WebRTC-HTTP egress protocol (WHEP)
draft-murillo-whep-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Sergio Garcia Murillo , Cheng Chen | ||
| Last updated | 2022-07-25 | ||
| Replaced by | draft-ietf-wish-whep | ||
| RFC stream | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-murillo-whep-00
Network Working Group S. Murillo
Internet-Draft Millicast
Intended status: Informational C. Chen
Expires: 26 January 2023 ByteDance
25 July 2022
WebRTC-HTTP egress protocol (WHEP)
draft-murillo-whep-00
Abstract
This document describes a simple HTTP-based protocol that will allow
WebRTC-based viewers to watch content from streaming services and/or
Content Delivery Networks (CDNs) or WebRTC Transmission Network
(WTNs).
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 26 January 2023.
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.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 5
4.1. SDP offer generated by the WHEP player . . . . . . . . . 5
4.2. SDP offer generated by the WHEP endpoint . . . . . . . . 8
4.3. Common procedures . . . . . . . . . . . . . . . . . . . . 11
4.4. ICE and NAT support . . . . . . . . . . . . . . . . . . . 12
4.5. WebRTC constraints . . . . . . . . . . . . . . . . . . . 15
4.6. Load balancing and redirections . . . . . . . . . . . . . 15
4.7. STUN/TURN server configuration . . . . . . . . . . . . . 16
4.8. Authentication and authorization . . . . . . . . . . . . 16
4.9. Protocol extensions . . . . . . . . . . . . . . . . . . . 17
5. Security Considerations . . . . . . . . . . . . . . . . . . . 17
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
6.1. Registration of WHEP URN Sub-namespace and whep
Registry . . . . . . . . . . . . . . . . . . . . . . . . 18
6.2. URN Sub-namespace for whep . . . . . . . . . . . . . . . 18
6.2.1. Specification Template . . . . . . . . . . . . . . . 18
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.1. Normative References . . . . . . . . . . . . . . . . . . 20
8.2. Informative References . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction
The IETF RTCWEB working group standardized JSEP ([RFC8829]), a
mechanism used to control the setup, management, and teardown of a
multimedia session. It also describes how to negotiate media flows
using the Offer/Answer Model with the Session Description Protocol
(SDP) [RFC3264] as well as the formats for data sent over the wire
(e.g., media types, codec parameters, and encryption). WebRTC
intentionally does not specify a signaling transport protocol at
application level. This flexibility has allowed the implementation
of a wide range of services. However, those services are typically
standalone silos which don't require interoperability with other
services or leverage the existence of tools that can communicate with
them.
While some standard signaling protocols are available that can be
integrated with WebRTC, like SIP [RFC3261] or XMPP [RFC6120], they
are not designed to be used in broadcasting/streaming services, and
there also is no sign of adoption in that industry. RTSP [RFC7826],
which is based on RTP and may be the closest in terms of features to
WebRTC, is not compatible with the SDP offer/answer model [RFC3264].
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So, currently, there is no standard protocol designed for consuming
media from streaming service using WebRTC.
There are many situations in which the lack of a standard protocol
for consuming media from streaming service using WebRTC has become a
problem:
* Interoperability between WebRTC services and products.
* Reusing player software which can be integrated easily.
* Integration with Dynamic Adaptive Streaming over HTTP (DASH) for
offering live streams via WebRTC while offering a time-shifted
version via DASH.
* Playing WebRTC streams on devices that don't support custom
javascript to be run (like TVs).
This document mimics what has been done the WebRTC HTTP Ingest
Protocol (WHIP) [I-D.draft-ietf-wish-whip] for ingestion and
specifies a simple HTTP-based protocol that can be used for consuming
media from a streaming service using WebRTC.
2. Terminology
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.
* WHEP Player: WebRTC media player that acts as a client of the WHEP
protocol by receiving and decoding the media from a remote Media
Server.
* WHEP Endpoint: Egress server receiving the initial WHEP request.
* WHEP Endpoint URL: URL of the WHEP endpoint that will create the
WHEP resource.
* Media Server: WebRTC Media Server or consumer that establishes the
media session with the WHEP player and delivers the media to it.
* WHEP Resource: Allocated resource by the WHEP endpoint for an
ongoing egress session that the WHEP player can send requests for
altering the session (ICE operations or termination, for example).
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* WHEP Resource URL: URL allocated to a specific media session by
the WHEP endpoint which can be used to perform operations such as
terminating the session or ICE restarts.
3. Overview
The WebRTC-HTTP Egress Protocol (WHEP) uses an HTTP POST request to
perform a single-shot SDP offer/answer so an ICE/DTLS session can be
established between the WHEP Player and the streaming service
endpoint (Media Server).
