Changeset 346 for draft-ietf-httpbis/latest/p1-messaging.xml
- Timestamp:
- 12/11/08 19:58:51 (14 years ago)
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draft-ietf-httpbis/latest/p1-messaging.xml
r345 r346 306 306 </section> 307 307 308 <section title="Terminology" anchor="intro.terminology">309 <t>310 This specification uses a number of terms to refer to the roles311 played by participants in, and objects of, the HTTP communication.312 </t>313 <t>314 <iref item="connection"/>315 <x:dfn>connection</x:dfn>316 <list>317 <t>318 A transport layer virtual circuit established between two programs319 for the purpose of communication.320 </t>321 </list>322 </t>323 <t>324 <iref item="message"/>325 <x:dfn>message</x:dfn>326 <list>327 <t>328 The basic unit of HTTP communication, consisting of a structured329 sequence of octets matching the syntax defined in <xref target="http.message"/> and330 transmitted via the connection.331 </t>332 </list>333 </t>334 <t>335 <iref item="request"/>336 <x:dfn>request</x:dfn>337 <list>338 <t>339 An HTTP request message, as defined in <xref target="request"/>.340 </t>341 </list>342 </t>343 <t>344 <iref item="response"/>345 <x:dfn>response</x:dfn>346 <list>347 <t>348 An HTTP response message, as defined in <xref target="response"/>.349 </t>350 </list>351 </t>352 <t>353 <iref item="resource"/>354 <x:dfn>resource</x:dfn>355 <list>356 <t>357 A network data object or service that can be identified by a URI,358 as defined in <xref target="uri"/>. Resources may be available in multiple359 representations (e.g. multiple languages, data formats, size, and360 resolutions) or vary in other ways.361 </t>362 </list>363 </t>364 <t>365 <iref item="entity"/>366 <x:dfn>entity</x:dfn>367 <list>368 <t>369 The information transferred as the payload of a request or370 response. An entity consists of metainformation in the form of371 entity-header fields and content in the form of an entity-body, as372 described in &entity;.373 </t>374 </list>375 </t>376 <t>377 <iref item="representation"/>378 <x:dfn>representation</x:dfn>379 <list>380 <t>381 An entity included with a response that is subject to content382 negotiation, as described in &content.negotiation;. There may exist multiple383 representations associated with a particular response status.384 </t>385 </list>386 </t>387 <t>388 <iref item="content negotiation"/>389 <x:dfn>content negotiation</x:dfn>390 <list>391 <t>392 The mechanism for selecting the appropriate representation when393 servicing a request, as described in &content.negotiation;. The394 representation of entities in any response can be negotiated395 (including error responses).396 </t>397 </list>398 </t>399 <t>400 <iref item="variant"/>401 <x:dfn>variant</x:dfn>402 <list>403 <t>404 A resource may have one, or more than one, representation(s)405 associated with it at any given instant. Each of these406 representations is termed a `variant'. Use of the term `variant'407 does not necessarily imply that the resource is subject to content408 negotiation.409 </t>410 </list>411 </t>412 <t>413 <iref item="client"/>414 <x:dfn>client</x:dfn>415 <list>416 <t>417 A program that establishes connections for the purpose of sending418 requests.419 </t>420 </list>421 </t>422 <t>423 <iref item="user agent"/>424 <x:dfn>user agent</x:dfn>425 <list>426 <t>427 The client which initiates a request. These are often browsers,428 editors, spiders (web-traversing robots), or other end user tools.429 </t>430 </list>431 </t>432 <t>433 <iref item="server"/>434 <x:dfn>server</x:dfn>435 <list>436 <t>437 An application program that accepts connections in order to438 service requests by sending back responses. Any given program may439 be capable of being both a client and a server; our use of these440 terms refers only to the role being performed by the program for a441 particular connection, rather than to the program's capabilities442 in general. Likewise, any server may act