HTTP/1.1, part 2: Message SemanticsDay Software23 Corporate Plaza DR, Suite 280Newport BeachCA92660USA+1-949-706-5300+1-949-706-5305fielding@gbiv.comhttp://roy.gbiv.com/One Laptop per Child21 Oak Knoll RoadCarlisleMA01741USAjg@laptop.orghttp://www.laptop.org/Hewlett-Packard CompanyHP Labs, Large Scale Systems Group1501 Page Mill Road, MS 1177Palo AltoCA94304USAJeffMogul@acm.orgMicrosoft Corporation1 Microsoft WayRedmondWA98052USAhenrikn@microsoft.comAdobe Systems, Incorporated345 Park AveSan JoseCA95110USALMM@acm.orghttp://larry.masinter.net/Microsoft Corporation1 Microsoft WayRedmondWA98052paulle@microsoft.comWorld Wide Web ConsortiumMIT Computer Science and Artificial Intelligence LaboratoryThe Stata Center, Building 3232 Vassar StreetCambridgeMA02139USAtimbl@w3.orghttp://www.w3.org/People/Berners-Lee/World Wide Web ConsortiumW3C / ERCIM2004, rte des LuciolesSophia-AntipolisAM06902Franceylafon@w3.orghttp://www.raubacapeu.net/people/yves/greenbytes GmbHHafenweg 16MuensterNW48155Germany+49 251 2807760+49 251 2807761julian.reschke@greenbytes.dehttp://greenbytes.de/tech/webdav/HTTPbis Working Group
The Hypertext Transfer Protocol (HTTP) is an application-level
protocol for distributed, collaborative, hypermedia information
systems. HTTP has been in use by the World Wide Web global information
initiative since 1990. This document is Part 2 of the seven-part specification
that defines the protocol referred to as "HTTP/1.1" and, taken together,
obsoletes RFC 2616. Part 2 defines the semantics of HTTP messages
as expressed by request methods, request-header fields, response status codes,
and response-header fields.
Discussion of this draft should take place on the HTTPBIS working group
mailing list (ietf-http-wg@w3.org). The current issues list is
at
and related documents (including fancy diffs) can be found at
.
The changes in this draft are summarized in .
This document defines HTTP/1.1 request and response semantics. Each HTTP
message, as defined in , is in the form of either a request or
a response. An HTTP server listens on a connection for HTTP requests and
responds to each request, in the order received on that connection, with
one or more HTTP response messages. This document defines the commonly
agreed upon semantics of the HTTP uniform interface, the intentions defined
by each request method, and the various response messages that might be
expected as a result of applying that method for the requested resource.
This document is currently disorganized in order to minimize the changes
between drafts and enable reviewers to see the smaller errata changes.
The next draft will reorganize the sections to better reflect the content.
In particular, the sections will be ordered according to the typical
processing of an HTTP request message (after message parsing): resource
mapping, general header fields, methods, request modifiers, response
status, and resource metadata. The current mess reflects how widely
dispersed these topics and associated requirements had become in
.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in .
An implementation is not compliant if it fails to satisfy one or more
of the MUST or REQUIRED level requirements for the protocols it
implements. An implementation that satisfies all the MUST or REQUIRED
level and all the SHOULD level requirements for its protocols is said
to be "unconditionally compliant"; one that satisfies all the MUST
level requirements but not all the SHOULD level requirements for its
protocols is said to be "conditionally compliant."
This specification uses the ABNF syntax defined in Section 1.2 of (which
extends the syntax defined in with a list rule).
shows the collected ABNF, with the list
rule expanded.
The following core rules are included by
reference, as defined in , Appendix B.1:
ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
DIGIT (decimal 0-9), DQUOTE (double quote),
HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
OCTET (any 8-bit sequence of data), SP (space),
VCHAR (any visible USASCII character),
and WSP (whitespace).
The core rules below are defined in Section 1.2.2 of :
quoted-string =
token =
OWS =
RWS =
obs-text =
]]>
The ABNF rules below are defined in other parts:
fragment =
Host =
HTTP-date =
partial-URI =
product =
TE =
]]>
Accept-Charset =
Accept-Encoding =
Accept-Language =
]]>
If-Match =
If-Modified-Since =
If-None-Match =
If-Unmodified-Since =
]]>
If-Range =
Range =
]]>
Vary =
]]>
Proxy-Authenticate =
Proxy-Authorization =
WWW-Authenticate =
]]>
The Method token indicates the method to be performed on the
resource identified by the request-target. The method is case-sensitive.
The list of methods allowed by a resource can be specified in an
Allow header field (). The return code of the response
always notifies the client whether a method is currently allowed on a
resource, since the set of allowed methods can change dynamically. An
origin server SHOULD return the status code 405 (Method Not Allowed)
if the method is known by the origin server but not allowed for the
requested resource, and 501 (Not Implemented) if the method is
unrecognized or not implemented by the origin server. The methods GET
and HEAD MUST be supported by all general-purpose servers. All other
methods are OPTIONAL; however, if the above methods are implemented,
they MUST be implemented with the same semantics as those specified
in .
The HTTP Method Registry defines the name space for the Method token in the
Request line of an HTTP request.
Registrations MUST include the following fields:
Method Name (see )Safe ("yes" or "no", see )Pointer to specification text
Values to be added to this name space are subject to IETF review
(, Section 4.1). Any document registering
new method names should be traceable through statuses of either 'Obsoletes'
or 'Updates' to this document.
The registry itself is maintained at .
The request-header fields allow the client to pass additional
information about the request, and about the client itself, to the
server. These fields act as request modifiers, with semantics
equivalent to the parameters on a programming language method
invocation.
Request-header field names can be extended reliably only in
combination with a change in the protocol version. However, new or
experimental header fields MAY be given the semantics of request-header
fields if all parties in the communication recognize them to
be request-header fields. Unrecognized header fields are treated as
entity-header fields.
The Status-Code element is a 3-digit integer result code of the
attempt to understand and satisfy the request. The status codes listed
below are defined in .
The Reason-Phrase is intended to give a short
textual description of the Status-Code. The Status-Code is intended
for use by automata and the Reason-Phrase is intended for the human
user. The client is not required to examine or display the Reason-Phrase.
The individual values of the numeric status codes defined for
HTTP/1.1, and an example set of corresponding Reason-Phrase's, are
presented below. The reason phrases listed here are only
recommendations -- they MAY be replaced by local equivalents without
affecting the protocol.
HTTP status codes are extensible. HTTP applications are not required
to understand the meaning of all registered status codes, though such
understanding is obviously desirable. However, applications MUST
understand the class of any status code, as indicated by the first
digit, and treat any unrecognized response as being equivalent to the
x00 status code of that class, with the exception that an
unrecognized response MUST NOT be cached. For example, if an
unrecognized status code of 431 is received by the client, it can
safely assume that there was something wrong with its request and
treat the response as if it had received a 400 status code. In such
cases, user agents SHOULD present to the user the entity returned
with the response, since that entity is likely to include human-readable
information which will explain the unusual status.
The HTTP Status Code Registry defines the name space for the Status-Code
token in the Status line of an HTTP response.
Values to be added to this name space are subject to IETF review
(, Section 4.1). Any document registering
new status codes should be traceable through statuses of either 'Obsoletes'
or 'Updates' to this document.
The registry itself is maintained at .