Once the ICE/DTLS session is set up, the media will flow
unidirectionally from Media Server to the WHEP Player. In order to
reduce complexity, no SDP renegotiation is supported, so no tracks or
streams can be added or removed once the initial SDP offer/answer
over HTTP is completed.
+-------------+ +---------------+ +--------------+ +---------------+
| WHEP Player | | WHEP Endpoint | | Media Server | | WHEP Resource |
+--+----------+ +---------+-----+ +------+-------+ +--------|------+
| | | |
| | | |
|HTTP POST (SDP Offer) | | |
+------------------------>+ | |
|201 Created (SDP answer) | | |
+<------------------------+ | |
| ICE REQUEST | |
+--------------------------------------->+ |
| ICE RESPONSE | |
|<---------------------------------------+ |
| DTLS SETUP | |
|<======================================>| |
| RTP/RTCP FLOW | |
+<-------------------------------------->+ |
| HTTP DELETE |
+---------------------------------------------------------->+
| 200 OK |
<-----------------------------------------------------------x
Figure 1: WHEP session setup and teardown
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Alternatively, there are cases in which the WHEP Player may wish the
service to provide the SDP offer (for example to avoid setting up an
audio and video session when only audio is supported), so in this
case the initial HTTP POST request will not contain a body and the
response will contain the SDP offer from the service instead. The
WHEP Player will have to provide the SDP answer in a subsequent HTTP
PATCH request to the WHEP resource.
+-------------+ +---------------+ +--------------+ +---------------+
| WHEP Player | | WHEP Endpoint | | Media Server | | WHEP Resource |
+--+----------+ +---------+-----+ +------+-------+ +--------|------+
| | | |
| | | |
|HTTP POST (empty) | | |
+------------------------>+ | |
|201 Created (SDP offer) | | |
+<------------------------+ | |
| HTTP PATCH (SDP answer) | |
+---------------------------------------------------------->+
| 200 OK | |
<-----------------------------------------------------------x
| ICE REQUEST | |
+--------------------------------------->+ |
| ICE RESPONSE | |
|<---------------------------------------+ |
| DTLS SETUP | |
|<======================================>| |
| RTP/RTCP FLOW | |
+<-------------------------------------->+ |
| HTTP DELETE |
+---------------------------------------------------------->+
| 200 OK |
<-----------------------------------------------------------x
Figure 2: WHEP session setup and teardown
4. Protocol Operation
4.1. SDP offer generated by the WHEP player
In order to set up a streaming session, the WHEP Player will generate
an SDP offer according to the JSEP rules and perform an HTTP POST
request to the configured WHEP Endpoint URL.
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The HTTP POST request will have a content type of "application/sdp"
and contain the SDP offer as the body. The WHEP Endpoint will
generate an SDP answer and return a "201 Created" response with a
content type of "application/sdp", the SDP answer as the body, and a
Location header field pointing to the newly created resource.
The SDP offer SHOULD use the "recvonly" attribute and the SDP answer
MUST use "sendonly" the attribute.
POST /whep/endpoint HTTP/1.1
Host: whep.example.com
Content-Type: application/sdp
Content-Length: 1326
v=0
o=- 5228595038118931041 2 IN IP4 127.0.0.1
s=-
t=0 0
a=group:BUNDLE 0 1
a=extmap-allow-mixed
a=msid-semantic: WMS
m=audio 9 UDP/TLS/RTP/SAVPF 111
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:zjkk
a=ice-pwd:bP+XJMM09aR8AiX1jdukzR6Y
a=ice-options:trickle
a=fingerprint:sha-256 DA:7B:57:DC:28:CE:04:4F:31:79:85:C4:31:67:EB:27:58:29:ED:77:2A:0D:24:AE:ED:AD:30:BC:BD:F1:9C:02
a=setup:actpass
