idnits 2.17.1 draft-ietf-webpush-protocol-12.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (October 22, 2016) is 2736 days in the past. Is this intentional? 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'CAP-URI' ** Obsolete normative reference: RFC 2818 (Obsoleted by RFC 9110) ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126) ** Obsolete normative reference: RFC 5988 (Obsoleted by RFC 8288) ** Obsolete normative reference: RFC 7230 (Obsoleted by RFC 9110, RFC 9112) ** Obsolete normative reference: RFC 7231 (Obsoleted by RFC 9110) ** Obsolete normative reference: RFC 7232 (Obsoleted by RFC 9110) ** Obsolete normative reference: RFC 7525 (Obsoleted by RFC 9325) ** Obsolete normative reference: RFC 7540 (Obsoleted by RFC 9113) == Outdated reference: A later version (-09) exists of draft-ietf-webpush-encryption-04 == Outdated reference: A later version (-04) exists of draft-ietf-webpush-vapid-01 Summary: 8 errors (**), 0 flaws (~~), 4 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 WEBPUSH M. Thomson 3 Internet-Draft Mozilla 4 Intended status: Standards Track E. Damaggio 5 Expires: April 25, 2017 B. Raymor, Ed. 6 Microsoft 7 October 22, 2016 9 Generic Event Delivery Using HTTP Push 10 draft-ietf-webpush-protocol-12 12 Abstract 14 A simple protocol for the delivery of real-time events to user agents 15 is described. This scheme uses HTTP/2 server push. 17 Status of This Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF). Note that other groups may also distribute 24 working documents as Internet-Drafts. The list of current Internet- 25 Drafts is at http://datatracker.ietf.org/drafts/current/. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 This Internet-Draft will expire on April 25, 2017. 34 Copyright Notice 36 Copyright (c) 2016 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (http://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 52 1.1. Conventions and Terminology . . . . . . . . . . . . . . . 4 53 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5 54 2.1. HTTP Resources . . . . . . . . . . . . . . . . . . . . . 7 55 3. Connecting to the Push Service . . . . . . . . . . . . . . . 7 56 4. Subscribing for Push Messages . . . . . . . . . . . . . . . . 8 57 4.1. Collecting Subscriptions into Sets . . . . . . . . . . . 9 58 5. Requesting Push Message Delivery . . . . . . . . . . . . . . 10 59 5.1. Requesting Push Message Receipts . . . . . . . . . . . . 10 60 5.2. Push Message Time-To-Live . . . . . . . . . . . . . . . . 11 61 5.3. Push Message Urgency . . . . . . . . . . . . . . . . . . 13 62 5.4. Replacing Push Messages . . . . . . . . . . . . . . . . . 14 63 6. Receiving Push Messages for a Subscription . . . . . . . . . 15 64 6.1. Receiving Push Messages for a Subscription Set . . . . . 17 65 6.2. Acknowledging Push Messages . . . . . . . . . . . . . . . 18 66 6.3. Receiving Push Message Receipts . . . . . . . . . . . . . 19 67 7. Operational Considerations . . . . . . . . . . . . . . . . . 20 68 7.1. Load Management . . . . . . . . . . . . . . . . . . . . . 20 69 7.2. Push Message Expiration . . . . . . . . . . . . . . . . . 20 70 7.3. Subscription Expiration . . . . . . . . . . . . . . . . . 21 71 7.3.1. Subscription Set Expiration . . . . . . . . . . . . . 22 72 7.4. Implications for Application Reliability . . . . . . . . 22 73 7.5. Subscription Sets and Concurrent HTTP/2 streams . . . . . 22 74 8. Security Considerations . . . . . . . . . . . . . . . . . . . 23 75 8.1. Confidentiality from Push Service Access . . . . . . . . 23 76 8.2. Privacy Considerations . . . . . . . . . . . . . . . . . 23 77 8.3. Authorization . . . . . . . . . . . . . . . . . . . . . . 24 78 8.4. Denial of Service Considerations . . . . . . . . . . . . 25 79 8.5. Logging Risks . . . . . . . . . . . . . . . . . . . . . . 26 80 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26 81 9.1. Header Field Registrations . . . . . . . . . . . . . . . 26 82 9.2. Link Relation URNs . . . . . . . . . . . . . . . . . . . 26 83 9.3. Service Name and Port Number Registration . . . . . . . . 28 84 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29 85 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 29 86 11.1. Normative References . . . . . . . . . . . . . . . . . . 29 87 11.2. Informative References . . . . . . . . . . . . . . . . . 30 88 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 31 89 A.1. Since draft-ietf-webpush-protocol-00 . . . . . . . . . . 31 90 A.2. Since draft-ietf-webpush-protocol-01 . . . . . . . . . . 31 91 A.3. Since draft-ietf-webpush-protocol-02 . . . . . . . . . . 31 92 A.4. Since draft-ietf-webpush-protocol-03 . . . . . . . . . . 32 93 A.5. Since draft-ietf-webpush-protocol-04 . . . . . . . . . . 32 94 A.6. Since draft-ietf-webpush-protocol-05 . . . . . . . . . . 32 95 A.7. Since draft-ietf-webpush-protocol-06 . . . . . . . . . . 32 96 A.8. Since draft-ietf-webpush-protocol-07 . . . . . . . . . . 32 97 A.9. Since draft-ietf-webpush-protocol-08 . . . . . . . . . . 32 98 A.10. Since draft-ietf-webpush-protocol-09 . . . . . . . . . . 32 99 A.11. Since draft-ietf-webpush-protocol-10 . . . . . . . . . . 32 100 A.12. Since draft-ietf-webpush-protocol-11 . . . . . . . . . . 33 101 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33 103 1. Introduction 105 Many applications on mobile and embedded devices require continuous 106 access to network communications so that real-time events - such as 107 incoming calls or messages - can be delivered (or "pushed") in a 108 timely fashion. These devices typically have limited power reserves, 109 so finding more efficient ways to serve application requirements 110 greatly benefits the application ecosystem. 112 One significant contributor to power usage is the radio. Radio 113 communications consume a significant portion of the energy budget on 114 a wireless device. 116 Uncoordinated use of persistent connections or sessions from multiple 117 applications can contribute to unnecessary use of the device radio, 118 since each independent session can incur its own overhead. In 119 particular, keep alive traffic used to ensure that middleboxes do not 120 prematurely time out sessions, can result in significant waste. 121 Maintenance traffic tends to dominate over the long term, since 122 events are relatively rare. 124 Consolidating all real-time events into a single session ensures more 125 efficient use of network and radio resources. A single service 126 consolidates all events, distributing those events to applications as 127 they arrive. This requires just one session, avoiding duplicated 128 overhead costs. 130 The W3C Push API [API] describes an API that enables the use of a 131 consolidated push service from web applications. This document 132 expands on that work by describing a protocol that can be used to: 134 o request the delivery of a push message to a user agent, 136 o create new push message delivery subscriptions, and 138 o monitor for new push messages. 140 A standardized method of event delivery is particularly important for 141 the W3C Push API, where application servers might need to use 142 multiple push services. The subscription, management and monitoring 143 functions are currently fulfilled by proprietary protocols; these are 144 adequate, but do not offer any of the advantages that standardization 145 affords. 147 This document intentionally does not describe how a push service is 148 discovered. Discovery of push services is left for future efforts, 149 if it turns out to be necessary at all. User agents are expected to 150 be configured with a URL for a push service. 152 1.1. Conventions and Terminology 154 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 155 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 156 document are to be interpreted as described in [RFC2119]. 