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Changeset 1905 for draft-ietf-httpbis/latest/p1-messaging.html
- Timestamp:
- 18/09/12 09:26:12 (10 years ago)
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draft-ietf-httpbis/latest/p1-messaging.html (modified) (20 diffs)
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draft-ietf-httpbis/latest/p1-messaging.html
r1904 r1905 907 907 or an intranet-to-Internet privacy filter. Such transformations are presumed to be desired by the client (or client organization) 908 908 that selected the proxy and are beyond the scope of this specification. However, when a proxy is not intended to transform 909 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 7.3.4</a> of <a href="#Part2" id="rfc.xref.Part2.3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a> and <a href="p6-cache.html#header.warning" title="Warning">Section 7.5</a> of <a href="#Part6" id="rfc.xref.Part6.2"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a> for status and warning codes related to transformations.909 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 6.3.4</a> of <a href="#Part2" id="rfc.xref.Part2.3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a> and <a href="p6-cache.html#header.warning" title="Warning">Section 7.5</a> of <a href="#Part6" id="rfc.xref.Part6.2"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a> for status and warning codes related to transformations. 910 910 </p> 911 911 <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 … … 1077 1077 </p> 1078 1078 <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, 1079 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 7</a> of <a href="#Part2" id="rfc.xref.Part2.5"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>, then that response is considered an authoritative answer to the client's request.1079 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 6</a> of <a href="#Part2" id="rfc.xref.Part2.5"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>, then that response is considered an authoritative answer to the client's request. 1080 1080 </p> 1081 1081 <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 … … 1175 1175 </div> 1176 1176 <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> 1177 </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 5</a> of <a href="#Part2" id="rfc.xref.Part2.6"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>, along with information regarding the HTTP method registry and considerations for defining new methods.1177 </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 4</a> of <a href="#Part2" id="rfc.xref.Part2.6"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>, along with information regarding the HTTP method registry and considerations for defining new methods. 1178 1178 </p> 1179 1179 <div id="rfc.iref.r.6"></div> … … 1188 1188 </p> 1189 1189 <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 1190 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 7.5.12</a> of <a href="#Part2" id="rfc.xref.Part2.7"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>).1190 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 6.5.12</a> of <a href="#Part2" id="rfc.xref.Part2.7"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>). 1191 1191 </p> 1192 1192 <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. … … 1201 1201 <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 1202 1202 the client's corresponding request. The rest of the response message is to be interpreted in light of the semantics defined 1203 for that status code. See <a href="p2-semantics.html#status.codes" title="Response Status Codes">Section 7</a> of <a href="#Part2" id="rfc.xref.Part2.8"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a> for information about the semantics of status codes, including the classes of status code (indicated by the first digit),1203 for that status code. See <a href="p2-semantics.html#status.codes" title="Response Status Codes">Section 6</a> of <a href="#Part2" id="rfc.xref.Part2.8"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a> for information about the semantics of status codes, including the classes of status code (indicated by the first digit), 1204 1204 the status codes defined by this specification, considerations for the definition of new status codes, and the IANA registry. 1205 1205 </p> … … 1222 1222 ; see <a href="#field.parsing" title="Field Parsing">Section 3.2.2</a> 1223 1223 </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, 1224 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 8.2.1</a> of <a href="#Part2" id="rfc.xref.Part2.9"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a> as containing the origination timestamp for the message in which it appears.1224 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 7.2.1</a> of <a href="#Part2" id="rfc.xref.Part2.9"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a> as containing the origination timestamp for the message in which it appears. 