as an origin server,443 proxy, gateway, or tunnel, switching behavior based on the nature444 of each request.445 </t>446 </list>447 </t>448 <t>449 <iref item="origin server"/>450 <x:dfn>origin server</x:dfn>451 <list>452 <t>453 The server on which a given resource resides or is to be created.454 </t>455 </list>456 </t>457 <t>458 <iref item="proxy"/>459 <x:dfn>proxy</x:dfn>460 <list>461 <t>462 An intermediary program which acts as both a server and a client463 for the purpose of making requests on behalf of other clients.464 Requests are serviced internally or by passing them on, with465 possible translation, to other servers. A proxy &MUST; implement466 both the client and server requirements of this specification. A467 "transparent proxy" is a proxy that does not modify the request or468 response beyond what is required for proxy authentication and469 identification. A "non-transparent proxy" is a proxy that modifies470 the request or response in order to provide some added service to471 the user agent, such as group annotation services, media type472 transformation, protocol reduction, or anonymity filtering. Except473 where either transparent or non-transparent behavior is explicitly474 stated, the HTTP proxy requirements apply to both types of475 proxies.476 </t>477 </list>478 </t>479 <t>480 <iref item="gateway"/>481 <x:dfn>gateway</x:dfn>482 <list>483 <t>484 A server which acts as an intermediary for some other server.485 Unlike a proxy, a gateway receives requests as if it were the486 origin server for the requested resource; the requesting client487 may not be aware that it is communicating with a gateway.488 </t>489 </list>490 </t>491 <t>492 <iref item="tunnel"/>493 <x:dfn>tunnel</x:dfn>494 <list>495 <t>496 An intermediary program which is acting as a blind relay between497 two connections. Once active, a tunnel is not considered a party498 to the HTTP communication, though the tunnel may have been499 initiated by an HTTP request. The tunnel ceases to exist when both500 ends of the relayed connections are closed.501 </t>502 </list>503 </t>504 <t>505 <iref item="cache"/>506 <x:dfn>cache</x:dfn>507 <list>508 <t>509 A program's local store of response messages and the subsystem510 that controls its message storage, retrieval, and deletion. A511 cache stores cacheable responses in order to reduce the response512 time and network bandwidth consumption on future, equivalent513 requests. Any client or server may include a cache, though a cache514 cannot be used by a server that is acting as a tunnel.515 </t>516 </list>517 </t>518 <t>519 <iref item="cacheable"/>520 <x:dfn>cacheable</x:dfn>521 <list>522 <t>523 A response is cacheable if a cache is allowed to store a copy of524 the response message for use in answering subsequent requests. The525 rules for determining the cacheability of HTTP responses are526 defined in &caching;. Even if a resource is cacheable, there may527 be additional constraints on whether a cache can use the cached528 copy for a particular request.529 </t>530 </list>531 </t>532 <t>533 <iref item="upstream"/>534 <iref item="downstream"/>535 <x:dfn>upstream</x:dfn>/<x:dfn>downstream</x:dfn>536 <list>537 <t>538 Upstream and downstream describe the flow of a message: all539 messages flow from upstream to downstream.540 </t>541 </list>542 </t>543 <t>544 <iref item="inbound"/>545 <iref item="outbound"/>546 <x:dfn>inbound</x:dfn>/<x:dfn>outbound</x:dfn>547 <list>548 <t>549 Inbound and outbound refer to the request and response paths for550 messages: "inbound" means "traveling toward the origin server",551 and "outbound" means "traveling toward the user agent"552 </t>553 </list>554 </t>555 </section>556 557 308 <section title="Overall Operation" anchor="intro.overall.operation"> 558 309 <t> … … 4376 4127 </section> 4377 4128 4129 <section title="Terminology" anchor="terminology"> 4130 <t> 4131 This specification uses a number of terms to refer to the roles 4132 played by participants in, and objects of, the HTTP communication. 