158 This document defines the following terms: 160 application: Both the sender and ultimate consumer of push messages. 161 Many applications have components that are run on a user agent and 162 other components that run on servers. 164 application server: The component of an application that usually 165 runs on a server and requests the delivery of a push message. 167 push message subscription: A message delivery context that is 168 established between the user agent and the push service and shared 169 with the application server. All push messages are associated 170 with a push message subscription. 172 push message subscription set: A message delivery context that is 173 established between the user agent and the push service that 174 collects multiple push message subscriptions into a set. 176 push message: A message sent from an application server to a user 177 agent via a push service. 179 push message receipt: A message delivery confirmation sent from the 180 push service to the application server. 182 push service: A service that delivers push messages to user agents. 184 user agent: A device and software that is the recipient of push 185 messages. 187 Examples in this document use the HTTP/1.1 message format [RFC7230]. 188 Many of the exchanges can be completed using HTTP/1.1: 190 o Subscribing for Push Messages (Section 4) 191 o Requesting Push Message Delivery (Section 5) 193 o Replacing Push Messages (Section 5.4) 195 o Acknowledging Push Messages (Section 6.2) 197 When an example depends on HTTP/2 server push, the more verbose frame 198 format from [RFC7540] is used: 200 o Receiving Push Messages for a Subscription (Section 6) 202 o Receiving Push Messages for a Subscription Set (Section 6.1) 204 o Receiving Push Message Receipts (Section 6.3) 206 All examples use HTTPS over the default port (443) rather than the 207 registered port (WEBPUSH-PORT). A push service deployment might 208 prefer this configuration to maximize chances for user agents to 209 reach the service. A push service might use HTTP alternative 210 services to redirect a user agent to the registered port (WEBPUSH- 211 PORT) to gain the benefits of the standardized HTTPS port without 212 sacrificing reachability (see Section 3). This would only be 213 apparent in the examples through the inclusion of the Alt-Used header 214 field [RFC7838] in requests from the user agent to the push service. 216 Examples do not include specific methods for push message encryption 217 or application server authentication because the protocol does not 218 define a mandatory system. The examples in Voluntary Application 219 Server Identification [I-D.ietf-webpush-vapid] and Message Encryption 220 for WebPush [I-D.ietf-webpush-encryption] demonstrate the approach 221 adopted by the W3C Push API [API] for its requirements. 223 2. Overview 225 A general model for push services includes three basic actors: a user 226 agent, a push service, and an application (server). 228 +-------+ +--------------+ +-------------+ 229 | UA | | Push Service | | Application | 230 +-------+ +--------------+ | Server | 231 | | +-------------+ 232 | Subscribe | | 233 |--------------------->| | 234 | Monitor | | 235 |<====================>| | 236 | | | 237 | Distribute Push Resource | 238 |-------------------------------------------->| 239 | | | 240 : : : 241 | | Push Message | 242 | Push Message |<---------------------| 243 |<---------------------| | 244 | | | 246 Figure 1: Webpush Architecture 248 At the very beginning of the process, a new message subscription is 249 created by the user agent and then distributed to its application 250 server. This subscription is the basis of all future interactions 251 between the actors. A subscription is used by the application server 252 to send messages to the push service for being delivered to the user 253 agent. It is used by the user agent to monitor the push service for 254 any incoming message. 256 To offer more control for authorization, a message subscription is 257 modeled as two resources with different capabilities: 259 o A subscription resource is used to receive messages from a 260 subscription and to delete a subscription. It is private to the 261 user agent. 263 o A push resource is used to send messages to a subscription. It is 264 public and shared by the user agent with its application server. 266 It is expected that a unique subscription will be distributed to each 267 application; however, there are no inherent cardinality constraints 268 in the protocol. Multiple subscriptions might be created for the 269 same application, or multiple applications could use the same 270 subscription. Note however that sharing subscriptions has security 271 and privacy implications. 273 Subscriptions have a limited lifetime. They can also be terminated 274 by either the push service or user agent at any time. User agents 275 and application servers must be prepared to manage changes in 276 subscription state. 278 2.1. HTTP Resources 280 This protocol uses HTTP resources [RFC7230] and link relations 281 [RFC5988]. The following resources are defined: 283 push service: This resource is used to create push message 284 subscriptions (Section 4). A URL for the push service is 285 configured into user agents. 287 push message subscription: This resource provides read and delete 288 access for a message subscription. A user agent receives push 289 messages (Section 6) using a push message subscription. Every 290 push message subscription has exactly one push resource associated 291 with it. 293 push message subscription set: This resource provides read and 294 delete access for a collection of push message subscriptions. A 295 user agent receives push messages (Section 6.1) for all the push 296 message subscriptions in the set. A link relation of type 297 "urn:ietf:params:push:set" identifies a push message subscription 298 set. 300 push: An application server requests the delivery (Section 5) of a 301 push message using a push resource. A link relation of type 302 "urn:ietf:params:push" identifies a push resource. 304 push message: The push service creates a push message resource to 305 identify push messages that have been accepted for delivery 306 (Section 5). The push message resource is also deleted by the 307 user agent to acknowledge receipt (Section 6.2) of a push message. 309 receipt subscription: An application server receives delivery 310 confirmations (Section 5.1) for push messages using a receipt 311 subscription. A link relation of type 312 "urn:ietf:params:push:receipt" identifies a receipt subscription. 314 3. Connecting to the Push Service 316 The push service MUST use HTTP over TLS [RFC2818] following the 317 recommendations in [RFC7525]. The push service shares the same 318 default port number (443/TCP) with HTTPS, but MAY also advertise the 319 IANA allocated TCP System Port (WEBPUSH-PORT) using HTTP alternative 320 services [RFC7838]. 322 While the default port (443) offers broad reachability 323 characteristics, it is most often used for web browsing scenarios 324 with a lower idle timeout than other ports configured in middleboxes. 325 For webpush scenarios, this would contribute to unnecessary radio 326 communications to maintain the connection on battery-powered devices. 328 Advertising the alternate port (WEBPUSH-PORT) allows middleboxes to 329 optimize idle timeouts for connections specific to push scenarios 330 with the expectation that data exchange will be infrequent. 332 Middleboxes SHOULD comply with REQ-5 in [RFC5382] which requires that 333 "the value of the 'established connection idle-timeout' MUST NOT be 334 less than 2 hours 4 minutes". 336 4. Subscribing for Push Messages 338 A user agent sends a POST request to its configured push service 339 resource to create a new subscription. 