rfc9725.original   rfc9725.txt 
wish S. Murillo Internet Engineering Task Force (IETF) S. Murillo
Internet-Draft Millicast Request for Comments: 9725 Millicast
Updates: 8842, 8840 (if approved) A. Gouaillard Updates: 8840, 8842 A. Gouaillard
Intended status: Standards Track CoSMo Software Category: Standards Track CoSMo Software
Expires: 22 February 2025 21 August 2024 ISSN: 2070-1721 January 2025
WebRTC-HTTP ingestion protocol (WHIP) WebRTC-HTTP Ingestion Protocol (WHIP)
draft-ietf-wish-whip-16
Abstract Abstract
This document describes a simple HTTP-based protocol that will allow This document describes a simple HTTP-based protocol that will allow
WebRTC-based ingestion of content into streaming services and/or WebRTC-based ingestion of content into streaming services and/or
CDNs. Content Delivery Networks (CDNs).
This document updates RFC 8842 and RFC 8840. This document updates RFCs 8840 and 8842.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
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Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 22 February 2025. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9725.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Overview
4. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 6 4. Protocol Operation
4.1. HTTP usage . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. HTTP Usage
4.2. Ingest session set up . . . . . . . . . . . . . . . . . . 7 4.2. Ingest Session Setup
4.3. ICE support . . . . . . . . . . . . . . . . . . . . . . . 10 4.3. ICE Support
4.3.1. HTTP PATCH request usage . . . . . . . . . . . . . . 10 4.3.1. HTTP PATCH Request Usage
4.3.2. Trickle ICE . . . . . . . . . . . . . . . . . . . . . 11 4.3.2. Trickle ICE
4.3.3. ICE Restarts . . . . . . . . . . . . . . . . . . . . 13 4.3.3. ICE Restarts
4.4. WebRTC constraints . . . . . . . . . . . . . . . . . . . 15 4.4. WebRTC Constraints
4.4.1. SDP Bundle . . . . . . . . . . . . . . . . . . . . . 16 4.4.1. SDP Bundle
4.4.2. Single MediaStream . . . . . . . . . . . . . . . . . 16 4.4.2. Single MediaStream
4.4.3. No partially successful answers . . . . . . . . . . . 16 4.4.3. No Partially Successful Answers
4.4.4. DTLS setup role and SDP "setup" attribute . . . . . . 16 4.4.4. DTLS Setup Role and SDP "setup" Attribute
4.4.5. Trickle ICE and ICE restarts . . . . . . . . . . . . 17 4.4.5. Trickle ICE and ICE Restarts
4.5. Load balancing and redirections . . . . . . . . . . . . . 17 4.5. Load Balancing and Redirections
4.6. STUN/TURN server configuration . . . . . . . . . . . . . 17 4.6. STUN/TURN Server Configuration
4.6.1. Congestion control . . . . . . . . . . . . . . . . . 19 4.6.1. Congestion Control
4.7. Authentication and authorization . . . . . . . . . . . . 19 4.7. Authentication and Authorization
4.7.1. Bearer token authentication . . . . . . . . . . . . . 20 4.7.1. Bearer Token Authentication
4.8. Simulcast and scalable video coding . . . . . . . . . . . 20 4.8. Simulcast and Scalable Video Coding
4.9. Protocol extensions . . . . . . . . . . . . . . . . . . . 20 4.9. Protocol Extensions
5. Security Considerations . . . . . . . . . . . . . . . . . . . 21 5. Security Considerations
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 6. IANA Considerations
6.1. Link Relation Type: ice-server . . . . . . . . . . . . . 23 6.1. Link Relation Type: ice-server
6.2. WebRTC-HTTP Ingestion Protocol (WHIP) registry group . . 23 6.2. WebRTC-HTTP Ingestion Protocol (WHIP) Registry Group
6.3. Registration of WHIP URN Sub-namespace and WHIP 6.3. Registration of WHIP URN Sub-Namespace and WHIP Registries
registries . . . . . . . . . . . . . . . . . . . . . . . 23 6.3.1. WebRTC-HTTP Ingestion Protocol (WHIP) URNs Registry
6.3.1. WebRTC-HTTP ingestion protocol (WHIP) URNs 6.3.2. WebRTC-HTTP Ingestion Protocol (WHIP) Extension URNs
registry . . . . . . . . . . . . . . . . . . . . . . 24 Registry
6.3.2. WebRTC-HTTP ingestion protocol (WHIP) extension URNs 6.4. URN Sub-Namespace for WHIP
registry . . . . . . . . . . . . . . . . . . . . . . 24 6.4.1. Specification Template
6.4. URN Sub-namespace for WHIP . . . . . . . . . . . . . . . 25 6.5. Registering WHIP Protocol Extension URNs
6.4.1. Specification Template . . . . . . . . . . . . . . . 25 6.5.1. Registration Procedure
6.5. Registering WHIP Protocol Extensions URNs . . . . . . . . 27 6.5.2. Guidance for the Designated Expert
6.5.1. Registration Procedure . . . . . . . . . . . . . . . 27 6.5.3. Registration Template
6.5.2. Guidance for Designated Experts . . . . . . . . . . . 28 7. References
6.5.3. WHIP Protocol Extension Registration Template . . . . 28 7.1. Normative References
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29 7.2. Informative References
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 29 Acknowledgements
8.1. Normative References . . . . . . . . . . . . . . . . . . 29 Authors' Addresses
8.2. Informative References . . . . . . . . . . . . . . . . . 32
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34
1. Introduction 1. Introduction
The IETF RTCWEB working group standardized JSEP ([RFC9429]), a The IETF RTCWEB Working Group standardized the JavaScript Session
mechanism used to control the setup, management, and teardown of a Establishment Protocol (JSEP) [RFC9429], a mechanism used to control
multimedia session. It also describes how to negotiate media flows the setup, management, and teardown of a multimedia session. It also
using the Offer/Answer Model with the Session Description Protocol describes how to negotiate media flows using the offer/answer model
(SDP) [RFC3264] including the formats for data sent over the wire with the Session Description Protocol (SDP) [RFC3264], including the
(e.g., media types, codec parameters, and encryption). WebRTC formats for data sent over the wire (e.g., media types, codec
intentionally does not specify a signaling transport protocol at parameters, and encryption). WebRTC intentionally does not specify a
application level. signaling transport protocol at the application level.
Unfortunately, the lack of a standardized signaling mechanism in Unfortunately, the lack of a standardized signaling mechanism in
WebRTC has been an obstacle to adoption as an ingestion protocol WebRTC has been an obstacle to its adoption as an ingestion protocol
within the broadcast/streaming industry, where a streamlined within the broadcast and streaming industry, where a streamlined
production pipeline is taken for granted: plug in cables carrying raw production pipeline is taken for granted: plug in cables carrying raw
media to hardware encoders, then push the encoded media to any media to hardware encoders, then push the encoded media to any
streaming service or Content Delivery Network (CDN) ingest using an streaming service or Content Delivery Network (CDN) ingest using an
ingestion protocol. ingestion protocol.
While WebRTC can be integrated with standard signaling protocols like While WebRTC can be integrated with standard signaling protocols like
SIP [RFC3261] or XMPP [RFC6120], they are not designed to be used in SIP [RFC3261] or Extensible Messaging and Presence Protocol (XMPP)
broadcasting/streaming services, and there is also no sign of [RFC6120], they are not designed to be used in broadcasting and
adoption in that industry. RTSP [RFC7826], which is based on RTP, streaming services, and there is also no sign of adoption in that
does not support the SDP offer/answer model [RFC3264] for negotiating industry. The Real-Time Streaming Protocol (RTSP) [RFC7826], which
the characteristics of the media session. is based on RTP, does not support the SDP offer/answer model
[RFC3264] for negotiating the characteristics of the media session.
This document proposes a simple protocol based on HTTP for supporting This document proposes a simple protocol based on HTTP for supporting
WebRTC as media ingestion method which: WebRTC as a media ingestion method that:
* Is easy to implement, * is easy to implement,
* Is as easy to use as popular IP-based broadcast protocols * is as easy to use as popular IP-based broadcast protocols,
* Is fully compliant with WebRTC and RTCWEB specs * is fully compliant with WebRTC and RTCWEB specs,
* Enables ingestion on both classical media platforms and WebRTC * enables ingestion on both classical media platforms and WebRTC
end-to-end platforms, achieving the lowest possible latency. end-to-end platforms (achieving the lowest possible latency),
* Lowers the requirements on both hardware encoders and broadcasting * lowers the requirements on both hardware encoders and broadcasting
services to support WebRTC. services to support WebRTC, and
* Is usable both in web browsers and in standalone encoders. * is usable in both web browsers and standalone encoders.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Overview 3. Overview
The WebRTC-HTTP Ingest Protocol (WHIP) is designed to facilitate a The WebRTC-HTTP Ingestion Protocol (WHIP) is designed to facilitate a
one-time exchange of Session Description Protocol (SDP) offers and one-time exchange of Session Description Protocol (SDP) offers and
answers using HTTP POST requests. This exchange is a fundamental answers using HTTP POST requests. This exchange is a fundamental
step in establishing an Interactive Connectivity Establishment (ICE) step in establishing an Interactive Connectivity Establishment (ICE)
and Datagram Transport Layer Security (DTLS) session between the WHIP and Datagram Transport Layer Security (DTLS) session between the WHIP
client, which represents the encoder or media producer, and the media client, which represents the encoder or media producer, and the media
server, the broadcasting ingestion endpoint. server, which is the broadcasting ingestion endpoint.
Upon successful establishment of the ICE/DTLS session, unidirectional Upon successful establishment of the ICE/DTLS session, unidirectional
media data transmission commences from the WHIP client to the media media data transmission commences from the WHIP client to the media
server. It is important to note that SDP renegotiations are not server. It is important to note that SDP renegotiations are not
supported in WHIP, meaning that no modifications to the "m=" sections supported in WHIP. This means that no modifications to the "m="
can be made after the initial SDP offer/answer exchange via HTTP POST sections can be made after the initial SDP offer/answer exchange via
is completed and only ICE related information can be updated via HTTP HTTP POST is completed and that only ICE-related information can be
PATCH requests as defined in Section 4.3. updated via HTTP PATCH requests as defined in Section 4.3.
The following diagram illustrates the core operation of the WHIP The following diagram illustrates the core operation of the WHIP
protocol for initiating and terminating an ingest session: protocol for initiating and terminating an ingest session:
+-------------+ +---------------+ +--------------+ +---------------+ +-------------+ +---------------+ +--------------+ +---------------+
| WHIP client | | WHIP endpoint | | Media Server | | WHIP session | | WHIP client | | WHIP endpoint | | Media server | | WHIP session |
+--+----------+ +---------+-----+ +------+-------+ +--------|------+ +--+----------+ +---------+-----+ +------+-------+ +--------|------+
| | | | | | | |
| | | | | | | |
|HTTP POST (SDP Offer) | | | |HTTP POST (SDP offer) | | |
+------------------------>+ | | +------------------------>+ | |
|201 Created (SDP answer) | | | |201 Created (SDP answer) | | |
+<------------------------+ | | +<------------------------+ | |
| ICE REQUEST | | | ICE REQUEST | |
+--------------------------------------->+ | +--------------------------------------->+ |
| ICE RESPONSE | | | ICE RESPONSE | |
|<---------------------------------------+ | |<---------------------------------------+ |
| DTLS SETUP | | | DTLS SETUP | |
|<======================================>| | |<======================================>| |
| RTP/RTCP FLOW | | | RTP/RTCP FLOW | |
+<-------------------------------------->+ | +<-------------------------------------->+ |
| HTTP DELETE | | HTTP DELETE |
+---------------------------------------------------------->+ +---------------------------------------------------------->+
| 200 OK | | 200 OK |
<-----------------------------------------------------------x <-----------------------------------------------------------x
Figure 1: WHIP session setup and teardown Figure 1: WHIP Session Setup and Teardown
The elements in Figure 1 are described as follows: The elements in Figure 1 are described as follows:
* WHIP client: This represents the WebRTC media encoder or producer, WHIP client: This represents the WebRTC media encoder or producer,
which functions as a client of the WHIP protocol by encoding and which functions as a client of the WHIP protocol by encoding and
delivering media to a remote media server. delivering media to a remote media server.
* WHIP endpoint: This denotes the ingest server that receives the WHIP endpoint: This denotes the ingest server that receives the
initial WHIP request. initial WHIP request.
* WHIP endpoint URL: Refers to the URL of the WHIP endpoint WHIP endpoint URL: This refers to the URL of the WHIP endpoint
responsible for creating the WHIP session. responsible for creating the WHIP session.
* Media server: This is the WebRTC media server or consumer Media server: This is the WebRTC media server or consumer
responsible for establishing the media session with the WHIP responsible for establishing the media session with the WHIP
client and receiving the media content it produces. client and receiving the media content it produces.
* WHIP session: This indicates the server handling the allocated WHIP session: This indicates the server handling the allocated HTTP
HTTP resource by the WHIP endpoint for an ongoing ingest session. resource by the WHIP endpoint for an ongoing ingest session.
* WHIP session URL: Refers to the URL of the WHIP resource allocated WHIP session URL: This refers to the URL of the WHIP resource
by the WHIP endpoint for a specific media session. The WHIP allocated by the WHIP endpoint for a specific media session. The
client can send requests to the WHIP session using this URL to WHIP client can send requests to the WHIP session using this URL
modify the session, such as ICE operations or termination. to modify the session, such as ICE operations or termination.
The Figure 1 illustrates the communication flow between a WHIP Figure 1 illustrates the communication flow between a WHIP client,
client, WHIP endpoint, media server, and WHIP session. This flow WHIP endpoint, media server, and WHIP session. This flow outlines
outlines the process of setting up and tearing down an ingestion the process of setting up and tearing down an ingestion session using
session using the WHIP protocol, involving negotiation, ICE for the WHIP protocol, which involves negotiation, ICE for Network
Network Address Translation (NAT) traversal, DTLS and Secure Real- Address Translation (NAT) traversal, DTLS and the Secure Real-time
time Transport Protocol (SRTP) for security, and RTP/RTCP for media Transport Protocol (SRTP) for security, and RTP/RTCP for media
transport: transport:
* WHIP client: Initiates the communication by sending an HTTP POST * WHIP client: Initiates the communication by sending an HTTP POST
with an SDP Offer to the WHIP endpoint. with an SDP offer to the WHIP endpoint.
