method-w-body-02
* In Section 3, slightly rephrase statement about significance of
ordering (https://github.com/httpwg/http-extensions/issues/1896)
* Throughout: use "content" instead of "payload" or "body"
(https://github.com/httpwg/http-extensions/issues/1915)
* Updated references (https://github.com/httpwg/http-extensions/
issues/2157)
Authors' Addresses
Julian Reschke
greenbytes GmbH
Hafenweg 16
48155 Münster
Germany
Email: julian.reschke@greenbytes.de
URI: https://greenbytes.de/tech/webdav/
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Ashok Malhotra
Email: malhotrasahib@gmail.com
James M Snell
Email: jasnell@gmail.com
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