341 POST /subscribe HTTP/1.1 342 Host: push.example.net 344 A 201 (Created) response indicates that the push subscription was 345 created. A URI for the push message subscription resource that was 346 created in response to the request MUST be returned in the Location 347 header field. 349 The push service MUST provide a URI for the push resource 350 corresponding to the push message subscription in a link relation of 351 type "urn:ietf:params:push". 353 An application-specific method is used to distribute the push URI to 354 the application server. Confidentiality protection and application 355 server authentication MUST be used to ensure that this URI is not 356 disclosed to unauthorized recipients (Section 8.3). 358 HTTP/1.1 201 Created 359 Date: Thu, 11 Dec 2014 23:56:52 GMT 360 Link: ; 361 rel="urn:ietf:params:push" 362 Link: ; 363 rel="urn:ietf:params:push:set" 364 Location: https://push.example.net/subscription/LBhhw0OohO-Wl4Oi971UG 366 4.1. Collecting Subscriptions into Sets 368 Collecting multiple push message subscriptions into a subscription 369 set can represent a significant efficiency improvement for push 370 services and user agents. The push service MAY provide a URI for a 371 subscription set resource in a link relation of type 372 "urn:ietf:params:push:set". 374 When a subscription set is returned in a push message subscription 375 response, the user agent SHOULD include this subscription set in a 376 link relation of type "urn:ietf:params:push:set" in subsequent 377 requests to create new push message subscriptions. 379 A user agent MAY omit the subscription set if it is unable to receive 380 push messages in an aggregated way for the lifetime of the 381 subscription. This might be necessary if the user agent is 382 monitoring subscriptions on behalf of other push message receivers. 384 POST /subscribe HTTP/1.1 385 Host: push.example.net 386 Link: ; 387 rel="urn:ietf:params:push:set" 389 The push service SHOULD return the same subscription set in its 390 response, although it MAY return a new subscription set if it is 391 unable to reuse the one provided by the user agent. 393 HTTP/1.1 201 Created 394 Date: Thu, 11 Dec 2014 23:56:52 GMT 395 Link: ; 396 rel="urn:ietf:params:push" 397 Link: ; 398 rel="urn:ietf:params:push:set" 399 Location: https://push.example.net/subscription/i-nQ3A9Zm4kgSWg8_ZijV 401 A push service MUST return a 400 (Bad Request) status code for 402 requests which contain an invalid subscription set. A push service 403 MAY return a 429 (Too Many Requests) status code [RFC6585] to reject 404 requests which omit a subscription set. 406 How a push service detects that requests originate from the same user 407 agent is implementation-specific but could take ambient information 408 into consideration, such as the TLS connection, source IP address and 409 port. Implementers are reminded that some heuristics can produce 410 false positives and cause requests to be rejected incorrectly. 412 5. Requesting Push Message Delivery 414 An application server requests the delivery of a push message by 415 sending a HTTP POST request to a push resource distributed to the 416 application server by a user agent. The content of the push message 417 is included in the body of the request. 419 POST /push/JzLQ3raZJfFBR0aqvOMsLrt54w4rJUsV HTTP/1.1 420 Host: push.example.net 421 TTL: 15 422 Content-Type: text/plain;charset=utf8 423 Content-Length: 36 425 iChYuI3jMzt3ir20P8r_jgRR-dSuN182x7iB 427 A 201 (Created) response indicates that the push message was 428 accepted. A URI for the push message resource that was created in 429 response to the request MUST be returned in the Location header 430 field. This does not indicate that the message was delivered to the 431 user agent. 433 HTTP/1.1 201 Created 434 Date: Thu, 11 Dec 2014 23:56:55 GMT 435 Location: https://push.example.net/message/qDIYHNcfAIPP_5ITvURr-d6BGt 437 5.1. Requesting Push Message Receipts 439 An application server can include the Prefer header field [RFC7240] 440 with the "respond-async" preference to request confirmation from the 441 push service when a push message is delivered and then acknowledged 442 by the user agent. The push service MUST support delivery 443 confirmations. 445 POST /push/JzLQ3raZJfFBR0aqvOMsLrt54w4rJUsV HTTP/1.1 446 Host: push.example.net 447 Prefer: respond-async 448 TTL: 15 449 Content-Type: text/plain;charset=utf8 450 Content-Length: 36 452 iChYuI3jMzt3ir20P8r_jgRR-dSuN182x7iB 453 When the push service accepts the message for delivery with 454 confirmation, it MUST return a 202 (Accepted) response. A URI for 455 the push message resource that was created in response to the request 456 MUST be returned in the Location header field. The push service MUST 457 also provide a URI for the receipt subscription resource in a link 458 relation of type "urn:ietf:params:push:receipt". 460 HTTP/1.1 202 Accepted 461 Date: Thu, 11 Dec 2014 23:56:55 GMT 462 Link: ; 463 rel="urn:ietf:params:push:receipt" 464 Location: https://push.example.net/message/qDIYHNcfAIPP_5ITvURr-d6BGt 466 For subsequent receipt requests to the same origin [RFC6454], the 467 application server SHOULD include the returned receipt subscription 468 in a link relation of type "urn:ietf:params:push:receipt". This 469 gives the push service an option to aggregate the receipts. The push 470 service SHOULD return the same receipt subscription in its response, 471 although it MAY return a new receipt subscription if it is unable to 472 reuse the one provided by the application server. 474 An application server MAY omit the receipt subscription if it is 475 unable to receive receipts in an aggregated way for the lifetime of 476 the receipt subscription. This might be necessary if the application 477 server is monitoring receipt subscriptions on the behalf of other 478 push message senders. 480 A push service MUST return a 400 (Bad Request) status code for 481 requests which contain an invalid receipt subscription. If a push 482 service wishes to limit the number of receipt subscriptions that it 483 maintains, it MAY return a 429 (Too Many Requests) status code 484 [RFC6585] to reject receipt requests which omit a receipt 485 subscription. 487 5.2. Push Message Time-To-Live 489 A push service can improve the reliability of push message delivery 490 considerably by storing push messages for a period. User agents are 491 often only intermittently connected, and so benefit from having short 492 term message storage at the push service. 494 Delaying delivery might also be used to batch communication with the 495 user agent, thereby conserving radio resources. 497 Some push messages are not useful once a certain period of time 498 elapses. Delivery of messages after they have ceased to be relevant 499 is wasteful. For example, if the push message contains a call 500 notification, receiving a message after the caller has abandoned the 501 call is of no value; the application at the user agent is forced to 502 suppress the message so that it does not generate a useless alert. 504 An application server MUST include the TTL (Time-To-Live) header 505 field in its request for push message delivery. The TTL header field 506 contains a value in seconds that suggests how long a push message is 507 retained by the push service. 509 The TTL rule specifies a non-negative integer, representing time in 510 seconds. A recipient parsing and converting a TTL value to binary 511 form SHOULD use an arithmetic type of at least 31 bits of non- 512 negative integer range. If a recipient receives a TTL value greater 513 than the greatest integer it can represent, or if any of its 514 subsequent calculations overflows, it MUST consider the value to be 515 2147483648 (2^31). 517 TTL = 1*DIGIT 519 A push service MUST return a 400 (Bad Request) status code in 520 response to requests that omit the TTL header field. 