Changeset 1839 for draft-ietf-httpbis/latest/p1-messaging.html
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- 25/08/12 09:08:32 (10 years ago)
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draft-ietf-httpbis/latest/p1-messaging.html
r1838 r1839 449 449 } 450 450 @bottom-center { 451 content: "Expires February 2 1, 2013";451 content: "Expires February 25, 2013"; 452 452 } 453 453 @bottom-right { … … 492 492 <meta name="dct.creator" content="Reschke, J. F."> 493 493 <meta name="dct.identifier" content="urn:ietf:id:draft-ietf-httpbis-p1-messaging-latest"> 494 <meta name="dct.issued" scheme="ISO8601" content="2012-08-2 0">494 <meta name="dct.issued" scheme="ISO8601" content="2012-08-24"> 495 495 <meta name="dct.replaces" content="urn:ietf:rfc:2145"> 496 496 <meta name="dct.replaces" content="urn:ietf:rfc:2616"> … … 524 524 </tr> 525 525 <tr> 526 <td class="left">Expires: February 2 1, 2013</td>526 <td class="left">Expires: February 25, 2013</td> 527 527 <td class="right">greenbytes</td> 528 528 </tr> 529 529 <tr> 530 530 <td class="left"></td> 531 <td class="right">August 2 0, 2012</td>531 <td class="right">August 24, 2012</td> 532 532 </tr> 533 533 </tbody> … … 556 556 in progress”. 557 557 </p> 558 <p>This Internet-Draft will expire on February 2 1, 2013.</p>558 <p>This Internet-Draft will expire on February 25, 2013.</p> 559 559 <h1><a id="rfc.copyrightnotice" href="#rfc.copyrightnotice">Copyright Notice</a></h1> 560 560 <p>Copyright © 2012 IETF Trust and the persons identified as the document authors. All rights reserved.</p> … … 584 584 <li><a href="#rfc.section.2.3">2.3</a> <a href="#intermediaries">Intermediaries</a></li> 585 585 <li><a href="#rfc.section.2.4">2.4</a> <a href="#caches">Caches</a></li> 586 <li><a href="#rfc.section.2.5">2.5</a> <a href="# intro.conformance.and.error.handling">Conformance and Error Handling</a></li>586 <li><a href="#rfc.section.2.5">2.5</a> <a href="#conformance">Conformance and Error Handling</a></li> 587 587 <li><a href="#rfc.section.2.6">2.6</a> <a href="#http.version">Protocol Versioning</a></li> 588 588 <li><a href="#rfc.section.2.7">2.7</a> <a href="#uri">Uniform Resource Identifiers</a><ul> … … 776 776 in this document are to be interpreted as described in <a href="#RFC2119" id="rfc.xref.RFC2119.1"><cite title="Key words for use in RFCs to Indicate Requirement Levels">[RFC2119]</cite></a>. 777 777 </p> 778 <p id="rfc.section.1.1.p.2">Conformance criteria and considerations regarding error handling are defined in <a href="#conformance" title="Conformance and Error Handling">Section 2.5</a>. 779 </p> 778 780 <div id="rfc.iref.g.1"></div> 779 781 <div id="rfc.iref.g.2"></div> … … 906 908 or an intranet-to-Internet privacy filter. Such transformations are presumed to be desired by the client (or client organization) 907 909 that selected the proxy and are beyond the scope of this specification. However, when a proxy is not intended to transform 908 a given message, we use the term "<dfn>non-transforming proxy</dfn>" to target requirements that preserve HTTP message semantics. See <a href="p2-semantics.html#status.203" title="203 Non-Authoritative Information">Section 4.4.4</a> of <a href="#Part2" id="rfc.xref.Part2.3"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a> and <a href="p6-cache.html#header.warning" title="Warning">Section 7.6</a> of <a href="#Part6" id="rfc.xref.Part6.2"><cite title="HTTP/1.1, part 6: Caching">[Part6]</cite></a> for status and warning codes related to transformations.910 a given message, we use the term "<dfn>non-transforming proxy</dfn>" to target requirements that preserve HTTP message semantics. See <a href="p2-semantics.html#status.203" title="203 Non-Authoritative Information">Section 5.4.4</a> of <a href="#Part2" id="rfc.xref.Part2.3"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a> and <a href="p6-cache.html#header.warning" title="Warning">Section 7.6</a> of <a href="#Part6" id="rfc.xref.Part6.2"><cite title="HTTP/1.1, part 6: Caching">[Part6]</cite></a> for status and warning codes related to transformations. 909 911 </p> 910 912 <p id="rfc.section.2.3.p.7"><span id="rfc.iref.g.13"></span><span id="rfc.iref.r.4"></span> <span id="rfc.iref.a.1"></span> A "<dfn>gateway</dfn>" (a.k.a., "<dfn>reverse proxy</dfn>") is a receiving agent that acts as a layer above some other server(s) and translates the received requests to the underlying … … 957 959 on. 958 960 </p> 959 <h2 id="rfc.section.2.5"><a href="#rfc.section.2.5">2.5</a> <a id=" intro.conformance.and.error.handling" href="#intro.conformance.and.error.handling">Conformance and Error Handling</a></h2>961 <h2 id="rfc.section.2.5"><a href="#rfc.section.2.5">2.5</a> <a id="conformance" href="#conformance">Conformance and Error Handling</a></h2> 960 962 <p id="rfc.section.2.5.p.1">This specification targets conformance criteria according to the role of a participant in HTTP communication. Hence, HTTP 961 963 requirements are placed on senders, recipients, clients, servers, user agents, intermediaries, origin servers, proxies, gateways, … … 1076 1078 </p> 1077 1079 <p id="rfc.section.2.7.1.p.6">When an "http" URI is used within a context that calls for access to the indicated resource, a client <em