4133 </t> 4134 <t> 4135 <iref item="connection"/> 4136 <x:dfn>connection</x:dfn> 4137 <list> 4138 <t> 4139 A transport layer virtual circuit established between two programs 4140 for the purpose of communication. 4141 </t> 4142 </list> 4143 </t> 4144 <t> 4145 <iref item="message"/> 4146 <x:dfn>message</x:dfn> 4147 <list> 4148 <t> 4149 The basic unit of HTTP communication, consisting of a structured 4150 sequence of octets matching the syntax defined in <xref target="http.message"/> and 4151 transmitted via the connection. 4152 </t> 4153 </list> 4154 </t> 4155 <t> 4156 <iref item="request"/> 4157 <x:dfn>request</x:dfn> 4158 <list> 4159 <t> 4160 An HTTP request message, as defined in <xref target="request"/>. 4161 </t> 4162 </list> 4163 </t> 4164 <t> 4165 <iref item="response"/> 4166 <x:dfn>response</x:dfn> 4167 <list> 4168 <t> 4169 An HTTP response message, as defined in <xref target="response"/>. 4170 </t> 4171 </list> 4172 </t> 4173 <t> 4174 <iref item="resource"/> 4175 <x:dfn>resource</x:dfn> 4176 <list> 4177 <t> 4178 A network data object or service that can be identified by a URI, 4179 as defined in <xref target="uri"/>. Resources may be available in multiple 4180 representations (e.g. multiple languages, data formats, size, and 4181 resolutions) or vary in other ways. 4182 </t> 4183 </list> 4184 </t> 4185 <t> 4186 <iref item="entity"/> 4187 <x:dfn>entity</x:dfn> 4188 <list> 4189 <t> 4190 The information transferred as the payload of a request or 4191 response. An entity consists of metainformation in the form of 4192 entity-header fields and content in the form of an entity-body, as 4193 described in &entity;. 4194 </t> 4195 </list> 4196 </t> 4197 <t> 4198 <iref item="representation"/> 4199 <x:dfn>representation</x:dfn> 4200 <list> 4201 <t> 4202 An entity included with a response that is subject to content 4203 negotiation, as described in &content.negotiation;. There may exist multiple 4204 representations associated with a particular response status. 4205 </t> 4206 </list> 4207 </t> 4208 <t> 4209 <iref item="content negotiation"/> 4210 <x:dfn>content negotiation</x:dfn> 4211 <list> 4212 <t> 4213 The mechanism for selecting the appropriate representation when 4214 servicing a request, as described in &content.negotiation;. The 4215 representation of entities in any response can be negotiated 4216 (including error responses). 4217 </t> 4218 </list> 4219 </t> 4220 <t> 4221 <iref item="variant"/> 4222 <x:dfn>variant</x:dfn> 4223 <list> 4224 <t> 4225 A resource may have one, or more than one, representation(s) 4226 associated with it at any given instant. Each of these 4227 representations is termed a `variant'. Use of the term `variant' 4228 does not necessarily imply that the resource is subject to content 4229 negotiation. 4230 </t> 4231 </list> 4232 </t> 4233 <t> 4234 <iref item="client"/> 4235 <x:dfn>client</x:dfn> 4236 <list> 4237 <t> 4238 A program that establishes connections for the purpose of sending 4239 requests. 4240 </t> 4241 </list> 4242 </t> 4243 <t> 4244 <iref item="user agent"/> 4245 <x:dfn>user agent</x:dfn> 4246 <list> 4247 <t> 4248 The client which initiates a request. These are often browsers, 4249 editors, spiders (web-traversing robots), or other end user tools. 4250 </t> 4251 </list> 4252 </t> 4253 <t> 4254 <iref item="server"/> 4255 <x:dfn>server</x:dfn> 4256 <list> 4257 <t> 4258 An application program that accepts connections in order to 4259 service requests by sending back responses. Any given program may 4260 be capable of being both a client and a server; our use of these 4261 terms refers only to the role being performed by the program for a 4262 particular connection, rather than to the program's capabilities 4263 in general. Likewise, any server may act as an origin server, 4264 proxy, gateway, or tunnel, switching behavior based on the nature 4265 of each request. 