* WHIP endpoint: Responds with a "201 Created" message containing an * WHIP endpoint: Responds with a "201 Created" message containing an
SDP answer. SDP answer.
* WHIP client and media server: Establish an ICE and DTLS sessions * WHIP client and media server: Establish ICE and DTLS sessions for
for NAT traversal and secure communication. NAT traversal and secure communication.
* RTP/RTCP Flow: Real-time Transport Protocol and Real-time * RTP/RTCP flow: RTP and RTCP flows are established for media
Transport Control Protocol flows are established for media
transmission from the WHIP client to the media server, secured by transmission from the WHIP client to the media server, secured by
the SRTP profile. the SRTP profile.
* WHIP client: Sends an HTTP DELETE to terminate the WHIP session. * WHIP client: Sends an HTTP DELETE to terminate the WHIP session.
* WHIP session: Responds with a "200 OK" to confirm the session * WHIP session: Responds with a "200 OK" to confirm the session
termination. termination.
4. Protocol Operation 4. Protocol Operation
4.1. HTTP usage 4.1. HTTP Usage
Following [BCP56] guidelines, WHIP clients MUST NOT match error codes Following the guidelines in [BCP56], WHIP clients MUST NOT match
returned by the WHIP endpoints and resources to a specific error error codes returned by the WHIP endpoints and resources to a
cause indicated in this specification. WHIP clients MUST be able to specific error cause indicated in this specification. WHIP clients
handle all applicable status codes gracefully falling back to the MUST be able to handle all applicable status codes by gracefully
generic n00 semantics of a given status code on unknown error codes. falling back to the generic n00 semantics of a given status code on
WHIP endpoints and resources could convey finer-grained error unknown error codes. WHIP endpoints and resources could convey
information by a problem statement json object in the response finer-grained error information by a problem statement json object in
message body of the failed request as per [RFC9457]. the response message body of the failed request as per [RFC9457].
The WHIP endpoints and sessions are origin servers as defined in The WHIP endpoints and sessions are origin servers as defined in
Section 3.6. of [RFC9110] handling the requests and providing Section 3.6 of [RFC9110]; they handle the requests and provide
responses for the underlying HTTP resources. Those HTTP resources do responses for the underlying HTTP resources. Those HTTP resources do
not have any representation defined in this specification, so the not have any representation defined in this specification, so the
WHIP endpoints and sessions MUST return a 2XX sucessfull response WHIP endpoints and sessions MUST return a 2xx successful response
with no content when a GET request is received. with no content when a GET request is received.
4.2. Ingest session set up 4.2. Ingest Session Setup
In order to set up an ingestion session, the WHIP client MUST In order to set up an ingestion session, the WHIP client MUST
generate an SDP offer according to the JSEP rules for an initial generate an SDP offer according to the JSEP rules for an initial
offer as in Section 5.2.1 of [RFC9429] and perform an HTTP POST offer as per Section 5.2.1 of [RFC9429] and perform an HTTP POST
request as per Section 9.3.3 of [RFC9110] to the configured WHIP request as per Section 9.3.3 of [RFC9110] to the configured WHIP
endpoint URL. endpoint URL.
The HTTP POST request MUST have a content type of "application/sdp" The HTTP POST request MUST have a content type of "application/sdp"
and contain the SDP offer as the body. The WHIP endpoint MUST and contain the SDP offer as the body. The WHIP endpoint MUST
generate an SDP answer according to the JSEP rules for an initial generate an SDP answer according to the JSEP rules for an initial
answer as in Section 5.3.1 of [RFC9429] and return a "201 Created" answer as per Section 5.3.1 of [RFC9429] and return the following: a
response with a content type of "application/sdp", the SDP answer as "201 Created" response with a content type of "application/sdp", the
the body, and a Location header field pointing to the newly created SDP answer as the body, and a Location header field pointing to the
WHIP session. If the HTTP POST to the WHIP endpoint has a content newly created WHIP session. If the HTTP POST to the WHIP endpoint
type different than "application/sdp" or the SDP is malformed, the has a content type different than "application/sdp" or the SDP is
WHIP endpoint MUST reject the HTTP POST request with an appropiate malformed, the WHIP endpoint MUST reject the HTTP POST request with
4XX error response. an appropriate 4xx error response.
As the WHIP protocol only supports the ingestion use case with As the WHIP protocol only supports the ingestion use case with
unidirectional media, the WHIP client SHOULD use "sendonly" attribute unidirectional media, the WHIP client SHOULD use the "sendonly"
in the SDP offer but MAY use the "sendrecv" attribute instead, attribute in the SDP offer but MAY use the "sendrecv" attribute
"inactive" and "recvonly" attributes MUST NOT be used. The WHIP instead; the "inactive" and "recvonly" attributes MUST NOT be used.
endpoint MUST use "recvonly" attribute in the SDP answer. The WHIP endpoint MUST use the "recvonly" attribute in the SDP
answer.
Following Figure 2 is an example of an HTTP POST sent from a WHIP Figure 2 is an example of an HTTP POST sent from a WHIP client to a
client to a WHIP endpoint and the "201 Created" response from the WHIP endpoint and the "201 Created" response from the WHIP endpoint
WHIP endpoint containing the Location header pointing to the newly containing the Location header pointing to the newly created WHIP
created WHIP session: session.
POST /whip/endpoint HTTP/1.1 POST /whip/endpoint HTTP/1.1
Host: whip.example.com Host: whip.example.com
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 1101 Content-Length: 1101
v=0 v=0
o=- 5228595038118931041 2 IN IP4 127.0.0.1 o=- 5228595038118931041 2 IN IP4 127.0.0.1
s=- s=-
t=0 0 t=0 0
a=group:BUNDLE 0 1 a=group:BUNDLE 0 1
a=extmap-allow-mixed a=extmap-allow-mixed
a=ice-options:trickle ice2 a=ice-options:trickle ice2
m=audio 9 UDP/TLS/RTP/SAVPF 111 m=audio 9 UDP/TLS/RTP/SAVPF 111
c=IN IP4 0.0.0.0 c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0 a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:EsAw a=ice-ufrag:EsAw
a=ice-pwd:bP+XJMM09aR8AiX1jdukzR6Y a=ice-pwd:bP+XJMM09aR8AiX1jdukzR6Y
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=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=setup:actpass
a=mid:0 a=mid:0
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=sendonly a=sendonly
a=msid:d46fb922-d52a-4e9c-aa87-444eadc1521b ce326ecf-a081-453a-8f9f-0605d5ef4128 a=msid:d46fb922-d52a-4e9c-aa87-444eadc1521b ce326ecf-a081-453a-8f9f-0605d5ef4128
a=rtcp-mux a=rtcp-mux
a=rtcp-mux-only a=rtcp-mux-only
a=rtpmap:111 opus/48000/2 a=rtpmap:111 opus/48000/2
a=fmtp:111 minptime=10;useinbandfec=1 a=fmtp:111 minptime=10;useinbandfec=1
m=video 0 UDP/TLS/RTP/SAVPF 96 97 m=video 0 UDP/TLS/RTP/SAVPF 96 97
a=mid:1 a=mid:1
a=bundle-only a=bundle-only
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=extmap:10 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id 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=extmap:11 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id
a=sendonly a=sendonly
a=msid:d46fb922-d52a-4e9c-aa87-444eadc1521b 3956b460-40f4-4d05-acef-03abcdd8c6fd a=msid:d46fb922-d52a-4e9c-aa87-444eadc1521b 3956b460-40f4-4d05-acef-03abcdd8c6fd
a=rtpmap:96 VP8/90000 a=rtpmap:96 VP8/90000
a=rtcp-fb:96 ccm fir a=rtcp-fb:96 ccm fir
a=rtcp-fb:96 nack a=rtcp-fb:96 nack
a=rtcp-fb:96 nack pli a=rtcp-fb:96 nack pli
a=rtpmap:97 rtx/90000 a=rtpmap:97 rtx/90000
a=fmtp:97 apt=96 a=fmtp:97 apt=96
HTTP/1.1 201 Created HTTP/1.1 201 Created
ETag: "xyzzy" ETag: "xyzzy"
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 1053 Content-Length: 1053
Location: https://whip.example.com/session/id Location: https://whip.example.com/session/id
v=0 v=0
o=- 1657793490019 1 IN IP4 127.0.0.1 o=- 1657793490019 1 IN IP4 127.0.0.1
s=- s=-
t=0 0 t=0 0
a=group:BUNDLE 0 1 a=group:BUNDLE 0 1
a=extmap-allow-mixed a=extmap-allow-mixed
a=ice-lite a=ice-lite
a=ice-options:trickle ice2 a=ice-options:trickle ice2
m=audio 9 UDP/TLS/RTP/SAVPF 111 m=audio 9 UDP/TLS/RTP/SAVPF 111
c=IN IP4 0.0.0.0 c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0 a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:38sdf4fdsf54 a=ice-ufrag:38sdf4fdsf54
a=ice-pwd:2e13dde17c1cb009202f627fab90cbec358d766d049c9697 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=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=candidate:1 1 UDP 2130706431 198.51.100.1 39132 typ host
a=setup:passive a=setup:passive
a=mid:0 a=mid:0
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=recvonly a=recvonly
a=rtcp-mux a=rtcp-mux
a=rtcp-mux-only a=rtcp-mux-only
a=rtpmap:111 opus/48000/2 a=rtpmap:111 opus/48000/2
a=fmtp:111 minptime=10;useinbandfec=1 a=fmtp:111 minptime=10;useinbandfec=1
m=video 0 UDP/TLS/RTP/SAVPF 96 97 m=video 0 UDP/TLS/RTP/SAVPF 96 97
c=IN IP4 0.0.0.0 c=IN IP4 0.0.0.0
a=mid:1 a=mid:1
a=bundle-only a=bundle-only
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=extmap:10 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id 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=extmap:11 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id
a=recvonly a=recvonly
a=rtpmap:96 VP8/90000 a=rtpmap:96 VP8/90000
a=rtcp-fb:96 ccm fir a=rtcp-fb:96 ccm fir
a=rtcp-fb:96 nack a=rtcp-fb:96 nack
a=rtcp-fb:96 nack pli a=rtcp-fb:96 nack pli
a=rtpmap:97 rtx/90000 a=rtpmap:97 rtx/90000
a=fmtp:97 apt=96 a=fmtp:97 apt=96
Figure 2: Example of SDP offer/answer exchange done via an HTTP POST Figure 2: Example of the SDP Offer/Answer Exchange Done via an
HTTP POST
Once a session is set up, consent freshness as per [RFC7675] SHALL be Once a session is set up, consent freshness as per [RFC7675] SHALL be
used to detect non-graceful disconnection by full ICE implementations used to detect non-graceful disconnection by full ICE implementations
and DTLS teardown for session termination by either side. and DTLS teardown for session termination by either side.
To explicitly terminate a WHIP session, the WHIP client MUST perform To explicitly terminate a WHIP session, the WHIP client MUST perform
an HTTP DELETE request to the WHIP session URL returned in the an HTTP DELETE request to the WHIP session URL returned in the
Location header field of the initial HTTP POST. Upon receiving the Location header field of the initial HTTP POST. Upon receiving the
HTTP DELETE request, the WHIP session will be removed and the HTTP DELETE request, the WHIP session will be removed and the
resources freed on the media server, terminating the ICE and DTLS resources freed on the media server, terminating the ICE and DTLS
sessions. sessions.
A media server terminating a session MUST follow the procedures in A media server terminating a session MUST follow the procedures in
Section 5.2 of [RFC7675] for immediate revocation of consent. Section 5.2 of [RFC7675] for immediate revocation of consent.
The WHIP endpoints MUST support OPTIONS requests for Cross-Origin The WHIP endpoints MUST support OPTIONS requests for Cross-Origin
Resource Sharing (CORS) as defined in [FETCH]. The "200 OK" response Resource Sharing (CORS) as defined in [FETCH]. The "200 OK" response
to any OPTIONS request SHOULD include an "Accept-Post" header with a to any OPTIONS request SHOULD include an "Accept-Post" header with a
media type value of "application/sdp" as per [W3C.REC-ldp-20150226]. media type value of "application/sdp" as per [W3C.REC-ldp-20150226].
4.3. ICE support 4.3. ICE Support
ICE [RFC8845] is a protocol addressing the complexities of NAT ICE [RFC8845] is a protocol that addresses the complexities of NAT
traversal, commonly encountered in Internet communication. NATs traversal commonly encountered in Internet communication. NATs
hinder direct communication between devices on different local hinder direct communication between devices on different local
networks, posing challenges for real-time applications. ICE networks, posing challenges for real-time applications. ICE
facilitates seamless connectivity by employing techniques to discover facilitates seamless connectivity by employing techniques to discover
and negotiate efficient communication paths. and negotiate efficient communication paths.
Trickle ICE [RFC8838] optimizes the connectivity process by Trickle ICE [RFC8838] optimizes the connectivity process by
incrementally sharing potential communication paths, reducing incrementally sharing potential communication paths, reducing
latency, and facilitating quicker establishment. latency, and facilitating quicker establishment.
ICE Restarts are crucial for maintaining connectivity in dynamic ICE restarts are crucial for maintaining connectivity in dynamic
network conditions or disruptions, allowing devices to re-establish network conditions or disruptions, allowing devices to re-establish
communication paths without complete renegotiation. This ensures communication paths without complete renegotiation. This ensures
minimal latency and reliable real-time communication. minimal latency and reliable real-time communication.
Trickle ICE and ICE restart support are RECOMMENDED for both WHIP Trickle ICE and ICE restart support are RECOMMENDED for both WHIP
sessions and clients. sessions and clients.