class="bcp14">MAY</em> attempt access by resolving the host to an IP address, establishing a TCP connection to that address on the indicated port, 1078 and sending an HTTP request message (<a href="#http.message" title="Message Format">Section 3</a>) containing the URI's identifying data (<a href="#message.routing" title="Message Routing">Section 5</a>) to the server. If the server responds to that request with a non-interim HTTP response message, as described in <a href="p2-semantics.html#status.codes" title=" Status Codes">Section 4</a> of <a href="#Part2" id="rfc.xref.Part2.4"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>, then that response is considered an authoritative answer to the client's request.1080 and sending an HTTP request message (<a href="#http.message" title="Message Format">Section 3</a>) containing the URI's identifying data (<a href="#message.routing" title="Message Routing">Section 5</a>) to the server. If the server responds to that request with a non-interim HTTP response message, as described in <a href="p2-semantics.html#status.codes" title="Response Status Codes">Section 5</a> of <a href="#Part2" id="rfc.xref.Part2.4"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>, then that response is considered an authoritative answer to the client's request. 1079 1081 </p> 1080 1082 <p id="rfc.section.2.7.1.p.7">Although HTTP is independent of the transport protocol, the "http" scheme is specific to TCP-based services because the name … … 1174 1176 </div> 1175 1177 <div id="rfc.figure.u.14"></div><pre class="inline"><span id="rfc.iref.g.29"></span> <a href="#method" class="smpl">method</a> = <a href="#rule.token.separators" class="smpl">token</a> 1176 </pre><p id="rfc.section.3.1.1.p.6">The methods defined by this specification can be found in <a href="p2-semantics.html#methods" title=" Methods">Section 2</a> of <a href="#Part2" id="rfc.xref.Part2.5"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>, along with information regarding the HTTP method registry and considerations for defining new methods.1178 </pre><p id="rfc.section.3.1.1.p.6">The methods defined by this specification can be found in <a href="p2-semantics.html#methods" title="Request Methods">Section 3</a> of <a href="#Part2" id="rfc.xref.Part2.5"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>, along with information regarding the HTTP method registry and considerations for defining new methods. 1177 1179 </p> 1178 1180 <div id="rfc.iref.r.6"></div> … … 1187 1189 </p> 1188 1190 <p id="rfc.section.3.1.1.p.10">HTTP does not place a pre-defined limit on the length of a request-line. A server that receives a method longer than any that 1189 it implements <em class="bcp14">SHOULD</em> respond with either a <a href="p2-semantics.html#status.405" class="smpl">405 (Method Not Allowed)</a>, if it is an origin server, or a <a href="p2-semantics.html#status.501" class="smpl">501 (Not Implemented)</a> status code. A server <em class="bcp14">MUST</em> be prepared to receive URIs of unbounded length and respond with the <a href="p2-semantics.html#status.414" class="smpl">414 (URI Too Long)</a> status code if the received request-target would be longer than the server wishes to handle (see <a href="p2-semantics.html#status.414" title="414 URI Too Long">Section 4.6.12</a> of <a href="#Part2" id="rfc.xref.Part2.6"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>).1191 it implements <em class="bcp14">SHOULD</em> respond with either a <a href="p2-semantics.html#status.405" class="smpl">405 (Method Not Allowed)</a>, if it is an origin server, or a <a href="p2-semantics.html#status.501" class="smpl">501 (Not Implemented)</a> status code. A server <em class="bcp14">MUST</em> be prepared to receive URIs of unbounded length and respond with the <a href="p2-semantics.html#status.414" class="smpl">414 (URI Too Long)</a> status code if the received request-target would be longer than the server wishes to handle (see <a href="p2-semantics.html#status.414" title="414 URI Too Long">Section 5.6.12</a> of <a href="#Part2" id="rfc.xref.Part2.6"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). 1190 1192 </p> 1191 1193 <p id="rfc.section.3.1.1.p.11">Various ad-hoc limitations on request-line length are found in practice. It is <em class="bcp14">RECOMMENDED</em> that all HTTP senders and recipients support, at a minimum, request-line lengths of up to 8000 octets. … … 1200 1202 <p id="rfc.section.3.1.2.p.4">The status-code element is a 3-digit integer code describing the result of the server's attempt to understand and satisfy 1201 1203 the client's corresponding request. The rest of the response message is to be interpreted in light of the semantics defined 1202 for that status code. See <a href="p2-semantics.html#status.codes" title=" Status Codes">Section 4</a> of <a href="#Part2" id="rfc.xref.Part2.7"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a> for information about the semantics of status codes, including the classes of status code (indicated by the first digit),1204 for that status code. See <a href="p2-semantics.html#status.codes" title="Response Status Codes">Section 5</a> of <a href="#Part2" id="rfc.xref.Part2.7"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a> for information about the semantics of status codes, including the classes of status code (indicated by the first digit), 1203 1205 the status codes defined by this specification, considerations for the definition of new status codes, and the IANA registry. 