The response-header fields allow the server to pass additional
information about the response which cannot be placed in the Status-Line.
These header fields give information about the server and about
further access to the resource identified by the request-target.
Response-header field names can be extended reliably only in
combination with a change in the protocol version. However, new or
experimental header fields MAY be given the semantics of response-header
fields if all parties in the communication recognize them to
be response-header fields. Unrecognized header fields are treated as
entity-header fields.
Request and Response messages MAY transfer an entity if not otherwise
restricted by the request method or response status code. An entity
consists of entity-header fields and an entity-body, although some
responses will only include the entity-headers. HTTP entity-body and
entity-header fields are defined in .
An entity-body is only present in a message when a message-body is
present, as described in Section 4.3 of . The entity-body is obtained
from the message-body by decoding any Transfer-Encoding that might
have been applied to ensure safe and proper transfer of the message.
The set of common methods for HTTP/1.1 is defined below. Although
this set can be expanded, additional methods cannot be assumed to
share the same semantics for separately extended clients and servers.
Implementors should be aware that the software represents the user in
their interactions over the Internet, and should be careful to allow
the user to be aware of any actions they might take which may have an
unexpected significance to themselves or others.
In particular, the convention has been established that the GET and
HEAD methods SHOULD NOT have the significance of taking an action
other than retrieval. These methods ought to be considered "safe".
This allows user agents to represent other methods, such as POST, PUT
and DELETE, in a special way, so that the user is made aware of the
fact that a possibly unsafe action is being requested.
Naturally, it is not possible to ensure that the server does not
generate side-effects as a result of performing a GET request; in
fact, some dynamic resources consider that a feature. The important
distinction here is that the user did not request the side-effects,
so therefore cannot be held accountable for them.
Methods can also have the property of "idempotence" in that (aside
from error or expiration issues) the side-effects of N > 0 identical
requests is the same as for a single request. The methods GET, HEAD,
PUT and DELETE share this property. Also, the methods OPTIONS and
TRACE SHOULD NOT have side effects, and so are inherently idempotent.
However, it is possible that a sequence of several requests is non-idempotent,
even if all of the methods executed in that sequence are
idempotent. (A sequence is idempotent if a single execution of the
entire sequence always yields a result that is not changed by a
reexecution of all, or part, of that sequence.) For example, a
sequence is non-idempotent if its result depends on a value that is
later modified in the same sequence.
A sequence that never has side effects is idempotent, by definition
(provided that no concurrent operations are being executed on the
same set of resources).
The OPTIONS method represents a request for information about the
communication options available on the request/response chain
identified by the request-target. This method allows the client to
determine the options and/or requirements associated with a resource,
or the capabilities of a server, without implying a resource action
or initiating a resource retrieval.
Responses to this method are not cacheable.
If the OPTIONS request includes an entity-body (as indicated by the
presence of Content-Length or Transfer-Encoding), then the media type
MUST be indicated by a Content-Type field. Although this
specification does not define any use for such a body, future
extensions to HTTP might use the OPTIONS body to make more detailed
queries on the server.
If the request-target is an asterisk ("*"), the OPTIONS request is
intended to apply to the server in general rather than to a specific
resource. Since a server's communication options typically depend on
the resource, the "*" request is only useful as a "ping" or "no-op"
type of method; it does nothing beyond allowing the client to test
the capabilities of the server. For example, this can be used to test
a proxy for HTTP/1.1 compliance (or lack thereof).
If the request-target is not an asterisk, the OPTIONS request applies
only to the options that are available when communicating with that
resource.
A 200 response SHOULD include any header fields that indicate
optional features implemented by the server and applicable to that
resource (e.g., Allow), possibly including extensions not defined by
this specification. The response body, if any, SHOULD also include
information about the communication options. The format for such a
body is not defined by this specification, but might be defined by
future extensions to HTTP. Content negotiation MAY be used to select
the appropriate response format. If no response body is included, the
response MUST include a Content-Length field with a field-value of
"0".
The Max-Forwards request-header field MAY be used to target a
specific proxy in the request chain. When a proxy receives an OPTIONS
request on an absolute-URI for which request forwarding is permitted,
the proxy MUST check for a Max-Forwards field. If the Max-Forwards
field-value is zero ("0"), the proxy MUST NOT forward the message;
instead, the proxy SHOULD respond with its own communication options.
If the Max-Forwards field-value is an integer greater than zero, the
proxy MUST decrement the field-value when it forwards the request. If
no Max-Forwards field is present in the request, then the forwarded
request MUST NOT include a Max-Forwards field.
The GET method means retrieve whatever information (in the form of an
entity) is identified by the request-target. If the request-target refers
to a data-producing process, it is the produced data which shall be
returned as the entity in the response and not the source text of the
process, unless that text happens to be the output of the process.
The semantics of the GET method change to a "conditional GET" if the
request message includes an If-Modified-Since, If-Unmodified-Since,
If-Match, If-None-Match, or If-Range header field. A conditional GET
method requests that the entity be transferred only under the
circumstances described by the conditional header field(s). The
conditional GET method is intended to reduce unnecessary network
usage by allowing cached entities to be refreshed without requiring
multiple requests or transferring data already held by the client.
The semantics of the GET method change to a "partial GET" if the
request message includes a Range header field. A partial GET requests
that only part of the entity be transferred, as described in Section 5.4 of .
The partial GET method is intended to reduce unnecessary
network usage by allowing partially-retrieved entities to be
completed without transferring data already held by the client.
The response to a GET request is cacheable if and only if it meets
the requirements for HTTP caching described in .
See for security considerations when used for forms.
The HEAD method is identical to GET except that the server MUST NOT
return a message-body in the response. The metainformation contained
in the HTTP headers in response to a HEAD request SHOULD be identical
to the information sent in response to a GET request. This method can
be used for obtaining metainformation about the entity implied by the
request without transferring the entity-body itself. This method is
often used for testing hypertext links for validity, accessibility,
and recent modification.
The response to a HEAD request MAY be cacheable in the sense that the
information contained in the response MAY be used to update a
previously cached entity from that resource. If the new field values
indicate that the cached entity differs from the current entity (as
would be indicated by a change in Content-Length, Content-MD5, ETag
or Last-Modified), then the cache MUST treat the cache entry as
stale.
The POST method is used to request that the origin server accept the
entity enclosed in the request as data to be processed by the resource
identified by the request-target in the Request-Line. POST is designed
to allow a uniform method to cover the following functions:
Annotation of existing resources;
Posting a message to a bulletin board, newsgroup, mailing list,
or similar group of articles;
Providing a block of data, such as the result of submitting a
form, to a data-handling process;
Extending a database through an append operation.
The actual function performed by the POST method is determined by the
server and is usually dependent on the request-target.
The action performed by the POST method might not result in a
resource that can be identified by a URI. In this case, either 200
(OK) or 204 (No Content) is the appropriate response status,
depending on whether or not the response includes an entity that
describes the result.
If a resource has been created on the origin server, the response
SHOULD be 201 (Created) and contain an entity which describes the
status of the request and refers to the new resource, and a Location
header (see ).
Responses to this method are not cacheable, unless the response
includes appropriate Cache-Control or Expires header fields. However,
the 303 (See Other) response can be used to direct the user agent to
retrieve a cacheable resource.