4.3.1. HTTP PATCH request usage 4.3.1. HTTP PATCH Request Usage
The WHIP client MAY perform trickle ICE or ICE restarts by sending an The WHIP client MAY perform Trickle ICE or ICE restarts by sending an
HTTP PATCH request as per [RFC5789] to the WHIP session URL, with a HTTP PATCH request as per [RFC5789] to the WHIP session URL, with a
body containing an SDP fragment with media type "application/trickle- body containing an SDP fragment with media type "application/trickle-
ice-sdpfrag" as specified in [RFC8840] carrying the relevant ICE ice-sdpfrag" as specified in [RFC8840] carrying the relevant ICE
information. If the HTTP PATCH to the WHIP session has a content information. If the HTTP PATCH to the WHIP session has a content
type different than "application/trickle-ice-sdpfrag" or the SDP type different than "application/trickle-ice-sdpfrag" or the SDP
fragment is malformed, the WHIP session MUST reject the HTTP PATCH fragment is malformed, the WHIP session MUST reject the HTTP PATCH
with an appropiate 4XX error response. with an appropriate 4xx error response.
If the WHIP session supports either Trickle ICE or ICE restarts, but If the WHIP session supports either Trickle ICE or ICE restarts, but
not both, it MUST return a "422 Unprocessable Content" error response not both, it MUST return a "422 Unprocessable Content" error response
for the HTTP PATCH requests that are not supported as per for the HTTP PATCH requests that are not supported as per
Section 15.5.21 of [RFC9110]. Section 15.5.21 of [RFC9110].
The WHIP client MAY send overlapping HTTP PATCH requests to one WHIP The WHIP client MAY send overlapping HTTP PATCH requests to one WHIP
session. Consequently, as those HTTP PATCH requests may be received session. Consequently, those HTTP PATCH requests may be received out
out-of-order by the WHIP session, if WHIP session supports ICE of order by the WHIP session. Thus, if the WHIP session supports ICE
restarts, it MUST generate a unique strong entity-tag identifying the restarts, it MUST generate a unique strong entity-tag identifying the
ICE session as per Section 8.8.3 of [RFC9110], being OPTIONAL ICE session as per Section 8.8.3 of [RFC9110], being OPTIONAL
otherwise. The initial value of the entity-tag identifying the otherwise. The initial value of the entity-tag identifying the
initial ICE session MUST be returned in an ETag header field in the initial ICE session MUST be returned in an ETag header field in the
"201 Created" response to the initial POST request to the WHIP "201 Created" response to the initial POST request to the WHIP
endpoint. endpoint.
WHIP clients SHOULD NOT use entity-tag validation when matching a WHIP clients SHOULD NOT use entity-tag validation when matching a
specific ICE session is not required, such as for example when specific ICE session is not required, for example, when initiating a
initiating a DELETE request to terminate a session. WHIP sessions DELETE request to terminate a session. WHIP sessions MUST ignore any
MUST ignore any entity-tag value sent by the WHIP client when ICE entity-tag value sent by the WHIP client when ICE session matching is
session matching is not required, as in the HTTP DELETE request. not required, as in the HTTP DELETE request.
Missing or outdated ETags in the PATCH requests from WHIP clients Missing or outdated ETags in the PATCH requests from WHIP clients
will be answered by WHIP sessions as per Section 13.1.1 of [RFC9110] will be answered by WHIP sessions as per Section 13.1.1 of [RFC9110]
and Section 3 of [RFC6585], with a "428 Precondition Required" and Section 3 of [RFC6585], with a "428 Precondition Required"
response for a missing entity tag, and a "412 Precondition Failed" response for a missing entity-tag and a "412 Precondition Failed"
response for a non-matching entity tag. response for a non-matching entity-tag.
4.3.2. Trickle ICE 4.3.2. Trickle ICE
Depending on the Trickle ICE support on the WHIP client, the initial Depending on the Trickle ICE support on the WHIP client, the initial
offer by the WHIP client MAY be sent after the full ICE gathering is offer by the WHIP client MAY be sent after the full ICE gathering is
complete with the full list of ICE candidates, or it MAY only contain complete with the full list of ICE candidates, or it MAY only contain
local candidates (or even an empty list of candidates) as per local candidates (or even an empty list of candidates) as per
[RFC8845]. For the purpose of reducing setup times, when using [RFC8845]. For the purpose of reducing setup times, when using
Trickle ICE the WHIP client SHOULD send the SDP offer as soon as Trickle ICE, the WHIP client SHOULD send the SDP offer (containing
possible, containing either locally gathered ICE candidates or an either locally gathered ICE candidates or an empty list of
empty list of candidates. candidates) as soon as possible.
In order to simplify the protocol, the WHIP session cannot signal In order to simplify the protocol, the WHIP session cannot signal
additional ICE candidates to the WHIP client after the SDP answer has additional ICE candidates to the WHIP client after the SDP answer has
been sent. The WHIP endpoint SHALL gather all the ICE candidates for been sent. The WHIP endpoint SHALL gather all the ICE candidates for
the media server before responding to the client request and the SDP the media server before responding to the client request, and the SDP
answer SHALL contain the full list of ICE candidates of the media answer SHALL contain the full list of ICE candidates of the media
server. server.
As the WHIP client needs to know the WHIP session URL associated with As the WHIP client needs to know the WHIP session URL associated with
the ICE session in order to send a PATCH request containing new ICE the ICE session in order to send a PATCH request containing new ICE
candidates, it MUST wait and buffer any gathered candidates until the candidates, it MUST wait and buffer any gathered candidates until the
"201 Created" HTTP response to the initial POST request is received. "201 Created" HTTP response to the initial POST request is received.
In order to lower the HTTP traffic and processing time required the In order to reduce the HTTP traffic and processing time required, the
WHIP client SHOULD send a single aggregated HTTP PATCH request with WHIP client SHOULD send a single aggregated HTTP PATCH request with
all the buffered ICE candidates once the response is received. all the buffered ICE candidates once the response is received.
Additionally, if ICE restarts are supported by the WHIP session, the Additionally, if ICE restarts are supported by the WHIP session, the
WHIP client needs to know the entity-tag associated with the ICE WHIP client needs to know the entity-tag associated with the ICE
session in order to send a PATCH request containing new ICE session in order to send a PATCH request containing new ICE
candidates, so it MUST also wait and buffer any gathered candidates candidates; thus, it MUST also wait and buffer any gathered
until it receives the HTTP response with the new entity-tag value to candidates until it receives the HTTP response with the new entity-
the last PATCH request performing an ICE restart. tag value to the last PATCH request performing an ICE restart.
WHIP clients generating the HTTP PATCH body with the SDP fragment and WHIP clients generating the HTTP PATCH body with the SDP fragment and
its subsequent processing by WHIP sessions MUST follow to the its subsequent processing by WHIP sessions MUST follow the guidelines
guidelines defined in Section 4.4 of [RFC8840] with the following defined in Section 4.4 of [RFC8840] with the following
considerations: considerations:
* As per [RFC9429], only m-sections not marked as bundle-only can * As per [RFC9429], only "m=" sections not marked as bundle-only can
gather ICE candidates, so given that the "max-bundle" policy is gather ICE candidates, so given that the "max-bundle" policy is
being used, the SDP fragment will contain only the offerer-tagged being used, the SDP fragment will contain only the offerer-tagged
m-line of the bundle group. "m=" line of the bundle group.
* The WHIP client MAY exclude ICE candidates from the HTTP PATCH * The WHIP client MAY exclude ICE candidates from the HTTP PATCH
body if they have already been confirmed by the WHIP session with body if they have already been confirmed by the WHIP session with
a successful HTTP response to a previous HTTP PATCH request. a successful HTTP response to a previous HTTP PATCH request.
WHIP sessions and clients that support Trickle ICE MUST make use of WHIP sessions and clients that support Trickle ICE MUST make use of
entity-tags and conditional requests as explained in Section 4.3.1. entity-tags and conditional requests as explained in Section 4.3.1.
When a WHIP session receives a PATCH request that adds new ICE When a WHIP session receives a PATCH request that adds new ICE
candidates without performing an ICE restart, it MUST return a "204 candidates without performing an ICE restart, it MUST return a "204
No Content" response without a body and MUST NOT include an ETag No Content" response without a body and MUST NOT include an ETag
header in the response. If the WHIP session does not support a header in the response. If the WHIP session does not support a
candidate transport or is not able to resolve the connection address, candidate transport or is not able to resolve the connection address,
it MUST silently discard the candidate and continue processing the it MUST silently discard the candidate and continue processing the
rest of the request normally. rest of the request normally.
PATCH /session/id HTTP/1.1 PATCH /session/id HTTP/1.1
Host: whip.example.com Host: whip.example.com
If-Match: "xyzzy" If-Match: "xyzzy"
Content-Type: application/trickle-ice-sdpfrag Content-Type: application/trickle-ice-sdpfrag
Content-Length: 576 Content-Length: 576
a=group:BUNDLE 0 1 a=group:BUNDLE 0 1
m=audio 9 UDP/TLS/RTP/SAVPF 111 m=audio 9 UDP/TLS/RTP/SAVPF 111
a=mid:0 a=mid:0
a=ice-ufrag:EsAw a=ice-ufrag:EsAw
a=ice-pwd:P2uYro0UCOQ4zxjKXaWCBui1 a=ice-pwd:P2uYro0UCOQ4zxjKXaWCBui1
a=candidate:1387637174 1 udp 2122260223 192.0.2.1 61764 typ host generation 0 ufrag EsAw network-id 1 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 198.51.100.2 61765 typ host generation 0 ufrag EsAw network-id 2 a=candidate:3471623853 1 udp 2122194687 198.51.100.2 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: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=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 a=end-of-candidates
HTTP/1.1 204 No Content HTTP/1.1 204 No Content
Figure 3: Example of a Trickle ICE request and response Figure 3: Example of a Trickle ICE Request and Response
Figure 3 shows an example of the Trickle ICE procedure where the WHIP Figure 3 shows an example of the Trickle ICE procedure where the WHIP
client sends a PATCH request with updated ICE candidate information client sends a PATCH request with updated ICE candidate information
and receives a successful response from the WHIP session. and receives a successful response from the WHIP session.
4.3.3. ICE Restarts 4.3.3. ICE Restarts
As defined in [RFC8839], when an ICE restart occurs, a new SDP offer/ As defined in [RFC8839], when an ICE restart occurs, a new SDP offer/
answer exchange is triggered. However, as WHIP does not support answer exchange is triggered. However, as WHIP does not support
renegotiation of non-ICE related SDP information, a WHIP client will renegotiation of non-ICE-related SDP information, a WHIP client will
not send a new offer when an ICE restart occurs. Instead, the WHIP not send a new offer when an ICE restart occurs. Instead, the WHIP
client and WHIP session will only exchange the relevant ICE client and WHIP session will only exchange the relevant ICE
information via an HTTP PATCH request as defined in Section 4.3.1 and information via an HTTP PATCH request as defined in Section 4.3.1 and
MUST assume that the previously negotiated non-ICE related SDP MUST assume that the previously negotiated non-ICE-related SDP
information still apply after the ICE restart. information still applies after the ICE restart.
When performing an ICE restart, the WHIP client MUST include the When performing an ICE restart, the WHIP client MUST include the
updated "ice-pwd" and "ice-ufrag" in the SDP fragment of the HTTP updated "ice-pwd" and "ice-ufrag" in the SDP fragment of the HTTP
PATCH request body as well as the new set of gathered ICE candidates PATCH request body as well as the new set of gathered ICE candidates
as defined in [RFC8840]. Similar what is defined in Section 4.3.2, as defined in [RFC8840]. Similar to what is defined in
as per [RFC9429] only m-sections not marked as bundle-only can gather Section 4.3.2, as per [RFC9429], only "m=" sections not marked as
ICE candidates, so given that the "max-bundle" policy is being used, bundle-only can gather ICE candidates, so given that the "max-bundle"
the SDP fragment will contain only the offerer-tagged m-line of the policy is being used, the SDP fragment will contain only the offerer-
bundle group. A WHIP client sending a PATCH request for performing tagged "m=" line of the bundle group. A WHIP client sending a PATCH
ICE restart MUST contain an "If-Match" header field with a field- request for performing ICE restart MUST contain an "If-Match" header
value "*" as per Section 13.1.1 of [RFC9110]. field with a field-value of "*" as per Section 13.1.1 of [RFC9110].
[RFC8840] states that an agent MUST discard any received requests [RFC8840] states that an agent MUST discard any received requests
containing "ice-pwd" and "ice-ufrag" attributes that do not match containing "ice-pwd" and "ice-ufrag" attributes that do not match
those of the current ICE Negotiation Session, however, any WHIP those of the current ICE Negotiation Session. However, any WHIP
session receiving an updated "ice-pwd" and "ice-ufrag" attributes session receiving updated "ice-pwd" and "ice-ufrag" attributes MUST
MUST consider the request as performing an ICE restart instead and, consider the request as performing an ICE restart instead and, if
if supported, SHALL return a "200 OK" with an "application/trickle- supported, SHALL return a "200 OK" with an "application/trickle-ice-
ice-sdpfrag" body containing the new ICE username fragment and sdpfrag" body containing the new ICE username fragment and password
password and a new set of ICE candidates for the WHIP session. Also, and a new set of ICE candidates for the WHIP session. Also, the "200
the "200 OK" response for a successful ICE restart MUST contain the OK" response for a successful ICE restart MUST contain the new
new entity-tag corresponding to the new ICE session in an ETag entity-tag corresponding to the new ICE session in an ETag response
response header field and MAY contain a new set of ICE candidates for header field and MAY contain a new set of ICE candidates for the
the media server. media server.
As defined in Section 4.4.1.1.1 of [RFC8839] the set of candidates As defined in Section 4.4.1.1.1 of [RFC8839], the set of candidates
after an ICE restart may include some, none, or all of the previous after an ICE restart may include some, none, or all of the previous
candidates for that data stream and may include a totally new set of candidates for that data stream and may include a totally new set of
candidates. So after performing a successful ICE restart, both the candidates. Therefore, after performing a successful ICE restart,
WHIP client and the WHIP session MUST replace the previous set of both the WHIP client and the WHIP session MUST replace the previous
remote candidates with the new set exchanged in the HTTP PATCH set of remote candidates with the new set exchanged in the HTTP PATCH
request and response, discarding any remote ICE candidate not present request and response, discarding any remote ICE candidate not present
on the new set. Both the WHIP client and the WHIP session MUST on the new set. Both the WHIP client and the WHIP session MUST
ensure that the HTTP PATCH requests and response bodies include the ensure that the HTTP PATCH request and response bodies include the
same 'ice-options,' 'ice-pacing,' and 'ice-lite' attributes as those same "ice-options," "ice-pacing," and "ice-lite" attributes as those
used in the SDP offer or answer. used in the SDP offer or answer.
