wdiff rfc9725.original rfc9725.txt

wish

Internet Engineering Task Force (IETF) S. Murillo
Internet-Draft
Request for Comments: 9725 Millicast
Updates: 8842, 8840 (if approved) 8840, 8842 A. Gouaillard
Intended status:
Category: Standards Track CoSMo Software
Expires: 22 February
ISSN: 2070-1721 January 2025 21 August 2024

WebRTC-HTTP ingestion protocol Ingestion Protocol (WHIP)
draft-ietf-wish-whip-16

Abstract

This document describes a simple HTTP-based protocol that will allow
WebRTC-based ingestion of content into streaming services and/or
CDNs.
Content Delivery Networks (CDNs).

This document updates RFC 8842 RFCs 8840 and RFC 8840. 8842.

Status of This Memo

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list It represents the consensus of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of six months RFC 7841.

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material or to cite them other than as "work in progress."

This Internet-Draft will expire on 22 February 2025.
https://www.rfc-editor.org/info/rfc9725.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 6
4.1. HTTP usage . . . . . . . . . . . . . . . . . . . . . . . 6 Usage
4.2. Ingest session set up . . . . . . . . . . . . . . . . . . 7 Session Setup
4.3. ICE support . . . . . . . . . . . . . . . . . . . . . . . 10 Support
4.3.1. HTTP PATCH request usage . . . . . . . . . . . . . . 10 Request Usage
4.3.2. Trickle ICE . . . . . . . . . . . . . . . . . . . . . 11
4.3.3. ICE Restarts . . . . . . . . . . . . . . . . . . . . 13
4.4. WebRTC constraints . . . . . . . . . . . . . . . . . . . 15 Constraints
4.4.1. SDP Bundle . . . . . . . . . . . . . . . . . . . . . 16
4.4.2. Single MediaStream . . . . . . . . . . . . . . . . . 16
4.4.3. No partially successful answers . . . . . . . . . . . 16 Partially Successful Answers
4.4.4. DTLS setup role Setup Role and SDP "setup" attribute . . . . . . 16 Attribute
4.4.5. Trickle ICE and ICE restarts . . . . . . . . . . . . 17 Restarts
4.5. Load balancing Balancing and redirections . . . . . . . . . . . . . 17 Redirections
4.6. STUN/TURN server configuration . . . . . . . . . . . . . 17 Server Configuration
4.6.1. Congestion control . . . . . . . . . . . . . . . . . 19 Control
4.7. Authentication and authorization . . . . . . . . . . . . 19 Authorization
4.7.1. Bearer token authentication . . . . . . . . . . . . . 20 Token Authentication
4.8. Simulcast and scalable video coding . . . . . . . . . . . 20 Scalable Video Coding
4.9. Protocol extensions . . . . . . . . . . . . . . . . . . . 20 Extensions
5. Security Considerations . . . . . . . . . . . . . . . . . . . 21
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
6.1. Link Relation Type: ice-server . . . . . . . . . . . . . 23
6.2. WebRTC-HTTP Ingestion Protocol (WHIP) registry group . . 23 Registry Group
6.3. Registration of WHIP URN Sub-namespace Sub-Namespace and WHIP
registries . . . . . . . . . . . . . . . . . . . . . . . 23 Registries
6.3.1. WebRTC-HTTP ingestion protocol Ingestion Protocol (WHIP) URNs
registry . . . . . . . . . . . . . . . . . . . . . . 24 Registry
6.3.2. WebRTC-HTTP ingestion protocol Ingestion Protocol (WHIP) extension Extension URNs
registry . . . . . . . . . . . . . . . . . . . . . . 24
Registry
6.4. URN Sub-namespace Sub-Namespace for WHIP . . . . . . . . . . . . . . . 25
6.4.1. Specification Template . . . . . . . . . . . . . . . 25
6.5. Registering WHIP Protocol Extensions Extension URNs . . . . . . . . 27
6.5.1. Registration Procedure . . . . . . . . . . . . . . . 27
6.5.2. Guidance for the Designated Experts . . . . . . . . . . . 28 Expert
6.5.3. WHIP Protocol Extension Registration Template . . . . 28
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.1.
7.1. Normative References . . . . . . . . . . . . . . . . . . 29
8.2.
7.2. Informative References . . . . . . . . . . . . . . . . . 32
Acknowledgements
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34

1. Introduction

The IETF RTCWEB working group Working Group standardized JSEP ([RFC9429]), the JavaScript Session
Establishment Protocol (JSEP) [RFC9429], a mechanism used to control
the setup, management, and teardown of a multimedia session. It also
describes how to negotiate media flows using the Offer/Answer Model offer/answer model
with the Session Description Protocol (SDP) [RFC3264] [RFC3264], including the
formats for data sent over the wire (e.g., media types, codec
parameters, and encryption). WebRTC intentionally does not specify a
signaling transport protocol at the application level.

Unfortunately, the lack of a standardized signaling mechanism in
WebRTC has been an obstacle to its adoption as an ingestion protocol
within the broadcast/streaming broadcast and streaming industry, where a streamlined
production pipeline is taken for granted: plug in cables carrying raw
media to hardware encoders, then push the encoded media to any
streaming service or Content Delivery Network (CDN) ingest using an
ingestion protocol.

While WebRTC can be integrated with standard signaling protocols like
SIP [RFC3261] or XMPP Extensible Messaging and Presence Protocol (XMPP)
[RFC6120], they are not designed to be used in
broadcasting/streaming broadcasting and
streaming services, and there is also no sign of adoption in that
industry. RTSP The Real-Time Streaming Protocol (RTSP) [RFC7826], which
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
WebRTC as a media ingestion method which: that:

* Is is easy to implement,

* Is is as easy to use as popular IP-based broadcast protocols protocols,

* Is is fully compliant with WebRTC and RTCWEB specs specs,

* Enables enables ingestion on both classical media platforms and WebRTC
end-to-end platforms, achieving platforms (achieving the lowest possible latency. latency),

* Lowers lowers the requirements on both hardware encoders and broadcasting
services to support WebRTC. WebRTC, and

* Is is usable both in both web browsers and in standalone encoders.

2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.

3. Overview

The WebRTC-HTTP Ingest Ingestion Protocol (WHIP) is designed to facilitate a
one-time exchange of Session Description Protocol (SDP) offers and
answers using HTTP POST requests. This exchange is a fundamental
step in establishing an Interactive Connectivity Establishment (ICE)
and Datagram Transport Layer Security (DTLS) session between the WHIP
client, which represents the encoder or media producer, and the media
server, which is the broadcasting ingestion endpoint.

Upon successful establishment of the ICE/DTLS session, unidirectional
media data transmission commences from the WHIP client to the media
server. It is important to note that SDP renegotiations are not
supported in WHIP, meaning WHIP. This means that no modifications to the "m="
sections can be made after the initial SDP offer/answer exchange via
HTTP POST is completed and that only ICE related ICE-related information can be
updated via HTTP PATCH requests as defined in Section 4.3.

The following diagram illustrates the core operation of the WHIP
protocol for initiating and terminating an ingest session:

+-------------+ +---------------+ +--------------+ +---------------+
| WHIP client | | WHIP endpoint | | Media Server server | | WHIP session |
+--+----------+ +---------+-----+ +------+-------+ +--------|------+
| | | |
| | | |
|HTTP POST (SDP Offer) offer) | | |
+------------------------>+ | |
|201 Created (SDP answer) | | |
+<------------------------+ | |
| ICE REQUEST | |
+--------------------------------------->+ |
| ICE RESPONSE | |
|<---------------------------------------+ |
| DTLS SETUP | |
|<======================================>| |
| RTP/RTCP FLOW | |
+<-------------------------------------->+ |
| HTTP DELETE |
+---------------------------------------------------------->+
| 200 OK |
<-----------------------------------------------------------x

Figure 1: WHIP session setup Session Setup and teardown Teardown

The elements in Figure 1 are described as follows:

WHIP client: This represents the WebRTC media encoder or producer,
which functions as a client of the WHIP protocol by encoding and
delivering media to a remote media server.