The PUT method requests that the enclosed entity be stored at the
supplied request-target. If the request-target refers to an already
existing resource, the enclosed entity SHOULD be considered as a
modified version of the one residing on the origin server. If the
request-target does not point to an existing resource, and that URI is
capable of being defined as a new resource by the requesting user
agent, the origin server can create the resource with that URI. If a
new resource is created at the request-target, the origin server MUST
inform the user agent
via the 201 (Created) response. If an existing resource is modified,
either the 200 (OK) or 204 (No Content) response codes SHOULD be sent
to indicate successful completion of the request. If the resource
could not be created or modified with the request-target, an appropriate
error response SHOULD be given that reflects the nature of the
problem. The recipient of the entity MUST NOT ignore any Content-*
headers (headers starting with the prefix 'Content-') that it does
not understand or implement
and MUST return a 501 (Not Implemented) response in such cases.
If the request passes through a cache and the request-target identifies
one or more currently cached entities, those entries SHOULD be
treated as stale. Responses to this method are not cacheable.
The fundamental difference between the POST and PUT requests is
reflected in the different meaning of the request-target. The URI in a
POST request identifies the resource that will handle the enclosed
entity. That resource might be a data-accepting process, a gateway to
some other protocol, or a separate entity that accepts annotations.
In contrast, the URI in a PUT request identifies the entity enclosed
with the request -- the user agent knows what URI is intended and the
server MUST NOT attempt to apply the request to some other resource.
If the server desires that the request be applied to a different URI,
it MUST send a 301 (Moved Permanently) response; the user agent MAY
then make its own decision regarding whether or not to redirect the
request.
A single resource MAY be identified by many different URIs. For
example, an article might have a URI for identifying "the current
version" which is separate from the URI identifying each particular
version. In this case, a PUT request on a general URI might result in
several other URIs being defined by the origin server.
HTTP/1.1 does not define how a PUT method affects the state of an
origin server.
Unless otherwise specified for a particular entity-header, the
entity-headers in the PUT request SHOULD be applied to the resource
created or modified by the PUT.
The DELETE method requests that the origin server delete the resource
identified by the request-target. This method MAY be overridden by human
intervention (or other means) on the origin server. The client cannot
be guaranteed that the operation has been carried out, even if the
status code returned from the origin server indicates that the action
has been completed successfully. However, the server SHOULD NOT
indicate success unless, at the time the response is given, it
intends to delete the resource or move it to an inaccessible
location.
A successful response SHOULD be 200 (OK) if the response includes an
entity describing the status, 202 (Accepted) if the action has not
yet been enacted, or 204 (No Content) if the action has been enacted
but the response does not include an entity.
If the request passes through a cache and the request-target identifies
one or more currently cached entities, those entries SHOULD be
treated as stale. Responses to this method are not cacheable.
The TRACE method is used to invoke a remote, application-layer loop-back
of the request message. The final recipient of the request
SHOULD reflect the message received back to the client as the
entity-body of a 200 (OK) response. The final recipient is either the
origin server or the first proxy or gateway to receive a Max-Forwards
value of zero (0) in the request (see ). A TRACE request
MUST NOT include an entity.
TRACE allows the client to see what is being received at the other
end of the request chain and use that data for testing or diagnostic
information. The value of the Via header field (Section 8.9 of ) is of
particular interest, since it acts as a trace of the request chain.
Use of the Max-Forwards header field allows the client to limit the
length of the request chain, which is useful for testing a chain of
proxies forwarding messages in an infinite loop.
If the request is valid, the response SHOULD contain the entire
request message in the entity-body, with a Content-Type of
"message/http" (see Section 9.3.1 of ). Responses to this method
MUST NOT be cached.
This specification reserves the method name CONNECT for use with a
proxy that can dynamically switch to being a tunnel (e.g. SSL
tunneling ).
Each Status-Code is described below, including a description of which
method(s) it can follow and any metainformation required in the
response.
This class of status code indicates a provisional response,
consisting only of the Status-Line and optional headers, and is
terminated by an empty line. There are no required headers for this
class of status code. Since HTTP/1.0 did not define any 1xx status
codes, servers MUST NOT send a 1xx response to an HTTP/1.0 client
except under experimental conditions.
A client MUST be prepared to accept one or more 1xx status responses
prior to a regular response, even if the client does not expect a 100
(Continue) status message. Unexpected 1xx status responses MAY be
ignored by a user agent.
Proxies MUST forward 1xx responses, unless the connection between the
proxy and its client has been closed, or unless the proxy itself
requested the generation of the 1xx response. (For example, if a
proxy adds a "Expect: 100-continue" field when it forwards a request,
then it need not forward the corresponding 100 (Continue)
response(s).)
The client SHOULD continue with its request. This interim response is
used to inform the client that the initial part of the request has
been received and has not yet been rejected by the server. The client
SHOULD continue by sending the remainder of the request or, if the
request has already been completed, ignore this response. The server
MUST send a final response after the request has been completed. See
Section 7.2.3 of for detailed discussion of the use and handling of this
status code.
The server understands and is willing to comply with the client's
request, via the Upgrade message header field (Section 5.4 of ), for a
change in the application protocol being used on this connection. The
server will switch protocols to those defined by the response's
Upgrade header field immediately after the empty line which
terminates the 101 response.
The protocol SHOULD be switched only when it is advantageous to do
so. For example, switching to a newer version of HTTP is advantageous
over older versions, and switching to a real-time, synchronous
protocol might be advantageous when delivering resources that use
such features.
This class of status code indicates that the client's request was
successfully received, understood, and accepted.
The request has succeeded. The information returned with the response
is dependent on the method used in the request, for example:
an entity corresponding to the requested resource is sent in
the response;
the entity-header fields corresponding to the requested
resource are sent in the response without any message-body;
an entity describing or containing the result of the action;
an entity containing the request message as received by the
end server.
The request has been fulfilled and resulted in a new resource being
created. The newly created resource can be referenced by the URI(s)
returned in the entity of the response, with the most specific URI
for the resource given by a Location header field. The response
SHOULD include an entity containing a list of resource
characteristics and location(s) from which the user or user agent can
choose the one most appropriate. The entity format is specified by
the media type given in the Content-Type header field. The origin
server MUST create the resource before returning the 201 status code.
If the action cannot be carried out immediately, the server SHOULD
respond with 202 (Accepted) response instead.
A 201 response MAY contain an ETag response header field indicating
the current value of the entity tag for the requested variant just
created, see Section 6.1 of .
The request has been accepted for processing, but the processing has
not been completed. The request might or might not eventually be
acted upon, as it might be disallowed when processing actually takes
place. There is no facility for re-sending a status code from an
asynchronous operation such as this.
The 202 response is intentionally non-committal. Its purpose is to
allow a server to accept a request for some other process (perhaps a
batch-oriented process that is only run once per day) without
requiring that the user agent's connection to the server persist
until the process is completed. The entity returned with this
response SHOULD include an indication of the request's current status
and either a pointer to a status monitor or some estimate of when the
user can expect the request to be fulfilled.
The returned metainformation in the entity-header is not the
definitive set as available from the origin server, but is gathered
from a local or a third-party copy. The set presented MAY be a subset
or superset of the original version. For example, including local
annotation information about the resource might result in a superset
of the metainformation known by the origin server. Use of this
response code is not required and is only appropriate when the
response would otherwise be 200 (OK).