If the ICE restart request cannot be satisfied by the WHIP session, If the ICE restart request cannot be satisfied by the WHIP session,
the resource MUST return an appropriate HTTP error code and MUST NOT the resource MUST return an appropriate HTTP error code and MUST NOT
terminate the session immediately and keep the existing ICE session. terminate the session immediately and keep the existing ICE session.
The WHIP client MAY retry performing a new ICE restart or terminate The WHIP client MAY retry performing a new ICE restart or terminate
the session by issuing an HTTP DELETE request instead. In any case, the session by issuing an HTTP DELETE request instead. In any case,
the session MUST be terminated if the ICE consent expires as a the session MUST be terminated if the ICE consent expires as a
consequence of the failed ICE restart as per Section 5.1 of consequence of the failed ICE restart as per Section 5.1 of
[RFC7675]. [RFC7675].
In case of unstable network conditions, the ICE restart HTTP PATCH In case of unstable network conditions, the ICE restart HTTP PATCH
requests and responses might be received out of order. In order to requests and responses might be received out of order. In order to
mitigate this scenario, when the client performs an ICE restart, it mitigate this scenario, when the client performs an ICE restart, it
MUST discard any previous ICE username and passwords fragments and MUST discard any previous ICE username and password fragments and
ignore any further HTTP PATCH response received from a pending HTTP ignore any further HTTP PATCH response received from a pending HTTP
PATCH request. WHIP clients MUST apply only the ICE information PATCH request. WHIP clients MUST apply only the ICE information
received in the response to the last sent request. If there is a received in the response to the last sent request. If there is a
mismatch between the ICE information at the WHIP client and at the mismatch between the ICE information at the WHIP client and at the
WHIP session (because of an out-of-order request), the STUN requests WHIP session (because of an out-of-order request), the Session
will contain invalid ICE information and will be dropped by the Traversal Utilities for NAT (STUN) requests will contain invalid ICE
receiving side. If this situation is detected by the WHIP client, it information and will be dropped by the receiving side. If this
MUST send a new ICE restart request to the server. situation is detected by the WHIP client, it MUST send a new ICE
restart request to the server.
PATCH /session/id HTTP/1.1 PATCH /session/id HTTP/1.1
Host: whip.example.com Host: whip.example.com
If-Match: "*" If-Match: "*"
Content-Type: application/trickle-ice-sdpfrag Content-Type: application/trickle-ice-sdpfrag
Content-Length: 82 Content-Length: 82
a=ice-options:trickle ice2 a=ice-options:trickle ice2
a=group:BUNDLE 0 1 a=group:BUNDLE 0 1
m=audio 9 UDP/TLS/RTP/SAVPF 111 m=audio 9 UDP/TLS/RTP/SAVPF 111
a=mid:0 a=mid:0
a=ice-ufrag:ysXw a=ice-ufrag:ysXw
a=ice-pwd:vw5LmwG4y/e6dPP/zAP9Gp5k a=ice-pwd:vw5LmwG4y/e6dPP/zAP9Gp5k
a=candidate:1387637174 1 udp 2122260223 192.0.2.1 61764 typ host generation 0 ufrag EsAw network-id 1 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 198.51.100.2 61765 typ host generation 0 ufrag EsAw network-id 2 a=candidate:3471623853 1 udp 2122194687 198.51.100.2 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: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=candidate:2154773085 1 tcp 1518214911 198.51.100.2 9 typ host tcptype active generation 0 ufrag EsAw network-id 2
HTTP/1.1 200 OK HTTP/1.1 200 OK
ETag: "abccd" ETag: "abccd"
Content-Type: application/trickle-ice-sdpfrag Content-Type: application/trickle-ice-sdpfrag
Content-Length: 252 Content-Length: 252
a=ice-lite a=ice-lite
a=ice-options:trickle ice2 a=ice-options:trickle ice2
a=group:BUNDLE 0 1 a=group:BUNDLE 0 1
m=audio 9 UDP/TLS/RTP/SAVPF 111 m=audio 9 UDP/TLS/RTP/SAVPF 111
a=mid:0 a=mid:0
a=ice-ufrag:289b31b754eaa438 a=ice-ufrag:289b31b754eaa438
a=ice-pwd:0b66f472495ef0ccac7bda653ab6be49ea13114472a5d10a a=ice-pwd:0b66f472495ef0ccac7bda653ab6be49ea13114472a5d10a
a=candidate:1 1 udp 2130706431 198.51.100.1 39132 typ host a=candidate:1 1 udp 2130706431 198.51.100.1 39132 typ host
a=end-of-candidates a=end-of-candidates
Figure 4: Example of an ICE restart request and response Figure 4: Example of an ICE Restart Request and Response
Figure 3 demonstrates a Trickle ICE restart procedure example. The Figure 4 demonstrates a Trickle ICE restart procedure example. The
WHIP client sends a PATCH request containing updated ICE information, WHIP client sends a PATCH request containing updated ICE information,
including a new ufrag and password, along with newly gathered ICE including a new ufrag and password, along with newly gathered ICE
candidates. In response, the WHIP session provides ICE information candidates. In response, the WHIP session provides ICE information
for the session after the ICE restart, including the updated ufrag for the session after the ICE restart, including the updated ufrag
and password, as well as the previous ICE candidate. and password, as well as the previous ICE candidate.
4.4. WebRTC constraints 4.4. WebRTC Constraints
To simplify the implementation of WHIP in both clients and media To simplify the implementation of WHIP in both clients and media
servers, WHIP introduces specific restrictions on WebRTC usage. The servers, WHIP introduces specific restrictions on WebRTC usage. The
following subsections will explain these restrictions in detail: following subsections will explain these restrictions in detail.
4.4.1. SDP Bundle 4.4.1. SDP Bundle
Both the WHIP client and the WHIP endpoint SHALL support [RFC9143] Both the WHIP client and the WHIP endpoint SHALL support [RFC9143]
and use "max-bundle" policy as defined in [RFC9429]. The WHIP client and use the "max-bundle" policy as defined in [RFC9429]. The WHIP
and the media server MUST support multiplexed media associated with client and the media server MUST support multiplexed media associated
the BUNDLE group as per Section 9 of [RFC9143]. In addition, per with the BUNDLE group as per Section 9 of [RFC9143]. In addition,
[RFC9143] the WHIP client and media server SHALL use RTP/RTCP per [RFC9143], the WHIP client and media server SHALL use RTP/RTCP
multiplexing for all bundled media. In order to reduce the network multiplexing for all bundled media. In order to reduce the network
resources required at the media server, both The WHIP client and WHIP resources required at the media server, both the WHIP client and WHIP
endpoints MUST include the "rtcp-mux-only" attribute in each bundled endpoints MUST include the "rtcp-mux-only" attribute in each bundled
"m=" sections as per Section 3 of [RFC8858]. "m=" section as per Section 3 of [RFC8858].
4.4.2. Single MediaStream 4.4.2. Single MediaStream
WHIP only supports a single MediaStream as defined in [RFC8830] and WHIP only supports a single MediaStream as defined in [RFC8830];
therefore all "m=" sections MUST contain a "msid" attribute with the therefore, all "m=" sections MUST contain a "msid" attribute with the
same value. The MediaStream MUST contain at least one same value. The MediaStream MUST contain at least one
MediaStreamTrack of any media kind and it MUST NOT have two or more MediaStreamTrack of any media kind, and it MUST NOT have two or more
than MediaStreamTracks for the same media (audio or video). However, MediaStreamTracks for the same media (audio or video). However, it
it would be possible for future revisions of this spec to allow more would be possible for future revisions of this specification to allow
than a single MediaStream or MediaStreamTrack of each media kind, so more than a single MediaStream or MediaStreamTrack of each media
in order to ensure forward compatibility, if the number of audio and kind. Therefore, in order to ensure forward compatibility, if the
or video MediaStreamTracks or number of MediaStreams are not number of audio and/or video MediaStreamTracks or the number of
supported by the WHIP endpoint, it MUST reject the HTTP POST request MediaStreams are not supported by the WHIP endpoint, it MUST reject
with an "422 Unprocessable Content" or "400 Bad Request" error the HTTP POST request with a "422 Unprocessable Content" or "400 Bad
response. The WHIP endpoint MAY also return a problem statement as Request" error response. The WHIP endpoint MAY also return a problem
recommended in Section 4.1 proving further error details about the statement as recommended in Section 4.1 proving further error details
failed request. about the failed request.
4.4.3. No partially successful answers 4.4.3. No Partially Successful Answers
The WHIP endpoint SHOULD NOT reject individual "m=" sections as per The WHIP endpoint SHOULD NOT reject individual "m=" sections as per
Section 5.3.1 of [RFC9429] in case there is any error processing the Section 5.3.1 of [RFC9429] in case there is any error processing the
"m=" section, but reject the HTTP POST request with an "422 "m=" section, but reject the HTTP POST request with a "422
Unprocessable Content" or "400 Bad Request" error response to prevent Unprocessable Content" or "400 Bad Request" error response to prevent
having partially successful ingest sessions which can be misleading having partially successful ingest sessions, which can be misleading
to end users. The WHIP endpoint MAY also return a problem statement to end users. The WHIP endpoint MAY also return a problem statement
as recommended in Section 4.1 proving further error details about the as recommended in Section 4.1 proving further error details about the
failed request. failed request.
4.4.4. DTLS setup role and SDP "setup" attribute 4.4.4. DTLS Setup Role and SDP "setup" Attribute
When a WHIP client sends an SDP offer, it SHOULD insert an SDP When a WHIP client sends an SDP offer, it SHOULD insert an SDP
"setup" attribute with an "actpass" attribute value, as defined in "setup" attribute with an "actpass" attribute value, as defined in
[RFC8842]. However, if the WHIP client only implements the DTLS [RFC8842]. However, if the WHIP client only implements the DTLS
client role, it MAY use an SDP "setup" attribute with an "active" client role, it MAY use an SDP "setup" attribute with an "active"
attribute value. If the WHIP endpoint does not support an SDP offer attribute value. If the WHIP endpoint does not support an SDP offer
with an SDP "setup" attribute with an "active" attribute value, it with an SDP "setup" attribute with an "active" attribute value, it
SHOULD reject the request with an "422 Unprocessable Content" or "400 SHOULD reject the request with a "422 Unprocessable Content" or "400
Bad Request" error response. Bad Request" error response.
NOTE: [RFC8842] defines that the offerer must insert an SDP "setup" NOTE: [RFC8842] defines that the offerer must insert an SDP "setup"
attribute with an "actpass" attribute value. However, the WHIP attribute with an "actpass" attribute value. However, the WHIP
client will always communicate with a media server that is expected client will always communicate with a media server that is expected
to support the DTLS server role, in which case the client might to support the DTLS server role, in which case the client might
choose to only implement support for the DTLS client role. choose to only implement support for the DTLS client role.
4.4.5. Trickle ICE and ICE restarts 4.4.5. Trickle ICE and ICE Restarts
The media server SHOULD support full ICE, unless it is connected to The media server SHOULD support full ICE, unless it is connected to
the Internet with an IP address that is accessible by each WHIP the Internet with an IP address that is accessible by each WHIP
client that is authorized to use it, in which case it MAY support client that is authorized to use it, in which case it MAY support
only ICE lite. The WHIP client MUST implement and use full ICE. only ICE lite. The WHIP client MUST implement and use full ICE.
Trickle ICE and ICE restarts support is OPTIONAL for both the WHIP Trickle ICE and ICE restart support is OPTIONAL for both the WHIP
clients and media servers as explained in Section 4.3. clients and media servers as explained in Section 4.3.
4.5. Load balancing and redirections 4.5. Load Balancing and Redirections
WHIP endpoints and media servers might not be colocated on the same WHIP endpoints and media servers might not be colocated on the same
server, so it is possible to load balance incoming requests to server, so it is possible to load balance incoming requests to
different media servers. different media servers.
WHIP clients SHALL support HTTP redirections as per Section 15.4 of WHIP clients SHALL support HTTP redirections as per Section 15.4 of
[RFC9110]. In order to avoid POST requests to be redirected as GET [RFC9110]. In order to avoid POST requests being redirected as GET
requests, status codes 301 and 302 MUST NOT be used and the preferred requests, status codes 301 and 302 MUST NOT be used; the preferred
method for performing load balancing is via the "307 Temporary method for performing load balancing is via the "307 Temporary
Redirect" response status code as described in Section 15.4.8 of Redirect" response status code as described in Section 15.4.8 of
[RFC9110]. Redirections are not required to be supported for the [RFC9110]. Redirections are not required to be supported for the
PATCH and DELETE requests. PATCH and DELETE requests.
In case of high load, the WHIP endpoints MAY return a "503 Service In case of high load, the WHIP endpoints MAY return a "503 Service
Unavailable" response indicating that the server is currently unable Unavailable" response indicating that the server is currently unable
to handle the request due to a temporary overload or scheduled to handle the request due to a temporary overload or scheduled
maintenance as described in Section 15.6.4 of [RFC9110], which will maintenance as described in Section 15.6.4 of [RFC9110], which will
likely be alleviated after some delay. The WHIP endpoint might send likely be alleviated after some delay. The WHIP endpoint might send
a Retry-After header field indicating the minimum time that the user a Retry-After header field indicating the minimum time that the user
agent ought to wait before making a follow-up request as described in agent ought to wait before making a follow-up request as described in
Section 10.2.3 of [RFC9110]. Section 10.2.3 of [RFC9110].