522 A push service MAY retain a push message for a shorter duration than 523 requested. It indicates this by returning a TTL header field in its 524 response with the actual TTL. This TTL value MUST be less than or 525 equal to the value provided by the application server. 527 Once the TTL period elapses, the push service MUST NOT attempt to 528 deliver the push message to the user agent. A push service might 529 adjust the TTL value to account for time accounting errors in 530 processing. For instance, distributing a push message within a 531 server cluster might accrue errors due to clock skew or propagation 532 delays. 534 A push service is not obligated to account for time spent by the 535 application server in sending a push message to the push service, or 536 delays incurred while sending a push message to the user agent. An 537 application server needs to account for transit delays in selecting a 538 TTL header field value. 540 A Push message with a zero TTL is immediately delivered if the user 541 agent is available to receive the message. After delivery, the push 542 service is permitted to immediately remove a push message with a zero 543 TTL. This might occur before the user agent acknowledges receipt of 544 the message by performing a HTTP DELETE on the push message resource. 545 Consequently, an application server cannot rely on receiving 546 acknowledgement receipts for zero TTL push messages. 548 If the user agent is unavailable, a push message with a zero TTL 549 expires and is never delivered. 551 5.3. Push Message Urgency 553 For a device that is battery-powered, it is often critical that it 554 remains dormant for extended periods. Radio communication in 555 particular consumes significant power and limits the length of time 556 that the device can operate. 558 To avoid consuming resources to receive trivial messages, it is 559 helpful if an application server can communicate the urgency of a 560 message and if the user agent can request that the push server only 561 forward messages of a specific urgency. 563 An application server MAY include an Urgency header field in its 564 request for push message delivery. This header field indicates the 565 message urgency. The push service MUST NOT forward the Urgency 566 header field to the user agent. A push message without the Urgency 567 header field defaults to a value of "normal". 569 A user agent MAY include the Urgency header field when monitoring for 570 push messages to indicate the lowest urgency of push messages that it 571 is willing to receive. A push service MUST NOT deliver push messages 572 with lower urgency than the value indicated by the user agent in its 573 monitoring request. Push messages of any urgency are delivered to a 574 user agent that does not include an Urgency header field when 575 monitoring for messages. 577 Urgency = urgency-option 578 urgency-option = ("very-low" / "low" / "normal" / "high") 580 In order of increasing urgency: 582 +----------+-----------------------------+--------------------------+ 583 | Urgency | Device State | Example Application | 584 | | | Scenario | 585 +----------+-----------------------------+--------------------------+ 586 | very-low | On power and wifi | Advertisements | 587 | low | On either power or wifi | Topic updates | 588 | normal | On neither power nor wifi | Chat or Calendar Message | 589 | high | Low battery | Incoming phone call or | 590 | | | time-sensitive alert | 591 +----------+-----------------------------+--------------------------+ 593 Table 1: Illustrative Urgency Values 595 Multiple values for the Urgency header field MUST NOT be included in 596 requests; otherwise, the push service MUST return a 400 (Bad Request) 597 status code. 599 5.4. Replacing Push Messages 601 A push message that has been stored by the push service can be 602 replaced with new content. If the user agent is offline during the 603 time that the push messages are sent, updating a push message avoids 604 the situation where outdated or redundant messages are sent to the 605 user agent. 607 Only push messages that have been assigned a topic can be replaced. 608 A push message with a topic replaces any outstanding push message 609 with an identical topic. 611 A push message topic is a string carried in a Topic header field. A 612 topic is used to correlate push messages sent to the same 613 subscription and does not convey any other semantics. 615 The grammar for the Topic header field uses the "token" rule defined 616 in [RFC7230]. 618 Topic = token 620 For use with this protocol, the Topic header field MUST be restricted 621 to no more than 32 characters from the URL and filename safe Base 64 622 alphabet [RFC4648]. A push service that receives a request with a 623 Topic header field that does not meet these constraints MUST return a 624 400 (Bad Request) status code to the application server. 626 A push message replacement request creates a new push message 627 resource and simultaneously deletes any existing message resource 628 that has a matching topic. If an attempt was made to deliver the 629 deleted push message, an acknowledgment could arrive at the push 630 service after the push message has been replaced. Delivery receipts 631 for such deleted messages SHOULD be suppressed. 633 The replacement request also replaces the stored TTL, Urgency, and 634 any receipt subscription associated with the previous message in the 635 matching topic. 637 A push message with a topic that is not shared by an outstanding 638 message to the same subscription is stored or delivered as normal. 640 For example, the following message could cause an existing message to 641 be replaced: 643 POST /push/JzLQ3raZJfFBR0aqvOMsLrt54w4rJUsV HTTP/1.1 644 Host: push.example.net 645 TTL: 600 646 Topic: upd 647 Content-Type: text/plain;charset=utf8 648 Content-Length: 36 650 ZuHSZPKa2b1jtOKLGpWrcrn8cNqt0iVQyroF 652 If the push service identifies an outstanding push message with a 653 topic of "upd", then that message resource is deleted. A 201 654 (Created) response indicates that the push message replacement was 655 accepted. A URI for the new push message resource that was created 656 in response to the request is included in the Location header field. 658 HTTP/1.1 201 Created 659 Date: Thu, 11 Dec 2014 23:57:02 GMT 660 Location: https://push.example.net/message/qDIYHNcfAIPP_5ITvURr-d6BGt 662 The value of the Topic header field MUST NOT be forwarded to user 663 agents. Its value is neither encrypted nor authenticated. 665 6. Receiving Push Messages for a Subscription 667 A user agent requests the delivery of new push messages by making a 668 GET request to a push message subscription resource. The push 669 service does not respond to this request, it instead uses HTTP/2 670 server push [RFC7540] to send the contents of push messages as they 671 are sent by application servers. 673 A user agent MAY include a Urgency header field in its request. The 674 push service MUST NOT deliver messages with lower urgency than the 675 value of the header field as defined in the 676 Illustrative Urgency Values. 678 Each push message is pushed as the response to a synthesized GET 679 request sent in a PUSH_PROMISE. This GET request is made to the push 680 message resource that was created by the push service when the 681 application server requested message delivery. The response headers 682 SHOULD provide a URI for the push resource corresponding to the push 683 message subscription in a link relation of type 684 "urn:ietf:params:push". The response body is the entity body from 685 the most recent request sent to the push resource by the application 686 server. 688 The following example request is made over HTTP/2. 690 HEADERS [stream 7] +END_STREAM +END_HEADERS 691 :method = GET 692 :path = /subscription/LBhhw0OohO-Wl4Oi971UG 693 :authority = push.example.net 695 The push service permits the request to remain outstanding. When a 696 push message is sent by an application server, a server push is 697 generated in association with the initial request. The response for 698 the server push includes the push message. 