1225 1225 </p> 1226 1226 <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 … … 1230 1230 them. 1231 1231 </p> 1232 <p id="rfc.section.3.2.p.5">New HTTP header fields <em class="bcp14">SHOULD</em> be registered with IANA in the Message Header Field Registry, as described in <a href="p2-semantics.html#header.field.registry" title="Header Field Registry">Section 10.3</a> of <a href="#Part2" id="rfc.xref.Part2.10"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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 <p id="rfc.section.3.2.p.5">New HTTP header fields <em class="bcp14">SHOULD</em> be registered with IANA in the Message Header Field Registry, as described in <a href="p2-semantics.html#header.field.registry" title="Header Field Registry">Section 9.3</a> of <a href="#Part2" id="rfc.xref.Part2.10"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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 1233 </p> 1234 1234 <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 1381 <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 1382 </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 9.4</a> of <a href="#Part2" id="rfc.xref.Part2.11"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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.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 8.4</a> of <a href="#Part2" id="rfc.xref.Part2.11"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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 1384 </p> 1385 1385 <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="Hypertext Transfer Protocol (HTTP/1.1): 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 … … 1655 1655 </p> 1656 1656 <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 case-insensitive "q" parameter (similar to the qvalues used in content negotiation 1657 fields, <a href="p2-semantics.html#quality.values" title="Quality Values">Section 6.3.1</a> of <a href="#Part2" id="rfc.xref.Part2.12"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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;1657 fields, <a href="p2-semantics.html#quality.values" title="Quality Values">Section 5.3.1</a> of <a href="#Part2" id="rfc.xref.Part2.12"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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; 1658 1658 a value of 0 means "not acceptable". 1659 1659 </p> … … 1735 1735 </p> 1736 1736 <div id="authority-form"> 1737 <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 5.3.6</a> of <a href="#Part2" id="rfc.xref.Part2.14"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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,1737 <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 4.3.6</a> of <a href="#Part2" id="rfc.xref.Part2.14"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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, 1738 1738 </p> 1739 1739 </div> 1740 1740 <div id="rfc.figure.u.41"></div><pre class="text2">CONNECT www.example.com:80 HTTP/1.1 1741 1741 </pre><div id="asterisk-form"> 1742 <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 5.3.7</a> of <a href="#Part2" id="rfc.xref.Part2.15"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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,1742 <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 4.3.7</a> of <a href="#Part2" id="rfc.xref.Part2.15"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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, 1743 1743 the client <em class="bcp14">MUST</em> send only "*" (%x2A) as the request-target. For example, 1744 1744 </p> … … 1876 1876 except as noted above to replace an empty path with "/" or "*". 1877 1877 </p> 1878 <p id="rfc.section.5.8.p.3">A non-transforming proxy <em class="bcp14">MUST</em> preserve the message payload (<a href=" #Part2" id="rfc.xref.Part2.16"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>), though it <em class="bcp14">MAY</em> change the message body through application or removal of a transfer-coding (<a href="#transfer.codings" title="Transfer Codings">Section 4</a>).1878 <p id="rfc.section.5.8.p.3">A non-transforming proxy <em class="bcp14">MUST</em> preserve the message payload (<a href="p2-semantics.html#payload" title="Message Payload">Section 3.1</a> of <a href="#Part2" id="rfc.xref.Part2.16"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>), though it <em class="bcp14">MAY</em> change the message body through application or removal of a transfer-coding (<a href="#transfer.codings" title="Transfer Codings">Section 4</a>). 1879 1879 </p> 1880 1880 <p id="rfc.section.5.8.p.4">A non-transforming proxy <em class="bcp14">SHOULD NOT</em> modify header fields that provide information about the end points of the communication chain, the resource state, or the … … 1884 1884 </p> 1885 1885 <ul> 1886 <li><a href="p2-semantics.html#header.allow" class="smpl">Allow</a> (<a href="p2-semantics.html#header.allow" title="Allow">Section 8.4.1</a> of <a href="#Part2" id="rfc.xref.Part2.17"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>)1887 </li> 1888 <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 3. 