The server has fulfilled the request but does not need to return an
entity-body, and might want to return updated metainformation. The
response MAY include new or updated metainformation in the form of
entity-headers, which if present SHOULD be associated with the
requested variant.
If the client is a user agent, it SHOULD NOT change its document view
from that which caused the request to be sent. This response is
primarily intended to allow input for actions to take place without
causing a change to the user agent's active document view, although
any new or updated metainformation SHOULD be applied to the document
currently in the user agent's active view.
The 204 response MUST NOT include a message-body, and thus is always
terminated by the first empty line after the header fields.
The server has fulfilled the request and the user agent SHOULD reset
the document view which caused the request to be sent. This response
is primarily intended to allow input for actions to take place via
user input, followed by a clearing of the form in which the input is
given so that the user can easily initiate another input action. The
response MUST NOT include an entity.
The server has fulfilled the partial GET request for the resource
and the enclosed entity is a partial representation as defined in .
This class of status code indicates that further action needs to be
taken by the user agent in order to fulfill the request. The action
required MAY be carried out by the user agent without interaction
with the user if and only if the method used in the second request is
GET or HEAD. A client SHOULD detect infinite redirection loops, since
such loops generate network traffic for each redirection.
Note: previous versions of this specification recommended a
maximum of five redirections. Content developers should be aware
that there might be clients that implement such a fixed
limitation.
The requested resource corresponds to any one of a set of
representations, each with its own specific location, and agent-driven
negotiation information (Section 4 of ) is being provided so that
the user (or user agent) can select a preferred representation and
redirect its request to that location.
Unless it was a HEAD request, the response SHOULD include an entity
containing a list of resource characteristics and location(s) from
which the user or user agent can choose the one most appropriate. The
entity format is specified by the media type given in the Content-Type
header field. Depending upon the format and the capabilities of
the user agent, selection of the most appropriate choice MAY be
performed automatically. However, this specification does not define
any standard for such automatic selection.
If the server has a preferred choice of representation, it SHOULD
include the specific URI for that representation in the Location
field; user agents MAY use the Location field value for automatic
redirection. This response is cacheable unless indicated otherwise.
The requested resource has been assigned a new permanent URI and any
future references to this resource SHOULD use one of the returned
URIs. Clients with link editing capabilities ought to automatically
re-link references to the request-target to one or more of the new
references returned by the server, where possible. This response is
cacheable unless indicated otherwise.
The new permanent URI SHOULD be given by the Location field in the
response. Unless the request method was HEAD, the entity of the
response SHOULD contain a short hypertext note with a hyperlink to
the new URI(s).
If the 301 status code is received in response to a request method
that is known to be "safe", as defined in ,
then the request MAY be automatically redirected by the user agent without
confirmation. Otherwise, the user agent MUST NOT automatically redirect the
request unless it can be confirmed by the user, since this might
change the conditions under which the request was issued.
Note: When automatically redirecting a POST request after
receiving a 301 status code, some existing HTTP/1.0 user agents
will erroneously change it into a GET request.
The requested resource resides temporarily under a different URI.
Since the redirection might be altered on occasion, the client SHOULD
continue to use the request-target for future requests. This response
is only cacheable if indicated by a Cache-Control or Expires header
field.
The temporary URI SHOULD be given by the Location field in the
response. Unless the request method was HEAD, the entity of the
response SHOULD contain a short hypertext note with a hyperlink to
the new URI(s).
If the 302 status code is received in response to a request method
that is known to be "safe", as defined in ,
then the request MAY be automatically redirected by the user agent without
confirmation. Otherwise, the user agent MUST NOT automatically redirect the
request unless it can be confirmed by the user, since this might
change the conditions under which the request was issued.
Note: and specify that the client is not allowed
to change the method on the redirected request. However, most
existing user agent implementations treat 302 as if it were a 303
response, performing a GET on the Location field-value regardless
of the original request method. The status codes 303 and 307 have
been added for servers that wish to make unambiguously clear which
kind of reaction is expected of the client.
The server directs the user agent to a different resource, indicated
by a URI in the Location header field, that provides an indirect
response to the original request. The user agent MAY perform a GET
request on the URI in the Location field in order to obtain a
representation corresponding to the response, be redirected again,
or end with an error status. The Location URI is not a substitute
reference for the originally requested resource.
The 303 status is generally applicable to any HTTP method. It is
primarily used to allow the output of a POST action to redirect
the user agent to a selected resource, since doing so provides the
information corresponding to the POST response in a form that
can be separately identified, bookmarked, and cached independent
of the original request.
A 303 response to a GET request indicates that the requested
resource does not have a representation of its own that can be
transferred by the server over HTTP. The Location URI indicates a
resource that is descriptive of the requested resource such that
the follow-on representation may be useful without implying that
it adequately represents the previously requested resource.
Note that answers to the questions of what can be represented, what
representations are adequate, and what might be a useful description
are outside the scope of HTTP and thus entirely determined by the
resource owner(s).
A 303 response SHOULD NOT be cached unless it is indicated as
cacheable by Cache-Control or Expires header fields. Except for
responses to a HEAD request, the entity of a 303 response SHOULD
contain a short hypertext note with a hyperlink to the Location URI.
The response to the request has not been modified since the conditions
indicated by the client's conditional GET request, as defined in .
The 305 status was defined in a previous version of this specification
(see ), and is now deprecated.
The 306 status code was used in a previous version of the
specification, is no longer used, and the code is reserved.
The requested resource resides temporarily under a different URI.
Since the redirection MAY be altered on occasion, the client SHOULD
continue to use the request-target for future requests. This response
is only cacheable if indicated by a Cache-Control or Expires header
field.
The temporary URI SHOULD be given by the Location field in the
response. Unless the request method was HEAD, the entity of the
response SHOULD contain a short hypertext note with a hyperlink to
the new URI(s) , since many pre-HTTP/1.1 user agents do not
understand the 307 status. Therefore, the note SHOULD contain the
information necessary for a user to repeat the original request on
the new URI.
If the 307 status code is received in response to a request method
that is known to be "safe", as defined in ,
then the request MAY be automatically redirected by the user agent without
confirmation. Otherwise, the user agent MUST NOT automatically redirect the
request unless it can be confirmed by the user, since this might
change the conditions under which the request was issued.
The 4xx class of status code is intended for cases in which the
client seems to have erred. Except when responding to a HEAD request,
the server SHOULD include an entity containing an explanation of the
error situation, and whether it is a temporary or permanent
condition. These status codes are applicable to any request method.
User agents SHOULD display any included entity to the user.
If the client is sending data, a server implementation using TCP
SHOULD be careful to ensure that the client acknowledges receipt of
the packet(s) containing the response, before the server closes the
input connection. If the client continues sending data to the server
after the close, the server's TCP stack will send a reset packet to
the client, which may erase the client's unacknowledged input buffers
before they can be read and interpreted by the HTTP application.
The request could not be understood by the server due to malformed
syntax. The client SHOULD NOT repeat the request without
modifications.
The request requires user authentication (see ).
This code is reserved for future use.
The server understood the request, but is refusing to fulfill it.
Authorization will not help and the request SHOULD NOT be repeated.
If the request method was not HEAD and the server wishes to make
public why the request has not been fulfilled, it SHOULD describe the
reason for the refusal in the entity. If the server does not wish to
make this information available to the client, the status code 404
(Not Found) can be used instead.