WHIP endpoint: This denotes the ingest server that receives the
initial WHIP request.

WHIP endpoint URL: Refers This refers to the URL of the WHIP endpoint
responsible for creating the WHIP session.

Media server: This is the WebRTC media server or consumer
responsible for establishing the media session with the WHIP
client and receiving the media content it produces.

WHIP session: This indicates the server handling the allocated HTTP
resource by the WHIP endpoint for an ongoing ingest session.

WHIP session URL: Refers This refers to the URL of the WHIP resource
allocated by the WHIP endpoint for a specific media session. The
WHIP client can send requests to the WHIP session using this URL
to modify the session, such as ICE operations or termination.

The

Figure 1 illustrates the communication flow between a WHIP client,
WHIP endpoint, media server, and WHIP session. This flow outlines
the process of setting up and tearing down an ingestion session using
the WHIP protocol, involving which involves negotiation, ICE for Network
Address Translation (NAT) traversal, DTLS and the Secure Real-
time Real-time
Transport Protocol (SRTP) for security, and RTP/RTCP for media
transport:

* WHIP client: Initiates the communication by sending an HTTP POST
with an SDP Offer offer to the WHIP endpoint.

* WHIP endpoint: Responds with a "201 Created" message containing an
SDP answer.

* WHIP client and media server: Establish an ICE and DTLS sessions for
NAT traversal and secure communication.

* RTP/RTCP Flow: Real-time Transport Protocol flow: RTP and Real-time
Transport Control Protocol RTCP flows are established for media
transmission from the WHIP client to the media server, secured by
the SRTP profile.

* WHIP client: Sends an HTTP DELETE to terminate the WHIP session.

* WHIP session: Responds with a "200 OK" to confirm the session
termination.

4. Protocol Operation

4.1. HTTP usage Usage

Following [BCP56] guidelines, the guidelines in [BCP56], WHIP clients MUST NOT match
error codes returned by the WHIP endpoints and resources to a
specific error cause indicated in this specification. WHIP clients
MUST be able to handle all applicable status codes by gracefully
falling back to the generic n00 semantics of a given status code on
unknown error codes. WHIP endpoints and resources could convey
finer-grained error information by a problem statement json object in
the response message body of the failed request as per [RFC9457].

The WHIP endpoints and sessions are origin servers as defined in
Section 3.6. 3.6 of [RFC9110] handling [RFC9110]; they handle the requests and providing provide
responses for the underlying HTTP resources. Those HTTP resources do
not have any representation defined in this specification, so the
WHIP endpoints and sessions MUST return a 2XX sucessfull 2xx successful response
with no content when a GET request is received.

4.2. Ingest session set up Session Setup

In order to set up an ingestion session, the WHIP client MUST
generate an SDP offer according to the JSEP rules for an initial
offer as in 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
endpoint URL.

The HTTP POST request MUST have a content type of "application/sdp"
and contain the SDP offer as the body. The WHIP endpoint MUST
generate an SDP answer according to the JSEP rules for an initial
answer as in per Section 5.3.1 of [RFC9429] and return the following: a
"201 Created" response with a content type of "application/sdp", the
SDP answer as the body, and a Location header field pointing to the
newly created WHIP session. If the HTTP POST to the WHIP endpoint
has a content type different than "application/sdp" or the SDP is
malformed, the WHIP endpoint MUST reject the HTTP POST request with
an appropiate
4XX appropriate 4xx error response.

As the WHIP protocol only supports the ingestion use case with
unidirectional media, the WHIP client SHOULD use the "sendonly"
attribute in the SDP offer but MAY use the "sendrecv" attribute instead,
instead; the "inactive" and "recvonly" attributes MUST NOT be used.
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 client to a
WHIP endpoint and the "201 Created" response from the WHIP endpoint
containing the Location header pointing to the newly created WHIP session:
session.

POST /whip/endpoint HTTP/1.1
Host: whip.example.com
Content-Type: application/sdp
Content-Length: 1101

v=0
o=- 5228595038118931041 2 IN IP4 127.0.0.1
s=-
t=0 0
a=group:BUNDLE 0 1
a=extmap-allow-mixed
a=ice-options:trickle ice2
m=audio 9 UDP/TLS/RTP/SAVPF 111
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:EsAw
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=setup:actpass
a=mid:0
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=sendonly
a=msid:d46fb922-d52a-4e9c-aa87-444eadc1521b ce326ecf-a081-453a-8f9f-0605d5ef4128
a=rtcp-mux
a=rtcp-mux-only
a=rtpmap:111 opus/48000/2
a=fmtp:111 minptime=10;useinbandfec=1
m=video 0 UDP/TLS/RTP/SAVPF 96 97
a=mid:1
a=bundle-only
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=extmap:10 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id
a=extmap:11 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id
a=sendonly
a=msid:d46fb922-d52a-4e9c-aa87-444eadc1521b 3956b460-40f4-4d05-acef-03abcdd8c6fd
a=rtpmap:96 VP8/90000
a=rtcp-fb:96 ccm fir
a=rtcp-fb:96 nack
a=rtcp-fb:96 nack pli
a=rtpmap:97 rtx/90000
a=fmtp:97 apt=96

HTTP/1.1 201 Created
ETag: "xyzzy"
Content-Type: application/sdp
Content-Length: 1053
Location: https://whip.example.com/session/id

v=0
o=- 1657793490019 1 IN IP4 127.0.0.1
s=-
t=0 0
a=group:BUNDLE 0 1
a=extmap-allow-mixed
a=ice-lite
a=ice-options:trickle ice2
m=audio 9 UDP/TLS/RTP/SAVPF 111
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:38sdf4fdsf54
a=ice-pwd:2e13dde17c1cb009202f627fab90cbec358d766d049c9697
a=fingerprint:sha-256 F7:EB:F3:3E:AC:D2:EA:A7:C1:EC:79:D9:B3:8A:35:DA:70:86:4F:46:D9:2D:CC:D0:BC:81:9F:67:EF:34:2E:BD
a=candidate:1 1 UDP 2130706431 198.51.100.1 39132 typ host
a=setup:passive
a=mid:0
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=recvonly
a=rtcp-mux
a=rtcp-mux-only
a=rtpmap:111 opus/48000/2
a=fmtp:111 minptime=10;useinbandfec=1
m=video 0 UDP/TLS/RTP/SAVPF 96 97
c=IN IP4 0.0.0.0
a=mid:1
a=bundle-only
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=extmap:10 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id
a=extmap:11 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id
a=recvonly
a=rtpmap:96 VP8/90000
a=rtcp-fb:96 ccm fir
a=rtcp-fb:96 nack
a=rtcp-fb:96 nack pli
a=rtpmap:97 rtx/90000
a=fmtp:97 apt=96

Figure 2: Example of the SDP offer/answer exchange done Offer/Answer Exchange Done via an
HTTP POST

Once a session is set up, consent freshness as per [RFC7675] SHALL be
used to detect non-graceful disconnection by full ICE implementations
and DTLS teardown for session termination by either side.