4.6. STUN/TURN server configuration 4.6. STUN/TURN Server Configuration
The WHIP endpoint MAY return STUN/TURN server configuration URLs and The WHIP endpoint MAY return STUN/TURN server configuration URLs and
credentials usable by the client in the "201 Created" response to the credentials usable by the client in the "201 Created" response to the
HTTP POST request to the WHIP endpoint URL. HTTP POST request to the WHIP endpoint URL.
A reference to each STUN/TURN server will be returned using the A reference to each STUN/TURN server will be returned using the
"Link" header field [RFC8288] with a "rel" attribute value of "ice- "Link" header field [RFC8288] with a "rel" attribute value of "ice-
server". The Link target URI is the server URI as defined in server". The Link target URI is the server URI as defined in
[RFC7064] and [RFC7065]. The credentials are encoded in the Link [RFC7064] and [RFC7065]. The credentials are encoded in the Link
target attributes as follows: target attributes as follows:
* username: If the Link header field represents a TURN server, and * username: If the Link header field represents a Traversal Using
credential-type is "password", then this attribute specifies the Relays around NAT (TURN) server and the "credential-type"
username to use with that TURN server. attribute has a "password" value, then this attribute specifies
the username to use with that TURN server.
* credential: If the "credential-type" attribute is missing or has a * credential: If the "credential-type" attribute is missing or has a
"password" value, the credential attribute represents a long-term "password" value, this attribute represents a long-term
authentication password, as described in Section 9.2 of [RFC8489]. authentication password, as described in Section 9.2 of [RFC8489].
* credential-type: If the Link header field represents a TURN * credential-type: If the Link header field represents a TURN
server, then this attribute specifies how the credential attribute server, then this attribute specifies how the "credential"
value should be used when that TURN server requests authorization. attribute value should be used when that TURN server requests
The default value if the attribute is not present is "password". authorization. The default value if the attribute is not present
is "password".
Link: <stun:stun.example.net>; rel="ice-server" Link: <stun:stun.example.net>; rel="ice-server"
Link: <turn:turn.example.net?transport=udp>; rel="ice-server"; Link: <turn:turn.example.net?transport=udp>; rel="ice-server";
username="user"; credential="myPassword"; credential-type="password" username="user"; credential="myPassword"; credential-type="password"
Link: <turn:turn.example.net?transport=tcp>; rel="ice-server"; Link: <turn:turn.example.net?transport=tcp>; rel="ice-server";
username="user"; credential="myPassword"; credential-type="password" username="user"; credential="myPassword"; credential-type="password"
Link: <turns:turn.example.net?transport=tcp>; rel="ice-server"; Link: <turns:turn.example.net?transport=tcp>; rel="ice-server";
username="user"; credential="myPassword"; credential-type="password" username="user"; credential="myPassword"; credential-type="password"
Figure 5: Example of a STUN/TURN servers configuration Figure 5: Example of a STUN/TURN Server's Configuration
Figure 5 illustrates the Link headers included in a 201 Created Figure 5 illustrates the Link headers included in a "201 Created"
response, providing the ICE server URLs and associated credentials. response, providing the ICE server URLs and associated credentials.
NOTE: The naming of both the "rel" attribute value of "ice-server" NOTE: The naming of both the "rel" attribute value of "ice-server"
and the target attributes follows the one used on the W3C WebRTC and the target attributes follows that used in the RTCConfiguration
recommendation [W3C.REC-webrtc-20210126] RTCConfiguration dictionary dictionary in Section 4.2.1 of the W3C WebRTC recommendation (see
in section 4.2.1. "rel" attribute value of "ice-server" is not [W3C.REC-webrtc-20210126]). The "rel" attribute value of "ice-
prepended with the "urn:ietf:params:whip:" so it can be reused by server" is not prepended with the "urn:ietf:params:whip:" so it can
other specifications which may use this mechanism to configure the be reused by other specifications, which may use this mechanism to
usage of STUN/TURN servers. configure the usage of STUN/TURN servers.
NOTE: Depending on the ICE Agent implementation, the WHIP client may NOTE: Depending on the ICE agent implementation, the WHIP client may
need to call the setConfiguration method before calling the need to call the setConfiguration method before calling the
setLocalDescription method with the local SDP offer in order to avoid setLocalDescription method with the local SDP offer in order to avoid
having to perform an ICE restart for applying the updated STUN/TURN having to perform an ICE restart for applying the updated STUN/TURN
server configuration on the next ICE gathering phase. server configuration on the next ICE gathering phase.
There are some WebRTC implementations that do not support updating There are some WebRTC implementations that do not support updating
the STUN/TURN server configuration after the local offer has been the STUN/TURN server configuration after the local offer has been
created as specified in Section 4.1.18 of [RFC9429]. In order to created as specified in Section 4.1.18 of [RFC9429]. In order to
support these clients, the WHIP endpoint MAY also include the STUN/ support these clients, the WHIP endpoint MAY also include the STUN/
TURN server configuration on the responses to OPTIONS request sent to TURN server configuration on the responses to OPTIONS requests sent
the WHIP endpoint URL before the POST request is sent. However, this to the WHIP endpoint URL before the POST request is sent. However,
method is NOT RECOMMENDED to be used by the WHIP clients and, if this method is NOT RECOMMENDED to be used by the WHIP clients, and if
supported by the underlying WHIP client's webrtc implementation, the it is supported by the underlying WHIP client's WebRTC
WHIP client SHOULD wait for the information to be returned by the implementation, the WHIP client SHOULD wait for the information to be
WHIP endpoint on the response of the HTTP POST request instead. returned by the WHIP endpoint on the response of the HTTP POST
request instead.
The generation of the TURN server credentials may require performing The generation of the TURN server credentials may require performing
a request to an external provider, which can both add latency to the a request to an external provider, which can both add latency to the
OPTIONS request processing and increase the processing required to OPTIONS request processing and increase the processing required to
handle that request. In order to prevent this, the WHIP endpoint handle that request. In order to prevent this, the WHIP endpoint
SHOULD NOT return the STUN/TURN server configuration if the OPTIONS SHOULD NOT return the STUN/TURN server configuration if the OPTIONS
request is a preflight request for CORS as defined in [FETCH], that request is a preflight request for CORS as defined in [FETCH], that
is, if The OPTIONS request does not contain an Access-Control- is, if the OPTIONS request does not contain an Access-Control-
Request-Method with "POST" value and the Access-Control-Request- Request-Method with a "POST" value and the Access-Control-Request-
Headers HTTP header does not contain the "Link" value. Headers HTTP header does not contain the "Link" value.
The WHIP clients MAY also support configuring the STUN/TURN server The WHIP clients MAY also support configuring the STUN/TURN server
URIs with long term credentials provided by either the broadcasting URIs with long-term credentials provided by either the broadcasting
service or an external TURN provider, overriding the values provided service or an external TURN provider, overriding the values provided
by the WHIP endpoint. by the WHIP endpoint.
4.6.1. Congestion control 4.6.1. Congestion Control
[RFC8836] defines the congestion control requirements for interactive [RFC8836] defines the congestion control requirements for interactive
Real-Time media to be used in WebRTC. These requirements are based real-time media to be used in WebRTC. These requirements are based
on the assumption of the need to provide the data continuously, on the assumption that the data needs to be provided continuously
within a very limited time window (no more delay than hundreds of within a very limited time window (a delay of no more than hundreds
milliseconds end-to-end). If the latency target is higher, some of of milliseconds end-to-end). If the latency target is higher, some
the requirements present in RFC8836 could be relaxed to allow more of the requirements present in [RFC8836] could be relaxed to allow
flexible implementations. more flexible implementations.
4.7. Authentication and authorization 4.7. Authentication and Authorization
All WHIP endpoints, sessions and clients MUST support HTTP All WHIP endpoints, sessions, and clients MUST support HTTP
Authentication as per Section 11 of [RFC9110] and in order to ensure authentication as per Section 11 of [RFC9110]. Additionally, in
interoperability, bearer token authentication as defined in the next order to ensure interoperability, bearer token authentication as
section MUST be supported by all WHIP entities. However, this does defined in the next section MUST be supported by all WHIP entities.
not preclude the support of additional HTTP authentication schemes as However, this does not preclude the support of additional HTTP
defined in Section 11.6 of [RFC9110]. authentication schemes as defined in Section 11.6 of [RFC9110].
4.7.1. Bearer token authentication 4.7.1. Bearer Token Authentication
WHIP endpoints and sessions MAY require the HTTP request to be WHIP endpoints and sessions MAY require the HTTP request to be
authenticated using an HTTP Authorization header field with a Bearer authenticated using an HTTP Authorization header field with a bearer
token as specified in Section 2.1 of [RFC6750]. WHIP clients MUST token as specified in Section 2.1 of [RFC6750]. WHIP clients MUST
implement this authentication and authorization mechanism and send implement this authentication and authorization mechanism and send
the HTTP Authorization header field in all HTTP requests sent to the HTTP Authorization header field in all HTTP requests sent to
either the WHIP endpoint or session except the preflight OPTIONS either the WHIP endpoint or session (except the preflight OPTIONS
requests for CORS. requests for CORS).
The nature, syntax, and semantics of the bearer token, as well as how 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 to distribute it to the client, are outside the scope of this
document. Some examples of the kind of tokens that could be used document. Examples of tokens that could be used include, but are not
are, but are not limited to, JWT tokens as per [RFC6750] and limited to, JSON Web Tokens (JWTs) as per [RFC6750] and [RFC8725] and
[RFC8725] or a shared secret stored on a database. The tokens are a shared secret stored on a database. The tokens are typically made
typically made available to the end user alongside the WHIP endpoint available to the end user alongside the WHIP endpoint URL and
URL and configured on the WHIP clients (similar to the way RTMP URLs configured on the WHIP clients (similar to the way Real Time
and Stream Keys are distributed). Messaging Protocol (RTMP) URLs and Stream Keys are distributed).
WHIP endpoints and sessions could perform the authentication and WHIP endpoints and sessions could perform the authentication and
authorization by encoding an authentication token within the URLs for authorization by encoding an authentication token within the URLs for
the WHIP endpoints or sessions instead. In case the WHIP client is the WHIP endpoints or sessions instead. In case the WHIP client is
not configured to use a bearer token, the HTTP Authorization header not configured to use a bearer token, the HTTP Authorization header
field MUST NOT be sent in any request. field MUST NOT be sent in any request.
4.8. Simulcast and scalable video coding 4.8. Simulcast and Scalable Video Coding
Simulcast as per [RFC8853] MAY be supported by both the media servers Simulcast as per [RFC8853] MAY be supported by both the media servers
and WHIP clients through negotiation in the SDP offer/answer. and WHIP clients through negotiation in the SDP offer/answer.
If the client supports simulcast and wants to enable it for If the client supports simulcast and wants to enable it for
ingesting, it MUST negotiate the support in the SDP offer according ingesting, it MUST negotiate the support in the SDP offer according
to the procedures in Section 5.3 of [RFC8853]. A server accepting a to the procedures in Section 5.3 of [RFC8853]. A server accepting a
simulcast offer MUST create an answer according to the procedures in simulcast offer MUST create an answer according to the procedures in
Section 5.3.2 of [RFC8853]. Section 5.3.2 of [RFC8853].
It is possible for both media servers and WHIP clients to support It is possible for both media servers and WHIP clients to support
Scalable Video Coding (SVC). However, as there is no universal Scalable Video Coding (SVC). However, as there is no universal
negotiation mechanism in SDP for SVC, the encoder must consider the negotiation mechanism in SDP for SVC, the encoder must consider the
negotiated codec(s), intended usage, and SVC support in available negotiated codec(s), intended usage, and SVC support in available
decoders when configuring SVC. decoders when configuring SVC.
4.9. Protocol extensions 4.9. Protocol Extensions
In order to support future extensions to be defined for the WHIP In order to support future extensions to be defined for the WHIP
protocol, a common procedure for registering and announcing the new protocol, a common procedure for registering and announcing the new
extensions is defined. extensions is defined.
Protocol extensions supported by the WHIP sessions MUST be advertised Protocol extensions supported by the WHIP sessions MUST be advertised
to the WHIP client in the "201 Created" response to the initial HTTP to the WHIP client in the "201 Created" response to the initial HTTP
POST request sent to the WHIP endpoint. The WHIP endpoint MUST POST request sent to the WHIP endpoint. The WHIP endpoint MUST
return one "Link" header field for each extension that it supports, return one "Link" header field for each extension that it supports,
with the extension "rel" attribute value containing the extension URN with the extension "rel" attribute value containing the extension URN
and the URL for the HTTP resource that will be available for and the URL for the HTTP resource that will be available for
receiving requests related to that extension. receiving requests related to that extension.
Protocol extensions are optional for both WHIP clients and servers. Protocol extensions are optional for both WHIP clients and servers.
WHIP clients MUST ignore any Link attribute with an unknown "rel" WHIP clients MUST ignore any Link attribute with an unknown "rel"
attribute value and WHIP sessions MUST NOT require the usage of any attribute value, and WHIP sessions MUST NOT require the usage of any
extension. extension.
Each protocol extension MUST register a unique "rel" attribute value Each protocol extension MUST register a unique "rel" attribute value
at IANA starting with the prefix: "urn:ietf:params:whip:ext" as that starts with the prefix "urn:ietf:params:whip:ext" (as defined in
defined in Section 6.4. Section 6.4) in the "WebRTC-HTTP Ingestion Protocol (WHIP) Extension
URNs" registry (Section 6.3.2).
For example, considering a potential extension of server-to-client For example, consider a potential extension of server-to-client
communication using server-sent events as specified in communication using server-sent events as specified in Section 9.2 of
https://html.spec.whatwg.org/multipage/server-sent- [HTML]. The URL for connecting to the server-sent event resource for
events.html#server-sent-events, the URL for connecting to the server- the ingested stream could be returned in the initial HTTP "201
sent event resource for the ingested stream could be returned in the Created" response with a "Link" header field and a "rel" attribute of
initial HTTP "201 Created" response with a "Link" header field and a "urn:ietf:params:whip:ext:example:server-sent-events" (this document
"rel" attribute of "urn:ietf:params:whip:ext:example:server-sent- does not specify such an extension and uses it only as an example).
events" (this document does not specify such an extension, and uses
it only as an example).