2.4</a> of <a href="#Part2" id="rfc.xref.Part2.18"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>)1886 <li><a href="p2-semantics.html#header.allow" class="smpl">Allow</a> (<a href="p2-semantics.html#header.allow" title="Allow">Section 7.4.1</a> of <a href="#Part2" id="rfc.xref.Part2.17"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) 1887 </li> 1888 <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 3.3.4</a> of <a href="#Part2" id="rfc.xref.Part2.18"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) 1889 1889 </li> 1890 1890 <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>) … … 1894 1894 <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="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>) 1895 1895 </li> 1896 <li><a href="p2-semantics.html#header.server" class="smpl">Server</a> (<a href="p2-semantics.html#header.server" title="Server">Section 8.4.2</a> of <a href="#Part2" id="rfc.xref.Part2.19"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>)1896 <li><a href="p2-semantics.html#header.server" class="smpl">Server</a> (<a href="p2-semantics.html#header.server" title="Server">Section 7.4.2</a> of <a href="#Part2" id="rfc.xref.Part2.19"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) 1897 1897 </li> 1898 1898 </ul> … … 1902 1902 </p> 1903 1903 <ul> 1904 <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 3. 2.2</a> of <a href="#Part2" id="rfc.xref.Part2.20"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>)1904 <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 3.3.2</a> of <a href="#Part2" id="rfc.xref.Part2.20"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) 1905 1905 </li> 1906 1906 <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="Hypertext Transfer Protocol (HTTP/1.1): Range Requests">[Part5]</cite></a>) 1907 1907 </li> 1908 <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 3. 2.1</a> of <a href="#Part2" id="rfc.xref.Part2.21"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>)1908 <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 3.3.1</a> of <a href="#Part2" id="rfc.xref.Part2.21"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) 1909 1909 </li> 1910 1910 </ul> … … 1919 1919 <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 1920 1920 messages. Hence, it relies on the order of response arrival to correspond exactly to the order in which requests are made 1921 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 7.2</a> of <a href="#Part2" id="rfc.xref.Part2.22"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) precede a final response to the same request.1921 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 6.2</a> of <a href="#Part2" id="rfc.xref.Part2.22"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) precede a final response to the same request. 1922 1922 </p> 1923 1923 <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. … … 2040 2040 <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. 2041 2041 </p> 2042 <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 5.2.2</a> of <a href="#Part2" id="rfc.xref.Part2.23"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>). Otherwise, a premature termination of the transport connection could lead to indeterminate results. A client wishing to2042 <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 4.2.2</a> of <a href="#Part2" id="rfc.xref.Part2.23"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>). Otherwise, a premature termination of the transport connection could lead to indeterminate results. A client wishing to 2043 2043 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. 2044 2044 </p> 2045 2045 <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> 2046 2046 <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 2047 sequence is idempotent (see <a href="p2-semantics.html#idempotent.methods" title="Idempotent Methods">Section 5.2.2</a> of <a href="#Part2" id="rfc.xref.Part2.24"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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 understanding2047 sequence is idempotent (see <a href="p2-semantics.html#idempotent.methods" title="Idempotent Methods">Section 4.2.2</a> of <a href="#Part2" id="rfc.xref.Part2.24"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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 2048 2048 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. 2049 2049 </p> … … 2138 2138 </p> 2139 2139 <p id="rfc.section.6.3.p.9">The Upgrade header field only applies to switching application-level protocols on the existing connection; it cannot be used 2140 to switch to a protocol on a different connection. For that purpose, it 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 7.4</a> of <a href="#Part2" id="rfc.xref.Part2.25"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>).2140 to switch to a protocol on a different connection. For that purpose, it 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 6.4</a> of <a href="#Part2" id="rfc.xref.Part2.25"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>). 2141 2141 </p> 2142 2142 <p id="rfc.section.6.3.p.10">This specification only defines the protocol name "HTTP" for use by the family of Hypertext Transfer Protocols, as defined … … 2399 2399 <li>Pointer to specification text</li> 2400 2400 </ul> 2401 <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 9.4</a> of <a href="#Part2" id="rfc.xref.Part2.26"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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>.2401 <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 8.4</a> of <a href="#Part2" id="rfc.xref.Part2.26"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[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>. 2402 2402 </p> 2403 2403 <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 … … 2554 2554 that most implementations will choose substantially higher limits. 