a=mid:0
a=bundle-only
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=recvonly
a=rtcp-mux
a=rtpmap:111 opus/48000/2
a=fmtp:111 minptime=10;useinbandfec=1
m=video 9 UDP/TLS/RTP/SAVPF 96 97
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:zjkk
a=ice-pwd:bP+XJMM09aR8AiX1jdukzR6Y
a=ice-options:trickle
a=fingerprint:sha-256 DA:7B:57:DC:28:CE:04:4F:31:79:85:C4:31:67:EB:27:58:29:ED:77:2A:0D:24:AE:ED:AD:30:BC:BD:F1:9C:02
a=setup:actpass
a=mid:1
a=bundle-only
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=extmap:10 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id
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a=extmap:11 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id
a=recvonly
a=rtcp-mux
a=rtcp-rsize
a=rtpmap:96 VP8/90000
a=rtcp-fb:96 ccm fir
a=rtcp-fb:96 nack
a=rtcp-fb:96 nack pli
a=rtpmap:97 rtx/90000
a=fmtp:97 apt=96
HTTP/1.1 201 Created
ETag: "38sdf4fdsf54:EsAw"
Content-Type: application/sdp
Content-Length: 1400
Location: https://whep.example.org/resource/id
v=0
o=- 1657793490019 1 IN IP4 127.0.0.1
s=-
t=0 0
a=group:BUNDLE 0 1
a=extmap-allow-mixed
a=ice-lite
a=msid-semantic: WMS *
m=audio 9 UDP/TLS/RTP/SAVPF 111
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:526be20a538ee422
a=ice-pwd:2e13dde17c1cb009202f627fab90cbec358d766d049c9697
a=fingerprint:sha-256 F7:EB:F3:3E:AC:D2:EA:A7:C1:EC:79:D9:B3:8A:35:DA:70:86:4F:46:D9:2D:CC:D0:BC:81:9F:67:EF:34:2E:BD
a=candidate:1 1 UDP 2130706431 198.51.100.1 39132 typ host
a=setup:passive
a=mid:0
a=bundle-only
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=sendonly
a=rtcp-mux
a=rtcp-rsize
a=rtpmap:111 opus/48000/2
a=fmtp:111 minptime=10;useinbandfec=1
a=msid:- d46fb922-d52a-4e9c-aa87-444eadc1521b
m=video 9 UDP/TLS/RTP/SAVPF 96 97
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:526be20a538ee422
a=ice-pwd:2e13dde17c1cb009202f627fab90cbec358d766d049c9697
a=fingerprint:sha-256 F7:EB:F3:3E:AC:D2:EA:A7:C1:EC:79:D9:B3:8A:35:DA:70:86:4F:46:D9:2D:CC:D0:BC:81:9F:67:EF:34:2E:BD
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a=candidate:1 1 UDP 2130706431 198.51.100.1 39132 typ host
a=setup:passive
a=mid:1
a=bundle-only
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=extmap:10 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id
a=extmap:11 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id
a=sendonly
a=rtcp-mux
a=rtcp-rsize
a=rtpmap:96 VP8/90000
a=rtcp-fb:96 ccm fir
a=rtcp-fb:96 nack
a=rtcp-fb:96 nack pli
a=rtpmap:97 rtx/90000
a=fmtp:97 apt=96
a=msid:- d46fb922-d52a-4e9c-aa87-444eadc1521b
Figure 3: HTTP POST and PATCH doing SDP O/A example
4.2. SDP offer generated by the WHEP endpoint
If the WHEP player prefers the WHEP Endpoint to generate the SDP
offer, the WHEP Player will send a POST request without HTTP BODY and
an Accept HTTP header of "application/sdp" to the configured WHEP
endpoint URL.
The WHEP Endpoint will generate an SDP offer according to the JSEP
rules and return a "201 Created" response with a content type of
"application/sdp", the SDP offer as the body, a Location header field
pointing to the newly created resource and an Expire header
indicating the maximum time that the WHEP player is allowed to send
the SDP answer to the WHEP Resource.
The WHEP Player MUST generate an SDP answer to SDP offer provided by
the WHEP Endpoint and send an HTTP PATCH request to the URL provided
in the Location header for the WHEP Resource. The HTTP PATCH request
will have a content type of "application/sdp" and contain the SDP
answer as the body. If the SDP offer is not accepted by the WHEP
player, it MUST perform an HTTP DELETE operation for terminating the
session to the WHEP Resource URL.
The SDP offer SHOULD use the "sendonly" attribute and the SDP answer
MUST use "recvonly" attribute in this case.