In this theoretical case, the "201 Created" response to the HTTP POST In this theoretical case, the "201 Created" response to the HTTP POST
request would look like: request would look like:
HTTP/1.1 201 Created HTTP/1.1 201 Created
Content-Type: application/sdp Content-Type: application/sdp
Location: https://whip.example.com/session/id Location: https://whip.example.com/session/id
Link: <https://whip.example.com/session/id/sse>; Link: <https://whip.example.com/session/id/sse>;
rel="urn:ietf:params:whip:ext:example:server-sent-events" rel="urn:ietf:params:whip:ext:example:server-sent-events"
Figure 6: Example of a WHIP protocol extension Figure 6: Example of a WHIP Protocol Extension
Figure 6 shows an example of a WHIP protocol extension supported by Figure 6 shows an example of a WHIP protocol extension supported by
the WHIP session, as indicated in the Link header of the 201 Created the WHIP session, as indicated in the Link header of the "201
response. Created" response.
5. Security Considerations 5. Security Considerations
This document specifies a new protocol on top of HTTP and WebRTC, This document specifies a new protocol on top of HTTP and WebRTC;
thus, security protocols and considerations from related thus, security protocols and considerations from related
specifications apply to the WHIP specification. These include: specifications apply to the WHIP specification. These include:
* WebRTC security considerations: [RFC8826]. HTTPS SHALL be used in * WebRTC security considerations: See [RFC8826]. HTTPS SHALL be
order to preserve the WebRTC security model. used in order to preserve the WebRTC security model.
* Transport Layer Security (TLS): [RFC8446] and [RFC9147]. * Transport Layer Security (TLS): See [RFC8446] and [RFC9147].
* HTTP security: Section 11 of [RFC9112] and Section 17 of * HTTP security: See Section 11 of [RFC9112] and Section 17 of
[RFC9110]. [RFC9110].
* URI security: Section 7 of [RFC3986]. * URI security: See Section 7 of [RFC3986].
On top of that, the WHIP protocol exposes a thin new attack surface On top of that, the WHIP protocol exposes a thin new attack surface
specific of the REST API methods used within it: specific to the REST API methods used within it:
* HTTP POST flooding and resource exhaustion: It would be possible * HTTP POST flooding and resource exhaustion: It would be possible
for an attacker in possession of authentication credentials valid for an attacker in possession of authentication credentials valid
for ingesting a WHIP stream to make multiple HTTP POST to the WHIP for ingesting a WHIP stream to make multiple HTTP POST requests to
endpoint. This will force the WHIP endpoint to process the the WHIP endpoint. This will force the WHIP endpoint to process
incoming SDP and allocate resources for being able to set up the the incoming SDP and allocate resources for being able to set up
DTLS/ICE connection. While the malicious client does not need to the DTLS/ICE connection. While the malicious client does not need
initiate the DTLS/ICE connection at all, the WHIP session will to initiate the DTLS/ICE connection at all, the WHIP session will
have to wait for the DTLS/ICE connection timeout in order to have to wait for the DTLS/ICE connection timeout in order to
release the associated resources. If the connection rate is high release the associated resources. If the connection rate is high
enough, this could lead to resource exhaustion on the servers enough, this could lead to resource exhaustion on the servers
handling the requests and it will not be able to process handling the requests, and it will not be able to process
legitimate incoming ingests. In order to prevent this scenario, legitimate incoming ingests. In order to prevent this scenario,
WHIP endpoints SHOULD implement a rate limit and avalanche control WHIP endpoints SHOULD implement a rate limit and avalanche control
mechanism for incoming initial HTTP POST requests. mechanism for incoming initial HTTP POST requests.
* Insecure direct object references (IDOR) on the WHIP session * Insecure Direct Object References (IDORs) on the WHIP session
locations: If the URLs returned by the WHIP endpoint for the WHIP locations: If the URLs returned by the WHIP endpoint for the WHIP
sessions location are easy to guess, it would be possible for an sessions location are easy to guess, it would be possible for an
attacker to send multiple HTTP DELETE requests and terminate all attacker to send multiple HTTP DELETE requests and terminate all
the WHIP sessions currently running. In order to prevent this the WHIP sessions currently running. In order to prevent this
scenario, WHIP endpoints SHOULD generate URLs with enough scenario, WHIP endpoints SHOULD generate URLs with enough
randomness, using a cryptographically secure pseudorandom number randomness, using a cryptographically secure pseudorandom number
generator following the best practices in Randomness Requirements generator following the best practices in "Randomness Requirements
for Security [RFC4086], and implement a rate limit and avalanche for Security" [RFC4086], and implement a rate limit and avalanche
control mechanism for HTTP DELETE requests. The security control mechanism for HTTP DELETE requests. The security
considerations for Universally Unique IDentifier (UUID) [RFC9562], considerations for Universally Unique IDentifiers (UUIDs) in
Section 8 are applicable for generating the WHIP sessions location Section 8 of [RFC9562] are applicable for generating the WHIP
URL. sessions location URL.
* HTTP PATCH flooding: Similar to the HTTP POST flooding, a * HTTP PATCH flooding: Similar to the HTTP POST flooding, a
malicious client could also create a resource exhaustion by malicious client could also create resource exhaustion by sending
sending multiple HTTP PATCH request to the WHIP session, although multiple HTTP PATCH requests to the WHIP session, although the
the WHIP sessions can limit the impact by not allocating new ICE WHIP sessions can limit the impact by not allocating new ICE
candidates and reusing the existing ICE candidates when doing ICE candidates and reusing the existing ICE candidates when doing ICE
restarts. In order to prevent this scenario, WHIP endpoints restarts. In order to prevent this scenario, WHIP endpoints
SHOULD implement a rate limit and avalanche control mechanism for SHOULD implement a rate limit and avalanche control mechanism for
incoming HTTP PATCH requests. incoming HTTP PATCH requests.
6. IANA Considerations 6. IANA Considerations
This specification adds a new link relation type and a registry for This specification adds a new link relation type and a registry for
URN sub-namespaces for WHIP protocol extensions. URN sub-namespaces for WHIP protocol extensions.
6.1. Link Relation Type: ice-server 6.1. Link Relation Type: ice-server
The link relation type below has been registered by IANA per The link relation type below has been registered by IANA in the "Link
Section 4.2 of [RFC8288]. Relation Types" registry per Section 4.2 of [RFC8288]:
Relation Name: ice-server
Description: Conveys the STUN and TURN servers that can be used by an
ICE Agent to establish a connection with a peer.
Reference: TBD Relation Name: ice-server
6.2. WebRTC-HTTP Ingestion Protocol (WHIP) registry group Description: Conveys the STUN and TURN servers that can be used by
an ICE agent to establish a connection with a peer.
IANA is asked to create a new registry group called "WebRTC-HTTP Reference: RFC 9725
Ingestion Protocol (WHIP)". This group includes the "WebRTC-HTTP
ingestion protocol (WHIP) URNs" and "WebRTC-HTTP ingestion protocol
(WHIP) extension URNs" registries described below.
6.3. Registration of WHIP URN Sub-namespace and WHIP registries 6.2. WebRTC-HTTP Ingestion Protocol (WHIP) Registry Group
IANA is asked to add an entry to the "IETF URN Sub-namespace for IANA has created a new registry group called "WebRTC-HTTP Ingestion
Registered Protocol Parameter Identifiers" registry and create a sub- Protocol (WHIP)". This group includes the "WebRTC-HTTP Ingestion
namespace for the Registered Parameter Identifier as per [RFC3553]: Protocol (WHIP) URNs" and "WebRTC-HTTP Ingestion Protocol (WHIP)
"urn:ietf:params:whip". Extension URNs" registries described in Sections 6.3.1 and 6.3.2.
To manage this sub-namespace, IANA is asked to create the "WebRTC- 6.3. Registration of WHIP URN Sub-Namespace and WHIP Registries
HTTP ingestion protocol (WHIP) URNs" and "WebRTC-HTTP ingestion
protocol (WHIP) extension URNs".
6.3.1. WebRTC-HTTP ingestion protocol (WHIP) URNs registry IANA has added an entry in the "IETF URN Sub-namespace for Registered
Protocol Parameter Identifiers" registry [RFC3553] for
"urn:ietf:params:whip" as follows:
The "WebRTC-HTTP ingestion protocol (WHIP) URNs" registry is used to Registered Parameter Identifier: whip
manage entries within the "urn:ietf:params:whip" namespace. The
registry descriptions is as follows:
* Registry group: WebRTC-HTTP ingestion protocol (WHIP) Reference: RFC 9725
* Registry name: WebRTC-HTTP ingestion protocol (WHIP) URNs IANA Registry Reference: <https://www.iana.org/assignments/whip>
* Specification: this document (RFC TBD) To manage this sub-namespace, IANA has created the "WebRTC-HTTP
Ingestion Protocol (WHIP) URNs" and "WebRTC-HTTP Ingestion Protocol
(WHIP) Extension URNs" registries described below.
* Registration procedure: Specification Required 6.3.1. WebRTC-HTTP Ingestion Protocol (WHIP) URNs Registry
* Field names: URI, description, change controller, reference and The "WebRTC-HTTP Ingestion Protocol (WHIP) URNs" registry is used to
IANA registry reference manage entries within the "urn:ietf:params:whip" namespace. The
registration procedure is "Specification Required" [RFC8126]. The
registry contains the following fields: URI, Description, Reference,
IANA Registry Reference, and Change Controller. This document is
listed as the reference.
The registry contains a single initial value: The registry contains a single initial entry:
* URI: urn:ietf:params:whip:ext URI: urn:ietf:params:whip:ext
* Description: WebRTC-HTTP ingestion protocol (WHIP) extension URNs Description: WebRTC-HTTP ingestion protocol (WHIP) extension URNs
* Change Controller: IETF Reference: Section 6.3.2 of RFC 9725
* Reference: this document (RFC TBD) Section Section 6.3.2 IANA Registry Reference: See "WebRTC-HTTP Ingestion Protocol (WHIP)
Extension URNs" on <https://www.iana.org/assignments/whip>
* IANA registry reference: WebRTC-HTTP ingestion protocol (WHIP) Change Controller: IETF
extension URNs registry.
6.3.2. WebRTC-HTTP ingestion protocol (WHIP) extension URNs registry 6.3.2. WebRTC-HTTP Ingestion Protocol (WHIP) Extension URNs Registry
The "WebRTC-HTTP ingestion protocol (WHIP) Extension URNs" is used to The "WebRTC-HTTP Ingestion Protocol (WHIP) Extension URNs" is used to
manage entries within the "urn:ietf:params:whip:ext" namespace. The manage entries within the "urn:ietf:params:whip:ext" namespace. The
registry descriptions is as follows: registration procedure is "Specification Required" [RFC8126]. The
registry contains the following fields: URI, Description, Reference,
* Registry group: WebRTC-HTTP ingestion protocol (WHIP) IANA Registry Reference, and Change Controller. This document is
listed as the reference.
* Registry name: WebRTC-HTTP ingestion protocol (WHIP) Extension
URNs
* Specification: this document (RFC TBD)
* Registration procedure: Specification Required
* Field names: URI, description, change controller, reference and
IANA registry reference
6.4. URN Sub-namespace for WHIP 6.4. URN Sub-Namespace for WHIP
WHIP endpoint utilizes URNs to identify the supported WHIP protocol A WHIP endpoint utilizes URNs to identify the supported WHIP protocol
extensions on the "rel" attribute of the Link header as defined in extensions on the "rel" attribute of the Link header as defined in
Section 4.9. Section 4.9.
This section creates and registers an IETF URN Sub-namespace for use This section creates and registers an IETF URN sub-namespace for use
in the WHIP specifications and future extensions. in the WHIP specifications and future extensions.
6.4.1. Specification Template 6.4.1. Specification Template
Namespace ID: Namespace ID:
whip
* The Namespace ID "whip" has been assigned.
Registration Information: Registration Information:
Version: 1
* Version: 1 Date: TBD
* Date: TBD
Declared registrant of the namespace: Declared registrant of the namespace:
Registering organization: IETF
* Registering organization: The Internet Engineering Task Force. Designated contact: A designated expert (DE) will monitor the
public mailing list <wish@ietf.org>.
* Designated contact: A designated expert will monitor the WHIP
public mailing list, "wish@ietf.org".
Declaration of Syntactic Structure: Declaration of Syntactic Structure:
The Namespace Specific String (NSS) of all URNs that use the
* The Namespace Specific String (NSS) of all URNs that use the
"whip" Namespace ID shall have the following structure: "whip" Namespace ID shall have the following structure:
urn:ietf:params:whip:{type}:{name}:{other}. urn:ietf:params:whip:{type}:{name}:{other}.
* The keywords have the following meaning: The keywords have the following meanings:
- type: The entity type. This specification only defines the type: The entity type. This specification only defines the "ext"
"ext" type. type.
- name: A required ASCII string that conforms to the URN syntax name: A required ASCII string that conforms to the URN syntax
requirements (see [RFC8141]) and defines a major namespace of a requirements (see [RFC8141]) and defines a major namespace of a
WHIP protocol extension. The value MAY also be an industry WHIP protocol extension. The value MAY also be an industry
name or organization name. name or organization name.
- other: Any ASCII string that conforms to the URN syntax other: Any ASCII string that conforms to the URN syntax
requirements (see [RFC8141]) and defines the sub-namespace requirements (see [RFC8141]) and defines the sub-namespace
(which MAY be further broken down in namespaces delimited by (which MAY be further broken down in namespaces delimited by
colons) as needed to uniquely identify an WHIP protocol colons) as needed to uniquely identify a WHIP protocol
extension. extension.
Relevant Ancillary Documentation: Relevant Ancillary Documentation:
None
* None
Identifier Uniqueness Considerations: Identifier Uniqueness Considerations:
The designated contact shall be responsible for reviewing and
* The designated contact shall be responsible for reviewing and
enforcing uniqueness. enforcing uniqueness.
Identifier Persistence Considerations: Identifier Persistence Considerations:
* Once a name has been allocated, it MUST NOT be reallocated for
a different purpose.
* Once a name has been allocated, it MUST NOT be reallocated for a * The rules provided for assignments of values within a sub-
different purpose. namespace MUST be constructed so that the meanings of values
cannot change.