700 PUSH_PROMISE [stream 7; promised stream 4] +END_HEADERS 701 :method = GET 702 :path = /message/qDIYHNcfAIPP_5ITvURr-d6BGt 703 :authority = push.example.net 705 HEADERS [stream 4] +END_HEADERS 706 :status = 200 707 date = Thu, 11 Dec 2014 23:56:56 GMT 708 last-modified = Thu, 11 Dec 2014 23:56:55 GMT 709 cache-control = private 710 link = ; 711 rel="urn:ietf:params:push" 712 content-type = text/plain;charset=utf8 713 content-length = 36 715 DATA [stream 4] +END_STREAM 716 iChYuI3jMzt3ir20P8r_jgRR-dSuN182x7iB 718 HEADERS [stream 7] +END_STREAM +END_HEADERS 719 :status = 200 721 A user agent can also request the contents of the push message 722 subscription resource immediately by including a Prefer header field 723 [RFC7240] with a "wait" preference set to "0". In response to this 724 request, the push service MUST generate a server push for all push 725 messages that have not yet been delivered. 727 A 204 (No Content) status code with no associated server pushes 728 indicates that no messages are presently available. This could be 729 because push messages have expired. 731 6.1. Receiving Push Messages for a Subscription Set 733 There are minor differences between receiving push messages for a 734 subscription and a subscription set. If a subscription set is 735 available, the user agent SHOULD use the subscription set to monitor 736 for push messages rather than individual push message subscriptions. 738 A user agent requests the delivery of new push messages for a 739 collection of push message subscriptions by making a GET request to a 740 push message subscription set resource. The push service does not 741 respond to this request, it instead uses HTTP/2 server push [RFC7540] 742 to send the contents of push messages as they are sent by application 743 servers. 745 A user agent MAY include a Urgency header field in its request. The 746 push service MUST NOT deliver messages with lower urgency than the 747 value of the header field as defined in the 748 Illustrative Urgency Values. 750 Each push message is pushed as the response to a synthesized GET 751 request sent in a PUSH_PROMISE. This GET request is made to the push 752 message resource that was created by the push service when the 753 application server requested message delivery. The synthetic request 754 MUST provide a URI for the push resource corresponding to the push 755 message subscription in a link relation of type 756 "urn:ietf:params:push". This enables the user agent to differentiate 757 the source of the message. The response body is the entity body from 758 the most recent request sent to the push resource by an application 759 server. 761 The following example request is made over HTTP/2. 763 HEADERS [stream 7] +END_STREAM +END_HEADERS 764 :method = GET 765 :path = /subscription-set/4UXwi2Rd7jGS7gp5cuutF8ZldnEuvbOy 766 :authority = push.example.net 768 The push service permits the request to remain outstanding. When a 769 push message is sent by an application server, a server push is 770 generated in association with the initial request. The server push's 771 response includes the push message. 773 PUSH_PROMISE [stream 7; promised stream 4] +END_HEADERS 774 :method = GET 775 :path = /message/qDIYHNcfAIPP_5ITvURr-d6BGt 776 :authority = push.example.net 778 HEADERS [stream 4] +END_HEADERS 779 :status = 200 780 date = Thu, 11 Dec 2014 23:56:56 GMT 781 last-modified = Thu, 11 Dec 2014 23:56:55 GMT 782 link = ; 783 rel="urn:ietf:params:push" 784 cache-control = private 785 content-type = text/plain;charset=utf8 786 content-length = 36 788 DATA [stream 4] +END_STREAM 789 iChYuI3jMzt3ir20P8r_jgRR-dSuN182x7iB 791 HEADERS [stream 7] +END_STREAM +END_HEADERS 792 :status = 200 794 A user agent can request the contents of the push message 795 subscription set resource immediately by including a Prefer header 796 field [RFC7240] with a "wait" preference set to "0". In response to 797 this request, the push service MUST generate a server push for all 798 push messages that have not yet been delivered. 800 A 204 (No Content) status code with no associated server pushes 801 indicates that no messages are presently available. This could be 802 because push messages have expired. 804 6.2. Acknowledging Push Messages 806 To ensure that a push message is properly delivered to the user agent 807 at least once, the user agent MUST acknowledge receipt of the message 808 by performing a HTTP DELETE on the push message resource. 810 DELETE /message/qDIYHNcfAIPP_5ITvURr-d6BGt HTTP/1.1 811 Host: push.example.net 812 If the push service receives the acknowledgement and the application 813 has requested a delivery receipt, the push service MUST return a 204 814 (No Content) response to the application server monitoring the 815 receipt subscription. 817 If the push service does not receive the acknowledgement within a 818 reasonable amount of time, then the message is considered to be not 819 yet delivered. The push service SHOULD continue to retry delivery of 820 the message until its advertised expiration. 822 The push service MAY cease to retry delivery of the message prior to 823 its advertised expiration due to scenarios such as an unresponsive 824 user agent or operational constraints. If the application has 825 requested a delivery receipt, then the push service MUST return a 410 826 (Gone) response to the application server monitoring the receipt 827 subscription. 829 6.3. Receiving Push Message Receipts 831 The application server requests the delivery of receipts from the 832 push service by making a HTTP GET request to the receipt subscription 833 resource. The push service does not respond to this request, it 834 instead uses HTTP/2 server push [RFC7540] to send push receipts when 835 messages are acknowledged (Section 6.2) by the user agent. 837 Each receipt is pushed as the response to a synthesized GET request 838 sent in a PUSH_PROMISE. This GET request is made to the same push 839 message resource that was created by the push service when the 840 application server requested message delivery. The response includes 841 a status code indicating the result of the message delivery and 842 carries no data. 844 The following example request is made over HTTP/2. 846 HEADERS [stream 13] +END_STREAM +END_HEADERS 847 :method = GET 848 :path = /receipt-subscription/3ZtI4YVNBnUUZhuoChl6omUvG4ZM 849 :authority = push.example.net 851 The push service permits the request to remain outstanding. When the 852 user agent acknowledges the message, the push service pushes a 853 delivery receipt to the application server. A 204 (No Content) 854 status code confirms that the message was delivered and acknowledged. 856 PUSH_PROMISE [stream 13; promised stream 82] +END_HEADERS 857 :method = GET 858 :path = /message/qDIYHNcfAIPP_5ITvURr-d6BGt 859 :authority = push.example.net 861 HEADERS [stream 82] +END_STREAM 862 +END_HEADERS 863 :status = 204 864 date = Thu, 11 Dec 2014 23:56:56 GMT 866 If the user agent fails to acknowledge the receipt of the push 867 message and the push service ceases to retry delivery of the message 868 prior to its advertised expiration, then the push service MUST push a 869 failure response with a status code of 410 (Gone). 871 7. Operational Considerations 873 7.1. Load Management 875 A push service is likely to have to maintain a very large number of 876 open TCP connections. Effective management of those connections can 877 depend on being able to move connections between server instances. 879 A user agent MUST support the 307 (Temporary Redirect) status code 880 [RFC7231], which can be used by a push service to redistribute load 881 at the time that a new subscription is requested. 