1204 1206 </p> … … 1221 1223 ; see <a href="#field.parsing" title="Field Parsing">Section 3.2.2</a> 1222 1224 </pre><p id="rfc.section.3.2.p.3">The field-name token labels the corresponding field-value as having the semantics defined by that header field. For example, 1223 the <a href="p2-semantics.html#header.date" class="smpl">Date</a> header field is defined in <a href="p2-semantics.html#header.date" title="Date">Section 9.10</a> of <a href="#Part2" id="rfc.xref.Part2.8"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a> as containing the origination timestamp for the message in which it appears.1225 the <a href="p2-semantics.html#header.date" class="smpl">Date</a> header field is defined in <a href="p2-semantics.html#header.date" title="Date">Section 10.10</a> of <a href="#Part2" id="rfc.xref.Part2.8"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a> as containing the origination timestamp for the message in which it appears. 1224 1226 </p> 1225 1227 <p id="rfc.section.3.2.p.4">HTTP header fields are fully extensible: there is no limit on the introduction of new field names, each presumably defining … … 1229 1231 them. 1230 1232 </p> 1231 <p id="rfc.section.3.2.p.5">New HTTP header fields <em class="bcp14">SHOULD</em> be registered with IANA according to the procedures in <a href="p2-semantics.html#considerations.for.creating.header.fields" title="Considerations for Creating Header Fields">Section 3.1</a> of <a href="#Part2" id="rfc.xref.Part2.9"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>. Unrecognized header fields <em class="bcp14">MUST</em> be forwarded by a proxy unless the field-name is listed in the <a href="#header.connection" class="smpl">Connection</a> header field (<a href="#header.connection" id="rfc.xref.header.connection.3" title="Connection">Section 6.1</a>) or the proxy is specifically configured to block or otherwise transform such fields. Unrecognized header fields <em class="bcp14">SHOULD</em> be ignored by other recipients.1233 <p id="rfc.section.3.2.p.5">New HTTP header fields <em class="bcp14">SHOULD</em> be registered with IANA according to the procedures in <a href="p2-semantics.html#considerations.for.creating.header.fields" title="Considerations for Creating Header Fields">Section 4.5</a> of <a href="#Part2" id="rfc.xref.Part2.9"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>. Unrecognized header fields <em class="bcp14">MUST</em> be forwarded by a proxy unless the field-name is listed in the <a href="#header.connection" class="smpl">Connection</a> header field (<a href="#header.connection" id="rfc.xref.header.connection.3" title="Connection">Section 6.1</a>) or the proxy is specifically configured to block or otherwise transform such fields. Unrecognized header fields <em class="bcp14">SHOULD</em> be ignored by other recipients. 1232 1234 </p> 1233 1235 <p id="rfc.section.3.2.p.6">The order in which header fields with differing field names are received is not significant. However, it is "good practice" … … 1381 1383 <p id="rfc.section.3.3.1.p.6">If more than one Transfer-Encoding header field is present in a message, the multiple field-values <em class="bcp14">MUST</em> be combined into one field-value, according to the algorithm defined in <a href="#header.fields" title="Header Fields">Section 3.2</a>, before determining the message body length. 1382 1384 </p> 1383 <p id="rfc.section.3.3.1.p.7">Unlike <a href="p2-semantics.html#header.content-encoding" class="smpl">Content-Encoding</a> (<a href="p2-semantics.html#content.codings" title="Content Codings">Section 5.4</a> of <a href="#Part2" id="rfc.xref.Part2.10"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>), Transfer-Encoding is a property of the message, not of the payload, and thus <em class="bcp14">MAY</em> be added or removed by any implementation along the request/response chain. Additional information about the encoding parameters <em class="bcp14">MAY</em> be provided by other header fields not defined by this specification.1385 <p id="rfc.section.3.3.1.p.7">Unlike <a href="p2-semantics.html#header.content-encoding" class="smpl">Content-Encoding</a> (<a href="p2-semantics.html#content.codings" title="Content Codings">Section 6.4</a> of <a href="#Part2" id="rfc.xref.Part2.10"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>), Transfer-Encoding is a property of the message, not of the payload, and thus <em class="bcp14">MAY</em> be added or removed by any implementation along the request/response chain. Additional information about the encoding parameters <em class="bcp14">MAY</em> be provided by other header fields not defined by this specification. 1384 1386 </p> 1385 1387 <p id="rfc.section.3.3.1.p.8">Transfer-Encoding <em class="bcp14">MAY</em> be sent in a response to a HEAD request or in a <a href="p4-conditional.html#status.304" class="smpl">304 (Not Modified)</a> response (<a href="p4-conditional.html#status.304" title="304 Not Modified">Section 4.1</a> of <a href="#Part4" id="rfc.xref.Part4.2"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>) to a GET request, neither of which includes a message body, to indicate that the origin server would have applied a transfer … … 1661 1663 that a client can be assured of buffering the entire response. 