4266 </t> 4267 </list> 4268 </t> 4269 <t> 4270 <iref item="origin server"/> 4271 <x:dfn>origin server</x:dfn> 4272 <list> 4273 <t> 4274 The server on which a given resource resides or is to be created. 4275 </t> 4276 </list> 4277 </t> 4278 <t> 4279 <iref item="proxy"/> 4280 <x:dfn>proxy</x:dfn> 4281 <list> 4282 <t> 4283 An intermediary program which acts as both a server and a client 4284 for the purpose of making requests on behalf of other clients. 4285 Requests are serviced internally or by passing them on, with 4286 possible translation, to other servers. A proxy &MUST; implement 4287 both the client and server requirements of this specification. A 4288 "transparent proxy" is a proxy that does not modify the request or 4289 response beyond what is required for proxy authentication and 4290 identification. A "non-transparent proxy" is a proxy that modifies 4291 the request or response in order to provide some added service to 4292 the user agent, such as group annotation services, media type 4293 transformation, protocol reduction, or anonymity filtering. Except 4294 where either transparent or non-transparent behavior is explicitly 4295 stated, the HTTP proxy requirements apply to both types of 4296 proxies. 4297 </t> 4298 </list> 4299 </t> 4300 <t> 4301 <iref item="gateway"/> 4302 <x:dfn>gateway</x:dfn> 4303 <list> 4304 <t> 4305 A server which acts as an intermediary for some other server. 4306 Unlike a proxy, a gateway receives requests as if it were the 4307 origin server for the requested resource; the requesting client 4308 may not be aware that it is communicating with a gateway. 4309 </t> 4310 </list> 4311 </t> 4312 <t> 4313 <iref item="tunnel"/> 4314 <x:dfn>tunnel</x:dfn> 4315 <list> 4316 <t> 4317 An intermediary program which is acting as a blind relay between 4318 two connections. Once active, a tunnel is not considered a party 4319 to the HTTP communication, though the tunnel may have been 4320 initiated by an HTTP request. The tunnel ceases to exist when both 4321 ends of the relayed connections are closed. 4322 </t> 4323 </list> 4324 </t> 4325 <t> 4326 <iref item="cache"/> 4327 <x:dfn>cache</x:dfn> 4328 <list> 4329 <t> 4330 A program's local store of response messages and the subsystem 4331 that controls its message storage, retrieval, and deletion. A 4332 cache stores cacheable responses in order to reduce the response 4333 time and network bandwidth consumption on future, equivalent 4334 requests. Any client or server may include a cache, though a cache 4335 cannot be used by a server that is acting as a tunnel. 4336 </t> 4337 </list> 4338 </t> 4339 <t> 4340 <iref item="cacheable"/> 4341 <x:dfn>cacheable</x:dfn> 4342 <list> 4343 <t> 4344 A response is cacheable if a cache is allowed to store a copy of 4345 the response message for use in answering subsequent requests. The 4346 rules for determining the cacheability of HTTP responses are 4347 defined in &caching;. Even if a resource is cacheable, there may 4348 be additional constraints on whether a cache can use the cached 4349 copy for a particular request. 4350 </t> 4351 </list> 4352 </t> 4353 <t> 4354 <iref item="upstream"/> 4355 <iref item="downstream"/> 4356 <x:dfn>upstream</x:dfn>/<x:dfn>downstream</x:dfn> 4357 <list> 4358 <t> 4359 Upstream and downstream describe the flow of a message: all 4360 messages flow from upstream to downstream. 4361 </t> 4362 </list> 4363 </t> 4364 <t> 4365 <iref item="inbound"/> 4366 <iref item="outbound"/> 4367 <x:dfn>inbound</x:dfn>/<x:dfn>outbound</x:dfn> 4368 <list> 4369 <t> 4370 Inbound and outbound refer to the request and response paths for 4371 messages: "inbound" means "traveling toward the origin server", 4372 and "outbound" means "traveling toward the user agent" 4373 </t> 4374 </list> 4375 </t> 4376 </section> 4377 4378 4378 <section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log"> 4379 4379
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