883 A server that wishes to redistribute load can do so using HTTP 884 alternative services [RFC7838]. HTTP alternative services allows for 885 redistribution of load while maintaining the same URIs for various 886 resources. A user agent can ensure a graceful transition by using 887 the GOAWAY frame once it has established a replacement connection. 889 7.2. Push Message Expiration 891 Storage of push messages based on the TTL header field comprises a 892 potentially significant amount of storage for a push service. A push 893 service is not obligated to store messages indefinitely. A push 894 service is able to indicate how long it intends to retain a message 895 to an application server using the TTL header field (Section 5.2). 897 A user agent that does not actively monitor for push messages will 898 not receive messages that expire during that interval. 900 Push messages that are stored and have not been delivered to a user 901 agent are delivered when the user agent recommences monitoring. 902 Stored push messages SHOULD include a Last-Modified header field 903 (Section 2.2 of [RFC7232]) indicating when delivery was requested by 904 an application server. 906 A GET request to a push message subscription resource with only 907 expired messages results in a response as though no push message was 908 ever sent. 910 Push services might need to limit the size and number of stored push 911 messages to avoid overloading. To limit the size of messages, the 912 push service MAY return a 413 (Payload Too Large) status code 913 [RFC7231] in response to requests that include an entity body that is 914 too large. Push services MUST NOT return a 413 status code in 915 responses to an entity body that is 4096 bytes or less in size. 917 To limit the number of stored push messages, the push service MAY 918 respond with a shorter Time-To-Live than proposed by the application 919 server in its request for push message delivery (Section 5.2). Once 920 a message has been accepted, the push service MAY later expire the 921 message prior to its advertised Time-To-Live. If the application 922 server requested a delivery receipt, the push service MUST return a 923 failure response (Section 6.2). 925 7.3. Subscription Expiration 927 In some cases, it may be necessary to terminate subscriptions so that 928 they can be refreshed. This applies to both push message 929 subscriptions and receipt subscriptions. 931 A push service MAY expire a subscription at any time. If there are 932 outstanding requests to an expired push message subscription resource 933 (Section 6) from a user agent or to an expired receipt subscription 934 resource (Section 6.3) from an application server, this MUST be 935 signaled by returning a 404 (Not Found) status code. 937 A push service MUST return a 404 (Not Found) status code if an 938 application server attempts to send a push message to an expired push 939 message subscription. 941 A user agent can remove its push message subscription by sending a 942 DELETE request to the corresponding URI. An application server can 943 remove its receipt subscription by sending a DELETE request to the 944 corresponding URI. 946 7.3.1. Subscription Set Expiration 948 A push service MAY expire a subscription set at any time and MUST 949 also expire all push message subscriptions in the set. If a user 950 agent has an outstanding request to a push subscription set 951 (Section 6.1) this MUST be signaled by returning a 404 (Not Found) 952 status code. 954 A user agent can request that a subscription set be removed by 955 sending a DELETE request to the subscription set URI. This MUST also 956 remove all push message subscriptions in the set. 958 If a specific push message subscription that is a member of a 959 subscription set is expired or removed, then it MUST also be removed 960 from its subscription set. 962 7.4. Implications for Application Reliability 964 A push service that does not support reliable delivery over 965 intermittent network connections or failing applications on devices, 966 forces the device to acknowledge receipt directly to the application 967 server, incurring additional power drain in order to establish and 968 maintain (usually secure) connections to the individual application 969 servers. 971 Push message reliability can be important if messages contain 972 information critical to the state of an application. Repairing state 973 can be expensive, particularly for devices with limited 974 communications capacity. Knowing that a push message has been 975 correctly received avoids retransmissions, polling, and state 976 resynchronization. 978 The availability of push message delivery receipts ensures that the 979 application developer is not tempted to create alternative mechanisms 980 for message delivery in case the push service fails to deliver a 981 critical message. Setting up a polling mechanism or a backup 982 messaging channel in order to compensate for these shortcomings 983 negates almost all of the advantages a push service provides. 985 However, reliability might not be necessary for messages that are 986 transient (e.g. an incoming call) or messages that are quickly 987 superceded (e.g. the current number of unread emails). 989 7.5. Subscription Sets and Concurrent HTTP/2 streams 991 If the push service requires that the user agent use push message 992 subscription sets, then it MAY limit the number of concurrently 993 active streams with the SETTINGS_MAX_CONCURRENT_STREAMS parameter 994 within a HTTP/2 SETTINGS frame [RFC7540]. The user agent MAY be 995 limited to one concurrent stream to manage push message subscriptions 996 and one concurrent stream for each subscription set returned by the 997 push service. This could force the user agent to serialize 998 subscription requests to the push service. 1000 8. Security Considerations 1002 This protocol MUST use HTTP over TLS [RFC2818] following the 1003 recommendations in [RFC7525]. This includes any communications 1004 between user agent and push service, plus communications between the 1005 application server and the push service. All URIs therefore use the 1006 "https" scheme. This provides confidentiality and integrity 1007 protection for subscriptions and push messages from external parties. 1009 8.1. Confidentiality from Push Service Access 1011 The protection afforded by TLS does not protect content from the push 1012 service. Without additional safeguards, a push service can inspect 1013 and modify the message content. 1015 Applications using this protocol MUST use mechanisms that provide 1016 end-to-end confidentiality, integrity and data origin authentication. 1017 The application server sending the push message and the application 1018 on the user agent that receives it are frequently just different 1019 instances of the same application, so no standardized protocol is 1020 needed to establish a proper security context. The distribution of 1021 subscription information from the user agent to its application 1022 server also offers a convenient medium for key agreement. 1024 For this requirement, the W3C Push API [API] has adopted Message 1025 Encryption for WebPush [I-D.ietf-webpush-encryption] to secure the 1026 content of messages from the push service. Other scenarios can be 1027 addressed by similar policies. 1029 The Topic header field exposes information that allows more granular 1030 correlation of push messages on the same subject. This might be used 1031 to aid traffic analysis of push messages by the push service. 1033 8.2. Privacy Considerations 1035 Push message confidentiality does not ensure that the identity of who 1036 is communicating and when they are communicating is protected. 1037 However, the amount of information that is exposed can be limited. 