1662 1664 </p> 1663 <p id="rfc.section.4.3.p.7">When multiple transfer-codings are acceptable, the client <em class="bcp14">MAY</em> rank the codings by preference using a "q" parameter (similar to the qvalues used in content negotiation fields, <a href="p2-semantics.html#quality.values" title="Quality Values">Section 8.3</a> of <a href="#Part2" id="rfc.xref.Part2.11"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). The rank value is a real number in the range 0 through 1, where 0.001 is the least preferred and 1 is the most preferred;1665 <p id="rfc.section.4.3.p.7">When multiple transfer-codings are acceptable, the client <em class="bcp14">MAY</em> rank the codings by preference using a "q" parameter (similar to the qvalues used in content negotiation fields, <a href="p2-semantics.html#quality.values" title="Quality Values">Section 9.3</a> of <a href="#Part2" id="rfc.xref.Part2.11"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). The rank value is a real number in the range 0 through 1, where 0.001 is the least preferred and 1 is the most preferred; 1664 1666 a value of 0 means "not acceptable". 1665 1667 </p> … … 1685 1687 for client-side processing (<a href="#RFC3986" id="rfc.xref.RFC3986.18"><cite title="Uniform Resource Identifier (URI): Generic Syntax">[RFC3986]</cite></a>, <a href="http://tools.ietf.org/html/rfc3986#section-3.5">Section 3.5</a>). 1686 1688 </p> 1687 <p id="rfc.section.5.1.p.3">HTTP intermediaries obtain the request semantics and target URI from the request-line of an incoming request message.</p>1688 1689 <h2 id="rfc.section.5.2"><a href="#rfc.section.5.2">5.2</a> <a id="connecting.inbound" href="#connecting.inbound">Connecting Inbound</a></h2> 1689 1690 <p id="rfc.section.5.2.p.1">Once the target URI is determined, a client needs to decide whether a network request is necessary to accomplish the desired … … 1742 1743 </p> 1743 1744 <div id="authority-form"> 1744 <p id="rfc.section.5.3.p.13"><span id="rfc.iref.a.3"></span> The authority-form of request-target is only used for CONNECT requests (<a href="p2-semantics.html#CONNECT" title="CONNECT">Section 2.3.8</a> of <a href="#Part2" id="rfc.xref.Part2.13"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). When making a CONNECT request to establish a tunnel through one or more proxies, a client <em class="bcp14">MUST</em> send only the target URI's authority component (excluding any userinfo) as the request-target. For example,1745 <p id="rfc.section.5.3.p.13"><span id="rfc.iref.a.3"></span> The authority-form of request-target is only used for CONNECT requests (<a href="p2-semantics.html#CONNECT" title="CONNECT">Section 3.3.8</a> of <a href="#Part2" id="rfc.xref.Part2.13"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). When making a CONNECT request to establish a tunnel through one or more proxies, a client <em class="bcp14">MUST</em> send only the target URI's authority component (excluding any userinfo) as the request-target. For example, 1745 1746 </p> 1746 1747 </div> 1747 1748 <div id="rfc.figure.u.41"></div><pre class="text2">CONNECT www.example.com:80 HTTP/1.1 1748 1749 </pre><div id="asterisk-form"> 1749 <p id="rfc.section.5.3.p.15"><span id="rfc.iref.a.4"></span> The asterisk-form of request-target is only used for a server-wide OPTIONS request (<a href="p2-semantics.html#OPTIONS" title="OPTIONS">Section 2.3.1</a> of <a href="#Part2" id="rfc.xref.Part2.14"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). When a client wishes to request OPTIONS for the server as a whole, as opposed to a specific named resource of that server,1750 <p id="rfc.section.5.3.p.15"><span id="rfc.iref.a.4"></span> The asterisk-form of request-target is only used for a server-wide OPTIONS request (<a href="p2-semantics.html#OPTIONS" title="OPTIONS">Section 3.3.1</a> of <a href="#Part2" id="rfc.xref.Part2.14"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). When a client wishes to request OPTIONS for the server as a whole, as opposed to a specific named resource of that server, 1750 1751 the client <em class="bcp14">MUST</em> send only "*" (%x2A) as the request-target. For example, 1751 1752 </p> … … 1893 1894 </p> 1894 1895 <ul> 1895 <li><a href="p2-semantics.html#header.allow" class="smpl">Allow</a> (<a href="p2-semantics.html#header.allow" title="Allow">Section 9.5</a> of <a href="#Part2" id="rfc.xref.Part2.16"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>)1896 </li> 1897 <li><a href="p2-semantics.html#header.content-location" class="smpl">Content-Location</a> (<a href="p2-semantics.html#header.content-location" title="Content-Location">Section 9.8</a> of <a href="#Part2" id="rfc.xref.Part2.17"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>)1896 <li><a href="p2-semantics.html#header.allow" class="smpl">Allow</a> (<a href="p2-semantics.html#header.allow" title="Allow">Section 10.5</a> of <a href="#Part2" id="rfc.xref.Part2.16"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) 