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Versions: (draft-holmberg-rtcweb-ucreqs) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 RFC 7478

RTCWEB Working Group                                         C. Holmberg
Internet-Draft                                              S. Hakansson
Intended status: Informational                               G. Eriksson
Expires: March 18, 2012                                         Ericsson
                                                      September 15, 2011


         Web Real-Time Communication Use-cases and Requirements
          draft-ietf-rtcweb-use-cases-and-requirements-05.txt

Abstract

   This document describes web based real-time communication use-cases.
   Based on the use-cases, the document also derives requirements
   related to the browser, and the API used by web applications to
   request and control media stream services provided by the browser.

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on March 18, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   4.  Use-cases  . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     4.1.  Introduction . . . . . . . . . . . . . . . . . . . . . . .  3
     4.2.  Browser-to-browser use-cases . . . . . . . . . . . . . . .  3
       4.2.1.  Simple Video Communication Service . . . . . . . . . .  3
       4.2.2.  Simple Video Communication Service, NAT/FW that
               blocks UDP . . . . . . . . . . . . . . . . . . . . . .  4
       4.2.3.  Simple Video Communication Service, access change  . .  4
       4.2.4.  Simple Video Communication Service, QoS  . . . . . . .  5
       4.2.5.  Simple video communication service with
               inter-operator calling . . . . . . . . . . . . . . . .  5
       4.2.6.  Hockey Game Viewer . . . . . . . . . . . . . . . . . .  6
       4.2.7.  Multiparty video communication . . . . . . . . . . . .  7
       4.2.8.  Multiparty on-line game with voice communication . . .  8
       4.2.9.  Distributed Music Band . . . . . . . . . . . . . . . .  8
     4.3.  Browser - GW/Server use cases  . . . . . . . . . . . . . .  9
       4.3.1.  Telephony terminal . . . . . . . . . . . . . . . . . .  9
       4.3.2.  Fedex Call . . . . . . . . . . . . . . . . . . . . . .  9
       4.3.3.  Video conferencing system with central server  . . . . 10
   5.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 11
     5.1.  General  . . . . . . . . . . . . . . . . . . . . . . . . . 11
     5.2.  Browser requirements . . . . . . . . . . . . . . . . . . . 11
     5.3.  API requirements . . . . . . . . . . . . . . . . . . . . . 13
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 15
     7.1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . 15
     7.2.  Browser Considerations . . . . . . . . . . . . . . . . . . 15
     7.3.  Web Application Considerations . . . . . . . . . . . . . . 16
   8.  Additional use-cases . . . . . . . . . . . . . . . . . . . . . 16
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
   10. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 17
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 19
     11.2. Informative References . . . . . . . . . . . . . . . . . . 19
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19












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1.  Introduction

   This document presents a few use-cases of web applications that are
   executed in a browser and use real-time communication capabilities.
   Based on the use-cases, the document derives requirements related to
   the browser and the API used by web applications in the browser.

   The requirements related to the browser are named "Fn" and are
   described in Section 5.2

   The requirements related to the API are named "An" and are described
   in Section 5.3

   The document focuses on requirements related to real-time media
   streams.  Requirements related to privacy, signalling between the
   browser and web server etc. are currently not considered.


2.  Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in BCP 14, RFC 2119
   [RFC2119].


3.  Definitions

   TBD


4.  Use-cases

4.1.  Introduction

   This section describes web based real-time communication use-cases,
   from which requirements are derived.

4.2.  Browser-to-browser use-cases

4.2.1.  Simple Video Communication Service

4.2.1.1.  Description

   Two or more users have loaded a video communication web application
   into their browsers, provided by the same service provider, and
   logged into the service it provides.  The web service publishes
   information about user login status by pushing updates to the web



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   application in the browsers.  When one online user selects a peer
   online user, a 1-1 video communication session between the browsers
   of the two peers is initiated.  The invited user might accept or
   reject the session.

   During session establishment a self-view is displayed, and once the
   session has been established the video sent from the remote peer is
   displayed in addition to the self-view.  During the session, each
   user can select to remove and re-insert the self-view as often as
   desired.  Each user can also change the sizes of his/her two video
   displays during the session.  Each user can also pause sending of
   media (audio, video, or both) and mute incoming media

   It is essential that the communication cannot be eavesdropped.