To explicitly terminate a WHIP session, the WHIP client MUST perform
an HTTP DELETE request to the WHIP session URL returned in the
Location header field of the initial HTTP POST. Upon receiving the
HTTP DELETE request, the WHIP session will be removed and the
resources freed on the media server, terminating the ICE and DTLS
sessions.

A media server terminating a session MUST follow the procedures in
Section 5.2 of [RFC7675] for immediate revocation of consent.

The WHIP endpoints MUST support OPTIONS requests for Cross-Origin
Resource Sharing (CORS) as defined in [FETCH]. The "200 OK" response
to any OPTIONS request SHOULD include an "Accept-Post" header with a
media type value of "application/sdp" as per [W3C.REC-ldp-20150226].

4.3. ICE support Support

ICE [RFC8845] is a protocol addressing that addresses the complexities of NAT
traversal,
traversal commonly encountered in Internet communication. NATs
hinder direct communication between devices on different local
networks, posing challenges for real-time applications. ICE
facilitates seamless connectivity by employing techniques to discover
and negotiate efficient communication paths.

Trickle ICE [RFC8838] optimizes the connectivity process by
incrementally sharing potential communication paths, reducing
latency, and facilitating quicker establishment.

ICE Restarts restarts are crucial for maintaining connectivity in dynamic
network conditions or disruptions, allowing devices to re-establish
communication paths without complete renegotiation. This ensures
minimal latency and reliable real-time communication.

Trickle ICE and ICE restart support are RECOMMENDED for both WHIP
sessions and clients.

4.3.1. HTTP PATCH request usage Request Usage

The WHIP client MAY perform trickle Trickle ICE or ICE restarts by sending an
HTTP PATCH request as per [RFC5789] to the WHIP session URL, with a
body containing an SDP fragment with media type "application/trickle-
ice-sdpfrag" as specified in [RFC8840] carrying the relevant ICE
information. If the HTTP PATCH to the WHIP session has a content
type different than "application/trickle-ice-sdpfrag" or the SDP
fragment is malformed, the WHIP session MUST reject the HTTP PATCH
with an appropiate 4XX appropriate 4xx error response.

If the WHIP session supports either Trickle ICE or ICE restarts, but
not both, it MUST return a "422 Unprocessable Content" error response
for the HTTP PATCH requests that are not supported as per
Section 15.5.21 of [RFC9110].

The WHIP client MAY send overlapping HTTP PATCH requests to one WHIP
session. Consequently, as those HTTP PATCH requests may be received
out-of-order out
of order by the WHIP session, session. Thus, if the WHIP session supports ICE
restarts, it MUST generate a unique strong entity-tag identifying the
ICE session as per Section 8.8.3 of [RFC9110], being OPTIONAL
otherwise. The initial value of the entity-tag identifying 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
endpoint.

WHIP clients SHOULD NOT use entity-tag validation when matching a
specific ICE session is not required, such as for example example, when initiating a
DELETE request to terminate a session. WHIP sessions MUST ignore any
entity-tag value sent by the WHIP client when ICE session matching is
not required, as in the HTTP DELETE request.

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]
and Section 3 of [RFC6585], with a "428 Precondition Required"
response for a missing entity tag, entity-tag and a "412 Precondition Failed"
response for a non-matching entity tag. entity-tag.

4.3.2. Trickle ICE

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
complete with the full list of ICE candidates, or it MAY only contain
local candidates (or even an empty list of candidates) as per
[RFC8845]. For the purpose of reducing setup times, when using
Trickle ICE ICE, the WHIP client SHOULD send the SDP offer as soon as
possible, containing (containing
either locally gathered ICE candidates or an empty list of candidates.
candidates) as soon as possible.

In order to simplify the protocol, the WHIP session cannot signal
additional ICE candidates to the WHIP client after the SDP answer has
been sent. The WHIP endpoint SHALL gather all the ICE candidates for
the media server before responding to the client request request, and the SDP
answer SHALL contain the full list of ICE candidates of the media
server.

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
candidates, it MUST wait and buffer any gathered candidates until the
"201 Created" HTTP response to the initial POST request is received.
In order to lower reduce the HTTP traffic and processing time required required, the
WHIP client SHOULD send a single aggregated HTTP PATCH request with
all the buffered ICE candidates once the response is received.
Additionally, if ICE restarts are supported by the WHIP session, the
WHIP client needs to know the entity-tag associated with the ICE
session in order to send a PATCH request containing new ICE
candidates, so
candidates; thus, it MUST also wait and buffer any gathered
candidates until it receives the HTTP response with the new entity-tag entity-
tag value to the last PATCH request performing an ICE restart.

WHIP clients generating the HTTP PATCH body with the SDP fragment and
its subsequent processing by WHIP sessions MUST follow to the guidelines
defined in Section 4.4 of [RFC8840] with the following
considerations:

* As per [RFC9429], only m-sections "m=" sections not marked as bundle-only can
gather ICE candidates, so given that the "max-bundle" policy is
being used, the SDP fragment will contain only the offerer-tagged
m-line
"m=" line of the bundle group.

* The WHIP client MAY exclude ICE candidates from the HTTP PATCH
body if they have already been confirmed by the WHIP session with
a successful HTTP response to a previous HTTP PATCH request.

WHIP sessions and clients that support Trickle ICE MUST make use of
entity-tags and conditional requests as explained in Section 4.3.1.

When a WHIP session receives a PATCH request that adds new ICE
candidates without performing an ICE restart, it MUST return a "204
No Content" response without a body and MUST NOT include an ETag
header in the response. If the WHIP session does not support a
candidate transport or is not able to resolve the connection address,
it MUST silently discard the candidate and continue processing the
rest of the request normally.

PATCH /session/id HTTP/1.1
Host: whip.example.com
If-Match: "xyzzy"
Content-Type: application/trickle-ice-sdpfrag
Content-Length: 576

a=group:BUNDLE 0 1
m=audio 9 UDP/TLS/RTP/SAVPF 111
a=mid:0
a=ice-ufrag:EsAw
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: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:2154773085 1 tcp 1518214911 198.51.100.2 9 typ host tcptype active generation 0 ufrag EsAw network-id 2
a=end-of-candidates

HTTP/1.1 204 No Content

Figure 3: Example of a Trickle ICE request Request and response Response

Figure 3 shows an example of the Trickle ICE procedure where the WHIP
client sends a PATCH request with updated ICE candidate information
and receives a successful response from the WHIP session.

4.3.3. ICE Restarts

As defined in [RFC8839], when an ICE restart occurs, a new SDP offer/
answer exchange is triggered. However, as WHIP does not support
renegotiation of non-ICE related non-ICE-related SDP information, a WHIP client will
not send a new offer when an ICE restart occurs. Instead, the WHIP
client and WHIP session will only exchange the relevant ICE
information via an HTTP PATCH request as defined in Section 4.3.1 and
MUST assume that the previously negotiated non-ICE related non-ICE-related SDP
information still apply applies after the ICE restart.

When performing an ICE restart, the WHIP client MUST include the
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
as defined in [RFC8840]. Similar to what is defined in
Section 4.3.2, as per [RFC9429] [RFC9429], only m-sections "m=" sections not marked as
bundle-only can gather ICE candidates, so given that the "max-bundle"
policy is being used, the SDP fragment will contain only the offerer-tagged m-line offerer-
tagged "m=" line of the bundle group. A WHIP client sending a PATCH
request for performing ICE restart MUST contain an "If-Match" header
field with a field-
value field-value of "*" as per Section 13.1.1 of [RFC9110].