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POST /whep/endpoint HTTP/1.1
Host: whep.example.com
Content-Length: 0
Accept: application/sdp
HTTP/1.1 201 Created
Content-Type: application/sdp
Content-Length: 1400
Location: https://whep.example.com/resource/id
Expires: Wed, 27 Jul 2022 07:28:00 GMT
v=0
o=- 5228595038118931041 2 IN IP4 127.0.0.1
s=-
t=0 0
a=group:BUNDLE 0 1
a=extmap-allow-mixed
a=msid-semantic: WMS
m=audio 9 UDP/TLS/RTP/SAVPF 111
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:zjkk
a=ice-pwd:bP+XJMM09aR8AiX1jdukzR6Y
a=ice-options:trickle
a=fingerprint:sha-256 DA:7B:57:DC:28:CE:04:4F:31:79:85:C4:31:67:EB:27:58:29:ED:77:2A:0D:24:AE:ED:AD:30:BC:BD:F1:9C:02
a=setup:actpass
a=mid:0
a=bundle-only
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=sendonly
a=msid:- d46fb922-d52a-4e9c-aa87-444eadc1521b
a=rtcp-mux
a=rtpmap:111 opus/48000/2
a=fmtp:111 minptime=10;useinbandfec=1
m=video 9 UDP/TLS/RTP/SAVPF 96 97
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:zjkk
a=ice-pwd:bP+XJMM09aR8AiX1jdukzR6Y
a=ice-options:trickle
a=fingerprint:sha-256 DA:7B:57:DC:28:CE:04:4F:31:79:85:C4:31:67:EB:27:58:29:ED:77:2A:0D:24:AE:ED:AD:30:BC:BD:F1:9C:02
a=setup:actpass
a=mid:1
a=bundle-only
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=extmap:10 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id
a=extmap:11 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id
a=sendonly
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a=msid:- d46fb922-d52a-4e9c-aa87-444eadc1521b
a=rtcp-mux
a=rtcp-rsize
a=rtpmap:96 VP8/90000
a=rtcp-fb:96 ccm fir
a=rtcp-fb:96 nack
a=rtcp-fb:96 nack pli
a=rtpmap:97 rtx/90000
a=fmtp:97 apt=96
PATCH /resource/id HTTP/1.1
Host: whep.example.com
Content-Type: application/sdp
Content-Length: 1326
v=0
o=- 1657793490019 1 IN IP4 127.0.0.1
s=-
t=0 0
a=group:BUNDLE 0 1
a=extmap-allow-mixed
a=ice-lite
a=msid-semantic: WMS *
m=audio 9 UDP/TLS/RTP/SAVPF 111
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:526be20a538ee422
a=ice-pwd:2e13dde17c1cb009202f627fab90cbec358d766d049c9697
a=fingerprint:sha-256 F7:EB:F3:3E:AC:D2:EA:A7:C1:EC:79:D9:B3:8A:35:DA:70:86:4F:46:D9:2D:CC:D0:BC:81:9F:67:EF:34:2E:BD
a=candidate:1 1 UDP 2130706431 198.51.100.1 39132 typ host
a=setup:passive
a=mid:0
a=bundle-only
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=recvonly
a=rtcp-mux
a=rtcp-rsize
a=rtpmap:111 opus/48000/2
a=fmtp:111 minptime=10;useinbandfec=1
m=video 9 UDP/TLS/RTP/SAVPF 96 97
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:526be20a538ee422
a=ice-pwd:2e13dde17c1cb009202f627fab90cbec358d766d049c9697
a=fingerprint:sha-256 F7:EB:F3:3E:AC:D2:EA:A7:C1:EC:79:D9:B3:8A:35:DA:70:86:4F:46:D9:2D:CC:D0:BC:81:9F:67:EF:34:2E:BD
a=candidate:1 1 UDP 2130706431 198.51.100.1 39132 typ host
a=setup:passive
a=mid:1
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a=bundle-only
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=extmap:10 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id
a=extmap:11 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id
a=recvonly
a=rtcp-mux
a=rtcp-rsize
a=rtpmap:96 VP8/90000
a=rtcp-fb:96 ccm fir
a=rtcp-fb:96 nack
a=rtcp-fb:96 nack pli
a=rtpmap:97 rtx/90000
a=fmtp:97 apt=96
HTTP/1.1 204 No Content
ETag: "38sdf4fdsf54:EsAw"
Figure 4: HTTP POST and PATCH doing SDP O/A example
If the WHEP Resource does not receive an HTTP PATCH request before
the time indicated in the Expire header HTTP POST response, it SHOULD
delete the resource and respond with a 404 Not Found response to any
request on the WHEP Resource URL received afterwards.
4.3. Common procedures
The WHEP Resource COULD require a live publishing to be happening in
order to allow a WHEP Players to start viewing a stream. In that
case, the WHEP Resource SHALL return a 409 Conflict response to the
POST request issued by the WHEP Client with a Retry-After header
indicating the number of seconds before sending a new request. WHEP
Players MAY periodically try to connect to the WHEP Resource with
exponential backoff period with an initial value of the Retry-After
header value in the 409 Conflict response.
Once a session is set up, ICE consent freshness [RFC7675] will be
used to detect abrupt disconnection and DTLS teardown for session
termination by either side.
To explicitly terminate a session, the WHEP Player MUST perform an
HTTP DELETE request to the resource URL returned in the Location
header field of the initial HTTP POST. Upon receiving the HTTP
DELETE request, the WHEP resource will be removed and the resources
freed on the Media Server, terminating the ICE and DTLS sessions.
A Media Server terminating a session MUST follow the procedures in
[RFC7675] section 5.2 for immediate revocation of consent.
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The WHEP Endpoints MUST return an HTTP 405 response for any HTTP GET,
HEAD or PUT requests on the resource URL in order to reserve its
usage for future versions of this protocol specification.
The WHEP Resources MUST return an HTTP 405 response for any HTTP GET,
HEAD, POST or PUT requests on the resource URL in order to reserve
its usage for future versions of this protocol specification.