   Any session participant can end the session at any time.

   The two users may be using communication devices of different makes,
   with different operating systems and browsers from different vendors.

   One user has an unreliable Internet connection.  It sometimes loses
   packets, and sometimes goes down completely.

   One user is located behind a Network Address Translator (NAT).

4.2.1.2.  Derived Requirements

   F1, F2, F3, F4, F5, F6, F8, F9, F10, F17, F22, F25

   A1, A2, A3, A4, A5, A6, A7, A9, A10, A11, A12, A13

4.2.2.  Simple Video Communication Service, NAT/FW that blocks UDP

4.2.2.1.  Description

   This use-case is almost identical to the previos one.  The difference
   is that one of the users is behind a NAT that blocks UDP traffic.

4.2.2.2.  Derived Requirements

   F1, F2, F3, F4, F5, F6, F8, F9, F10, F17, F22, F23, F25, F26

   A1, A2, A3, A4, A5, A6, A7, A9, A10, A11, A12, A13

4.2.3.  Simple Video Communication Service, access change






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4.2.3.1.  Description

   This use-case is almost identical to "4.2.1 Simple Video
   Communication Service".  The difference is that the user changes
   network access during the session:

   The communication device used by one of the users have several
   network adapters (Ethernet, WiFi, Cellular).  The communication
   device is accessing the Internet using Ethernet, but the user has to
   start a trip during the session.  The communication device
   automatically changes to use WiFi when the Ethernet cable is removed
   and then moves to cellular access to the Internet when moving out of
   WiFi coverage.  The session continues even though the access method
   changes.

4.2.3.2.  Derived Requirements

   F1, F2, F3, F4, F5, F6, F8, F9, F10, F17, F22, F23, F25

   A1, A2, A3, A4, A5, A6, A7, A9, A10, A11, A12, A13

4.2.4.  Simple Video Communication Service, QoS

4.2.4.1.  Description

   This use-case is almost identical to the previous one.  The use of
   Quality of Service (QoS) capabilities is added:

   The user in the previous use case that starts a trip is behind a
   common residential router that supports prioritization of traffic.
   In addition, the user's provider of cellular access has QoS support
   enabled.  The user is able to take advantage of the QoS support both
   when accessing via the residential router and when using cellular.

4.2.4.2.  Derived Requirements

   F1, F2, F3, F4, F5, F6, F8, F9, F10, F17, F21, F22, F23, F25

   A1, A2, A3, A4, A5, A6, A7, A9, A10, A11, A12, A13

4.2.5.  Simple video communication service with inter-operator calling

4.2.5.1.  Description

   Two users have logged into two different web applications, provided
   by different service providers.

   The service providers are interconnected by some means, but exchange



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   no more information about the users than what can be carried using
   SIP.

   NOTE: More profiling of what this means may be needed.

   For each user Alice who has authorized another user Bob to receive
   login status information, Alice's service publishes Alice's login
   status information to Bob. How this authorization is defined and
   established is out of scope.

   The same functionality as in the "4.2.1 Simple Video Communication
   Service" is available.

   The same issues with connectivity apply.

4.2.5.2.  Derived requirements

   F1, F2, F3, F4, F5, F6, F8, F9, F10, F17, F22, F24, F25

   A1, A2, A3, A4, A5, A6, A7, A9, A10, A11, A12, A13

4.2.6.  Hockey Game Viewer

4.2.6.1.  Description

   An ice-hockey club uses an application that enables talent scouts to,
   in real-time, show and discuss games and players with the club
   manager.  The talent scouts use a mobile phone with two cameras, one
   front facing and one rear facing.

   The club manager uses a desktop, equipped with one camera, for
   viewing the game and discussing with the talent scout.

   Before the game starts, and during game breaks, the talent scout and
   the manager have a 1-1 video communication.  Only the rear facing
   camera of the mobile phone is used.  On the display of the mobile
   phone, the video of the club manager is shown with a picture-in-
   picture thumbnail of the rear facing camera (self-view).  On the
   display of the desktop, the video of the talent scout is shown with a
   picture-in-picture thumbnail of the desktop camera (self-view).