1897 </li> 1898 <li><a href="p2-semantics.html#header.content-location" class="smpl">Content-Location</a> (<a href="p2-semantics.html#header.content-location" title="Content-Location">Section 10.8</a> of <a href="#Part2" id="rfc.xref.Part2.17"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) 1898 1899 </li> 1899 1900 <li>Content-MD5 (<a href="http://tools.ietf.org/html/rfc2616#section-14.15">Section 14.15</a> of <a href="#RFC2616" id="rfc.xref.RFC2616.3"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>) … … 1903 1904 <li><a href="p4-conditional.html#header.last-modified" class="smpl">Last-Modified</a> (<a href="p4-conditional.html#header.last-modified" title="Last-Modified">Section 2.2</a> of <a href="#Part4" id="rfc.xref.Part4.5"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>) 1904 1905 </li> 1905 <li><a href="p2-semantics.html#header.server" class="smpl">Server</a> (<a href="p2-semantics.html#header.server" title="Server">Section 9.17</a> of <a href="#Part2" id="rfc.xref.Part2.18"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>)1906 <li><a href="p2-semantics.html#header.server" class="smpl">Server</a> (<a href="p2-semantics.html#header.server" title="Server">Section 10.17</a> of <a href="#Part2" id="rfc.xref.Part2.18"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) 1906 1907 </li> 1907 1908 </ul> … … 1911 1912 </p> 1912 1913 <ul> 1913 <li><a href="p2-semantics.html#header.content-encoding" class="smpl">Content-Encoding</a> (<a href="p2-semantics.html#header.content-encoding" title="Content-Encoding">Section 9.6</a> of <a href="#Part2" id="rfc.xref.Part2.19"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>)1914 <li><a href="p2-semantics.html#header.content-encoding" class="smpl">Content-Encoding</a> (<a href="p2-semantics.html#header.content-encoding" title="Content-Encoding">Section 10.6</a> of <a href="#Part2" id="rfc.xref.Part2.19"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) 1914 1915 </li> 1915 1916 <li><a href="p5-range.html#header.content-range" class="smpl">Content-Range</a> (<a href="p5-range.html#header.content-range" title="Content-Range">Section 5.2</a> of <a href="#Part5" id="rfc.xref.Part5.2"><cite title="HTTP/1.1, part 5: Range Requests">[Part5]</cite></a>) 1916 1917 </li> 1917 <li><a href="p2-semantics.html#header.content-type" class="smpl">Content-Type</a> (<a href="p2-semantics.html#header.content-type" title="Content-Type">Section 9.9</a> of <a href="#Part2" id="rfc.xref.Part2.20"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>)1918 <li><a href="p2-semantics.html#header.content-type" class="smpl">Content-Type</a> (<a href="p2-semantics.html#header.content-type" title="Content-Type">Section 10.9</a> of <a href="#Part2" id="rfc.xref.Part2.20"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) 1918 1919 </li> 1919 1920 </ul> … … 1928 1929 <p id="rfc.section.5.9.p.1">HTTP does not include a request identifier for associating a given request message with its corresponding one or more response 1929 1930 messages. Hence, it relies on the order of response arrival to correspond exactly to the order in which requests are made 1930 on the same connection. More than one response message per request only occurs when one or more informational responses (<a href="p2-semantics.html#status.1xx" class="smpl">1xx</a>, see <a href="p2-semantics.html#status.1xx" title="Informational 1xx">Section 4.3</a> of <a href="#Part2" id="rfc.xref.Part2.21"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) precede a final response to the same request.1931 on the same connection. More than one response message per request only occurs when one or more informational responses (<a href="p2-semantics.html#status.1xx" class="smpl">1xx</a>, see <a href="p2-semantics.html#status.1xx" title="Informational 1xx">Section 5.3</a> of <a href="#Part2" id="rfc.xref.Part2.21"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) precede a final response to the same request. 1931 1932 </p> 1932 1933 <p id="rfc.section.5.9.p.2">A client that uses persistent connections and sends more than one request per connection <em class="bcp14">MUST</em> maintain a list of outstanding requests in the order sent on that connection and <em class="bcp14">MUST</em> associate each received response message to the highest ordered request that has not yet received a final (non-<a href="p2-semantics.html#status.1xx" class="smpl">1xx</a>) response. … … 2037 2038 <p id="rfc.section.6.2.2.1.p.2">Clients which assume persistent connections and pipeline immediately after connection establishment <em class="bcp14">SHOULD</em> be prepared to retry their connection if the first pipelined attempt fails. If a client does such a retry, it <em class="bcp14">MUST NOT</em> pipeline before it knows the connection is persistent. Clients <em class="bcp14">MUST</em> also be prepared to resend their requests if the server closes the connection before sending all of the corresponding responses. 