2555 2555 </p> 2556 <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 7.5.12</a> of <a href="#Part2" id="rfc.xref.Part2.27"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) or request entities that are too large (<a href="p2-semantics.html#status.4xx" title="Client Error 4xx">Section 7.5</a> of <a href="#Part2" id="rfc.xref.Part2.28"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>).2556 <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 6.5.12</a> of <a href="#Part2" id="rfc.xref.Part2.27"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) or request entities that are too large (<a href="p2-semantics.html#status.4xx" title="Client Error 4xx">Section 6.5</a> of <a href="#Part2" id="rfc.xref.Part2.28"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>). 2557 2557 </p> 2558 2558 <p id="rfc.section.8.6.p.4">Recipients <em class="bcp14">SHOULD</em> carefully limit the extent to which they read other fields, including (but not limited to) request methods, response status … … 3632 3632 <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</a>, <a href="#rfc.xref.Part2.5">2.7.1</a>, <a href="#rfc.xref.Part2.6">3.1.1</a>, <a href="#rfc.xref.Part2.7">3.1.1</a>, <a href="#rfc.xref.Part2.8">3.1.2</a>, <a href="#rfc.xref.Part2.9">3.2</a>, <a href="#rfc.xref.Part2.10">3.2</a>, <a href="#rfc.xref.Part2.11">3.3.1</a>, <a href="#rfc.xref.Part2.12">4.3</a>, <a href="#rfc.xref.Part2.13">5.1</a>, <a href="#rfc.xref.Part2.14">5.3</a>, <a href="#rfc.xref.Part2.15">5.3</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">5.8</a>, <a href="#rfc.xref.Part2.22">5.9</a>, <a href="#rfc.xref.Part2.23">6.2.2.1</a>, <a href="#rfc.xref.Part2.24">6.2.2.2</a>, <a href="#rfc.xref.Part2.25">6.3</a>, <a href="#rfc.xref.Part2.26">7.4</a>, <a href="#rfc.xref.Part2.27">8.6</a>, <a href="#rfc.xref.Part2.28">8.6</a>, <a href="#Part2"><b>10.1</b></a><ul> 3633 3633 <li><em>Section 2</em> <a href="#rfc.xref.Part2.4">2.7</a></li> 3634 <li><em>Section 3.2.1</em> <a href="#rfc.xref.Part2.21">5.8</a></li> 3635 <li><em>Section 3.2.2</em> <a href="#rfc.xref.Part2.20">5.8</a></li> 3636 <li><em>Section 3.2.4</em> <a href="#rfc.xref.Part2.18">5.8</a></li> 3637 <li><em>Section 5</em> <a href="#rfc.xref.Part2.6">3.1.1</a></li> 3638 <li><em>Section 5.2.2</em> <a href="#rfc.xref.Part2.23">6.2.2.1</a>, <a href="#rfc.xref.Part2.24">6.2.2.2</a></li> 3639 <li><em>Section 5.3.6</em> <a href="#rfc.xref.Part2.14">5.3</a></li> 3640 <li><em>Section 5.3.7</em> <a href="#rfc.xref.Part2.15">5.3</a></li> 3641 <li><em>Section 6.3.1</em> <a href="#rfc.xref.Part2.12">4.3</a></li> 3642 <li><em>Section 7</em> <a href="#rfc.xref.Part2.5">2.7.1</a>, <a href="#rfc.xref.Part2.8">3.1.2</a></li> 3643 <li><em>Section 7.2</em> <a href="#rfc.xref.Part2.22">5.9</a></li> 3644 <li><em>Section 7.3.4</em> <a href="#rfc.xref.Part2.3">2.3</a></li> 3645 <li><em>Section 7.4</em> <a href="#rfc.xref.Part2.25">6.3</a></li> 3646 <li><em>Section 7.5</em> <a href="#rfc.xref.Part2.28">8.6</a></li> 3647 <li><em>Section 7.5.12</em> <a href="#rfc.xref.Part2.7">3.1.1</a>, <a href="#rfc.xref.Part2.27">8.6</a></li> 3648 <li><em>Section 8.2.1</em> <a href="#rfc.xref.Part2.9">3.2</a></li> 3649 <li><em>Section 8.4.1</em> <a href="#rfc.xref.Part2.17">5.8</a></li> 3650 <li><em>Section 8.4.2</em> <a href="#rfc.xref.Part2.19">5.8</a></li> 3651 <li><em>Section 9.4</em> <a href="#rfc.xref.Part2.11">3.3.1</a>, <a href="#rfc.xref.Part2.26">7.4</a></li> 3652 <li><em>Section 10.3</em> <a href="#rfc.xref.Part2.10">3.2</a></li> 3634 <li><em>Section 3.1</em> <a href="#rfc.xref.Part2.16">5.8</a></li> 3635 <li><em>Section 3.3.1</em> <a href="#rfc.xref.Part2.21">5.8</a></li> 3636 <li><em>Section 3.3.2</em> <a href="#rfc.xref.Part2.20">5.8</a></li> 3637 <li><em>Section 3.3.4</em> <a href="#rfc.xref.Part2.18">5.8</a></li> 3638 <li><em>Section 4</em> <a href="#rfc.xref.Part2.6">3.1.1</a></li> 3639 <li><em>Section 4.2.2</em> <a href="#rfc.xref.Part2.23">6.2.2.1</a>, <a href="#rfc.xref.Part2.24">6.2.2.2</a></li> 3640 <li><em>Section 4.3.6</em> <a href="#rfc.xref.Part2.14">5.3</a></li> 3641 <li><em>Section 4.3.7</em> <a href="#rfc.xref.Part2.15">5.3</a></li> 3642 <li><em>Section 5.3.1</em> <a href="#rfc.xref.Part2.12">4.3</a></li> 3643 <li><em>Section 6</em> <a href="#rfc.xref.Part2.5">2.7.1</a>, <a href="#rfc.xref.Part2.8">3.1.2</a></li> 3644 <li><em>Section 6.2</em> <a href="#rfc.xref.Part2.22">5.9</a></li> 3645 <li><em>Section 6.3.4</em> <a href="#rfc.xref.Part2.3">2.3</a></li> 3646 <li><em>Section 6.4</em> <a href="#rfc.xref.Part2.25">6.3</a></li> 3647 <li><em>Section 6.5</em> <a href="#rfc.xref.Part2.28">8.6</a></li> 3648 <li><em>Section 6.5.12</em> <a href="#rfc.xref.Part2.7">3.1.1</a>, <a href="#rfc.xref.Part2.27">8.6</a></li> 3649 <li><em>Section 7.2.1</em> <a href="#rfc.xref.Part2.9">3.2</a></li> 3650 <li><em>Section 7.4.1</em> <a href="#rfc.xref.Part2.17">5.8</a></li> 3651 <li><em>Section 7.4.2</em> <a href="#rfc.xref.Part2.19">5.8</a></li> 3652 <li><em>Section 8.4</em> <a href="#rfc.xref.Part2.11">3.3.1</a>, <a href="#rfc.xref.Part2.26">7.4</a></li> 3653 <li><em>Section 9.3</em> <a href="#rfc.xref.Part2.10">3.2</a></li> 3653 3654 <li><em>Appendix A</em> <a href="#rfc.xref.Part2.2">2.1</a></li> 3654 3655 </ul>
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