[RFC8840] states that an agent MUST discard any received requests
containing "ice-pwd" and "ice-ufrag" attributes that do not match
those of the current ICE Negotiation Session, however, Session. However, any WHIP
session receiving an updated "ice-pwd" and "ice-ufrag" attributes MUST
consider the request as performing an ICE restart instead and, if
supported, SHALL return a "200 OK" with an "application/trickle-
ice-sdpfrag" "application/trickle-ice-
sdpfrag" body containing the new ICE username fragment and password
and a new set of ICE candidates for the WHIP session. Also, the "200
OK" response for a successful ICE restart MUST contain the new
entity-tag corresponding to the new ICE session in an ETag response
header field and MAY contain a new set of ICE candidates for the
media server.

As defined in Section 4.4.1.1.1 of [RFC8839] [RFC8839], the set of candidates
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. So Therefore, after performing a successful ICE restart,
both the WHIP client and the WHIP session MUST replace the previous
set of remote candidates with the new set exchanged in the HTTP PATCH
request and response, discarding any remote ICE candidate not present
on the new set. Both the WHIP client and the WHIP session MUST
ensure that the HTTP PATCH requests request and response bodies include the
same 'ice-options,' 'ice-pacing,' "ice-options," "ice-pacing," and 'ice-lite' "ice-lite" attributes as those
used in the SDP offer or answer.

If the ICE restart request cannot be satisfied by the WHIP session,
the resource MUST return an appropriate HTTP error code and MUST NOT
terminate the session immediately and keep the existing ICE session.
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 MUST be terminated if the ICE consent expires as a
consequence of the failed ICE restart as per Section 5.1 of
[RFC7675].

In case of unstable network conditions, the ICE restart HTTP PATCH
requests and responses might be received out of order. In order to
mitigate this scenario, when the client performs an ICE restart, it
MUST discard any previous ICE username and passwords password fragments and
ignore any further HTTP PATCH response received from a pending HTTP
PATCH request. WHIP clients MUST apply only the ICE information
received in the response to the last sent request. If there is a
mismatch between the ICE information at the WHIP client and at the
WHIP session (because of an out-of-order request), the STUN Session
Traversal Utilities for NAT (STUN) requests will contain invalid ICE
information and will be dropped by the receiving side. If this
situation is detected by the WHIP client, it MUST send a new ICE
restart request to the server.

PATCH /session/id HTTP/1.1
Host: whip.example.com
If-Match: "*"
Content-Type: application/trickle-ice-sdpfrag
Content-Length: 82

a=ice-options:trickle ice2
a=group:BUNDLE 0 1
m=audio 9 UDP/TLS/RTP/SAVPF 111
a=mid:0
a=ice-ufrag:ysXw
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: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: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
ETag: "abccd"
Content-Type: application/trickle-ice-sdpfrag
Content-Length: 252

a=ice-lite
a=ice-options:trickle ice2
a=group:BUNDLE 0 1
m=audio 9 UDP/TLS/RTP/SAVPF 111
a=mid:0
a=ice-ufrag:289b31b754eaa438
a=ice-pwd:0b66f472495ef0ccac7bda653ab6be49ea13114472a5d10a
a=candidate:1 1 udp 2130706431 198.51.100.1 39132 typ host
a=end-of-candidates

Figure 4: Example of an ICE restart request Restart Request and response Response

Figure 3 4 demonstrates a Trickle ICE restart procedure example. The
WHIP client sends a PATCH request containing updated ICE information,
including a new ufrag and password, along with newly gathered ICE
candidates. In response, the WHIP session provides ICE information
for the session after the ICE restart, including the updated ufrag
and password, as well as the previous ICE candidate.

4.4. WebRTC constraints Constraints

To simplify the implementation of WHIP in both clients and media
servers, WHIP introduces specific restrictions on WebRTC usage. The
following subsections will explain these restrictions in detail: detail.

4.4.1. SDP Bundle

Both the WHIP client and the WHIP endpoint SHALL support [RFC9143]
and use the "max-bundle" policy as defined in [RFC9429]. The WHIP
client and the media server MUST support multiplexed media associated
with the BUNDLE group as per Section 9 of [RFC9143]. In addition,
per
[RFC9143] [RFC9143], the WHIP client and media server SHALL use RTP/RTCP
multiplexing for all bundled media. In order to reduce the network
resources required at the media server, both The the WHIP client and WHIP
endpoints MUST include the "rtcp-mux-only" attribute in each bundled
"m=" sections section as per Section 3 of [RFC8858].

4.4.2. Single MediaStream

WHIP only supports a single MediaStream as defined in [RFC8830] and
therefore [RFC8830];
therefore, all "m=" sections MUST contain a "msid" attribute with the
same value. The MediaStream MUST contain at least one
MediaStreamTrack of any media kind kind, and it MUST NOT have two or more
than
MediaStreamTracks for the same media (audio or video). However, it
would be possible for future revisions of this spec specification to allow
more than a single MediaStream or MediaStreamTrack of each media kind, so
kind. Therefore, in order to ensure forward compatibility, if the
number of audio and
or and/or video MediaStreamTracks or the number of
MediaStreams are not supported by the WHIP endpoint, it MUST reject
the HTTP POST request with an a "422 Unprocessable Content" or "400 Bad
Request" error response. The WHIP endpoint MAY also return a problem
statement as recommended in Section 4.1 proving further error details
about the failed request.

4.4.3. No partially successful answers Partially Successful Answers

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
"m=" section, but reject the HTTP POST request with an a "422
Unprocessable Content" or "400 Bad Request" error response to prevent
having partially successful ingest sessions sessions, which can be misleading
to end users. The WHIP endpoint MAY also return a problem statement
as recommended in Section 4.1 proving further error details about the
failed request.

4.4.4. DTLS setup role Setup Role and SDP "setup" attribute Attribute

When a WHIP client sends an SDP offer, it SHOULD insert an SDP
"setup" attribute with an "actpass" attribute value, as defined in
[RFC8842]. However, if the WHIP client only implements the DTLS
client role, it MAY use an SDP "setup" attribute with an "active"
attribute value. If the WHIP endpoint does not support an SDP offer
with an SDP "setup" attribute with an "active" attribute value, it
SHOULD reject the request with an a "422 Unprocessable Content" or "400
Bad Request" error response.

NOTE: [RFC8842] defines that the offerer must insert an SDP "setup"
attribute with an "actpass" attribute value. However, the WHIP
client will always communicate with a media server that is expected
to support the DTLS server role, in which case the client might
choose to only implement support for the DTLS client role.

4.4.5. Trickle ICE and ICE restarts Restarts

The media server SHOULD support full ICE, unless it is connected to
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
only ICE lite. The WHIP client MUST implement and use full ICE.

Trickle ICE and ICE restarts restart support is OPTIONAL for both the WHIP
clients and media servers as explained in Section 4.3.

4.5. Load balancing Balancing and redirections Redirections

WHIP endpoints and media servers might not be colocated on the same
server, so it is possible to load balance incoming requests to
different media servers.

WHIP clients SHALL support HTTP redirections as per Section 15.4 of
[RFC9110]. In order to avoid POST requests to be being redirected as GET
requests, status codes 301 and 302 MUST NOT be used and used; the preferred
method for performing load balancing is via the "307 Temporary
Redirect" response status code as described in Section 15.4.8 of
[RFC9110]. Redirections are not required to be supported for the
PATCH and DELETE requests.

In case of high load, the WHIP endpoints MAY return a "503 Service
Unavailable" response indicating that the server is currently unable
to handle the request due to a temporary overload or scheduled
maintenance as described in Section 15.6.4 of [RFC9110], which will
likely be alleviated after some delay. The WHIP endpoint might send
a Retry-After header field indicating the minimum time that the user
agent ought to wait before making a follow-up request as described in
Section 10.2.3 of [RFC9110].