4.4. ICE and NAT support
The SDP provided by the WHEP Player MAY be sent after the full ICE
gathering is complete with the full list of ICE candidates, or it MAY
only contain local candidates (or even an empty list of candidates).
In order to simplify the protocol, there is no support for exchanging
gathered trickle candidates from Media Server ICE candidates once the
SDP answer is sent. The WHEP Endpoint SHALL gather all the ICE
candidates for the Media Server before responding to the client
request and the SDP answer SHALL contain the full list of ICE
candidates of the Media Server. The Media Server MAY use ICE lite,
while the WHEP player MUST implement full ICE.
The WHEP Player MAY perform trickle ICE or ICE restarts [RFC8863] by
sending an HTTP PATCH request to the WHEP resource URL with a body
containing a SDP fragment with MIME type "application/trickle-ice-
sdpfrag" as specified in [RFC8840]. When used for trickle ICE, the
body of this PATCH message will contain the new ICE candidate; when
used for ICE restarts, it will contain a new ICE ufrag/pwd pair.
The WHEP Player MUST NOT send any ICE trickle or restart until the
SDP O/A is completed. So, if the WHEP Player is not acting as
offerer in the SDP O/A, it MUST NOT send any HTTP PATCH request for
ICE trickle or restart until the 200 OK response to the HTTP PATCH
request containing the SDP answer has been received.
Trickle ICE and ICE restart support is OPTIONAL for a WHEP resource.
If both Trickle ICE or ICE restarts are not supported by the WHEP
resource, it MUST return a 405 Method Not Allowed response for any
HTTP PATCH request. If the WHEP resource supports either Trickle ICE
or ICE restarts, but not both, it MUST return a 501 Not Implemented
for the HTTP PATCH requests that are not supported.
As the HTTP PATCH request sent by a WHEP player may be received out-
of-order by the WHEP Resource, the WHEP Resource MUST generate a
unique strong entity-tag identifying the ICE session as per [RFC9110]
section 2.3. The initial value of the entity-tag identifying the
initial ICE session MUST be returned in an ETag header field in the
201 response to the initial POST request to the WHEP Endpoint if the
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WHEP player is acting as SDP offerer, or in the HTTP PATCH response
containing the SDP answer otherwise. It MUST also be returned in the
200 OK of any PATCH request that triggers an ICE restart.
A WHEP Player sending a PATCH request for performing trickle ICE MUST
include an "If-Match" header field with the latest known entity-tag
as per [RFC9110] section 3.1. When the PATCH request is received by
the WHEP resource, it MUST compare the indicated entity-tag value
with the current entity-tag of the resource as per [RFC9110] section
3.1 and return a "412 Precondition Failed" response if they do not
match.
WHEP Players SHOULD NOT use entity-tag validation when matching a
specific ICE session is not required, such as when initiating a
DELETE request to terminate a session.
A WHEP Resource receiving a PATCH request with new ICE candidates,
but which does not perform an ICE restart, MUST return a "204 No
Content" response without body. If the Media Server does not support
a candidate transport or is not able to resolve the connection
address, it MUST accept the HTTP request with the 204 response and
silently discard the candidate.
PATCH /resource/id HTTP/1.1
Host: whep.example.com
If-Match: "38sdf4fdsf54:EsAw"
Content-Type: application/trickle-ice-sdpfrag
Content-Length: 548
a=ice-ufrag:EsAw
a=ice-pwd:P2uYro0UCOQ4zxjKXaWCBui1
m=audio RTP/AVP 0
a=mid:0
a=candidate:1387637174 1 udp 2122260223 192.0.2.1 61764 typ host generation 0 ufrag EsAw network-id 1
a=candidate:3471623853 1 udp 2122194687 198.51.100.1 61765 typ host generation 0 ufrag EsAw network-id 2
a=candidate:473322822 1 tcp 1518280447 192.0.2.1 9 typ host tcptype active generation 0 ufrag EsAw network-id 1
a=candidate:2154773085 1 tcp 1518214911 198.51.100.2 9 typ host tcptype active generation 0 ufrag EsAw network-id 2
a=end-of-candidates
HTTP/1.1 204 No Content
Figure 5: Trickle ICE request
A WHEP Player sending a PATCH request for performing ICE restart MUST
contain an "If-Match" header field with a field-value "*" as per
[RFC9110] section 3.1.
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If the HTTP PATCH request results in an ICE restart, the WHEP
resource SHALL return a "200 OK" with an "application/trickle-ice-
sdpfrag" body containing the new ICE username fragment and password.
The response may optionally contain the new set of ICE candidates for
the Media Server and the new entity-tag correspond to the new ICE
session in an ETag response header field.
If the ICE request cannot be satisfied by the WHEP Resource, the WHEP
Resource MUST return an appropriate HTTP error code and MUST NOT
terminate the session immediately. The WHEP Player MAY retry
performing a new ICE restart or terminate the session by issuing an
HTTP DELETE request instead. In either case, the session MUST be
terminated if the ICE consent expires as a consequence of the failed
ICE restart as per [RFC7675] section 5.1.