1039 The URIs provided for push resources MUST NOT provide any basis to 1040 correlate communications for a given user agent. It MUST NOT be 1041 possible to correlate any two push resource URIs based solely on 1042 their contents. This allows a user agent to control correlation 1043 across different applications, or over time. Of course, this does 1044 not prevent correlation using other information that a user agent 1045 might expose. 1047 Similarly, the URIs provided by the push service to identify a push 1048 message MUST NOT provide any information that allows for correlation 1049 across subscriptions. Push message URIs for the same subscription 1050 MAY contain information that would allow correlation with the 1051 associated subscription or other push messages for that subscription. 1053 User and device information MUST NOT be exposed through a push or 1054 push message URI. 1056 In addition, push URIs established by the same user agent or push 1057 message URIs for the same subscription MUST NOT include any 1058 information that allows them to be correlated with the user agent. 1060 Note: This need not be perfect as long as the resulting anonymity 1061 set ([RFC6973], Section 6.1.1) is sufficiently large. A push URI 1062 necessarily identifies a push service or a single server instance. 1063 It is also possible that traffic analysis could be used to 1064 correlate subscriptions. 1066 A user agent MUST be able to create new subscriptions with new 1067 identifiers at any time. 1069 8.3. Authorization 1071 This protocol does not define how a push service establishes whether 1072 a user agent is permitted to create a subscription, or whether push 1073 messages can be delivered to the user agent. A push service MAY 1074 choose to authorize requests based on any HTTP-compatible 1075 authorization method available, of which there are multiple options 1076 (including experimental options) with varying levels of security. 1077 The authorization process and any associated credentials are expected 1078 to be configured in the user agent along with the URI for the push 1079 service. 1081 Authorization is managed using capability URLs for the push message 1082 subscription, push, and receipt subscription resources ([CAP-URI]). 1083 A capability URL grants access to a resource based solely on 1084 knowledge of the URL. 1086 Capability URLs are used for their "easy onward sharing" and "easy 1087 client API" properties. These make it possible to avoid relying on 1088 relationships between push services and application servers, with the 1089 protocols necessary to build and support those relationships. 1091 Capability URLs act as bearer tokens. Knowledge of a push message 1092 subscription URI implies authorization to either receive push 1093 messages or delete the subscription. Knowledge of a push URI implies 1094 authorization to send push messages. Knowledge of a push message URI 1095 allows for reading and acknowledging that specific message. 1096 Knowledge of a receipt subscription URI implies authorization to 1097 receive push receipts. 1099 Encoding a large amount of random entropy (at least 120 bits) in the 1100 path component ensures that it is difficult to successfully guess a 1101 valid capability URL. 1103 8.4. Denial of Service Considerations 1105 A user agent can control where valid push messages originate by 1106 limiting the distribution of push URIs to authorized application 1107 servers. Ensuring that push URIs are hard to guess ensures that only 1108 application servers that have received a push URI can use it. 1110 Push messages that are not successfully authenticated by the user 1111 agent will not be delivered, but this can present a denial of service 1112 risk. Even a relatively small volume of push messages can cause 1113 battery-powered devices to exhaust power reserves. 1115 To address this case, the W3C Push API [API] has adopted Voluntary 1116 Application Server Identification [I-D.ietf-webpush-vapid], which 1117 allows a user agent to restrict a subscription to a specific 1118 application server. The push service can then identify and reject 1119 unwanted messages without contacting the user agent. 1121 A malicious application with a valid push URI could use the greater 1122 resources of a push service to mount a denial of service attack on a 1123 user agent. Push services SHOULD limit the rate at which push 1124 messages are sent to individual user agents. 1126 A push service MAY return a 429 (Too Many Requests) status code 1127 [RFC6585] when an application server has exceeded its rate limit for 1128 push message delivery to a push resource. The push service SHOULD 1129 also include a Retry-After header [RFC7231] to indicate how long the 1130 application server is requested to wait before it makes another 1131 request to the push resource. 1133 A push service or user agent MAY also terminate subscriptions 1134 (Section 7.3) that receive too many push messages. 1136 A push service is also able to deny service to user agents. 1137 Intentional failure to deliver messages is difficult to distinguish 1138 from faults, which might occur due to transient network errors, 1139 interruptions in user agent availability, or genuine service outages. 1141 8.5. Logging Risks 1143 Server request logs can reveal subscription-related URIs or 1144 relationships between subscription-related URIs for the same user 1145 agent. Limitations on log retention and strong access control 1146 mechanisms can ensure that URIs are not revealed to unauthorized 1147 entities. 1149 9. IANA Considerations 1151 This protocol defines new HTTP header fields in Section 9.1. New 1152 link relation types are identified using the URNs defined in 1153 Section 9.2. Port registration is defined in Section 9.3 1155 9.1. Header Field Registrations 1157 HTTP header fields are registered within the "Message Headers" 1158 registry maintained at . 1161 This document defines the following HTTP header fields, so their 1162 associated registry entries shall be added according to the permanent 1163 registrations below ([RFC3864]): 1165 +-------------------+----------+----------+--------------+ 1166 | Header Field Name | Protocol | Status | Reference | 1167 +-------------------+----------+----------+--------------+ 1168 | TTL | http | standard | Section 5.2 | 1169 | Urgency | http | standard | Section 5.3 | 1170 | Topic | http | standard | Section 5.4 | 1171 +-------------------+----------+----------+--------------+ 1173 The change controller is: "IETF (iesg@ietf.org) - Internet 1174 Engineering Task Force". 1176 9.2. Link Relation URNs 1178 This document registers URNs for use in identifying link relation 1179 types. These are added to a new "Web Push Identifiers" registry 1180 according to the procedures in Section 4 of [RFC3553]; the 1181 corresponding "push" sub-namespace is entered in the "IETF URN Sub- 1182 namespace for Registered Protocol Parameter Identifiers" registry. 1184 The "Web Push Identifiers" registry operates under the IETF Review 1185 policy [RFC5226]. 1187 Registry name: Web Push Identifiers 1189 URN Prefix: urn:ietf:params:push 1191 Specification: (this document) 1193 Repository: [Editor/IANA note: please include a link to the final 1194 registry location.] 1196 Index value: Values in this registry are URNs or URN prefixes that 1197 start with the prefix "urn:ietf:params:push". Each is registered 1198 independently. 1200 New registrations in the "Web Push Identifiers" are encouraged to 1201 include the following information: 1203 URN: A complete URN or URN prefix. 1205 Description: A summary description. 1207 Specification: A reference to a specification describing the 1208 semantics of the URN or URN prefix. 1210 Contact: Email for the person or group making the registration. 1212 Index value: As described in [RFC3553], URN prefixes that are 1213 registered include a description of how the URN is constructed. 1214 This is not applicable for specific URNs. 1216 These values are entered as the initial content of the "Web Push 1217 Identifiers" registry. 