   When the game is on-going, the talent scout activates the use of the
   front facing camera, and that stream is sent to the desktop (the
   stream from the rear facing camera continues to be sent all the
   time).  The video stream captured by the front facing camera (that is
   capturing the game) of the mobile phone is shown in a big window on
   the desktop screen, with picture-in-picture thumbnails of the rear
   facing camera and the desktop camera (self-view).  On the display of



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   the mobile phone the game is shown (front facing camera) with
   picture-in-picture thumbnails of the rear facing camera (self-view)
   and the desktop camera.

   It is essential that the communication cannot be eavesdropped.

4.2.6.2.  Derived Requirements

   F1, F2, F3, F4, F5, F6, F8, F9, F10, F14, F17

   A1, A2, A3, A4, A5, A7, A9, A10, A11, A12, A13, A15

4.2.7.  Multiparty video communication

4.2.7.1.  Description

   In this use-case the simple video communication service
   Section 4.2.1is extended by allowing multiparty sessions.  No central
   server is involved - the browser of each participant sends and
   receives streams to and from all other session participants.  The web
   application in the browser of each user is responsible for setting up
   streams to all receivers.

   In order to enhance intelligibility, the web application pans the
   audio from different participants differently when rendering the
   audio.  This is done automatically, but users can change how the
   different participants are placed in the (virtual) room.

   Each video stream received is by default displayed in a thumbnail
   frame within the browser, but users can change the display size.

   It is essential that the communication cannot be eavesdropped.

   Note: What this use-case adds in terms of requirements is
   capabilities to send streams to and receive streams from several
   peers concurrently, as well as the capabilities to render the video
   from all recevied streams and be able to spatialize and mix the audio
   from all received streams locally in the browser.

4.2.7.2.  Derived Requirements

   F1, F2, F3, F4, F5, F6, F8, F9, F10, F11, F12, F13, F14, F17, F22

   A1, A2, A3, A4, A5, A6, A7, A9, A10, A11, A12, A13, A14, A15







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4.2.8.  Multiparty on-line game with voice communication

4.2.8.1.  Description

   This use case is based on the previous one.  In this use-case, the
   voice part of the multiparty video communication use case is used in
   the context of an on-line game.  The received voice audio media is
   rendered together with game sound objects.  For example, the sound of
   a tank moving from left to right over the screen must be rendered and
   played to the user together with the voice media.

   Quick updates of the game state is required.

   It is essential that the communication cannot be eavesdropped.

   Note: the difference regarding local audio processing compared to the
   "Multiparty video communication" use-case is that other sound objects
   than the streams must be possible to be included in the
   spatialization and mixing.  "Other sound objects" could for example
   be a file with the sound of the tank; that file could be stored
   locally or remotely.

4.2.8.2.  Derived Requirements

   F1, F2, F3, F4, F5, F6, F8, F9, F11, F12, F13, F15, F17, F20

   A1, A2, A3, A4, A5, A7, A9, A10, A11, A12, A13, A14, A15, A16

4.2.9.  Distributed Music Band

4.2.9.1.  Description

   In this use-case, a music band is playing music while the members are
   at different physical locations.  No central server is used, instead
   all streams are set up in a mesh fashion.

   Discussion: This use-case was briefly discussed at the Quebec webrtc
   meeting and it got support.  So far the only concrete requirement
   (A17) derived is that the application must be able to ask the browser
   to treat the audio signal as audio (in contrast to speech).  However,
   the use case should be further analysed to determine other
   requirements (could be e.g. on delay mic->speaker, level control of
   audio signals, etc.).

4.2.9.2.  Derived Requirements

   F1, F2, F3, F4, F5, F6, F8, F9, F11, F12, F13




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   A1, A2, A3, A4, A5, A7, A9, A10, A11, A12, A13, A14, A15, A17

4.3.  Browser - GW/Server use cases

4.3.1.  Telephony terminal

4.3.1.1.  Description

   A mobile telephony operator allows its customers to use a web browser
   to access their services.  After a simple log in the user can place
   and receive calls in the same way as when using a normal mobile
   phone.  When a call is received or placed, the identity is shown in
   the same manner as when a mobile phone is used.

   It is essential that the communication cannot be eavesdropped.