The server has not found anything matching the request-target. No
indication is given of whether the condition is temporary or
permanent. The 410 (Gone) status code SHOULD be used if the server
knows, through some internally configurable mechanism, that an old
resource is permanently unavailable and has no forwarding address.
This status code is commonly used when the server does not wish to
reveal exactly why the request has been refused, or when no other
response is applicable.
The method specified in the Request-Line is not allowed for the
resource identified by the request-target. The response MUST include an
Allow header containing a list of valid methods for the requested
resource.
The resource identified by the request is only capable of generating
response entities which have content characteristics not acceptable
according to the accept headers sent in the request.
Unless it was a HEAD request, the response SHOULD include an entity
containing a list of available entity characteristics and location(s)
from which the user or user agent can choose the one most
appropriate. The entity format is specified by the media type given
in the Content-Type header field. Depending upon the format and the
capabilities of the user agent, selection of the most appropriate
choice MAY be performed automatically. However, this specification
does not define any standard for such automatic selection.
Note: HTTP/1.1 servers are allowed to return responses which are
not acceptable according to the accept headers sent in the
request. In some cases, this may even be preferable to sending a
406 response. User agents are encouraged to inspect the headers of
an incoming response to determine if it is acceptable.
If the response could be unacceptable, a user agent SHOULD
temporarily stop receipt of more data and query the user for a
decision on further actions.
This code is similar to 401 (Unauthorized), but indicates that the
client must first authenticate itself with the proxy (see ).
The client did not produce a request within the time that the server
was prepared to wait. The client MAY repeat the request without
modifications at any later time.
The request could not be completed due to a conflict with the current
state of the resource. This code is only allowed in situations where
it is expected that the user might be able to resolve the conflict
and resubmit the request. The response body SHOULD include enough
information for the user to recognize the source of the conflict.
Ideally, the response entity would include enough information for the
user or user agent to fix the problem; however, that might not be
possible and is not required.
Conflicts are most likely to occur in response to a PUT request. For
example, if versioning were being used and the entity being PUT
included changes to a resource which conflict with those made by an
earlier (third-party) request, the server might use the 409 response
to indicate that it can't complete the request. In this case, the
response entity would likely contain a list of the differences
between the two versions in a format defined by the response
Content-Type.
The requested resource is no longer available at the server and no
forwarding address is known. This condition is expected to be
considered permanent. Clients with link editing capabilities SHOULD
delete references to the request-target after user approval. If the
server does not know, or has no facility to determine, whether or not
the condition is permanent, the status code 404 (Not Found) SHOULD be
used instead. This response is cacheable unless indicated otherwise.
The 410 response is primarily intended to assist the task of web
maintenance by notifying the recipient that the resource is
intentionally unavailable and that the server owners desire that
remote links to that resource be removed. Such an event is common for
limited-time, promotional services and for resources belonging to
individuals no longer working at the server's site. It is not
necessary to mark all permanently unavailable resources as "gone" or
to keep the mark for any length of time -- that is left to the
discretion of the server owner.
The server refuses to accept the request without a defined Content-Length.
The client MAY repeat the request if it adds a valid
Content-Length header field containing the length of the message-body
in the request message.
The precondition given in one or more of the request-header fields
evaluated to false when it was tested on the server, as defined in
.
The server is refusing to process a request because the request
entity is larger than the server is willing or able to process. The
server MAY close the connection to prevent the client from continuing
the request.
If the condition is temporary, the server SHOULD include a Retry-After
header field to indicate that it is temporary and after what
time the client MAY try again.
The server is refusing to service the request because the request-target
is longer than the server is willing to interpret. This rare
condition is only likely to occur when a client has improperly
converted a POST request to a GET request with long query
information, when the client has descended into a URI "black hole" of
redirection (e.g., a redirected URI prefix that points to a suffix of
itself), or when the server is under attack by a client attempting to
exploit security holes present in some servers using fixed-length
buffers for reading or manipulating the request-target.
The server is refusing to service the request because the entity of
the request is in a format not supported by the requested resource
for the requested method.
The request included a Range request-header field (Section 5.4 of ) and none of
the range-specifier values in this field overlap the current extent
of the selected resource.
The expectation given in an Expect request-header field (see )
could not be met by this server, or, if the server is a proxy,
the server has unambiguous evidence that the request could not be met
by the next-hop server.
Response status codes beginning with the digit "5" indicate cases in
which the server is aware that it has erred or is incapable of
performing the request. Except when responding to a HEAD request, the
server SHOULD include an entity containing an explanation of the
error situation, and whether it is a temporary or permanent
condition. User agents SHOULD display any included entity to the
user. These response codes are applicable to any request method.
The server encountered an unexpected condition which prevented it
from fulfilling the request.
The server does not support the functionality required to fulfill the
request. This is the appropriate response when the server does not
recognize the request method and is not capable of supporting it for
any resource.
The server, while acting as a gateway or proxy, received an invalid
response from the upstream server it accessed in attempting to
fulfill the request.
The server is currently unable to handle the request due to a
temporary overloading or maintenance of the server. The implication
is that this is a temporary condition which will be alleviated after
some delay. If known, the length of the delay MAY be indicated in a
Retry-After header. If no Retry-After is given, the client SHOULD
handle the response as it would for a 500 response.
Note: The existence of the 503 status code does not imply that a
server must use it when becoming overloaded. Some servers may wish
to simply refuse the connection.
The server, while acting as a gateway or proxy, did not receive a
timely response from the upstream server specified by the URI (e.g.
HTTP, FTP, LDAP) or some other auxiliary server (e.g. DNS) it needed
to access in attempting to complete the request.
Note: Note to implementors: some deployed proxies are known to
return 400 or 500 when DNS lookups time out.
The server does not support, or refuses to support, the protocol
version that was used in the request message. The server is
indicating that it is unable or unwilling to complete the request
using the same major version as the client, as described in Section 3.1 of ,
other than with this error message. The response SHOULD contain
an entity describing why that version is not supported and what other
protocols are supported by that server.
This section defines the syntax and semantics of HTTP/1.1 header fields
related to request and response semantics.
For entity-header fields, both sender and recipient refer to either the
client or the server, depending on who sends and who receives the entity.
The response-header field "Allow" lists the set of methods advertised as
supported by the resource identified by the request-target. The purpose of
this field is strictly to inform the recipient of valid methods
associated with the resource. An Allow header field MUST be
present in a 405 (Method Not Allowed) response.
Example of use:
The actual set of allowed methods is defined
by the origin server at the time of each request.
A proxy MUST NOT modify the Allow header field even if it does not
understand all the methods specified, since the user agent might
have other means of communicating with the origin server.
The request-header field "Expect" is used to indicate that particular
server behaviors are required by the client.
A server that does not understand or is unable to comply with any of
the expectation values in the Expect field of a request MUST respond
with appropriate error status. The server MUST respond with a 417
(Expectation Failed) status if any of the expectations cannot be met
or, if there are other problems with the request, some other 4xx
status.
This header field is defined with extensible syntax to allow for
future extensions. If a server receives a request containing an
Expect field that includes an expectation-extension that it does not
support, it MUST respond with a 417 (Expectation Failed) status.
