Internet DRAFT - draft-schott-alto-new-transport-push
draft-schott-alto-new-transport-push
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.
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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
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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.
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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.
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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.
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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.
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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:
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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:
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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
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+ 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
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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"]
}
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},
"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"
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],
"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": {
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"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, <https://datatracker.ietf.org/doc/draft-
ietf-alto-new-transport/02/>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[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,
<https://www.rfc-editor.org/info/rfc7230>.
[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,
<https://www.rfc-editor.org/info/rfc7285>.
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[RFC7540] Belshe, M., Peon, R., and M. Thomson, "Hypertext Transfer
Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[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, <https://www.rfc-editor.org/info/rfc8895>.
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,
<https://www.rfc-editor.org/info/rfc7971>.
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
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Lauren Delwiche
Yale University
51 Prospect St
New Haven, CT 06520
United States of America
Email: lauren.delwiche@yale.edu
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