   Note: With "place and receive calls in the same way as when using a
   normal mobile phone" it is meant that you can dial a number, and that
   your mobile telephony operator has made available your phone contacts
   on line, so they are available and can be clicked to call, and be
   used to present the identity of an incoming call.  If the callee is
   not in your phone contacts the number is displayed.  Furthermore,
   your call logs are available, and updated with the calls made/
   received from the browser.  And for people receiving calls made from
   the web browser the usual identity (i.e. the phone number of the
   mobile phone) will be presented.

4.3.1.2.  Derived Requirements

   F1, F2, F3, F4, F5, F6, F8, F9, F10, F17, F18

   A1, A2, A3, A4, A7, A9, A10, A11, A12, A13

4.3.2.  Fedex Call

4.3.2.1.  Description

   Alice uses her web browser with a service something like Skype to be
   able to phone PSTN numbers.  Alice calls 1-800-gofedex.  Alice should
   be able to hear the initial prompts from the fedex IVR and when the
   IVR says press 1, there should be a way for Alice to navigate the
   IVR.

4.3.2.2.  Derived Requirements

   F1, F2, F3, F4, F5, F6, F8, F9, F10, F18, F19

   A1, A2, A3, A4, A7, A9, A10, A11, A12, A13



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4.3.3.  Video conferencing system with central server

4.3.3.1.  Description

   An organization uses a video communication system that supports the
   establishment of multiparty video sessions using a central conference
   server.

   The browser of each participant send an audio stream (type in terms
   of mono, stereo, 5.1, ... depending on the equipment of the
   participant) to the central server.  The central server mixes the
   audio streams (and can in the mixing process naturally add effects
   such as spatialization) and sends towards each participant a mixed
   audio stream which is played to the user.

   The browser of each participant sends video towards the server.  For
   each participant one high resolution video is displayed in a large
   window, while a number of low resolution videos are displayed in
   smaller windows.  The server selects what video streams to be
   forwarded as main- and thumbnail videos respectively, based on speech
   activity.  As the video streams to display can change quite
   frequently (as the conversation flows) it is important that the delay
   from when a video stream is selected for display until the video can
   be displayed is short.

   The organization has an internal network set up with an aggressive
   firewall handling access to the Internet.  If users cannot physically
   access the internal network, they can establish a Virtual Private
   Network (VPN).

   It is essential that the communication cannot be eavesdropped.

   All participants are authenticated by the central server, and
   authorized to connect to the central server.  The participants are
   identified to each other by the central server, and the participants
   do not have access to each others' credentials such as e-mail
   addresses or login IDs.

   Note: This use-case adds requirements on support for fast stream
   switches F7, on encryption of media and on ability to traverse very
   restrictive FWs.  There exist several solutions that enable the
   server to forward one high resolution and several low resolution
   video streams: a) each browser could send a high resolution, but
   scalable stream, and the server could send just the base layer for
   the low resolution streams, b) each browser could in a simulcast
   fashion send one high resolution and one low resolution stream, and
   the server just selects or c) each browser sends just a high
   resolution stream, the server transcodes into low resolution streams



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   as required.

4.3.3.2.  Derived Requirements

   F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F14, F16, F17

   A1, A2, A3, A4, A5, A7, A9, A10, A11, A12, A13, A15


5.  Requirements

5.1.  General

   This section contains the requirements derived from the use-cases in
   section 4.

   NOTE: It is assumed that the user applications are executed on a
   browser.  Whether the capabilities to implement specific browser
   requirements are implemented by the browser application, or are
   provided to the browser application by the underlying operating
   system, is outside the scope of this document.

5.2.  Browser requirements


   REQ-ID          DESCRIPTION
   ---------------------------------------------------------------
   F1              The browser MUST be able to use microphones and
                   cameras as input devices to generate streams.
   ----------------------------------------------------------------
   F2              The browser MUST be able to send streams to a
                   peer in the presence of NATs.
   ----------------------------------------------------------------
   F3              Transmitted streams MUST be rate controlled.
   ----------------------------------------------------------------
   F4              The browser MUST be able to receive, process and
                   render streams from peers.
   ----------------------------------------------------------------
   F5              The browser MUST be able to render good quality
                   audio and video even in the presence of reasonable
                   levels of jitter and packet losses.