Comparison of expectation values is case-insensitive for unquoted
tokens (including the 100-continue token), and is case-sensitive for
quoted-string expectation-extensions.
The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy MUST
return a 417 (Expectation Failed) status if it receives a request
with an expectation that it cannot meet. However, the Expect
request-header itself is end-to-end; it MUST be forwarded if the
request is forwarded.
Many older HTTP/1.0 and HTTP/1.1 applications do not understand the
Expect header.
See Section 7.2.3 of for the use of the 100 (Continue) status.
The request-header field "From", if given, SHOULD contain an Internet
e-mail address for the human user who controls the requesting user
agent. The address SHOULD be machine-usable, as defined by "mailbox"
in Section 3.4 of :
]]>
An example is:
This header field MAY be used for logging purposes and as a means for
identifying the source of invalid or unwanted requests. It SHOULD NOT
be used as an insecure form of access protection. The interpretation
of this field is that the request is being performed on behalf of the
person given, who accepts responsibility for the method performed. In
particular, robot agents SHOULD include this header so that the
person responsible for running the robot can be contacted if problems
occur on the receiving end.
The Internet e-mail address in this field MAY be separate from the
Internet host which issued the request. For example, when a request
is passed through a proxy the original issuer's address SHOULD be
used.
The client SHOULD NOT send the From header field without the user's
approval, as it might conflict with the user's privacy interests or
their site's security policy. It is strongly recommended that the
user be able to disable, enable, and modify the value of this field
at any time prior to a request.
The response-header field "Location" is used for the identification of a
new resource or to redirect the recipient to a location other than the
request-target for completion of the request. For 201 (Created)
responses, the Location is that of the new resource which was created
by the request. For 3xx responses, the location SHOULD indicate the
server's preferred URI for automatic redirection to the resource. The
field value consists of a single absolute URI.
An example is:
Note: The Content-Location header field (Section 5.7 of ) differs
from Location in that the Content-Location identifies the original
location of the entity enclosed in the response. It is therefore
possible for a response to contain header fields for both Location
and Content-Location.
There are circumstances in which a fragment identifier in a Location URL would not be appropriate:
With a 201 Created response, because in this usage the Location header specifies the URL for the entire created resource.With a 300 Multiple Choices, since the choice decision is intended to be made on resource characteristics and not fragment characteristics.With 305 Use Proxy.
The request-header "Max-Forwards" field provides a mechanism with the
TRACE () and OPTIONS () methods to limit the
number of proxies or gateways that can forward the request to the
next inbound server. This can be useful when the client is attempting
to trace a request chain which appears to be failing or looping in
mid-chain.
The Max-Forwards value is a decimal integer indicating the remaining
number of times this request message may be forwarded.
Each proxy or gateway recipient of a TRACE or OPTIONS request
containing a Max-Forwards header field MUST check and update its
value prior to forwarding the request. If the received value is zero
(0), the recipient MUST NOT forward the request; instead, it MUST
respond as the final recipient. If the received Max-Forwards value is
greater than zero, then the forwarded message MUST contain an updated
Max-Forwards field with a value decremented by one (1).
The Max-Forwards header field MAY be ignored for all other methods
defined by this specification and for any extension methods for which
it is not explicitly referred to as part of that method definition.
The request-header field "Referer" [sic] allows the client to specify,
for the server's benefit, the address (URI) of the resource from
which the request-target was obtained (the "referrer", although the
header field is misspelled.) The Referer request-header allows a
server to generate lists of back-links to resources for interest,
logging, optimized caching, etc. It also allows obsolete or mistyped
links to be traced for maintenance. The Referer field MUST NOT be
sent if the request-target was obtained from a source that does not have
its own URI, such as input from the user keyboard.
Example:
If the field value is a relative URI, it SHOULD be interpreted
relative to the request-target. The URI MUST NOT include a fragment. See
for security considerations.
The response-header "Retry-After" field can be used with a 503 (Service
Unavailable) response to indicate how long the service is expected to
be unavailable to the requesting client. This field MAY also be used
with any 3xx (Redirection) response to indicate the minimum time the
user-agent is asked wait before issuing the redirected request. The
value of this field can be either an HTTP-date or an integer number
of seconds (in decimal) after the time of the response.
Time spans are non-negative decimal integers, representing time in
seconds.
Two examples of its use are
In the latter example, the delay is 2 minutes.
The response-header field "Server" contains information about the
software used by the origin server to handle the request. The field
can contain multiple product tokens (Section 3.4 of ) and comments
identifying the server and any significant subproducts. The product
tokens are listed in order of their significance for identifying the
application.
Example:
If the response is being forwarded through a proxy, the proxy
application MUST NOT modify the Server response-header. Instead, it
MUST include a Via field (as described in Section 8.9 of ).
Note: Revealing the specific software version of the server might
allow the server machine to become more vulnerable to attacks
against software that is known to contain security holes. Server
implementors are encouraged to make this field a configurable
option.
The request-header field "User-Agent" contains information about the
user agent originating the request. This is for statistical purposes,
the tracing of protocol violations, and automated recognition of user
agents for the sake of tailoring responses to avoid particular user
agent limitations. User agents SHOULD include this field with
requests. The field can contain multiple product tokens (Section 3.4 of )
and comments identifying the agent and any subproducts which form a
significant part of the user agent. By convention, the product tokens
are listed in order of their significance for identifying the
application.
Example:
The registration procedure for HTTP Methods is defined by
of this document.
The HTTP Method Registry located at
should be populated with the registrations below:
MethodSafeReferenceCONNECTnoDELETEnoGETyesHEADyesOPTIONSyesPOSTnoPUTnoTRACEyes
The registration procedure for HTTP Status Codes -- previously defined
in Section 7.1 of -- is now defined
by of this document.
The HTTP Status Code Registry located at
should be updated with the registrations below:
ValueDescriptionReference100Continue101Switching Protocols200OK201Created202Accepted203Non-Authoritative Information204No Content205Reset Content206Partial Content300Multiple Choices301Moved Permanently302Found303See Other304Not Modified305Use Proxy306(Unused)307Temporary Redirect400Bad Request401Unauthorized402Payment Required403Forbidden404Not Found405Method Not Allowed406Not Acceptable407Proxy Authentication Required408Request Timeout409Conflict410Gone411Length Required412Precondition Failed413Request Entity Too Large414URI Too Long415Unsupported Media Type416Requested Range Not Satisfiable417Expectation Failed500Internal Server Error501Not Implemented502Bad Gateway503Service Unavailable504Gateway Timeout505HTTP Version Not Supported
The Message Header Registry located at should be updated
with the permanent registrations below (see ):
Header Field NameProtocolStatusReferenceAllowhttpstandardExpecthttpstandardFromhttpstandardLocationhttpstandardMax-ForwardshttpstandardRefererhttpstandardRetry-AfterhttpstandardServerhttpstandardUser-Agenthttpstandard
The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
This section is meant to inform application developers, information
providers, and users of the security limitations in HTTP/1.1 as
described by this document. The discussion does not include
definitive solutions to the problems revealed, though it does make
some suggestions for reducing security risks.
Like any generic data transfer protocol, HTTP cannot regulate the
content of the data that is transferred, nor is there any a priori
method of determining the sensitivity of any particular piece of
information within the context of any given request. Therefore,
applications SHOULD supply as much control over this information as
possible to the provider of that information. Four header fields are
worth special mention in this context: Server, Via, Referer and From.