PATCH /resource/id HTTP/1.1
Host: whep.example.com
If-Match: "*"
Content-Type: application/trickle-ice-sdpfrag
Content-Length: 54
a=ice-ufrag:ysXw
a=ice-pwd:vw5LmwG4y/e6dPP/zAP9Gp5k
HTTP/1.1 200 OK
ETag: "289b31b754eaa438:ysXw"
Content-Type: application/trickle-ice-sdpfrag
Content-Length: 102
a=ice-lite
a=ice-ufrag:289b31b754eaa438
a=ice-pwd:0b66f472495ef0ccac7bda653ab6be49ea13114472a5d10a
Figure 6: ICE restart request
Because the WHEP Player needs to know the entity-tag associated with
the ICE session in order to send new ICE candidates, it MUST buffer
any gathered candidates before it receives the HTTP response to the
initial POST request or the PATCH request with the new entity-tag
value. Once it knows the entity-tag value, the WHEP Player SHOULD
send a single aggregated HTTP PATCH request with all the ICE
candidates it has buffered so far.
In case of unstable network conditions, the ICE restart HTTP PATCH
requests and responses might be received out of order. In order to
mitigate this scenario, when the client performs an ICE restart, it
MUST discard any previous ice username/pwd frags and ignore any
further HTTP PATCH response received from a pending HTTP PATCH
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request. Clients MUST apply only the ICE information received in the
response to the last sent request. If there is a mismatch between
the ICE information at the client and at the server (because of an
out-of-order request), the STUN requests will contain invalid ICE
information and will be rejected by the server. When this situation
is detected by the WHEP Player, it SHOULD send a new ICE restart
request to the server.
4.5. WebRTC constraints
In the specific case of media consumption from a streaming service,
some assumptions can be made about the server-side which simplifies
the WebRTC compliance burden, as detailed in WebRTC-gateway document
[I-D.draft-ietf-rtcweb-gateways].
In order to reduce the complexity of implementing WHEP in both
players and Media Servers, WHEP imposes the following restrictions
regarding WebRTC usage:
Both the WHEP Player and the WHEP Endpoint SHALL use SDP bundle
[RFC9143]. Each "m=" section MUST be part of a single BUNDLE group.
Hence, when a WHEP Player or a WHEP Endpoints sends an SDP offer, it
MUST include a "bundle-only" attribute in each bundled "m=" section.
The WHEP player and the Media Server MUST support multiplexed media
associated with the BUNDLE group as per [RFC9143] section 9. In
addition, per [RFC9143] the WHEP Player and Media Server will use
RTP/RTCP multiplexing for all bundled media. The WHEP Player and
Media Server SHOULD include the "rtcp-mux-only" attribute in each
bundled "m=" section.
As the codecs for a given stream may not be known by the Media Server
when the WHEP Player starts watching a stream, if the WHEP Endpoint
is acting as SDP answerer, it MUST include all the offered codecs
that it supports in the SDP answer and not make any assumption about
which will be the codec that will be actually sent.
Trickle ICE and ICE restarts support is OPTIONAL for both the WHEP
Players and Media Servers as explained in section 4.1.
4.6. Load balancing and redirections
WHEP Endpoints and Media Servers might not be co-located on the same
server, so it is possible to load balance incoming requests to
different Media Servers. WHEP Players SHALL support HTTP redirection
via the "307 Temporary Redirect response code" as described in
[RFC9110] section 6.4.7. The WHEP Resource URL MUST be a final one,
and redirections are not required to be supported for the PATCH and
DELETE requests sent to it.
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In case of high load, the WHEP endpoints MAY return a 503 (Service
Unavailable) status code indicating that the server is currently
unable to handle the request due to a temporary overload or scheduled
maintenance, which will likely be alleviated after some delay. The
WHEP Endpoint might send a Retry-After header field indicating the
minimum time that the user agent ought to wait before making a
follow-up request.
4.7. STUN/TURN server configuration
The WHEP Endpoint MAY return STUN/TURN server configuration URLs and
credentials usable by the client in the "201 Created" response to the
HTTP POST request to the WHEP Endpoint URL.
Each STUN/TURN server will be returned using the "Link" header field
[RFC8288] with a "rel" attribute value of "ice-server" as specified
in [I-D.draft-ietf-wish-whip]
It might be also possible to configure the STUN/TURN server URLs with
long-term credentials provided by either the broadcasting service or
an external TURN provider on the WHEP Player, overriding the values
provided by the WHEP Endpoint.