* 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 * This registration mechanism is not appropriate for naming
whose meanings may change over time. values whose meanings may change over time.
Process of Identifier Assignment: Process of Identifier Assignment:
The namespace with type "ext" (e.g., "urn:ietf:params:whip:ext")
* Namespace with type "ext" (e.g., "urn:ietf:params:whip:ext") is is reserved for IETF-approved WHIP specifications.
reserved for IETF-approved WHIP specifications.
Process of Identifier Resolution: Process of Identifier Resolution:
None specified
* None specified.
Rules for Lexical Equivalence: Rules for Lexical Equivalence:
No special considerations; the rules for lexical equivalence
* No special considerations; the rules for lexical equivalence
specified in [RFC8141] apply. specified in [RFC8141] apply.
Conformance with URN Syntax: Conformance with URN Syntax:
No special considerations
* No special considerations.
Validation Mechanism: Validation Mechanism:
None specified
* None specified.
Scope: Scope:
Global
* Global. 6.5. Registering WHIP Protocol Extension URNs
6.5. Registering WHIP Protocol Extensions URNs
This section defines the process for registering new WHIP protocol This section defines the process for registering new WHIP protocol
extensions URNs with IANA in the "WebRTC-HTTP ingestion protocol extension URNs with IANA in the "WebRTC-HTTP Ingestion Protocol
(WHIP) extension URNs" registry (see Section 6.4). (WHIP) Extension URNs" registry (see Section 6.3.2).
A WHIP Protocol Extension URNs is used as a value in the "rel" A WHIP Protocol Extension URN is used as a value in the "rel"
attribute of the Link header as defined in Section 4.9 for the attribute of the Link header as defined in Section 4.9 for the
purpose of signaling the WHIP protocol extensions supported by the purpose of signaling the WHIP protocol extensions supported by the
WHIP endpoints. WHIP endpoint.
WHIP Protocol Extensions URNs have an "ext" type as defined in WHIP Protocol Extension URNs have an "ext" type as defined in
Section 6.4. Section 6.4.
6.5.1. Registration Procedure 6.5.1. Registration Procedure
The IETF has created a mailing list, "wish@ietf.org", which can be The IETF has created a mailing list, <wish@ietf.org>, which can be
used for public discussion of WHIP protocol extensions proposals used for public discussion of proposals regarding WHIP protocol
prior to registration. Use of the mailing list is strongly extensions prior to registration. Use of the mailing list is
encouraged. The IESG has appointed a designated expert as per strongly encouraged. A designated expert (DE) [RFC8126], appointed
[RFC8126] who will monitor the wish@ietf.org mailing list and review by the IESG, will monitor the <wish@ietf.org> mailing list and review
registrations. registrations.
Registration of new "ext" type URNs (in the namespace Registration of new "ext" type URNs (in the namespace
"urn:ietf:params:whip:ext") belonging to a WHIP Protocol Extension "urn:ietf:params:whip:ext") belonging to a WHIP Protocol Extension
MUST be documented in a permanent and readily available public MUST be documented in a permanent and readily available public
specification, in sufficient detail so that interoperability between specification, in sufficient detail so that interoperability between
independent implementations is possible and reviewed by the independent implementations is possible, and reviewed by the DE as
designated expert as per Section 4.6 of [RFC8126]. An Standards per Section 4.6 of [RFC8126]. A Standards Track RFC is REQUIRED for
Track RFC is REQUIRED for the registration of new value data types the registration of new value data types that modify existing
that modify existing properties. An Standards Track RFC is also properties. A Standards Track RFC is also REQUIRED for registration
REQUIRED for registration of WHIP Protocol Extensions URNs that of WHIP Protocol Extension URNs that modify WHIP Protocol Extensions
modify WHIP Protocol Extensions previously documented in an existing previously documented in an existing RFC.
RFC.
The registration procedure begins when a completed registration The registration procedure begins when a completed registration
template, defined in the sections below, is sent to iana@iana.org. template, defined in Section 6.5.3, is sent to <iana@iana.org>.
Decisions made by the designated expert can be appealed to an Decisions made by the DE can be appealed to an Applications and Real-
Applications and Real Time (ART) Area Director, then to the IESG. Time (ART) Area Director, then to the IESG. The normal appeals
The normal appeals procedure described in [BCP9] is to be followed. procedure described in [BCP9] is to be followed.
Once the registration procedure concludes successfully, IANA creates Once the registration procedure concludes successfully, IANA creates
or modifies the corresponding record in the WHIP Protocol Extension or modifies the corresponding record in the "WebRTC-HTTP ingestion
registry. protocol (WHIP) Extension URNs" registry.
An RFC specifying one or more new WHIP Protocol Extension URNs MUST An RFC specifying one or more new WHIP Protocol Extension URNs MUST
include the completed registration templates, which MAY be expanded include the completed registration template(s), which MAY be expanded
with additional information. These completed templates are intended with additional information. These completed template(s) are
to go in the body of the document, not in the IANA Considerations intended to go in the body of the document, not in the IANA
section. The RFC MUST include the syntax and semantics of any Considerations section. The RFC MUST include the syntax and
extension-specific attributes that may be provided in a Link header semantics of any extension-specific attributes that may be provided
field advertising the extension. in a Link header field advertising the extension.
6.5.2. Guidance for Designated Experts 6.5.2. Guidance for the Designated Expert
The Designated Expert (DE) is expected to ascertain the existence of The DE is expected to do the following:
suitable documentation (a specification) as described in [RFC8126]
and to verify that the document is permanently and publicly
available.
The DE is also expected to check the clarity of purpose and use of * Ascertain the existence of suitable documentation (a
the requested registration. specification) as described in [RFC8126] and verify that the
document is permanently and publicly available. Specifications
should be documented in an Internet-Draft.
Additionally, the DE must verify that any request for one of these * Check the clarity of purpose and use of the requested
registrations has been made available for review and comment by registration.
posting the request to the WebRTC Ingest Signaling over HTTPS (wish)
Working Group mailing list.
Specifications should be documented in an Internet-Draft. Lastly, * Verify that any request for one of these registrations has been
the DE must ensure that any other request for a code point does not made available for review and comments by posting the request to
conflict with work that is active in or already published by the the <wish@ietf.org> mailing list.
IETF.
6.5.3. WHIP Protocol Extension Registration Template * Ensure that any other request for a code point does not conflict
with work that is active or already published by the IETF.
A WHIP Protocol Extension URNs is defined by completing the following 6.5.3. Registration Template
A WHIP Protocol Extension URN is defined by completing the following
template: template:
* URN: A unique URN for the WHIP Protocol Extension (e.g., URN: A unique URN for the WHIP Protocol Extension (e.g.,
"urn:ietf:params:whip:ext:example:server-sent-events"). "urn:ietf:params:whip:ext:example:server-sent-events")
* Reference: A formal reference to the publicly available Reference: A formal reference to the publicly available
specification specification
* Name: A descriptive name of the WHIP Protocol Extension (e.g., Name: A descriptive name of the WHIP Protocol Extension (e.g.,
"Sender Side events"). "Sender Side events")
* Description: A brief description of the function of the extension, Description: A brief description of the function of the extension
in a short paragraph or two (short paragraph or two)
* Contact information: Contact information for the organization or Contact information: Contact information for the organization or
person making the registration person making the registration
7. Acknowledgements 7. References
The authors wish to thank Lorenzo Miniero, Juliusz Chroboczek, Adam
Roach, Nils Ohlmeier, Christer Holmberg, Cameron Elliott, Gustavo
Garcia, Jonas Birme, Sandro Gauci, Christer Holmberg and everyone
else in the WebRTC community that have provided comments, feedback,
text and improvement proposals on the document and contributed early
implementations of the spec.
8. References
8.1. Normative References 7.1. Normative References
[FETCH] WHATWG, "Fetch - Living Standard", n.d., [FETCH] WHATWG, "Fetch", WHATWG Living Standard,
<https://fetch.spec.whatwg.org>. <https://fetch.spec.whatwg.org>. Commit snapshot:
<https://fetch.spec.whatwg.org/commit-snapshots/
edfa8d100cf1ecfde385f65c172e0e8d018fcd98/>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, with Session Description Protocol (SDP)", RFC 3264,
DOI 10.17487/RFC3264, June 2002, DOI 10.17487/RFC3264, June 2002,
<https://www.rfc-editor.org/rfc/rfc3264>. <https://www.rfc-editor.org/info/rfc3264>.
[RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An [RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An
IETF URN Sub-namespace for Registered Protocol IETF URN Sub-namespace for Registered Protocol
Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June
2003, <https://www.rfc-editor.org/rfc/rfc3553>. 2003, <https://www.rfc-editor.org/info/rfc3553>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005, RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/rfc/rfc3986>. <https://www.rfc-editor.org/info/rfc3986>.
[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086, "Randomness Requirements for Security", BCP 106, RFC 4086,
DOI 10.17487/RFC4086, June 2005, DOI 10.17487/RFC4086, June 2005,
<https://www.rfc-editor.org/rfc/rfc4086>. <https://www.rfc-editor.org/info/rfc4086>.
[RFC5789] Dusseault, L. and J. Snell, "PATCH Method for HTTP", [RFC5789] Dusseault, L. and J. Snell, "PATCH Method for HTTP",
RFC 5789, DOI 10.17487/RFC5789, March 2010, RFC 5789, DOI 10.17487/RFC5789, March 2010,
<https://www.rfc-editor.org/rfc/rfc5789>. <https://www.rfc-editor.org/info/rfc5789>.
[RFC6585] Nottingham, M. and R. Fielding, "Additional HTTP Status [RFC6585] Nottingham, M. and R. Fielding, "Additional HTTP Status
Codes", RFC 6585, DOI 10.17487/RFC6585, April 2012, Codes", RFC 6585, DOI 10.17487/RFC6585, April 2012,
<https://www.rfc-editor.org/rfc/rfc6585>. <https://www.rfc-editor.org/info/rfc6585>.
[RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization [RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
Framework: Bearer Token Usage", RFC 6750, Framework: Bearer Token Usage", RFC 6750,
DOI 10.17487/RFC6750, October 2012, DOI 10.17487/RFC6750, October 2012,
<https://www.rfc-editor.org/rfc/rfc6750>. <https://www.rfc-editor.org/info/rfc6750>.
[RFC7064] Nandakumar, S., Salgueiro, G., Jones, P., and M. Petit- [RFC7064] Nandakumar, S., Salgueiro, G., Jones, P., and M. Petit-
Huguenin, "URI Scheme for the Session Traversal Utilities Huguenin, "URI Scheme for the Session Traversal Utilities
for NAT (STUN) Protocol", RFC 7064, DOI 10.17487/RFC7064, for NAT (STUN) Protocol", RFC 7064, DOI 10.17487/RFC7064,
November 2013, <https://www.rfc-editor.org/rfc/rfc7064>. November 2013, <https://www.rfc-editor.org/info/rfc7064>.
[RFC7065] Petit-Huguenin, M., Nandakumar, S., Salgueiro, G., and P. [RFC7065] Petit-Huguenin, M., Nandakumar, S., Salgueiro, G., and P.
Jones, "Traversal Using Relays around NAT (TURN) Uniform Jones, "Traversal Using Relays around NAT (TURN) Uniform
Resource Identifiers", RFC 7065, DOI 10.17487/RFC7065, Resource Identifiers", RFC 7065, DOI 10.17487/RFC7065,
November 2013, <https://www.rfc-editor.org/rfc/rfc7065>. November 2013, <https://www.rfc-editor.org/info/rfc7065>.
[RFC7675] Perumal, M., Wing, D., Ravindranath, R., Reddy, T., and M. [RFC7675] Perumal, M., Wing, D., Ravindranath, R., Reddy, T., and M.
Thomson, "Session Traversal Utilities for NAT (STUN) Usage Thomson, "Session Traversal Utilities for NAT (STUN) Usage
for Consent Freshness", RFC 7675, DOI 10.17487/RFC7675, for Consent Freshness", RFC 7675, DOI 10.17487/RFC7675,
October 2015, <https://www.rfc-editor.org/rfc/rfc7675>. October 2015, <https://www.rfc-editor.org/info/rfc7675>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8288] Nottingham, M., "Web Linking", RFC 8288, [RFC8288] Nottingham, M., "Web Linking", RFC 8288,
DOI 10.17487/RFC8288, October 2017, DOI 10.17487/RFC8288, October 2017,
<https://www.rfc-editor.org/rfc/rfc8288>. <https://www.rfc-editor.org/info/rfc8288>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/rfc/rfc8446>. <https://www.rfc-editor.org/info/rfc8446>.
[RFC8489] Petit-Huguenin, M., Salgueiro, G., Rosenberg, J., Wing, [RFC8489] Petit-Huguenin, M., Salgueiro, G., Rosenberg, J., Wing,
D., Mahy, R., and P. Matthews, "Session Traversal D., Mahy, R., and P. Matthews, "Session Traversal
Utilities for NAT (STUN)", RFC 8489, DOI 10.17487/RFC8489, Utilities for NAT (STUN)", RFC 8489, DOI 10.17487/RFC8489,
February 2020, <https://www.rfc-editor.org/rfc/rfc8489>. February 2020, <https://www.rfc-editor.org/info/rfc8489>.
[RFC8725] Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best [RFC8725] Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best
Current Practices", BCP 225, RFC 8725, Current Practices", BCP 225, RFC 8725,
DOI 10.17487/RFC8725, February 2020, DOI 10.17487/RFC8725, February 2020,
<https://www.rfc-editor.org/rfc/rfc8725>. <https://www.rfc-editor.org/info/rfc8725>.
[RFC8826] Rescorla, E., "Security Considerations for WebRTC", [RFC8826] Rescorla, E., "Security Considerations for WebRTC",
RFC 8826, DOI 10.17487/RFC8826, January 2021, RFC 8826, DOI 10.17487/RFC8826, January 2021,
<https://www.rfc-editor.org/rfc/rfc8826>. <https://www.rfc-editor.org/info/rfc8826>.
