ALTO Working Group R. Schott Internet-Draft Deutsche Telekom Intended status: Standards Track Y. Yang Expires: 24 April 2023 Yale University K. Gao Sichuan University L. Delwiche Yale University 21 October 2022 ALTO New Transport: Server Push using PUSH_PROMISE of HTTP/2 draft-schott-alto-new-transport-push-00 Abstract The ALTO New Transport [draft-ietf-alto-new-transport] introduces ALTO transport information structures (TIS) at an ALTO server. The introduction of ALTO TIS allows at least two types of efficient transport using HTTP: (1) HTTP/2/3 independent client long poll allowed by non-blocking, newer HTTP, and (2) HTTP/2 specific server push. This document defines HTTP/2 specific server-push ALTO transport based on ALTO TIS. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119][RFC8174] when, and only when, they appear in all capitals, as shown here. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 24 April 2023. Schott, et al. Expires 24 April 2023 [Page 1] Internet-Draft ALTO/H2 October 2022 Copyright Notice Copyright (c) 2022 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Manage Server Push: Receiver Set . . . . . . . . . . . . . . 5 2.1. Receiver Set Operations . . . . . . . . . . . . . . . . . 5 2.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Server Push of Incremental Updates . . . . . . . . . . . . . 8 3.1. Server Push . . . . . . . . . . . . . . . . . . . . . . . 8 3.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 8 4. Server Push Stream Management . . . . . . . . . . . . . . . . 10 4.1. Server -> Client [PUSH_PROMISE for Transport Queue on Stream SID_tq] . . . . . . . . . . . . . . . . . . . . . 10 5. Server Push Information Resource Directory (IRD) . . . . . . 10 6. Security Considerations . . . . . . . . . . . . . . . . . . . 13 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 9.1. Normative References . . . . . . . . . . . . . . . . . . 13 9.2. Informative References . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 1. Introduction The ALTO new transport [draft-ietf-alto-new-transport] introduces ALTO transport queues for an ALTO server to manage the transport of ALTO information to an ALTO client. The base design, however, supports only client pull. Hence, for a client to obtain the latest ALTO information, the client need to maintain a pending pull on the incremental updates queue. This document extends the base design to allow server push, potentially reducing information distribution delay. Schott, et al. Expires 24 April 2023 [Page 2] Internet-Draft ALTO/H2 October 2022 The extension to realize server push on a transport queue is by adding a receiver set. Figure 2 shows an example illustrating the additional receiver set at each transport queue. Schott, et al. Expires 24 April 2023 [Page 3] Internet-Draft ALTO/H2 October 2022 Information Resource: a) Static resource (#1) such as NetworkMap b) Filterable resource (#3) such as FilteredCostMap +-------------+ | | +--------------------| ALTO Server |-----------+ | +-| |-+ | | | +-------------+ | | | | | | ---------|------------------|-----------------|---------|------------ | | | | Information | | | | Resource +-------------+ +-------------+ +-------------+ +-------------+ | Information | | Information | | Information | | Information | | Resource #1 | | Resource #2 | | Resource #3 | | Resource #4 | +-------------+ +-------------+ +-------------+ +-------------+ | / \ -------|-----------------------------/------\------------------------ | / \ Transport | +----/ \------+ Queues | | | +--------+ +--------+ +--------+ | tq1 |-----+ | tq2 |-----+ | tq3 |-----+ +----|---+ | +----|---+ | +----|---+ | | | | | | | +----|---+ +---|----+ +----|---+ +---|----+ +----|---+ +---|----+ | tq1/uq | | tq1/rs | | tq2/uq | | tq2/rs | | tq3/uq | | tq3/rs | +--------+ +--------+ +--------+ +--------+ +--------+ +--------+ |\ /\ | / | | -------|-\-----/--\-------------|--------/------------|----------|--- | \ / +-------+ | / | | | +-/-----------+ \ | / | | | / \ \ | / A + + | / +--\--\-|----/--+ single \ / | / +---\--\|---/---+ http2/3 \ / +----------+ +----------+ connection +----------+ | Client 1 | | Client 2 | | Client 3 | +----------+ +------- --+ +----------+ tqi = transport queue i tqi/uq = incremental updates queue of transport queue i tqi/rs = receiver set of transport queue i Figure 1: ALTO New Transport Information Structure. Schott, et al. Expires 24 April 2023 [Page 4] Internet-Draft ALTO/H2 October 2022 This document specifies the operation to manage the receiver set. 2. Manage Server Push: Receiver Set 2.1. Receiver Set Operations A client starts to receive server push when it is added to the receiver set. A client can add itself to the receiver set when creating the transport queue, or add itself explicitly to the receiver set. A client can read the status of the receiver set and delete itself from the receiver set to stop server push. Implicit Create: As a short cut, when creating a transport queue, an ALTO client can start server push by setting the "incremental- changes" field to be true when creating a transport queue using the HTTP POST method with ALTO SSE AddUpdateReq ([RFC 8895] Sec. 6.5) as the parameter: object { ResourceID resource-id; [JSONString tag;] [Boolean incremental-changes;] [Object input;] } AddUpdateReq; PUT Create: A client can add itself in the receiver set by using the HTTP PUT method: PUT transport-queue/rs/self Read: A client can see only itself in the receiver set. The appearance of self in the receiver set (read does not return "not exists" error) is an indication that push starts. Delete: A client can delete itself (stops receiving push) either explicitly or implicitly. * Explicit delete: A client deletes itself using the HTTP DELETE method: DELETE transport-queue/rs/self. * Implicit delete: Transport queue is connection ephemeral: the close of connection or stream for the transport queue deletes the transport queue (from the view) for the client. Schott, et al. Expires 24 April 2023 [Page 5] Internet-Draft ALTO/H2 October 2022 2.2. Examples The first example is a client creating a transport queue and starting server push. Client -> server request HEADERS - END_STREAM + END_HEADERS :method = POST :scheme = https :path = /tqs host = alto.example.com accept = application/alto-error+json, application/alto-transport+json content-type = application/alto-transport+json content-length = TBD DATA - END_STREAM { "resource-id": "my-routingcost-map", "incremental-push": true } Server -> client response: HEADERS - END_STREAM + END_HEADERS :status = 200 content-type = application/alto-transport+json content-length = TBD DATA - END_STREAM {"tq": “/tqs/2718281828459”} If the client reads the status of the transport queue created above using the read operation (GET) in the same HTTP connection, the client should see itself in the receiver set: Schott, et al. Expires 24 April 2023 [Page 6] Internet-Draft ALTO/H2 October 2022 Client -> server request HEADERS - END_STREAM + END_HEADERS :method = GET :scheme = https :path = /tqs/2718281828459 host = alto.example.com accept = application/alto-error+json, application/alto-transport+json Server -> client response: HEADERS - END_STREAM + END_HEADERS :status = 200 content-type = application/alto-transport+json content-length = TBD DATA - END_STREAM { "uq": [ {“seq”: 101, "media-type": "application/alto-costmap+json", “tag”: "a10ce8b059740b0b2e3f8eb1d4785acd42231bfe" }, {“seq”: 102, "media-type": "application/merge-patch+json", “tag”: "cdf0222x59740b0b2e3f8eb1d4785acd42231bfe" }, {“seq”: 103, "media-type": "application/merge-patch+json", “tag”: "8eb1d4785acd42231bfecdf0222x59740b0b2e3f", "link": "/tqs/2718281828459/snapshot/2e3f"} ], "rs": ["self"] } A client can stop incremental push updates from the server to itself by sending the request: Schott, et al. Expires 24 April 2023 [Page 7] Internet-Draft ALTO/H2 October 2022 DELETE /tqs/2718281828459/rs/self HTTP/2 Accept: application/alto-transport+json HTTP/2 200 OK 3. Server Push of Incremental Updates 3.1. Server Push The work flow of server push of individual updates is the following: * Initialization: the first update pushed from the server to the client MUST be the later of the following two: (1) the last independent update in the incremental updates queue; and (2) the following entry of the entry that matches the tag when the client creates the transport queue. The client MUST set SETTINGS_ENABLE_PUSH to be consistent. * Push state: the server MUST maintain the last entry pushed to the client (and hence per client, per connection state) and schedule next update push accordingly. * Push management: The client MUST NOT cancel (RST_STREAM) a PUSH_PROMISE to avoid complex server state management. 