4.8. Authentication and authorization
WHEP Endpoints and Resources MAY require the HTTP request to be
authenticated using an HTTP Authorization header field with a Bearer
token as specified in [RFC6750] section 2.1. WHEP players MUST
implement this authentication and authorization mechanism and send
the HTTP Authorization header field in all HTTP requests sent to
either the WHEP endpoint or resource except the preflight OPTIONS
requests for CORS.
The nature, syntax, and semantics of the bearer token, as well as how
to distribute it to the client, is outside the scope of this
document. Some examples of the kind of tokens that could be used
are, but are not limited to, JWT tokens as per [RFC6750] and
[RFC8725] or a shared secret stored on a database.
WHEP Endpoints and Resources could perform the authentication and
authorization by encoding an authentication token within the URLs for
the WHEP Endpoints or Resources instead. In case the WHEP Player is
not configured to use a bearer token, the HTTP Authorization header
field must not be sent in any request.
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4.9. Protocol extensions
In order to support future extensions to be defined for the WHEP
protocol, a common procedure for registering and announcing the new
extensions is defined.
Protocol extensions supported by the WHEP server MUST be advertised
to the WHEP Player in the "201 Created" response to the initial HTTP
POST request sent to the WHEP Endpoint. The WHEP Endpoint MUST
return one "Link" header field for each extension, with the extension
"rel" type attribute and the URI for the HTTP resource that will be
available for receiving requests related to that extension.
Protocol extensions are optional for both WHEP Players and WHEP
Endpoints and Resources. WHEP Players MUST ignore any Link attribute
with an unknown "rel" attribute value and WHEP Endpoints and
Resources MUST NOT require the usage of any of the extensions.
Each protocol extension MUST register a unique "rel" attribute value
at IANA starting with the prefix: "urn:ietf:params:whep:ext" as
specified in Section 6.2.
For example, considering a potential extension of server-to-client
communication using server-sent events as specified in
https://html.spec.whatwg.org/multipage/server-sent-
events.html#server-sent-events, the URL for connecting to the server
side event resource for the published stream could be returned in the
initial HTTP "201 Created" response with a "Link" header field and a
"rel" attribute of "urn:ietf:params:whep:ext:example:server-sent-
events". (This document does not specify such an extension, and uses
it only as an example.)
In this theoretical case, the HTTP 201 response to the HTTP POST
request would look like:
HTTP/1.1 201 Created
Content-Type: application/sdp
Location: https://whep.example.org/resource/id
Link: <https://whep.ietf.org/publications/213786HF/sse>;
rel="urn:ietf:params:whep:ext:example:server-side-events"
5. Security Considerations
HTTPS SHALL be used in order to preserve the WebRTC security model.
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6. IANA Considerations
This specification adds a registry for URN sub-namespaces for WHEP
protocol extensions.
6.1. Registration of WHEP URN Sub-namespace and whep Registry
IANA has added an entry to the "IETF URN Sub-namespace for Registered
Protocol Parameter Identifiers" registry and created a sub-namespace
for the Registered Parameter Identifier as per [RFC3553]:
"urn:ietf:params:whep".
To manage this sub-namespace, IANA has created the "System for Cross-
domain Identity Management (WHEP) Schema URIs" registry, which is
used to manage entries within the "urn:ietf:params:whep" namespace.
The registry description is as follows:
* Registry name: WHEP
* Specification: this document (RFC TBD)
* Repository: See Section Section 6.2
* Index value: See Section Section 6.2
6.2. URN Sub-namespace for whep
whep Endpoint utilize URIs to identify the supported whep protocol
extensions on the "rel" attribute of the Link header as defined in
Section 4.9. This section creates and registers an IETF URN Sub-
namespace for use in the whep specifications and future extensions.
6.2.1. Specification Template
Namespace ID:
The Namespace ID "whep" has been assigned.
Registration Information:
Version: 1
Date: TBD
Declared registrant of the namespace:
The Internet Engineering Task Force.
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Designated contact:
A designated expert will monitor the whep public mailing list, "wish@ietf.org".
Declaration of Syntactic Structure:
The Namespace Specific String (NSS) of all URNs that use the "whep" Namespace ID shall have the following structure: urn:ietf:params:whep:{type}:{name}:{other}
The keywords have the following meaning:
- type: The entity type. This specification only defines the "ext" type.
- name: A required US-ASCII string that conforms to the URN syntax requirements (see {{RFC8141}}) and defines a major namespace of a whep protocol extension. The value MAY also be an industry name or organization name.
- other: Any US-ASCII string that conforms to the URN syntax requirements (see {{RFC8141}}) and defines the sub-namespace (which MAY be further broken down in namespaces delimited by colons) as needed to uniquely identify an whep protocol extension.
Relevant Ancillary Documentation:
None
Identifier Uniqueness Considerations:
The designated contact shall be responsible for reviewing and enforcing uniqueness.
Identifier Persistence Considerations:
Once a name has been allocated, it MUST NOT be reallocated for a different purpose.