2038 2039 </p> 2039 <p id="rfc.section.6.2.2.1.p.3">Clients <em class="bcp14">SHOULD NOT</em> pipeline requests using non-idempotent request methods or non-idempotent sequences of request methods (see <a href="p2-semantics.html#idempotent.methods" title="Idempotent Methods">Section 2.1.2</a> of <a href="#Part2" id="rfc.xref.Part2.22"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). Otherwise, a premature termination of the transport connection could lead to indeterminate results. A client wishing to2040 <p id="rfc.section.6.2.2.1.p.3">Clients <em class="bcp14">SHOULD NOT</em> pipeline requests using non-idempotent request methods or non-idempotent sequences of request methods (see <a href="p2-semantics.html#idempotent.methods" title="Idempotent Methods">Section 3.1.2</a> of <a href="#Part2" id="rfc.xref.Part2.22"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). Otherwise, a premature termination of the transport connection could lead to indeterminate results. A client wishing to 2040 2041 send a non-idempotent request <em class="bcp14">SHOULD</em> wait to send that request until it has received the response status line for the previous request. 2041 2042 </p> 2042 2043 <h4 id="rfc.section.6.2.2.2"><a href="#rfc.section.6.2.2.2">6.2.2.2</a> <a id="persistent.retrying.requests" href="#persistent.retrying.requests">Retrying Requests</a></h4> 2043 2044 <p id="rfc.section.6.2.2.2.p.1">Senders can close the transport connection at any time. Therefore, clients, servers, and proxies <em class="bcp14">MUST</em> be able to recover from asynchronous close events. Client software <em class="bcp14">MAY</em> reopen the transport connection and retransmit the aborted sequence of requests without user interaction so long as the request 2044 sequence is idempotent (see <a href="p2-semantics.html#idempotent.methods" title="Idempotent Methods">Section 2.1.2</a> of <a href="#Part2" id="rfc.xref.Part2.23"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). Non-idempotent request methods or sequences <em class="bcp14">MUST NOT</em> be automatically retried, although user agents <em class="bcp14">MAY</em> offer a human operator the choice of retrying the request(s). Confirmation by user-agent software with semantic understanding2045 sequence is idempotent (see <a href="p2-semantics.html#idempotent.methods" title="Idempotent Methods">Section 3.1.2</a> of <a href="#Part2" id="rfc.xref.Part2.23"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). Non-idempotent request methods or sequences <em class="bcp14">MUST NOT</em> be automatically retried, although user agents <em class="bcp14">MAY</em> offer a human operator the choice of retrying the request(s). Confirmation by user-agent software with semantic understanding 2045 2046 of the application <em class="bcp14">MAY</em> substitute for user confirmation. The automatic retry <em class="bcp14">SHOULD NOT</em> be repeated if the second sequence of requests fails. 2046 2047 </p> … … 2093 2094 </p> 2094 2095 <h2 id="rfc.section.6.3"><a href="#rfc.section.6.3">6.3</a> <a id="use.of.the.100.status" href="#use.of.the.100.status">Use of the 100 (Continue) Status</a></h2> 2095 <p id="rfc.section.6.3.p.1">The purpose of the <a href="p2-semantics.html#status.100" class="smpl">100 (Continue)</a> status code (see <a href="p2-semantics.html#status.100" title="100 Continue">Section 4.3.1</a> of <a href="#Part2" id="rfc.xref.Part2.24"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) is to allow a client that is sending a request message with a request body to determine if the origin server is willing2096 <p id="rfc.section.6.3.p.1">The purpose of the <a href="p2-semantics.html#status.100" class="smpl">100 (Continue)</a> status code (see <a href="p2-semantics.html#status.100" title="100 Continue">Section 5.3.1</a> of <a href="#Part2" id="rfc.xref.Part2.24"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) is to allow a client that is sending a request message with a request body to determine if the origin server is willing 2096 2097 to accept the request (based on the request header fields) before the client sends the request body. In some cases, it might 2097 2098 either be inappropriate or highly inefficient for the client to send the body if the server will reject the message without … … 2100 2101 <p id="rfc.section.6.3.p.2">Requirements for HTTP/1.1 clients: </p> 2101 2102 <ul> 2102 <li>If a client will wait for a <a href="p2-semantics.html#status.100" class="smpl">100 (Continue)</a> response before sending the request body, it <em class="bcp14">MUST</em> send an <a href="p2-semantics.html#header.expect" class="smpl">Expect</a> header field (<a href="p2-semantics.html#header.expect" title="Expect">Section 9.11</a> of <a href="#Part2" id="rfc.xref.Part2.25"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) with the "100-continue" expectation.2103 <li>If a client will wait for a <a href="p2-semantics.html#status.100" class="smpl">100 (Continue)</a> response before sending the request body, it <em class="bcp14">MUST</em> send an <a href="p2-semantics.html#header.expect" class="smpl">Expect</a> header field (<a href="p2-semantics.html#header.expect" title="Expect">Section 10.11</a> of <a href="#Part2" id="rfc.xref.Part2.25"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) with the "100-continue" expectation. 