Changeset 1796 for draft-ietf-httpbis/latest/p4-conditional.xml
- Timestamp:
- 16/07/12 05:38:18 (9 years ago)
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draft-ietf-httpbis/latest/p4-conditional.xml
r1786 r1796 171 171 for the selected representation. 172 172 </t> 173 174 <section title="Conformance and Error Handling" anchor="intro.conformance.and.error.handling"> 175 <t> 176 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 177 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 178 document are to be interpreted as described in <xref target="RFC2119"/>. 179 </t> 180 <t> 181 This specification targets conformance criteria according to the role of 182 a participant in HTTP communication. Hence, HTTP requirements are placed 183 on senders, recipients, clients, servers, user agents, intermediaries, 184 origin servers, proxies, gateways, or caches, depending on what behavior 185 is being constrained by the requirement. See &architecture; for definitions 186 of these terms. 187 </t> 188 <t> 189 The verb "generate" is used instead of "send" where a requirement 190 differentiates between creating a protocol element and merely forwarding a 191 received element downstream. 192 </t> 193 <t> 194 An implementation is considered conformant if it complies with all of the 195 requirements associated with the roles it partakes in HTTP. Note that 196 SHOULD-level requirements are relevant here, unless one of the documented 197 exceptions is applicable. 198 </t> 199 <t> 200 This document also uses ABNF to define valid protocol elements 201 (<xref target="notation"/>). 202 In addition to the prose requirements placed upon them, senders &MUST-NOT; 203 generate protocol elements that do not match the grammar defined by the 204 ABNF rules for those protocol elements that are applicable to the sender's 205 role. If a received protocol element is processed, the recipient &MUST; be 206 able to parse any value that would match the ABNF rules for that protocol 207 element, excluding only those rules not applicable to the recipient's role. 208 </t> 209 <t> 210 Unless noted otherwise, a recipient &MAY; attempt to recover a usable 211 protocol element from an invalid construct. HTTP does not define 212 specific error handling mechanisms except when they have a direct impact 213 on security, since different applications of the protocol require 214 different error handling strategies. For example, a Web browser might 215 wish to transparently recover from a response where the 216 <x:ref>Location</x:ref> header field doesn't parse according to the ABNF, 217 whereas a systems control client might consider any form of error recovery 218 to be dangerous. 219 </t> 220 </section> 221 222 <section title="Syntax Notation" anchor="notation"> 223 <x:anchor-alias value="ALPHA"/> 224 <x:anchor-alias value="CR"/> 225 <x:anchor-alias value="DIGIT"/> 226 <x:anchor-alias value="DQUOTE"/> 227 <x:anchor-alias value="LF"/> 228 <x:anchor-alias value="OCTET"/> 229 <x:anchor-alias value="VCHAR"/> 230 <x:anchor-alias value="core.rules"/> 231 <x:anchor-alias value="obs-text"/> 232 <x:anchor-alias value="OWS"/> 233 <x:anchor-alias value="HTTP-date"/> 234 <t> 235 This specification uses the Augmented Backus-Naur Form (ABNF) notation 236 of <xref target="RFC5234"/> with the list rule extension defined in 237 ¬ation;. <xref target="collected.abnf"/> shows the collected ABNF 238 with the list rule expanded. 239 </t> 240 <t> 241 The following core rules are included by 242 reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>: 243 ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls), 244 DIGIT (decimal 0-9), DQUOTE (double quote), 245 HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), 246 OCTET (any 8-bit sequence of data), SP (space), and 247 VCHAR (any visible US-ASCII character). 248 </t> 249 <t> 250 The ABNF rules below are defined in <xref target="Part1"/> and 251 <xref target="Part2"/>: 252 </t> 253 <figure><artwork type="abnf2616"> 254 <x:ref>OWS</x:ref> = <OWS, defined in &whitespace;> 255 <x:ref>obs-text</x:ref> = <obs-text, defined in &field-components;> 256 <x:ref>HTTP-date</x:ref> = <HTTP-date, defined in &http-date;> 257 </artwork></figure> 258 </section> 173 259 </section> 174 260 … … 1002 1088 </t> 1003 1089 </section> 1004 </section>1005 1006 <section title="ABNF Rules Defined Elsewhere" anchor="abnf.dependencies">1007 <x:anchor-alias value="ALPHA"/>1008 <x:anchor-alias value="CR"/>1009 <x:anchor-alias value="DIGIT"/>1010 <x:anchor-alias value="DQUOTE"/>1011 <x:anchor-alias value="LF"/>1012 <x:anchor-alias value="OCTET"/>1013 <x:anchor-alias value="VCHAR"/>1014 <x:anchor-alias value="core.rules"/>1015 <x:anchor-alias value="obs-text"/>1016 <x:anchor-alias value="OWS"/>1017 <x:anchor-alias value="HTTP-date"/>1018 <t>1019 This specification uses the Augmented Backus-Naur Form (ABNF) notation1020 of <xref target="RFC5234"/> with the list rule extension defined in1021 ¬ation;. <xref target="collected.abnf"/> shows the collected ABNF1022 with the list rule expanded.1023 </t>1024 <t>1025 The following core rules are included by1026 reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:1027 ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),1028 DIGIT (decimal 0-9), DQUOTE (double quote),1029 HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),1030 OCTET (any 8-bit sequence of data), SP (space), and1031 VCHAR (any visible US-ASCII character).1032 </t>1033 <t>1034 The ABNF rules below are defined in <xref target="Part1"/> and1035 <xref target="Part2"/>:1036 </t>1037 <figure><artwork type="abnf2616">1038 <x:ref>OWS</x:ref> = <OWS, defined in &whitespace;>1039 <x:ref>obs-text</x:ref> = <obs-text, defined in &field-components;>1040 <x:ref>HTTP-date</x:ref> = <HTTP-date, defined in &http-date;>1041 </artwork></figure>1042 <t>1043 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",1044 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this1045 document are to be interpreted as described in <xref target="RFC2119"/>.1046 </t>1047 1090 </section> 1048 1091
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