Revealing the specific software version of the server might allow the
server machine to become more vulnerable to attacks against software
that is known to contain security holes. Implementors SHOULD make the
Server header field a configurable option.
Proxies which serve as a portal through a network firewall SHOULD
take special precautions regarding the transfer of header information
that identifies the hosts behind the firewall. In particular, they
SHOULD remove, or replace with sanitized versions, any Via fields
generated behind the firewall.
The Referer header allows reading patterns to be studied and reverse
links drawn. Although it can be very useful, its power can be abused
if user details are not separated from the information contained in
the Referer. Even when the personal information has been removed, the
Referer header might indicate a private document's URI whose
publication would be inappropriate.
The information sent in the From field might conflict with the user's
privacy interests or their site's security policy, and hence it
SHOULD NOT be transmitted without the user being able to disable,
enable, and modify the contents of the field. The user MUST be able
to set the contents of this field within a user preference or
application defaults configuration.
We suggest, though do not require, that a convenient toggle interface
be provided for the user to enable or disable the sending of From and
Referer information.
The User-Agent () or Server () header
fields can sometimes be used to determine that a specific client or
server have a particular security hole which might be exploited.
Unfortunately, this same information is often used for other valuable
purposes for which HTTP currently has no better mechanism.
Because the source of a link might be private information or might
reveal an otherwise private information source, it is strongly
recommended that the user be able to select whether or not the
Referer field is sent. For example, a browser client could have a
toggle switch for browsing openly/anonymously, which would
respectively enable/disable the sending of Referer and From
information.
Clients SHOULD NOT include a Referer header field in a (non-secure)
HTTP request if the referring page was transferred with a secure
protocol.
Authors of services should not use
GET-based forms for the submission of sensitive data because that
data will be encoded in the Request-target. Many existing
servers, proxies, and user agents log or display the Request-target in
places where it might be visible to third parties. Such services can
use POST-based form submission instead.
If a single server supports multiple organizations that do not trust
one another, then it MUST check the values of Location and Content-Location
headers in responses that are generated under control of
said organizations to make sure that they do not attempt to
invalidate resources over which they have no authority.
HTTP/1.1, part 1: URIs, Connections, and Message ParsingDay Softwarefielding@gbiv.comOne Laptop per Childjg@laptop.orgHewlett-Packard CompanyJeffMogul@acm.orgMicrosoft Corporationhenrikn@microsoft.comAdobe Systems, IncorporatedLMM@acm.orgMicrosoft Corporationpaulle@microsoft.comWorld Wide Web Consortiumtimbl@w3.orgWorld Wide Web Consortiumylafon@w3.orggreenbytes GmbHjulian.reschke@greenbytes.deHTTP/1.1, part 3: Message Payload and Content NegotiationDay Softwarefielding@gbiv.comOne Laptop per Childjg@laptop.orgHewlett-Packard CompanyJeffMogul@acm.orgMicrosoft Corporationhenrikn@microsoft.comAdobe Systems, IncorporatedLMM@acm.orgMicrosoft Corporationpaulle@microsoft.comWorld Wide Web Consortiumtimbl@w3.orgWorld Wide Web Consortiumylafon@w3.orggreenbytes GmbHjulian.reschke@greenbytes.deHTTP/1.1, part 4: Conditional RequestsDay Softwarefielding@gbiv.comOne Laptop per Childjg@laptop.orgHewlett-Packard CompanyJeffMogul@acm.orgMicrosoft Corporationhenrikn@microsoft.comAdobe Systems, IncorporatedLMM@acm.orgMicrosoft Corporationpaulle@microsoft.comWorld Wide Web Consortiumtimbl@w3.orgWorld Wide Web Consortiumylafon@w3.orggreenbytes GmbHjulian.reschke@greenbytes.deHTTP/1.1, part 5: Range Requests and Partial ResponsesDay Softwarefielding@gbiv.comOne Laptop per Childjg@laptop.orgHewlett-Packard CompanyJeffMogul@acm.orgMicrosoft Corporationhenrikn@microsoft.comAdobe Systems, IncorporatedLMM@acm.orgMicrosoft Corporationpaulle@microsoft.comWorld Wide Web Consortiumtimbl@w3.orgWorld Wide Web Consortiumylafon@w3.orggreenbytes GmbHjulian.reschke@greenbytes.deHTTP/1.1, part 6: CachingDay Softwarefielding@gbiv.comOne Laptop per Childjg@laptop.orgHewlett-Packard CompanyJeffMogul@acm.orgMicrosoft Corporationhenrikn@microsoft.comAdobe Systems, IncorporatedLMM@acm.orgMicrosoft Corporationpaulle@microsoft.comWorld Wide Web Consortiumtimbl@w3.orgWorld Wide Web Consortiumylafon@w3.orggreenbytes GmbHjulian.reschke@greenbytes.deHTTP/1.1, part 7: AuthenticationDay Softwarefielding@gbiv.comOne Laptop per Childjg@laptop.orgHewlett-Packard CompanyJeffMogul@acm.orgMicrosoft Corporationhenrikn@microsoft.comAdobe Systems, IncorporatedLMM@acm.orgMicrosoft Corporationpaulle@microsoft.comWorld Wide Web Consortiumtimbl@w3.orgWorld Wide Web Consortiumylafon@w3.orggreenbytes GmbHjulian.reschke@greenbytes.deKey words for use in RFCs to Indicate Requirement LevelsHarvard Universitysob@harvard.eduAugmented BNF for Syntax Specifications: ABNFBrandenburg InternetWorking675 Spruce Dr.SunnyvaleCA94086US+1.408.246.8253dcrocker@bbiw.netTHUS plc.1/2 Berkeley Square99 Berkely StreetGlasgowG3 7HRUKpaul.overell@thus.netHypertext Transfer Protocol -- HTTP/1.0MIT, Laboratory for Computer Sciencetimbl@w3.orgUniversity of California, Irvine, Department of Information and Computer Sciencefielding@ics.uci.eduW3 Consortium, MIT Laboratory for Computer Sciencefrystyk@w3.orgHypertext Transfer Protocol -- HTTP/1.1University of California, Irvine, Department of Information and Computer Sciencefielding@ics.uci.eduMIT Laboratory for Computer Sciencejg@w3.orgDigital Equipment Corporation, Western Research Laboratorymogul@wrl.dec.comMIT Laboratory for Computer Sciencefrystyk@w3.orgMIT Laboratory for Computer Sciencetimbl@w3.orgHypertext Transfer Protocol -- HTTP/1.1University of California, Irvinefielding@ics.uci.eduW3Cjg@w3.orgCompaq Computer Corporationmogul@wrl.dec.comMIT Laboratory for Computer Sciencefrystyk@w3.orgXerox Corporationmasinter@parc.xerox.comMicrosoft Corporationpaulle@microsoft.comW3Ctimbl@w3.orgUpgrading to TLS Within HTTP/1.14K Associates / UC Irvinerohit@4K-associates.comAgranat Systems, Inc.lawrence@agranat.comRegistration Procedures for Message Header FieldsNine by NineGK-IETF@ninebynine.orgBEA Systemsmnot@pobox.comHP LabsJeffMogul@acm.orgGuidelines for Writing an IANA Considerations Section in RFCsIBMnarten@us.ibm.comGoogleHarald@Alvestrand.noInternet Message FormatQualcomm Incorporated
Clarified which error code should be used for inbound server failures
(e.g. DNS failures). ().