2103 2104 </li> 2104 2105 <li>A client <em class="bcp14">MUST NOT</em> send an <a href="p2-semantics.html#header.expect" class="smpl">Expect</a> header field with the "100-continue" expectation if it does not intend to send a request body. … … 2138 2139 <li>Proxies <em class="bcp14">SHOULD</em> maintain a record of the HTTP version numbers received from recently-referenced next-hop servers. 2139 2140 </li> 2140 <li>A proxy <em class="bcp14">MUST NOT</em> forward a <a href="p2-semantics.html#status.100" class="smpl">100 (Continue)</a> response if the request message was received from an HTTP/1.0 (or earlier) client and did not include an <a href="p2-semantics.html#header.expect" class="smpl">Expect</a> header field with the "100-continue" expectation. This requirement overrides the general rule for forwarding of <a href="p2-semantics.html#status.1xx" class="smpl">1xx</a> responses (see <a href="p2-semantics.html#status.1xx" title="Informational 1xx">Section 4.3</a> of <a href="#Part2" id="rfc.xref.Part2.26"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>).2141 <li>A proxy <em class="bcp14">MUST NOT</em> forward a <a href="p2-semantics.html#status.100" class="smpl">100 (Continue)</a> response if the request message was received from an HTTP/1.0 (or earlier) client and did not include an <a href="p2-semantics.html#header.expect" class="smpl">Expect</a> header field with the "100-continue" expectation. This requirement overrides the general rule for forwarding of <a href="p2-semantics.html#status.1xx" class="smpl">1xx</a> responses (see <a href="p2-semantics.html#status.1xx" title="Informational 1xx">Section 5.3</a> of <a href="#Part2" id="rfc.xref.Part2.26"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). 2141 2142 </li> 2142 2143 </ul> … … 2169 2170 </p> 2170 2171 <p id="rfc.section.6.4.p.8">The Upgrade header field cannot be used to indicate a switch to a protocol on a different connection. For that purpose, it 2171 is more appropriate to use a <a href="p2-semantics.html#status.3xx" class="smpl">3xx (Redirection)</a> response (<a href="p2-semantics.html#status.3xx" title="Redirection 3xx">Section 4.5</a> of <a href="#Part2" id="rfc.xref.Part2.27"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>).2172 is more appropriate to use a <a href="p2-semantics.html#status.3xx" class="smpl">3xx (Redirection)</a> response (<a href="p2-semantics.html#status.3xx" title="Redirection 3xx">Section 5.5</a> of <a href="#Part2" id="rfc.xref.Part2.27"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). 2172 2173 </p> 2173 2174 <p id="rfc.section.6.4.p.9">Servers <em class="bcp14">MUST</em> include the "Upgrade" header field in <a href="p2-semantics.html#status.101" class="smpl">101 (Switching … … 2433 2434 <li>Pointer to specification text</li> 2434 2435 </ul> 2435 <p id="rfc.section.7.4.p.3">Names of transfer codings <em class="bcp14">MUST NOT</em> overlap with names of content codings (<a href="p2-semantics.html#content.codings" title="Content Codings">Section 5.4</a> of <a href="#Part2" id="rfc.xref.Part2.28"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) unless the encoding transformation is identical, as is the case for the compression codings defined in <a href="#compression.codings" title="Compression Codings">Section 4.2</a>.2436 <p id="rfc.section.7.4.p.3">Names of transfer codings <em class="bcp14">MUST NOT</em> overlap with names of content codings (<a href="p2-semantics.html#content.codings" title="Content Codings">Section 6.4</a> of <a href="#Part2" id="rfc.xref.Part2.28"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) unless the encoding transformation is identical, as is the case for the compression codings defined in <a href="#compression.codings" title="Compression Codings">Section 4.2</a>. 2436 2437 </p> 2437 2438 <p id="rfc.section.7.4.p.4">Values to be added to this name space require IETF Review (see <a href="http://tools.ietf.org/html/rfc5226#section-4.1">Section 4.1</a> of <a href="#RFC5226" id="rfc.xref.RFC5226.1"><cite title="Guidelines for Writing an IANA Considerations Section in RFCs">[RFC5226]</cite></a>), and <em class="bcp14">MUST</em> conform to the purpose of transfer coding defined in this section. Use of program names for the identification of encoding … … 2589 2590 that most implementations will choose substantially higher limits. 2590 2591 </p> 2591 <p id="rfc.section.8.6.p.3">This specification also provides a way for servers to reject messages that have request-targets that are too long (<a href="p2-semantics.html#status.414" title="414 URI Too Long">Section 4.6.12</a> of <a href="#Part2" id="rfc.xref.Part2.29"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) or request entities that are too large (<a href="p2-semantics.html#status.4xx" title="Client Error 4xx">Section 4.6</a> of <a href="#Part2" id="rfc.xref.Part2.30"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>).2592 <p id="rfc.section.8.6.p.3">This specification also provides a way for servers to reject messages that have request-targets that are too long (<a href="p2-semantics.html#status.414" title="414 URI Too Long">Section 5.6.12</a> of <a href="#Part2" id="rfc.xref.Part2.29"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>) or request entities that are too large (<a href="p2-semantics.html#status.4xx" title="Client Error 4xx">Section 5.6</a> of <a href="#Part2" id="rfc.xref.Part2.30"><cite title="HTTP/1.1, part 2: Semantics and Payloads">[Part2]</cite></a>). 