4.6. STUN/TURN server configuration Server Configuration

The WHIP endpoint MAY return STUN/TURN server configuration URLs and
credentials usable by the client in the "201 Created" response to the
HTTP POST request to the WHIP endpoint URL.

A reference to each STUN/TURN server will be returned using the
"Link" header field [RFC8288] with a "rel" attribute value of "ice-
server". The Link target URI is the server URI as defined in
[RFC7064] and [RFC7065]. The credentials are encoded in the Link
target attributes as follows:

* username: If the Link header field represents a TURN server, Traversal Using
Relays around NAT (TURN) server and
credential-type is "password", the "credential-type"
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
"password" value, the credential this attribute represents a long-term
authentication password, as described in Section 9.2 of [RFC8489].

* credential-type: If the Link header field represents a TURN
server, then this attribute specifies how the credential "credential"
attribute value should be used when that TURN server requests
authorization. The default value if the attribute is not present
is "password".

Link: <stun:stun.example.net>; rel="ice-server"
Link: <turn:turn.example.net?transport=udp>; rel="ice-server";
username="user"; credential="myPassword"; credential-type="password"
Link: <turn:turn.example.net?transport=tcp>; rel="ice-server";
username="user"; credential="myPassword"; credential-type="password"
Link: <turns:turn.example.net?transport=tcp>; rel="ice-server";
username="user"; credential="myPassword"; credential-type="password"

Figure 5: Example of a STUN/TURN servers configuration Server's Configuration

Figure 5 illustrates the Link headers included in a 201 Created "201 Created"
response, providing the ICE server URLs and associated credentials.

NOTE: The naming of both the "rel" attribute value of "ice-server"
and the target attributes follows the one that used on in the W3C WebRTC
recommendation [W3C.REC-webrtc-20210126] RTCConfiguration
dictionary in section 4.2.1. Section 4.2.1 of the W3C WebRTC recommendation (see
[W3C.REC-webrtc-20210126]). The "rel" attribute value of "ice-server" "ice-
server" is not prepended with the "urn:ietf:params:whip:" so it can
be reused by other specifications specifications, which may use this mechanism to
configure the usage of STUN/TURN servers.

NOTE: Depending on the ICE Agent agent implementation, the WHIP client may
need to call the setConfiguration method before calling the
setLocalDescription method with the local SDP offer in order to avoid
having to perform an ICE restart for applying the updated STUN/TURN
server configuration on the next ICE gathering phase.

There are some WebRTC implementations that do not support updating
the STUN/TURN server configuration after the local offer has been
created as specified in Section 4.1.18 of [RFC9429]. In order to
support these clients, the WHIP endpoint MAY also include the STUN/
TURN server configuration on the responses to OPTIONS request requests sent
to the WHIP endpoint URL before the POST request is sent. However,
this method is NOT RECOMMENDED to be used by the WHIP clients and, clients, and if
it is supported by the underlying WHIP client's webrtc WebRTC
implementation, the WHIP client SHOULD wait for the information to be
returned by the WHIP endpoint on the response of the HTTP POST
request instead.

The generation of the TURN server credentials may require performing
a request to an external provider, which can both add latency to the
OPTIONS request processing and increase the processing required to
handle that request. In order to prevent this, the WHIP endpoint
SHOULD NOT return the STUN/TURN server configuration if the OPTIONS
request is a preflight request for CORS as defined in [FETCH], that
is, if The the OPTIONS request does not contain an Access-Control-
Request-Method with a "POST" value and the Access-Control-Request-
Headers HTTP header does not contain the "Link" value.

The WHIP clients MAY also support configuring the STUN/TURN server
URIs with long term long-term credentials provided by either the broadcasting
service or an external TURN provider, overriding the values provided
by the WHIP endpoint.

4.6.1. Congestion control Control

[RFC8836] defines the congestion control requirements for interactive
Real-Time
real-time media to be used in WebRTC. These requirements are based
on the assumption of the need to provide that the data continuously, needs to be provided continuously
within a very limited time window (no more (a delay of no more than hundreds
of milliseconds end-to-end). If the latency target is higher, some
of the requirements present in RFC8836 [RFC8836] could be relaxed to allow
more flexible implementations.

4.7. Authentication and authorization Authorization

All WHIP endpoints, sessions sessions, and clients MUST support HTTP
Authentication
authentication as per Section 11 of [RFC9110] and [RFC9110]. Additionally, in
order to ensure interoperability, bearer token authentication as
defined in the next section MUST be supported by all WHIP entities.
However, this does not preclude the support of additional HTTP
authentication schemes as defined in Section 11.6 of [RFC9110].

4.7.1. Bearer token authentication Token Authentication

WHIP endpoints and sessions MAY require the HTTP request to be
authenticated using an HTTP Authorization header field with a Bearer bearer
token as specified in Section 2.1 of [RFC6750]. WHIP clients MUST
implement this authentication and authorization mechanism and send
the HTTP Authorization header field in all HTTP requests sent to
either the WHIP endpoint or session except (except the preflight OPTIONS
requests for CORS. CORS).

The nature, syntax, and semantics of the bearer token, as well as how
to distribute it to the client, is are outside the scope of this
document. Some examples of the kind Examples of tokens that could be used
are, include, but are not
limited to, JWT tokens JSON Web Tokens (JWTs) as per [RFC6750] and [RFC8725] or and
a shared secret stored on a database. The tokens are typically made
available to the end user alongside the WHIP endpoint URL and
configured on the WHIP clients (similar to the way RTMP Real Time
Messaging Protocol (RTMP) URLs and Stream Keys are distributed).

WHIP endpoints and sessions could perform the authentication and
authorization by encoding an authentication token within the URLs for
the WHIP endpoints or sessions instead. In case the WHIP client is
not configured to use a bearer token, the HTTP Authorization header
field MUST NOT be sent in any request.

4.8. Simulcast and scalable video coding Scalable Video Coding

Simulcast as per [RFC8853] MAY be supported by both the media servers
and WHIP clients through negotiation in the SDP offer/answer.

If the client supports simulcast and wants to enable it for
ingesting, it MUST negotiate the support in the SDP offer according
to the procedures in Section 5.3 of [RFC8853]. A server accepting a
simulcast offer MUST create an answer according to the procedures in
Section 5.3.2 of [RFC8853].

It is possible for both media servers and WHIP clients to support
Scalable Video Coding (SVC). However, as there is no universal
negotiation mechanism in SDP for SVC, the encoder must consider the
negotiated codec(s), intended usage, and SVC support in available
decoders when configuring SVC.

4.9. Protocol extensions Extensions

In order to support future extensions to be defined for the WHIP
protocol, a common procedure for registering and announcing the new
extensions is defined.

Protocol extensions supported by the WHIP sessions MUST be advertised
to the WHIP client in the "201 Created" response to the initial HTTP
POST request sent to the WHIP endpoint. The WHIP endpoint MUST
return one "Link" header field for each extension that it supports,
with the extension "rel" attribute value containing the extension URN
and the URL for the HTTP resource that will be available for
receiving requests related to that extension.

Protocol extensions are optional for both WHIP clients and servers.
WHIP clients MUST ignore any Link attribute with an unknown "rel"
attribute value value, and WHIP sessions MUST NOT require the usage of any
extension.

Each protocol extension MUST register a unique "rel" attribute value
at IANA starting
that starts with the prefix: prefix "urn:ietf:params:whip:ext" as (as defined in
Section 6.4. 6.4) in the "WebRTC-HTTP Ingestion Protocol (WHIP) Extension
URNs" registry (Section 6.3.2).