201 (Created) had a race that required an Etag be sent when a resource is
first created. ().
Rewrite of message transmission requirements to make it much harder
for implementors to get it wrong, as the consequences of errors here
can have significant impact on the Internet, and to deal with the
following problems:
Changing "HTTP/1.1 or later" to "HTTP/1.1", in contexts where
this was incorrectly placing a requirement on the behavior of
an implementation of a future version of HTTP/1.xMade it clear that user-agents should retry requests, not
"clients" in general.Converted requirements for clients to ignore unexpected 100
(Continue) responses, and for proxies to forward 100 responses,
into a general requirement for 1xx responses.Modified some TCP-specific language, to make it clearer that
non-TCP transports are possible for HTTP.Require that the origin server MUST NOT wait for the request
body before it sends a required 100 (Continue) response.Allow, rather than require, a server to omit 100 (Continue) if
it has already seen some of the request body.Allow servers to defend against denial-of-service attacks and
broken clients.
This change adds the Expect header and 417 status code.
Clean up confusion between 403 and 404 responses. (Section ,
, and )
The PATCH, LINK, UNLINK methods were defined but not commonly
implemented in previous versions of this specification. See Section 19.6.1 of .
This document takes over the Status Code Registry, previously defined
in Section 7.1 of .
()
Clarify definition of POST.
()
Failed to consider that there are
many other request methods that are safe to automatically redirect,
and further that the user agent is able to make that determination
based on the request method semantics.
(Sections ,
and
)
Deprecate 305 Use Proxy status code, because user agents did not implement it.
It used to indicate that the requested resource must be accessed through the
proxy given by the Location field. The Location field gave the URI of the
proxy. The recipient was expected to repeat this single request via the proxy.
()
Reclassify Allow header as response header, removing the option to
specify it in a PUT request.
Relax the server requirement on the contents of the Allow header and
remove requirement on clients to always trust the header value.
()
Correct syntax of Location header to allow fragment,
as referred symbol wasn't what was expected, and add some
clarifications as to when it would not be appropriate.
()
In the description of the Server header, the Via field
was described as a SHOULD. The requirement was and is stated
correctly in the description of the Via header in Section 8.9 of .
()
Accept-Charset =
Accept-Encoding =
Accept-Language =
Accept-Ranges =
Age =
Allow = "Allow:" OWS Allow-v
Allow-v = [ ( "," / Method ) *( OWS "," [ OWS Method ] ) ]
Authorization =
ETag =
Expect = "Expect:" OWS Expect-v
Expect-v = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] )
From = "From:" OWS From-v
From-v = mailbox
HTTP-date =
Host =
If-Match =
If-Modified-Since =
If-None-Match =
If-Range =
If-Unmodified-Since =
Location = "Location:" OWS Location-v
Location-v = absolute-URI [ "#" fragment ]
Max-Forwards = "Max-Forwards:" OWS Max-Forwards-v
Max-Forwards-v = 1*DIGIT
Method = %x4F.50.54.49.4F.4E.53 / %x47.45.54 / %x48.45.41.44 /
%x50.4F.54 / %x50.55.54 / %x44.45.4C.45.54.45 / %x54.52.41.43.45 /
%x43.4E.4E.45.43.54 / extension-method
OWS =
Proxy-Authenticate =
Proxy-Authorization =
RWS =
Range =
Reason-Phrase = *( WSP / VCHAR / obs-text )
Referer = "Referer:" OWS Referer-v
Referer-v = absolute-URI / partial-URI
Retry-After = "Retry-After:" OWS Retry-After-v
Retry-After-v = HTTP-date / delta-seconds
Server = "Server:" OWS Server-v
Server-v = product *( RWS ( product / comment ) )
Status-Code = "100" / "101" / "200" / "201" / "202" / "203" / "204" /
"205" / "206" / "300" / "301" / "302" / "303" / "304" / "305" /
"307" / "400" / "401" / "402" / "403" / "404" / "405" / "406" /
"407" / "408" / "409" / "410" / "411" / "412" / "413" / "414" /
"415" / "416" / "417" / "500" / "501" / "502" / "503" / "504" /
"505" / extension-code
TE =
User-Agent = "User-Agent:" OWS User-Agent-v
User-Agent-v = product *( RWS ( product / comment ) )
Vary =
WWW-Authenticate =
absolute-URI =
comment =
delta-seconds = 1*DIGIT
expect-params = ";" token [ "=" ( token / quoted-string ) ]
expectation = "100-continue" / expectation-extension
expectation-extension = token [ "=" ( token / quoted-string )
*expect-params ]
extension-code = 3DIGIT
extension-method = token
fragment =
mailbox =
obs-text =
partial-URI =
product =
quoted-string =
request-header = Accept / Accept-Charset / Accept-Encoding /
Accept-Language / Authorization / Expect / From / Host / If-Match /
If-Modified-Since / If-None-Match / If-Range / If-Unmodified-Since /
Max-Forwards / Proxy-Authorization / Range / Referer / TE /
User-Agent
response-header = Accept-Ranges / Age / Allow / ETag / Location /
Proxy-Authenticate / Retry-After / Server / Vary / WWW-Authenticate
token =
]]>ABNF diagnostics:
Extracted relevant partitions from .
Closed issues:
:
"Via is a MUST"
()
:
"Fragments allowed in Location"
()
:
"Safe Methods vs Redirection"
()
:
"Revise description of the POST method"
()
:
"Normative and Informative references"
:
"RFC2606 Compliance"
:
"Informative references"
:
"Redundant cross-references"
Other changes:
Move definitions of 304 and 412 condition codes to
Closed issues:
:
"PUT side effects"
:
"Duplicate Host header requirements"
Ongoing work on ABNF conversion ():
Move "Product Tokens" section (back) into Part 1, as "token" is used
in the definition of the Upgrade header.
Add explicit references to BNF syntax and rules imported from other parts of the specification.
Copy definition of delta-seconds from Part6 instead of referencing it.
Closed issues:
:
"Requiring Allow in 405 responses"
:
"Status Code Registry"
:
"Redirection vs. Location"
:
"Cacheability of 303 response"
:
"305 Use Proxy"
:
"Classification for Allow header"
:
"PUT - 'store under' vs 'store at'"
Ongoing work on IANA Message Header Registration ():
Reference RFC 3984, and update header registrations for headers defined
in this document.
Ongoing work on ABNF conversion ():
Replace string literals when the string really is case-sensitive (method).
Closed issues:
:
"OPTIONS request bodies"
:
"Description of CONNECT should refer to RFC2817"
:
"Location Content-Location reference request/response mixup"
Ongoing work on Method Registry ():
Added initial proposal for registration process, plus initial
content (non-HTTP/1.1 methods to be added by a separate specification).
Closed issues:
:
"Content-*"
:
"RFC 2822 is updated by RFC 5322"
Ongoing work on ABNF conversion ():
Use "/" instead of "|" for alternatives.
Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
whitespace ("OWS") and required whitespace ("RWS").
Rewrite ABNFs to spell out whitespace rules, factor out
header value format definitions.
Closed issues:
:
"Reason-Phrase BNF"
Final work on ABNF conversion ():
Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.