2592 2593 </p> 2593 2594 <p id="rfc.section.8.6.p.4">Other fields (including but not limited to request methods, response status phrases, header field-names, and body chunks) <em class="bcp14">SHOULD</em> be limited by implementations carefully, so as to not impede interoperability. … … 3665 3666 <li><a id="rfc.index.P" href="#rfc.index.P"><b>P</b></a><ul> 3666 3667 <li><em>Part2</em> <a href="#rfc.xref.Part2.1">1</a>, <a href="#rfc.xref.Part2.2">2.1</a>, <a href="#rfc.xref.Part2.3">2.3</a>, <a href="#rfc.xref.Part2.4">2.7.1</a>, <a href="#rfc.xref.Part2.5">3.1.1</a>, <a href="#rfc.xref.Part2.6">3.1.1</a>, <a href="#rfc.xref.Part2.7">3.1.2</a>, <a href="#rfc.xref.Part2.8">3.2</a>, <a href="#rfc.xref.Part2.9">3.2</a>, <a href="#rfc.xref.Part2.10">3.3.1</a>, <a href="#rfc.xref.Part2.11">4.3</a>, <a href="#rfc.xref.Part2.12">5.1</a>, <a href="#rfc.xref.Part2.13">5.3</a>, <a href="#rfc.xref.Part2.14">5.3</a>, <a href="#rfc.xref.Part2.15">5.8</a>, <a href="#rfc.xref.Part2.16">5.8</a>, <a href="#rfc.xref.Part2.17">5.8</a>, <a href="#rfc.xref.Part2.18">5.8</a>, <a href="#rfc.xref.Part2.19">5.8</a>, <a href="#rfc.xref.Part2.20">5.8</a>, <a href="#rfc.xref.Part2.21">5.9</a>, <a href="#rfc.xref.Part2.22">6.2.2.1</a>, <a href="#rfc.xref.Part2.23">6.2.2.2</a>, <a href="#rfc.xref.Part2.24">6.3</a>, <a href="#rfc.xref.Part2.25">6.3</a>, <a href="#rfc.xref.Part2.26">6.3</a>, <a href="#rfc.xref.Part2.27">6.4</a>, <a href="#rfc.xref.Part2.28">7.4</a>, <a href="#rfc.xref.Part2.29">8.6</a>, <a href="#rfc.xref.Part2.30">8.6</a>, <a href="#Part2"><b>10.1</b></a><ul> 3667 <li><em>Section 2</em> <a href="#rfc.xref.Part2.5">3.1.1</a></li>3668 <li><em>Section 2.1.2</em> <a href="#rfc.xref.Part2.22">6.2.2.1</a>, <a href="#rfc.xref.Part2.23">6.2.2.2</a></li>3669 <li><em>Section 2.3.1</em> <a href="#rfc.xref.Part2.14">5.3</a></li>3670 <li><em>Section 2.3.8</em> <a href="#rfc.xref.Part2.13">5.3</a></li>3671 <li><em>Section 3.1</em> <a href="#rfc.xref.Part2.9">3.2</a></li>3672 <li><em>Section 4</em> <a href="#rfc.xref.Part2.4">2.7.1</a>, <a href="#rfc.xref.Part2.7">3.1.2</a></li>3673 <li><em>Section 4.3</em> <a href="#rfc.xref.Part2.21">5.9</a>, <a href="#rfc.xref.Part2.26">6.3</a></li>3674 <li><em>Section 4.3.1</em> <a href="#rfc.xref.Part2.24">6.3</a></li>3675 <li><em>Section 4.4.4</em> <a href="#rfc.xref.Part2.3">2.3</a></li>3676 <li><em>Section 4.5</em> <a href="#rfc.xref.Part2.27">6.4</a></li>3677 <li><em>Section 4.6</em> <a href="#rfc.xref.Part2.30">8.6</a></li>3678 <li><em>Section 4.6.12</em> <a href="#rfc.xref.Part2.6">3.1.1</a>, <a href="#rfc.xref.Part2.29">8.6</a></li>3679 <li><em>Section 5.4</em> <a href="#rfc.xref.Part2.10">3.3.1</a>, <a href="#rfc.xref.Part2.28">7.4</a></li>3680 <li><em>Section 8.3</em> <a href="#rfc.xref.Part2.11">4.3</a></li>3681 <li><em>Section 9.5</em> <a href="#rfc.xref.Part2.16">5.8</a></li>3682 <li><em>Section 9.6</em> <a href="#rfc.xref.Part2.19">5.8</a></li>3683 <li><em>Section 9.8</em> <a href="#rfc.xref.Part2.17">5.8</a></li>3684 <li><em>Section 9.9</em> <a href="#rfc.xref.Part2.20">5.8</a></li>3685 <li><em>Section 9.10</em> <a href="#rfc.xref.Part2.8">3.2</a></li>3686 <li><em>Section 9.11</em> <a href="#rfc.xref.Part2.25">6.3</a></li>3687 <li><em>Section 9.17</em> <a href="#rfc.xref.Part2.18">5.8</a></li>3668 <li><em>Section 3</em> <a href="#rfc.xref.Part2.5">3.1.1</a></li> 3669 <li><em>Section 3.1.2</em> <a href="#rfc.xref.Part2.22">6.2.2.1</a>, <a href="#rfc.xref.Part2.23">6.2.2.2</a></li> 3670 <li><em>Section 3.3.1</em> <a href="#rfc.xref.Part2.14">5.3</a></li> 3671 <li><em>Section 3.3.8</em> <a href="#rfc.xref.Part2.13">5.3</a></li> 3672 <li><em>Section 4.5</em> <a href="#rfc.xref.Part2.9">3.2</a></li> 3673 <li><em>Section 5</em> <a href="#rfc.xref.Part2.4">2.7.1</a>, <a href="#rfc.xref.Part2.7">3.1.2</a></li> 3674 <li><em>Section 5.3</em> <a href="#rfc.xref.Part2.21">5.9</a>, <a href="#rfc.xref.Part2.26">6.3</a></li> 3675 <li><em>Section 5.3.1</em> <a href="#rfc.xref.Part2.24">6.3</a></li> 3676 <li><em>Section 5.4.4</em> <a href="#rfc.xref.Part2.3">2.3</a></li> 3677 <li><em>Section 5.5</em> <a href="#rfc.xref.Part2.27">6.4</a></li> 3678 <li><em>Section 5.6</em> <a href="#rfc.xref.Part2.30">8.6</a></li> 3679 <li><em>Section 5.6.12</em> <a href="#rfc.xref.Part2.6">3.1.1</a>, <a href="#rfc.xref.Part2.29">8.6</a></li> 3680 <li><em>Section 6.4</em> <a href="#rfc.xref.Part2.10">3.3.1</a>, <a href="#rfc.xref.Part2.28">7.4</a></li> 3681 <li><em>Section 9.3</em> <a href="#rfc.xref.Part2.11">4.3</a></li> 3682 <li><em>Section 10.5</em> <a href="#rfc.xref.Part2.16">5.8</a></li> 3683 <li><em>Section 10.6</em> <a href="#rfc.xref.Part2.19">5.8</a></li> 3684 <li><em>Section 10.8</em> <a href="#rfc.xref.Part2.17">5.8</a></li> 3685 <li><em>Section 10.9</em> <a href="#rfc.xref.Part2.20">5.8</a></li> 3686 <li><em>Section 10.10</em> <a href="#rfc.xref.Part2.8">3.2</a></li> 3687 <li><em>Section 10.11</em> <a href="#rfc.xref.Part2.25">6.3</a></li> 3688 <li><em>Section 10.17</em> <a href="#rfc.xref.Part2.18">5.8</a></li> 3688 3689 <li><em>Appendix A</em> <a href="#rfc.xref.Part2.2">2.1</a></li> 3689 3690 </ul>
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