For example, considering consider a potential extension of server-to-client
communication using server-sent events as specified in
https://html.spec.whatwg.org/multipage/server-sent-
events.html#server-sent-events, the Section 9.2 of
[HTML]. The URL for connecting to the server-
sent server-sent event resource for
the ingested stream could be returned in the initial HTTP "201
Created" response with a "Link" header field and a "rel" attribute of "urn:ietf:params:whip:ext:example:server-sent-
events"
"urn:ietf:params:whip:ext:example:server-sent-events" (this document
does not specify such an extension, extension and uses it only as an example).

In this theoretical case, the "201 Created" response to the HTTP POST
request would look like:

HTTP/1.1 201 Created
Content-Type: application/sdp
Location: https://whip.example.com/session/id
Link: <https://whip.example.com/session/id/sse>;
rel="urn:ietf:params:whip:ext:example:server-sent-events"

Figure 6: Example of a WHIP protocol extension Protocol Extension

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 "201
Created" response.

5. Security Considerations

This document specifies a new protocol on top of HTTP and WebRTC, WebRTC;
thus, security protocols and considerations from related
specifications apply to the WHIP specification. These include:

* WebRTC security considerations: See [RFC8826]. HTTPS SHALL be
used in order to preserve the WebRTC security model.

* Transport Layer Security (TLS): See [RFC8446] and [RFC9147].

* HTTP security: See Section 11 of [RFC9112] and Section 17 of
[RFC9110].

* URI security: See Section 7 of [RFC3986].

On top of that, the WHIP protocol exposes a thin new attack surface
specific of to the REST API methods used within it:

* HTTP POST flooding and resource exhaustion: It would be possible
for an attacker in possession of authentication credentials valid
for ingesting a WHIP stream to make multiple HTTP POST requests to
the WHIP endpoint. This will force the WHIP endpoint to process
the incoming SDP and allocate resources for being able to set up
the DTLS/ICE connection. While the malicious client does not need
to initiate the DTLS/ICE connection at all, the WHIP session will
have to wait for the DTLS/ICE connection timeout in order to
release the associated resources. If the connection rate is high
enough, this could lead to resource exhaustion on the servers
handling the requests requests, and it will not be able to process
legitimate incoming ingests. In order to prevent this scenario,
WHIP endpoints SHOULD implement a rate limit and avalanche control
mechanism for incoming initial HTTP POST requests.

* Insecure direct object references (IDOR) Direct Object References (IDORs) on the WHIP session
locations: If the URLs returned by the WHIP endpoint for the WHIP
sessions location are easy to guess, it would be possible for an
attacker to send multiple HTTP DELETE requests and terminate all
the WHIP sessions currently running. In order to prevent this
scenario, WHIP endpoints SHOULD generate URLs with enough
randomness, using a cryptographically secure pseudorandom number
generator following the best practices in Randomness "Randomness Requirements
for Security Security" [RFC4086], and implement a rate limit and avalanche
control mechanism for HTTP DELETE requests. The security
considerations for Universally Unique IDentifier (UUID) [RFC9562], IDentifiers (UUIDs) in
Section 8 of [RFC9562] are applicable for generating the WHIP
sessions location URL.

* HTTP PATCH flooding: Similar to the HTTP POST flooding, a
malicious client could also create a resource exhaustion by sending
multiple HTTP PATCH request requests to the WHIP session, although the
WHIP sessions can limit the impact by not allocating new ICE
candidates and reusing the existing ICE candidates when doing ICE
restarts. In order to prevent this scenario, WHIP endpoints
SHOULD implement a rate limit and avalanche control mechanism for
incoming HTTP PATCH requests.

6. IANA Considerations

This specification adds a new link relation type and a registry for
URN sub-namespaces for WHIP protocol extensions.

6.1. Link Relation Type: ice-server

The link relation type below has been registered by IANA in the "Link
Relation Types" registry per Section 4.2 of [RFC8288]. [RFC8288]:

Relation Name: ice-server

Description: Conveys the STUN and TURN servers that can be used by
an ICE Agent agent to establish a connection with a peer.

Reference: TBD RFC 9725

6.2. WebRTC-HTTP Ingestion Protocol (WHIP) registry group Registry Group

IANA is asked to create has created a new registry group called "WebRTC-HTTP Ingestion
Protocol (WHIP)". This group includes the "WebRTC-HTTP
ingestion protocol Ingestion
Protocol (WHIP) URNs" and "WebRTC-HTTP ingestion protocol Ingestion Protocol (WHIP) extension
Extension URNs" registries described below. in Sections 6.3.1 and 6.3.2.

6.3. Registration of WHIP URN Sub-namespace Sub-Namespace and WHIP registries Registries

IANA is asked to add has added an entry to in the "IETF URN Sub-namespace for Registered
Protocol Parameter Identifiers" registry and create a sub-
namespace [RFC3553] for the
"urn:ietf:params:whip" as follows:

Registered Parameter Identifier as per [RFC3553]:
"urn:ietf:params:whip". Identifier: whip

Reference: RFC 9725

IANA Registry Reference: <https://www.iana.org/assignments/whip>

To manage this sub-namespace, IANA is asked to create has created the "WebRTC-
HTTP ingestion protocol "WebRTC-HTTP
Ingestion Protocol (WHIP) URNs" and "WebRTC-HTTP ingestion
protocol Ingestion Protocol
(WHIP) extension URNs". Extension URNs" registries described below.

6.3.1. WebRTC-HTTP ingestion protocol Ingestion Protocol (WHIP) URNs registry Registry

The "WebRTC-HTTP ingestion protocol Ingestion Protocol (WHIP) URNs" registry is used to
manage entries within the "urn:ietf:params:whip" namespace. The
registry descriptions
registration procedure is as follows:

* Registry group: WebRTC-HTTP ingestion protocol (WHIP)

* Registry name: WebRTC-HTTP ingestion protocol (WHIP) URNs

* Specification: this document (RFC TBD)

* Registration procedure: Specification Required

* Field names: "Specification Required" [RFC8126]. The
registry contains the following fields: URI, description, change controller, reference and Description, Reference,
IANA registry reference Registry Reference, and Change Controller. This document is
listed as the reference.

The registry contains a single initial value:

* entry:

URI: urn:ietf:params:whip:ext

Description: WebRTC-HTTP ingestion protocol (WHIP) extension URNs

* Change Controller: IETF

Reference: this document (RFC TBD) Section Section 6.3.2

* of RFC 9725

IANA registry reference: WebRTC-HTTP ingestion protocol Registry Reference: See "WebRTC-HTTP Ingestion Protocol (WHIP)
extension URNs registry.
Extension URNs" on <https://www.iana.org/assignments/whip>

Change Controller: IETF

6.3.2. WebRTC-HTTP ingestion protocol Ingestion Protocol (WHIP) extension Extension URNs registry Registry

The "WebRTC-HTTP ingestion protocol Ingestion Protocol (WHIP) Extension URNs" is used to
manage entries within the "urn:ietf:params:whip:ext" namespace. The
registry descriptions
registration procedure is as follows:

* Registry group: WebRTC-HTTP ingestion protocol (WHIP)

* Registry name: WebRTC-HTTP ingestion protocol (WHIP) Extension
URNs

* Specification: this document (RFC TBD)

* Registration procedure: Specification Required

6.4. URN Sub-namespace Sub-Namespace for WHIP

A WHIP endpoint utilizes URNs to identify the supported WHIP protocol
extensions on the "rel" attribute of the Link header as defined in
Section 4.9.