The rules provided for assignments of values within a sub-namespace MUST be constructed so that the meanings of values cannot change.
This registration mechanism is not appropriate for naming values whose meanings may change over time.
Process of Identifier Assignment:
Namespace with type "ext" (e.g., "urn:ietf:params:whep:ext") is reserved for IETF-approved whep specifications.
Process of Identifier Resolution:
None specified.
Rules for Lexical Equivalence:
No special considerations; the rules for lexical equivalence specified in {{RFC8141}} apply.
Conformance with URN Syntax:
No special considerations.
Validation Mechanism:
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None specified.
Scope:
Global.
7. Acknowledgements
8. References
8.1. Normative References
[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>.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264,
DOI 10.17487/RFC3264, June 2002,
<https://www.rfc-editor.org/info/rfc3264>.
[RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An
IETF URN Sub-namespace for Registered Protocol
Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June
2003, <https://www.rfc-editor.org/info/rfc3553>.
[RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
Framework: Bearer Token Usage", RFC 6750,
DOI 10.17487/RFC6750, October 2012,
<https://www.rfc-editor.org/info/rfc6750>.
[RFC7675] Perumal, M., Wing, D., Ravindranath, R., Reddy, T., and M.
Thomson, "Session Traversal Utilities for NAT (STUN) Usage
for Consent Freshness", RFC 7675, DOI 10.17487/RFC7675,
October 2015, <https://www.rfc-editor.org/info/rfc7675>.
[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>.
[RFC8288] Nottingham, M., "Web Linking", RFC 8288,
DOI 10.17487/RFC8288, October 2017,
<https://www.rfc-editor.org/info/rfc8288>.
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[RFC8725] Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best
Current Practices", BCP 225, RFC 8725,
DOI 10.17487/RFC8725, February 2020,
<https://www.rfc-editor.org/info/rfc8725>.
[RFC8829] Uberti, J., Jennings, C., and E. Rescorla, Ed.,
"JavaScript Session Establishment Protocol (JSEP)",
RFC 8829, DOI 10.17487/RFC8829, January 2021,
<https://www.rfc-editor.org/info/rfc8829>.
[RFC8840] Ivov, E., Stach, T., Marocco, E., and C. Holmberg, "A
Session Initiation Protocol (SIP) Usage for Incremental
Provisioning of Candidates for the Interactive
Connectivity Establishment (Trickle ICE)", RFC 8840,
DOI 10.17487/RFC8840, January 2021,
<https://www.rfc-editor.org/info/rfc8840>.
[RFC8863] Holmberg, C. and J. Uberti, "Interactive Connectivity
Establishment Patiently Awaiting Connectivity (ICE PAC)",
RFC 8863, DOI 10.17487/RFC8863, January 2021,
<https://www.rfc-editor.org/info/rfc8863>.
[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/info/rfc9110>.
[RFC9143] Holmberg, C., Alvestrand, H., and C. Jennings,
"Negotiating Media Multiplexing Using the Session
Description Protocol (SDP)", RFC 9143,
DOI 10.17487/RFC9143, February 2022,
<https://www.rfc-editor.org/info/rfc9143>.
8.2. Informative References
[I-D.draft-ietf-rtcweb-gateways]
Alvestrand, H. and U. Rauschenbach, "WebRTC Gateways",
Work in Progress, Internet-Draft, draft-ietf-rtcweb-
gateways-02, 21 January 2016,
<https://www.ietf.org/archive/id/draft-ietf-rtcweb-
gateways-02.txt>.
[I-D.draft-ietf-wish-whip]
Murillo, S. G. and A. Gouaillard, "WebRTC-HTTP ingestion
protocol (WHIP)", Work in Progress, Internet-Draft, draft-
ietf-wish-whip-04, 25 July 2022,
<https://www.ietf.org/archive/id/draft-ietf-wish-whip-
04.txt>.
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[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002,
<https://www.rfc-editor.org/info/rfc3261>.
[RFC6120] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Core", RFC 6120, DOI 10.17487/RFC6120,
March 2011, <https://www.rfc-editor.org/info/rfc6120>.
[RFC7826] Schulzrinne, H., Rao, A., Lanphier, R., Westerlund, M.,
and M. Stiemerling, Ed., "Real-Time Streaming Protocol
Version 2.0", RFC 7826, DOI 10.17487/RFC7826, December
2016, <https://www.rfc-editor.org/info/rfc7826>.
[RFC8141] Saint-Andre, P. and J. Klensin, "Uniform Resource Names
(URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017,
<https://www.rfc-editor.org/info/rfc8141>.
Authors' Addresses
Sergio Garcia Murillo
Millicast
Email: sergio.garcia.murillo@cosmosoftware.io
Cheng Chen
ByteDance
Email: webrtc@bytedance.com
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