[RFC8830] Alvestrand, H., "WebRTC MediaStream Identification in the [RFC8830] Alvestrand, H., "WebRTC MediaStream Identification in the
Session Description Protocol", RFC 8830, Session Description Protocol", RFC 8830,
DOI 10.17487/RFC8830, January 2021, DOI 10.17487/RFC8830, January 2021,
<https://www.rfc-editor.org/rfc/rfc8830>. <https://www.rfc-editor.org/info/rfc8830>.
[RFC8838] Ivov, E., Uberti, J., and P. Saint-Andre, "Trickle ICE: [RFC8838] Ivov, E., Uberti, J., and P. Saint-Andre, "Trickle ICE:
Incremental Provisioning of Candidates for the Interactive Incremental Provisioning of Candidates for the Interactive
Connectivity Establishment (ICE) Protocol", RFC 8838, Connectivity Establishment (ICE) Protocol", RFC 8838,
DOI 10.17487/RFC8838, January 2021, DOI 10.17487/RFC8838, January 2021,
<https://www.rfc-editor.org/rfc/rfc8838>. <https://www.rfc-editor.org/info/rfc8838>.
[RFC8839] Petit-Huguenin, M., Nandakumar, S., Holmberg, C., Keränen, [RFC8839] Petit-Huguenin, M., Nandakumar, S., Holmberg, C., Keränen,
A., and R. Shpount, "Session Description Protocol (SDP) A., and R. Shpount, "Session Description Protocol (SDP)
Offer/Answer Procedures for Interactive Connectivity Offer/Answer Procedures for Interactive Connectivity
Establishment (ICE)", RFC 8839, DOI 10.17487/RFC8839, Establishment (ICE)", RFC 8839, DOI 10.17487/RFC8839,
January 2021, <https://www.rfc-editor.org/rfc/rfc8839>. January 2021, <https://www.rfc-editor.org/info/rfc8839>.
[RFC8840] Ivov, E., Stach, T., Marocco, E., and C. Holmberg, "A [RFC8840] Ivov, E., Stach, T., Marocco, E., and C. Holmberg, "A
Session Initiation Protocol (SIP) Usage for Incremental Session Initiation Protocol (SIP) Usage for Incremental
Provisioning of Candidates for the Interactive Provisioning of Candidates for the Interactive
Connectivity Establishment (Trickle ICE)", RFC 8840, Connectivity Establishment (Trickle ICE)", RFC 8840,
DOI 10.17487/RFC8840, January 2021, DOI 10.17487/RFC8840, January 2021,
<https://www.rfc-editor.org/rfc/rfc8840>. <https://www.rfc-editor.org/info/rfc8840>.
[RFC8842] Holmberg, C. and R. Shpount, "Session Description Protocol [RFC8842] Holmberg, C. and R. Shpount, "Session Description Protocol
(SDP) Offer/Answer Considerations for Datagram Transport (SDP) Offer/Answer Considerations for Datagram Transport
Layer Security (DTLS) and Transport Layer Security (TLS)", Layer Security (DTLS) and Transport Layer Security (TLS)",
RFC 8842, DOI 10.17487/RFC8842, January 2021, RFC 8842, DOI 10.17487/RFC8842, January 2021,
<https://www.rfc-editor.org/rfc/rfc8842>. <https://www.rfc-editor.org/info/rfc8842>.
[RFC8845] Duckworth, M., Ed., Pepperell, A., and S. Wenger, [RFC8845] Duckworth, M., Ed., Pepperell, A., and S. Wenger,
"Framework for Telepresence Multi-Streams", RFC 8845, "Framework for Telepresence Multi-Streams", RFC 8845,
DOI 10.17487/RFC8845, January 2021, DOI 10.17487/RFC8845, January 2021,
<https://www.rfc-editor.org/rfc/rfc8845>. <https://www.rfc-editor.org/info/rfc8845>.
[RFC8853] Burman, B., Westerlund, M., Nandakumar, S., and M. Zanaty, [RFC8853] Burman, B., Westerlund, M., Nandakumar, S., and M. Zanaty,
"Using Simulcast in Session Description Protocol (SDP) and "Using Simulcast in Session Description Protocol (SDP) and
RTP Sessions", RFC 8853, DOI 10.17487/RFC8853, January RTP Sessions", RFC 8853, DOI 10.17487/RFC8853, January
2021, <https://www.rfc-editor.org/rfc/rfc8853>. 2021, <https://www.rfc-editor.org/info/rfc8853>.
[RFC8858] Holmberg, C., "Indicating Exclusive Support of RTP and RTP [RFC8858] Holmberg, C., "Indicating Exclusive Support of RTP and RTP
Control Protocol (RTCP) Multiplexing Using the Session Control Protocol (RTCP) Multiplexing Using the Session
Description Protocol (SDP)", RFC 8858, Description Protocol (SDP)", RFC 8858,
DOI 10.17487/RFC8858, January 2021, DOI 10.17487/RFC8858, January 2021,
<https://www.rfc-editor.org/rfc/rfc8858>. <https://www.rfc-editor.org/info/rfc8858>.
[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, [RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110, Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022, DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/rfc/rfc9110>. <https://www.rfc-editor.org/info/rfc9110>.
[RFC9112] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, [RFC9112] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP/1.1", STD 99, RFC 9112, DOI 10.17487/RFC9112, Ed., "HTTP/1.1", STD 99, RFC 9112, DOI 10.17487/RFC9112,
June 2022, <https://www.rfc-editor.org/rfc/rfc9112>. June 2022, <https://www.rfc-editor.org/info/rfc9112>.
[RFC9143] Holmberg, C., Alvestrand, H., and C. Jennings, [RFC9143] Holmberg, C., Alvestrand, H., and C. Jennings,
"Negotiating Media Multiplexing Using the Session "Negotiating Media Multiplexing Using the Session
Description Protocol (SDP)", RFC 9143, Description Protocol (SDP)", RFC 9143,
DOI 10.17487/RFC9143, February 2022, DOI 10.17487/RFC9143, February 2022,
<https://www.rfc-editor.org/rfc/rfc9143>. <https://www.rfc-editor.org/info/rfc9143>.
[RFC9147] Rescorla, E., Tschofenig, H., and N. Modadugu, "The [RFC9147] Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version Datagram Transport Layer Security (DTLS) Protocol Version
1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022, 1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022,
<https://www.rfc-editor.org/rfc/rfc9147>. <https://www.rfc-editor.org/info/rfc9147>.
[RFC9429] Uberti, J., Jennings, C., and E. Rescorla, Ed., [RFC9429] Uberti, J., Jennings, C., and E. Rescorla, Ed.,
"JavaScript Session Establishment Protocol (JSEP)", "JavaScript Session Establishment Protocol (JSEP)",
RFC 9429, DOI 10.17487/RFC9429, April 2024, RFC 9429, DOI 10.17487/RFC9429, April 2024,
<https://www.rfc-editor.org/rfc/rfc9429>. <https://www.rfc-editor.org/info/rfc9429>.
[RFC9562] Davis, K., Peabody, B., and P. Leach, "Universally Unique [RFC9562] Davis, K., Peabody, B., and P. Leach, "Universally Unique
IDentifiers (UUIDs)", RFC 9562, DOI 10.17487/RFC9562, May IDentifiers (UUIDs)", RFC 9562, DOI 10.17487/RFC9562, May
2024, <https://www.rfc-editor.org/rfc/rfc9562>. 2024, <https://www.rfc-editor.org/info/rfc9562>.
[W3C.REC-ldp-20150226] [W3C.REC-ldp-20150226]
Malhotra, A., Ed., Arwe, J., Ed., and S. Speicher, Ed., Arwe, J., Ed., Speicher, S., Ed., and A. Malhotra, Ed.,
"Linked Data Platform 1.0", W3C REC REC-ldp-20150226, W3C "Linked Data Platform 1.0", W3C Recommendation, 26
REC-ldp-20150226, 26 February 2015, February 2015,
<https://www.w3.org/TR/2015/REC-ldp-20150226/>. <https://www.w3.org/TR/2015/REC-ldp-20150226/>. Latest
version available at: <https://www.w3.org/TR/ldp/>.
8.2. Informative References 7.2. Informative References
[BCP56] Best Current Practice 56, [BCP56] Best Current Practice 56,
<https://www.rfc-editor.org/info/bcp56>. <https://www.rfc-editor.org/info/bcp56>.
At the time of writing, this BCP comprises the following: At the time of writing, this BCP comprises the following:
Nottingham, M., "Building Protocols with HTTP", BCP 56, Nottingham, M., "Building Protocols with HTTP", BCP 56,
RFC 9205, DOI 10.17487/RFC9205, June 2022, RFC 9205, DOI 10.17487/RFC9205, June 2022,
<https://www.rfc-editor.org/info/rfc9205>. <https://www.rfc-editor.org/info/rfc9205>.
[BCP9] Best Current Practice 9, [BCP9] Best Current Practice 9,
skipping to change at page 33, line 42 skipping to change at line 1459
Halpern, J., Ed. and E. Rescorla, Ed., "IETF Stream Halpern, J., Ed. and E. Rescorla, Ed., "IETF Stream
Documents Require IETF Rough Consensus", BCP 9, RFC 8789, Documents Require IETF Rough Consensus", BCP 9, RFC 8789,
DOI 10.17487/RFC8789, June 2020, DOI 10.17487/RFC8789, June 2020,
<https://www.rfc-editor.org/info/rfc8789>. <https://www.rfc-editor.org/info/rfc8789>.
Rosen, B., "Responsibility Change for the RFC Series", Rosen, B., "Responsibility Change for the RFC Series",
BCP 9, RFC 9282, DOI 10.17487/RFC9282, June 2022, BCP 9, RFC 9282, DOI 10.17487/RFC9282, June 2022,
<https://www.rfc-editor.org/info/rfc9282>. <https://www.rfc-editor.org/info/rfc9282>.
[HTML] WHATWG, "HTML", WHATWG Living Standard,
<https://html.spec.whatwg.org/>. Commit snapshot:
<https://html.spec.whatwg.org/commit-
snapshots/09db56ba9343c597340b2c7715f43ff9b10826f6/>.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261, Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002, DOI 10.17487/RFC3261, June 2002,
<https://www.rfc-editor.org/rfc/rfc3261>. <https://www.rfc-editor.org/info/rfc3261>.
[RFC6120] Saint-Andre, P., "Extensible Messaging and Presence [RFC6120] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Core", RFC 6120, DOI 10.17487/RFC6120, Protocol (XMPP): Core", RFC 6120, DOI 10.17487/RFC6120,
March 2011, <https://www.rfc-editor.org/rfc/rfc6120>. March 2011, <https://www.rfc-editor.org/info/rfc6120>.
[RFC7826] Schulzrinne, H., Rao, A., Lanphier, R., Westerlund, M., [RFC7826] Schulzrinne, H., Rao, A., Lanphier, R., Westerlund, M.,
and M. Stiemerling, Ed., "Real-Time Streaming Protocol and M. Stiemerling, Ed., "Real-Time Streaming Protocol
Version 2.0", RFC 7826, DOI 10.17487/RFC7826, December Version 2.0", RFC 7826, DOI 10.17487/RFC7826, December
2016, <https://www.rfc-editor.org/rfc/rfc7826>. 2016, <https://www.rfc-editor.org/info/rfc7826>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/rfc/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
[RFC8141] Saint-Andre, P. and J. Klensin, "Uniform Resource Names [RFC8141] Saint-Andre, P. and J. Klensin, "Uniform Resource Names
(URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017, (URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017,
<https://www.rfc-editor.org/rfc/rfc8141>. <https://www.rfc-editor.org/info/rfc8141>.
[RFC8836] Jesup, R. and Z. Sarker, Ed., "Congestion Control [RFC8836] Jesup, R. and Z. Sarker, Ed., "Congestion Control
Requirements for Interactive Real-Time Media", RFC 8836, Requirements for Interactive Real-Time Media", RFC 8836,
DOI 10.17487/RFC8836, January 2021, DOI 10.17487/RFC8836, January 2021,
<https://www.rfc-editor.org/rfc/rfc8836>. <https://www.rfc-editor.org/info/rfc8836>.
[RFC9457] Nottingham, M., Wilde, E., and S. Dalal, "Problem Details [RFC9457] Nottingham, M., Wilde, E., and S. Dalal, "Problem Details
for HTTP APIs", RFC 9457, DOI 10.17487/RFC9457, July 2023, for HTTP APIs", RFC 9457, DOI 10.17487/RFC9457, July 2023,
<https://www.rfc-editor.org/rfc/rfc9457>. <https://www.rfc-editor.org/info/rfc9457>.
[W3C.REC-webrtc-20210126] [W3C.REC-webrtc-20210126]
Jennings, C., Ed., Boström, H., Ed., and J. Bruaroey, Ed., Jennings, C., Ed., Boström, H., Ed., and J. Bruaroey, Ed.,
"WebRTC 1.0: Real-Time Communication Between Browsers", "WebRTC 1.0: Real-Time Communication Between Browsers",
W3C REC REC-webrtc-20210126, W3C REC-webrtc-20210126, 26 W3C Recommendation, 26 January 2021,
January 2021, <https://www.w3.org/TR/2021/REC-webrtc-20210126/>. Latest
<https://www.w3.org/TR/2021/REC-webrtc-20210126/>. version available at: <https://www.w3.org/TR/webrtc/>.
Acknowledgements
The authors wish to thank Lorenzo Miniero, Juliusz Chroboczek, Adam
Roach, Nils Ohlmeier, Christer Holmberg, Cameron Elliott, Gustavo
Garcia, Jonas Birme, Sandro Gauci, Christer Holmberg, and everyone
else in the WebRTC community that have provided comments, feedback,
text, and improvement proposals on the document and contributed early
implementations of the spec.
Authors' Addresses Authors' Addresses
Sergio Garcia Murillo Sergio Garcia Murillo
Millicast Millicast
Email: sergio.garcia.murillo@cosmosoftware.io Email: sergio.garcia.murillo@cosmosoftware.io
Alexandre Gouaillard Alexandre Gouaillard
CoSMo Software CoSMo Software
Email: alex.gouaillard@cosmosoftware.io Email: alex.gouaillard@cosmosoftware.io
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