This section creates and registers an IETF URN Sub-namespace sub-namespace for use
in the WHIP specifications and future extensions.

6.4.1. Specification Template

Namespace ID:

* The Namespace ID "whip" has been assigned.
whip

Registration Information:

*
Version: 1

Date: TBD

Declared registrant of the namespace:

*
Registering organization: The Internet Engineering Task Force.

* IETF

Designated contact: A designated expert (DE) will monitor the WHIP
public mailing list, "wish@ietf.org". list <wish@ietf.org>.

Declaration of Syntactic Structure:

*
The Namespace Specific String (NSS) of all URNs that use the
"whip" Namespace ID shall have the following structure:
urn:ietf:params:whip:{type}:{name}:{other}.

The keywords have the following meaning:

- meanings:

type: The entity type. This specification only defines the "ext"
type.

name: A required ASCII string that conforms to the URN syntax
requirements (see [RFC8141]) and defines a major namespace of a
WHIP protocol extension. The value MAY also be an industry
name or organization name.

other: Any ASCII string that conforms to the URN syntax
requirements (see [RFC8141]) and defines the sub-namespace
(which MAY be further broken down in namespaces delimited by
colons) as needed to uniquely identify an a WHIP protocol
extension.

Relevant Ancillary Documentation:

*
None

Identifier Uniqueness Considerations:

*
The designated contact shall be responsible for reviewing and
enforcing uniqueness.

Identifier Persistence Considerations:
* Once a name has been allocated, it MUST NOT be reallocated for
a different purpose.

* The rules provided for assignments of values within a sub-
namespace MUST be constructed so that the meanings of values
cannot change.

* This registration mechanism is not appropriate for naming
values whose meanings may change over time.

Process of Identifier Assignment:

* Namespace
The namespace with type "ext" (e.g., "urn:ietf:params:whip:ext")
is reserved for IETF-approved WHIP specifications.

Process of Identifier Resolution:

*
None specified. specified

Rules for Lexical Equivalence:

*
No special considerations; the rules for lexical equivalence
specified in [RFC8141] apply.

Conformance with URN Syntax:

*
No special considerations. considerations

Validation Mechanism:

*
None specified. specified

Scope:

* Global.
Global

6.5. Registering WHIP Protocol Extensions Extension URNs

This section defines the process for registering new WHIP protocol
extensions
extension URNs with IANA in the "WebRTC-HTTP ingestion protocol Ingestion Protocol
(WHIP) extension Extension URNs" registry (see Section 6.4). 6.3.2).

A WHIP Protocol Extension URNs URN is used as a value in the "rel"
attribute of the Link header as defined in Section 4.9 for the
purpose of signaling the WHIP protocol extensions supported by the
WHIP endpoints. endpoint.

WHIP Protocol Extensions Extension URNs have an "ext" type as defined in
Section 6.4.

6.5.1. Registration Procedure

The IETF has created a mailing list, "wish@ietf.org", <wish@ietf.org>, which can be
used for public discussion of proposals regarding WHIP protocol
extensions proposals prior to registration. Use of the mailing list is
strongly encouraged. The IESG has appointed a A designated expert as per
[RFC8126] who (DE) [RFC8126], appointed
by the IESG, will monitor the wish@ietf.org <wish@ietf.org> mailing list and review
registrations.

Registration of new "ext" type URNs (in the namespace
"urn:ietf:params:whip:ext") belonging to a WHIP Protocol Extension
MUST be documented in a permanent and readily available public
specification, in sufficient detail so that interoperability between
independent implementations is possible possible, and reviewed by the
designated expert DE as
per Section 4.6 of [RFC8126]. An A Standards Track RFC is REQUIRED for
the registration of new value data types that modify existing
properties. An A Standards Track RFC is also REQUIRED for registration
of WHIP Protocol Extensions Extension URNs that modify WHIP Protocol Extensions
previously documented in an existing RFC.

The registration procedure begins when a completed registration
template, defined in the sections below, Section 6.5.3, is sent to iana@iana.org. <iana@iana.org>.
Decisions made by the designated expert DE can be appealed to an Applications and Real Real-
Time (ART) Area Director, then to the IESG. The normal appeals
procedure described in [BCP9] is to be followed.

Once the registration procedure concludes successfully, IANA creates
or modifies the corresponding record in the WHIP Protocol "WebRTC-HTTP ingestion
protocol (WHIP) Extension URNs" registry.

An RFC specifying one or more new WHIP Protocol Extension URNs MUST
include the completed registration templates, template(s), which MAY be expanded
with additional information. These completed templates template(s) are
intended to go in the body of the document, not in the IANA
Considerations section. The RFC MUST include the syntax and
semantics of any extension-specific attributes that may be provided
in a Link header field advertising the extension.

6.5.2. Guidance for Designated Experts

The the Designated Expert (DE)

The DE is expected to ascertain do the following:

* Ascertain the existence of 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 Specifications
should be documented in an Internet-Draft.

* Check the clarity of purpose and use of the requested
registration.

Additionally, the DE must verify

* Verify that any request for one of these registrations has been
made available for review and comment comments by posting the request to
the WebRTC Ingest Signaling over HTTPS (wish)
Working Group <wish@ietf.org> mailing list.

Specifications should be documented in an Internet-Draft. Lastly,
the DE must ensure

* Ensure that any other request for a code point does not conflict
with work that is active in or already published by the IETF.

6.5.3. WHIP Protocol Extension Registration Template

A WHIP Protocol Extension URNs URN is defined by completing the following
template:

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
specification

Name: A descriptive name of the WHIP Protocol Extension (e.g.,
"Sender Side events").

* events")

Description: A brief description of the function of the extension,
in a short extension
(short paragraph or two

* two)

Contact information: Contact information for the organization or
person making the registration

7. 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.

8. References

8.1.

7.1. Normative References

[FETCH] WHATWG, "Fetch - "Fetch", WHATWG Living Standard", n.d., Standard,
<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
Requirement Levels", BCP 14, RFC 2119,
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
with Session Description Protocol (SDP)", RFC 3264,
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
IETF URN Sub-namespace for Registered Protocol
Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June
2003, <https://www.rfc-editor.org/rfc/rfc3553>. <https://www.rfc-editor.org/info/rfc3553>.

[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
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,
"Randomness Requirements for Security", BCP 106, RFC 4086,
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",
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
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
Framework: Bearer Token Usage", RFC 6750,
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-
Huguenin, "URI Scheme for the Session Traversal Utilities
for NAT (STUN) Protocol", RFC 7064, DOI 10.17487/RFC7064,
November 2013, <https://www.rfc-editor.org/rfc/rfc7064>. <https://www.rfc-editor.org/info/rfc7064>.

[RFC7065] Petit-Huguenin, M., Nandakumar, S., Salgueiro, G., and P.
Jones, "Traversal Using Relays around NAT (TURN) Uniform
Resource Identifiers", RFC 7065, DOI 10.17487/RFC7065,
November 2013, <https://www.rfc-editor.org/rfc/rfc7065>. <https://www.rfc-editor.org/info/rfc7065>.

[RFC7675] Perumal, M., Wing, D., Ravindranath, R., Reddy, T., and M.
Thomson, "Session Traversal Utilities for NAT (STUN) Usage
for Consent Freshness", RFC 7675, DOI 10.17487/RFC7675,
October 2015, <https://www.rfc-editor.org/rfc/rfc7675>. <https://www.rfc-editor.org/info/rfc7675>.

[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>. <https://www.rfc-editor.org/info/rfc8174>.

[RFC8288] Nottingham, M., "Web Linking", RFC 8288,
DOI 10.17487/RFC8288, October 2017,
<https://www.rfc-editor.org/rfc/rfc8288>.
<https://www.rfc-editor.org/info/rfc8288>.