3.2. Examples A client can wait for the server for incremental push, where the server first sends PUSH_PROMISE, for the first example in Sec. 2.2: Server -> client PUSH_PROMISE in current stream: PUSH_PROMISE - END_STREAM Promised Stream 4 HEADER BLOCK :method = GET :scheme = https :path = /tqs/2718281828459/uq/101 host = alto.example.com accept = application/alto-error+json, application/alto-costmap+json Server -> client content Stream 4: HEADERS + END_STREAM Schott, et al. Expires 24 April 2023 [Page 8] Internet-Draft ALTO/H2 October 2022 + END_HEADERS :status = 200 content-type = application/alto-costmap+json content-length = TBD DATA + END_STREAM { "meta" : { "dependent-vtags" : [{ "resource-id": "my-network-map", "tag": "da65eca2eb7a10ce8b059740b0b2e3f8eb1d4785" }], "cost-type" : { "cost-mode" : "numerical", "cost-metric": "routingcost" }, "vtag": { "resource-id" : "my-routingcost-map", "tag" : "3ee2cb7e8d63d9fab71b9b34cbf764436315542e" } }, "cost-map" : { "PID1": { "PID1": 1, "PID2": 5, "PID3": 10 }, "PID2": { "PID1": 5, "PID2": 1, "PID3": 15 }, "PID3": { "PID1": 20, "PID2": 15 } } } Server -> client PUSH_PROMISE in current stream: PUSH_PROMISE - END_STREAM Promised Stream 6 HEADER BLOCK :method = GET :scheme = https :path = /tqs/2718281828459/uq/102 host = alto.example.com accept = application/alto-error+json, application/merge-patch+json Server -> client content Stream 6 HEADERS + END_STREAM + END_HEADERS :status = 200 Schott, et al. Expires 24 April 2023 [Page 9] Internet-Draft ALTO/H2 October 2022 content-type = application/merge-patch+json content-length = TBD DATA + END_STREAM { ...} 4. Server Push Stream Management 4.1. Server -> Client [PUSH_PROMISE for Transport Queue on Stream SID_tq] The server push MUST satisfy the following requirements: * PUSH_PROMISE MUST be sent in stream SID_tq to serialize to allow the client to know the push order; * Each PUSH_PROMISE chooses a new server-selected stream ID, and the stream is closed after push. 5. Server Push Information Resource Directory (IRD) Extending the IRD example in Section 8.1 of [RFC8895], below is the IRD of an ALTO server supporting ALTO base protocol, ALTO/SSE, and Server Push. In particular, "my-network-map": { "uri": "https://alto.example.com/networkmap", "media-type": "application/alto-networkmap+json", }, "my-routingcost-map": { "uri": "https://alto.example.com/costmap/routingcost", "media-type": "application/alto-costmap+json", "uses": ["my-networkmap"], "capabilities": { "cost-type-names": ["num-routingcost"] } }, "my-hopcount-map": { "uri": "https://alto.example.com/costmap/hopcount", "media-type": "application/alto-costmap+json", "uses": ["my-networkmap"], "capabilities": { "cost-type-names": ["num-hopcount"] } Schott, et al. Expires 24 April 2023 [Page 10] Internet-Draft ALTO/H2 October 2022 }, "my-filtered-cost-map": { "uri": "https://alto.example.com/costmap/filtered/constraints", "media-type": "application/alto-costmap+json", "accepts": "application/alto-costmapfilter+json", "uses": ["my-networkmap"], "capabilities": { "cost-type-names": ["num-routingcost", "num-hopcount"], "cost-constraints": true } }, "my-simple-filtered-cost-map": { "uri": "https://alto.example.com/costmap/filtered/simple", "media-type": "application/alto-costmap+json", "accepts": "application/alto-costmapfilter+json", "uses": ["my-networkmap"], "capabilities": { "cost-type-names": ["num-routingcost", "num-hopcount"], "cost-constraints": false } }, "my-props": { "uri": "https://alto.example.com/properties", "media-type": "application/alto-endpointprops+json", "accepts": "application/alto-endpointpropparams+json", "capabilities": { "prop-types": ["priv:ietf-bandwidth"] } }, "my-pv": { "uri": "https://alto.example.com/endpointcost/pv", "media-type": "multipart/related; type=application/alto-endpointcost+json", "accepts": "application/alto-endpointcostparams+json", "capabilities": { "cost-type-names": [ "path-vector" ], "ane-properties": [ "maxresbw", "persistent-entities" ] } }, "update-my-costs": { "uri": "https://alto.example.com/updates/costs", "media-type": "text/event-stream", "accepts": "application/alto-updatestreamparams+json", "uses": [ "my-network-map", "my-routingcost-map", "my-hopcount-map", "my-simple-filtered-cost-map" Schott, et al. Expires 24 April 2023 [Page 11] Internet-Draft ALTO/H2 October 2022 ], "capabilities": { "incremental-change-media-types": { "my-network-map": "application/json-patch+json", "my-routingcost-map": "application/merge-patch+json", "my-hopcount-map": "application/merge-patch+json" }, "support-stream-control": true } }, "update-my-costs-h2": { "uri": "https://alto.example.com/updates-h2/costs", "media-type": "application/alto-transport+json", "accepts": "application/alto-updatestreamparams+json", "uses": [ "my-network-map", "my-routingcost-map", "my-hopcount-map", "my-simple-filtered-cost-map" ], "capabilities": { "incremental-change-media-types": { "my-network-map": "application/json-patch+json", "my-routingcost-map": "application/merge-patch+json", "my-hopcount-map": "application/merge-patch+json" }, "support-stream-control": true } }, "update-my-props": { "uri": "https://alto.example.com/updates/properties", "media-type": "text/event-stream", "uses": [ "my-props" ], "accepts": "application/alto-updatestreamparams+json", "capabilities": { "incremental-change-media-types": { "my-props": "application/merge-patch+json" }, "support-stream-control": true } }, "update-my-pv": { "uri": "https://alto.example.com/updates/pv", "media-type": "text/event-stream", "uses": [ "my-pv" ], "accepts": "application/alto-updatestreamparams+json", "capabilities": { Schott, et al. Expires 24 April 2023 [Page 12] Internet-Draft ALTO/H2 October 2022 "incremental-change-media-types": { "my-pv": "application/merge-patch+json" }, "support-stream-control": true } } 6. Security Considerations The properties defined in this document present no security considerations beyond those in Section 15 of the base ALTO specification [RFC7285]. 7. IANA Considerations IANA will need to register server push. 8. Acknowledgments The authors of this document would also like to thank many for the reviews and comments. 9. References 9.1. Normative References [draft-ietf-alto-new-transport] Schott, R. and Y. Yang, "ALTO New Transport: ALTO Transport Information Structures", Internet Draft ID, October 2022, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, June 2014, . [RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S., Previdi, S., Roome, W., Shalunov, S., and R. Woundy, "Application-Layer Traffic Optimization (ALTO) Protocol", RFC 7285, DOI 10.17487/RFC7285, September 2014, . Schott, et al. Expires 24 April 2023 [Page 13] Internet-Draft ALTO/H2 October 2022 [RFC7540] Belshe, M., Peon, R., and M. Thomson, "Hypertext Transfer Protocol Version 2 (HTTP/2)", RFC 7540, DOI 10.17487/RFC7540, May 2015, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8895] Roome, W. and Y. Yang, "Application-Layer Traffic Optimization (ALTO) Incremental Updates Using Server-Sent Events (SSE)", RFC 8895, DOI 10.17487/RFC8895, November 2020, . 9.2. Informative References [RFC7971] Stiemerling, M., Kiesel, S., Scharf, M., Seidel, H., and S. Previdi, "Application-Layer Traffic Optimization (ALTO) Deployment Considerations", RFC 7971, DOI 10.17487/RFC7971, October 2016, . Authors' Addresses Roland Schott Deutsche Telekom Heinrich-Hertz-Strasse 3-7 64295 Darmstadt Germany Email: Roland.Schott@telekom.de Y. Richard Yang Yale University 51 Prospect St New Haven, CT 06520 United States of America Email: yry@cs.yale.edu Kai Gao Sichuan University Chengdu 201804 China Email: kgao@scu.edu.cn Schott, et al. Expires 24 April 2023 [Page 14] Internet-Draft ALTO/H2 October 2022 Lauren Delwiche Yale University 51 Prospect St New Haven, CT 06520 United States of America Email: lauren.delwiche@yale.edu Schott, et al. Expires 24 April 2023 [Page 15]