1219 URN: urn:ietf:params:push 1221 Description: This link relation type is used to identify a resource 1222 for sending push messages. 1224 Specification: (this document) 1226 Contact: The Web Push WG (webpush@ietf.org) 1228 URN: urn:ietf:params:push:set 1230 Description: This link relation type is used to identify a 1231 collection of push message subscriptions. 1233 Specification: (this document) 1234 Contact: The Web Push WG (webpush@ietf.org) 1236 URN: urn:ietf:params:push:receipt 1238 Description: This link relation type is used to identify a resource 1239 for receiving delivery confirmations for push messages. 1241 Specification: (this document) 1243 Contact: The Web Push WG (webpush@ietf.org) 1245 9.3. Service Name and Port Number Registration 1247 Service names and port numbers are registered within the "Service 1248 Name and Transport Protocol Port Number Registry" maintained at 1249 . 1252 In accordance with [RFC6335], it is requested that IANA assign the 1253 suggested System Port number 1001 (or another port in the System 1254 range) and the service name "webpush". 1256 Service Name: 1257 webpush 1259 Transport Protocol: 1260 tcp 1262 Assignee: 1263 The IESG (iesg@ietf.org) 1265 Contact: 1266 The IETF Chair (chair@ietf.org) 1268 Description: 1269 HTTP Web Push 1271 Reference: 1272 [RFCthis] 1274 Port Number: 1275 1001 1277 [[The RFC Editor is requested to remove this editorial note at 1278 publication.]] 1279 This document uses a placeholder value for a system port pending IANA 1280 assignment which needs to be replaced with the finalized value at the 1281 time of publication. Please apply the following replacement: 1283 o "WEBPUSH-PORT" --> the assigned port value for "webpush" 1285 10. Acknowledgements 1287 Significant technical input to this document has been provided by Ben 1288 Bangert, Peter Beverloo, Kit Cambridge, JR Conlin, Lucas Jenss, 1289 Matthew Kaufman, Costin Manolache, Mark Nottingham, Idel Pivnitskiy, 1290 Robert Sparks, Darshak Thakore and many others. 1292 11. References 1294 11.1. Normative References 1296 [CAP-URI] Tennison, J., "Good Practices for Capability URLs", FPWD 1297 capability-urls, February 2014, 1298 . 1300 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1301 Requirement Levels", BCP 14, RFC 2119, March 1997. 1303 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. 1305 [RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An 1306 IETF URN Sub-namespace for Registered Protocol 1307 Parameters", BCP 73, RFC 3553, June 2003. 1309 [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration 1310 Procedures for Message Header Fields", BCP 90, RFC 3864, 1311 September 2004. 1313 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 1314 Encodings", RFC 4648, October 2006. 1316 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 1317 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 1318 May 2008. 1320 [RFC5382] Biswas, K., Ford, B., Sivakumar, S., and P. Srisuresh, 1321 "NAT Behavioral Requirements for TCP", RFC 5382, October 1322 2008. 1324 [RFC5988] Nottingham, M., "Web Linking", RFC 5988, October 2010. 1326 [RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. 1327 Cheshire, "Internet Assigned Numbers Authority (IANA) 1328 Procedures for the Management of the Service Name and 1329 Transport Protocol Port Number Registry", RFC 6335, August 1330 2011. 1332 [RFC6454] Barth, A., "The Web Origin Concept", RFC 6454, December 1333 2011. 1335 [RFC6585] Nottingham, M. and R. Fielding, "Additional HTTP Status 1336 Codes", RFC 6585, April 2012. 1338 [RFC7230] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol 1339 (HTTP/1.1): Message Syntax and Routing", RFC 7230, June 1340 2014. 1342 [RFC7231] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol 1343 (HTTP/1.1): Semantics and Content", RFC 7231, June 2014. 1345 [RFC7232] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol 1346 (HTTP/1.1): Conditional Requests", RFC 7232, June 2014. 1348 [RFC7240] Snell, J., "Prefer Header for HTTP", RFC 7240, June 2014. 1350 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 1351 "Recommendations for Secure Use of Transport Layer 1352 Security (TLS) and Datagram Transport Layer Security 1353 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 1354 2015. 1356 [RFC7540] Belshe, M., Peon, R., and M. Thomson, "Hypertext Transfer 1357 Protocol Version 2", RFC 7540, May 2015. 1359 [RFC7838] Nottingham, M., McManus, P., and J. Reschke, "HTTP 1360 Alternative Services", RFC 7838, April 2016. 1362 11.2. Informative References 1364 [API] van Ouwerkerk, M., Thomson, M., Sullivan, B., and E. 1365 Fullea, "W3C Push API", ED push-api, August 2016, 1366 . 1368 [I-D.ietf-webpush-encryption] 1369 Thomson, M., "Message Encryption for Web Push", draft- 1370 ietf-webpush-encryption-04 (work in progress), October 1371 2016, . 1374 [I-D.ietf-webpush-vapid] 1375 Thomson, M. and P. Beverloo, "Voluntary Application Server 1376 Identification for Web Push", draft-ietf-webpush-vapid-01 1377 (work in progress), June 2016, 1378 . 1381 [RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., 1382 Morris, J., Hansen, M., and R. Smith, "Privacy 1383 Considerations for Internet Protocols", RFC 6973, July 1384 2013. 1386 Appendix A. Change Log 1388 [[The RFC Editor is requested to remove this section at 1389 publication.]] 1391 A.1. Since draft-ietf-webpush-protocol-00 1393 Editorial changes for Push Message Time-To-Live 1395 Editorial changes for Push Acknowledgements 1397 Removed subscription expiration based on HTTP cache headers 1399 A.2. Since draft-ietf-webpush-protocol-01 1401 Added Subscription Sets 1403 Added System Port as an alternate service with guidance for idle 1404 timeouts 1406 Finalized status codes for acknowledgements 1408 Editorial changes for Rate Limits 1410 A.3. Since draft-ietf-webpush-protocol-02 1412 Added explicit correlation for Subscription Sets 1414 Added Push Message Updates (message collapsing) 1416 Renamed the push:receipt link relation to push:receipts and 1417 transitioned the Push-Receipt header field to the push:receipt link 1418 relation type 1420 A.4. Since draft-ietf-webpush-protocol-03 1422 An application server MUST include the TTL (Time-To-Live) header 1423 field in its request for push message delivery. 1425 Added Push Message Urgency header field 1427 A.5. Since draft-ietf-webpush-protocol-04 1429 Simplified design for Push Receipts and eliminated the 1430 urn:ietf:params:push:receipts link relation 1432 Clarified Security Considerations section and added informative 1433 references to Message Encryption and Voluntary Application Server 1434 Identification 1436 A.6. Since draft-ietf-webpush-protocol-05 1438 Addressed feedback from Working Group Last Call 1440 A.7. Since draft-ietf-webpush-protocol-06 1442 Updated informative references to W3C Push API, Message Encryption, 1443 and Voluntary Application Server Identification 1445 A.8. Since draft-ietf-webpush-protocol-07 1447 Minor editorial changes 1449 A.9. Since draft-ietf-webpush-protocol-08 1451 Minor correction to Acknowledgements 1453 Updated dates for informative references 1455 A.10. Since draft-ietf-webpush-protocol-09 1457 Updates for Area Director (Alissa Cooper) evaluation 1459 A.11. Since draft-ietf-webpush-protocol-10 1461 Updates for TSV-ART review from Magnus Westerlund 1463 Updated informative reference for Message Encryption 1465 A.12. Since draft-ietf-webpush-protocol-11 1467 Updates from IESG Evaluation 1469 Authors' Addresses 1471 Martin Thomson 1472 Mozilla 1473 331 E Evelyn Street 1474 Mountain View, CA 94041 1475 US 1477 Email: martin.thomson@gmail.com 1479 Elio Damaggio 1480 Microsoft 1481 One Microsoft Way 1482 Redmond, WA 98052 1483 US 1485 Email: elioda@microsoft.com 1487 Brian Raymor (editor) 1488 Microsoft 1489 One Microsoft Way 1490 Redmond, WA 98052 1491 US 1493 Email: brian.raymor@microsoft.com