[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
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,
D., Mahy, R., and P. Matthews, "Session Traversal
Utilities for NAT (STUN)", RFC 8489, DOI 10.17487/RFC8489,
February 2020, <https://www.rfc-editor.org/rfc/rfc8489>. <https://www.rfc-editor.org/info/rfc8489>.

[RFC8725] Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best
Current Practices", BCP 225, RFC 8725,
DOI 10.17487/RFC8725, February 2020,
<https://www.rfc-editor.org/rfc/rfc8725>.
<https://www.rfc-editor.org/info/rfc8725>.

[RFC8826] Rescorla, E., "Security Considerations for WebRTC",
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
Session Description Protocol", RFC 8830,
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:
Incremental Provisioning of Candidates for the Interactive
Connectivity Establishment (ICE) Protocol", RFC 8838,
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,
A., and R. Shpount, "Session Description Protocol (SDP)
Offer/Answer Procedures for Interactive Connectivity
Establishment (ICE)", RFC 8839, DOI 10.17487/RFC8839,
January 2021, <https://www.rfc-editor.org/rfc/rfc8839>. <https://www.rfc-editor.org/info/rfc8839>.

[RFC8840] Ivov, E., Stach, T., Marocco, E., and C. Holmberg, "A
Session Initiation Protocol (SIP) Usage for Incremental
Provisioning of Candidates for the Interactive
Connectivity Establishment (Trickle ICE)", RFC 8840,
DOI 10.17487/RFC8840, January 2021,
<https://www.rfc-editor.org/rfc/rfc8840>.
<https://www.rfc-editor.org/info/rfc8840>.

[RFC8842] Holmberg, C. and R. Shpount, "Session Description Protocol
(SDP) Offer/Answer Considerations for Datagram Transport
Layer Security (DTLS) and Transport Layer Security (TLS)",
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,
"Framework for Telepresence Multi-Streams", RFC 8845,
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,
"Using Simulcast in Session Description Protocol (SDP) and
RTP Sessions", RFC 8853, DOI 10.17487/RFC8853, January
2021, <https://www.rfc-editor.org/rfc/rfc8853>. <https://www.rfc-editor.org/info/rfc8853>.

[RFC8858] Holmberg, C., "Indicating Exclusive Support of RTP and RTP
Control Protocol (RTCP) Multiplexing Using the Session
Description Protocol (SDP)", RFC 8858,
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,
Ed., "HTTP Semantics", STD 97, RFC 9110,
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,
Ed., "HTTP/1.1", STD 99, RFC 9112, DOI 10.17487/RFC9112,
June 2022, <https://www.rfc-editor.org/rfc/rfc9112>. <https://www.rfc-editor.org/info/rfc9112>.

[RFC9143] Holmberg, C., Alvestrand, H., and C. Jennings,
"Negotiating Media Multiplexing Using the Session
Description Protocol (SDP)", RFC 9143,
DOI 10.17487/RFC9143, February 2022,
<https://www.rfc-editor.org/rfc/rfc9143>.
<https://www.rfc-editor.org/info/rfc9143>.

[RFC9147] Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version
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.,
"JavaScript Session Establishment Protocol (JSEP)",
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
IDentifiers (UUIDs)", RFC 9562, DOI 10.17487/RFC9562, May
2024, <https://www.rfc-editor.org/rfc/rfc9562>. <https://www.rfc-editor.org/info/rfc9562>.

[W3C.REC-ldp-20150226]
Malhotra, A., Ed.,
Arwe, J., Ed., and S. Speicher, S., Ed., and A. Malhotra, Ed.,
"Linked Data Platform 1.0", W3C REC REC-ldp-20150226, W3C
REC-ldp-20150226, Recommendation, 26
February 2015,
<https://www.w3.org/TR/2015/REC-ldp-20150226/>.

8.2. Latest
version available at: <https://www.w3.org/TR/ldp/>.

7.2. Informative References

[BCP56] Best Current Practice 56,
<https://www.rfc-editor.org/info/bcp56>.
At the time of writing, this BCP comprises the following:

Nottingham, M., "Building Protocols with HTTP", BCP 56,
RFC 9205, DOI 10.17487/RFC9205, June 2022,
<https://www.rfc-editor.org/info/rfc9205>.

[BCP9] Best Current Practice 9,
<https://www.rfc-editor.org/info/bcp9>.
At the time of writing, this BCP comprises the following:

Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, DOI 10.17487/RFC2026, October 1996,
<https://www.rfc-editor.org/info/rfc2026>.

Dusseault, L. and R. Sparks, "Guidance on Interoperation
and Implementation Reports for Advancement to Draft
Standard", BCP 9, RFC 5657, DOI 10.17487/RFC5657,
September 2009, <https://www.rfc-editor.org/info/rfc5657>.

Housley, R., Crocker, D., and E. Burger, "Reducing the
Standards Track to Two Maturity Levels", BCP 9, RFC 6410,
DOI 10.17487/RFC6410, October 2011,
<https://www.rfc-editor.org/info/rfc6410>.

Resnick, P., "Retirement of the "Internet Official
Protocol Standards" Summary Document", BCP 9, RFC 7100,
DOI 10.17487/RFC7100, December 2013,
<https://www.rfc-editor.org/info/rfc7100>.

Kolkman, O., Bradner, S., and S. Turner, "Characterization
of Proposed Standards", BCP 9, RFC 7127,
DOI 10.17487/RFC7127, January 2014,
<https://www.rfc-editor.org/info/rfc7127>.

Dawkins, S., "Increasing the Number of Area Directors in
an IETF Area", BCP 9, RFC 7475, DOI 10.17487/RFC7475,
March 2015, <https://www.rfc-editor.org/info/rfc7475>.

Halpern, J., Ed. and E. Rescorla, Ed., "IETF Stream
Documents Require IETF Rough Consensus", BCP 9, RFC 8789,
DOI 10.17487/RFC8789, June 2020,
<https://www.rfc-editor.org/info/rfc8789>.

Rosen, B., "Responsibility Change for the RFC Series",
BCP 9, RFC 9282, DOI 10.17487/RFC9282, June 2022,
<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,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002,
<https://www.rfc-editor.org/rfc/rfc3261>.
<https://www.rfc-editor.org/info/rfc3261>.

[RFC6120] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Core", RFC 6120, DOI 10.17487/RFC6120,
March 2011, <https://www.rfc-editor.org/rfc/rfc6120>. <https://www.rfc-editor.org/info/rfc6120>.

[RFC7826] Schulzrinne, H., Rao, A., Lanphier, R., Westerlund, M.,
and M. Stiemerling, Ed., "Real-Time Streaming Protocol
Version 2.0", RFC 7826, DOI 10.17487/RFC7826, December
2016, <https://www.rfc-editor.org/rfc/rfc7826>. <https://www.rfc-editor.org/info/rfc7826>.

[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
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
(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
Requirements for Interactive Real-Time Media", RFC 8836,
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
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]
Jennings, C., Ed., Boström, H., Ed., and J. Bruaroey, Ed.,
"WebRTC 1.0: Real-Time Communication Between Browsers",
W3C REC REC-webrtc-20210126, W3C REC-webrtc-20210126, Recommendation, 26 January 2021,
<https://www.w3.org/TR/2021/REC-webrtc-20210126/>. Latest
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

Sergio Garcia Murillo
Millicast
Email: sergio.garcia.murillo@cosmosoftware.io

Alexandre Gouaillard
CoSMo Software
Email: alex.gouaillard@cosmosoftware.io