                   TBD: What is a reasonable level?
   ----------------------------------------------------------------
   F6              The browser MUST be able to handle high loss and
                   jitter levels in a graceful way.
   ----------------------------------------------------------------
   F7              The browser MUST support fast stream switches.



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   ----------------------------------------------------------------
   F8              The browser MUST detect when a stream from a
                   peer is not received anymore
   ----------------------------------------------------------------
   F9              When there are both incoming and outgoing audio
                   streams, echo cancellation MUST be made available to
                   avoid disturbing echo during conversation.

                   QUESTION: How much control should be left to the
                   web application?
   ----------------------------------------------------------------
   F10             The browser MUST support synchronization of
                   audio and video.


                   QUESTION: How much control should be left to the
                   web application?
   ----------------------------------------------------------------
   F11             The browser MUST be able to transmit streams to
                   several peers concurrently.
   ----------------------------------------------------------------
   F12             The browser MUST be able to receive streams from
                   multiple peers concurrently.
   ----------------------------------------------------------------
   F13             The browser MUST be able to pan, mix and render
                   several concurrent audio streams.
   ----------------------------------------------------------------
   F14             The browser MUST be able to render several
                   concurrent video streams
   ----------------------------------------------------------------
   F15             The browser MUST be able to process and mix
                   sound objects (media that is retrieved from another
                   source than the established media stream(s) with the
                   peer(s) with audio streams).
   ----------------------------------------------------------------
   F16             Streams MUST be able to pass through restrictive
                   firewalls.
   ----------------------------------------------------------------
   F17             It MUST be possible to protect streams from
                   eavesdropping.
   ----------------------------------------------------------------
   F18             The browser MUST support an audio media format
                   (codec) that is commonly supported by existing
                   telephony services.

                   QUESTION: G.711?
   ----------------------------------------------------------------
   F19             There should be a way to navigate



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                   the IVR
   ----------------------------------------------------------------
   F20             The browser must be able to send short
                   latency datagram traffic to a peer browser
   ----------------------------------------------------------------
   F21             The browser MUST be able to take advantage of
                   capabilities to prioritize voice and video
                   appropriately.
   ----------------------------------------------------------------
   F22             The browser SHOULD use encoding of streams
                   suitable for the current rendering (e.g.
                   video display size) and SHOULD change parameters
                   if the rendering changes during the session
   ----------------------------------------------------------------
   F23             It MUST be possible to move from one network
                   interface to another one
   ----------------------------------------------------------------
   F24             The browser MUST be able to initiate and accept a
                   media session where the data needed for establishment
                   can be carried in SIP.
   ----------------------------------------------------------------
   F25             The browser MUST support a baseline audio and
                   video codec
   ----------------------------------------------------------------
   F26             The browser MUST be able to send streams to a
                   peer in the presence of NATs that block UDP traffic.
   ----------------------------------------------------------------

5.3.  API requirements


   REQ-ID          DESCRIPTION
   ----------------------------------------------------------------
   A1              The Web API MUST provide means for the
                   application to ask the browser for permission
                   to use cameras and microphones as input devices.
   ----------------------------------------------------------------
   A2              The Web API MUST provide means for the web
                   application to control how streams generated
                   by input devices are used.
   ----------------------------------------------------------------
   A3              The Web API MUST provide means for the web
                   application to control the local rendering of
                   streams (locally generated streams and streams
                   received from a peer).
   ----------------------------------------------------------------
   A4              The Web API MUST provide means for the web
                   application to initiate sending of



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                   stream/stream components to a peer.
   ----------------------------------------------------------------
   A5              The Web API MUST provide means for the web
                   application to control the media format (codec)
                   to be used for the streams sent to a peer.

                   NOTE: The level of control depends on whether
                   the codec negotiation is handled by the browser
                   or the web application.
   ----------------------------------------------------------------
   A6              The Web API MUST provide means for the web
                   application to modify the media format for
                   streams sent to a peer after a media stream
                   has been established.
   ----------------------------------------------------------------
   A7              The Web API MUST provide means for
                   informing the web application of whether the
                   establishment of a stream with a peer was
                   successful or not.
   ----------------------------------------------------------------
   A8              Removed.
   ----------------------------------------------------------------
   A9              The Web API MUST provide means for the web
                   application to mute/unmute a stream or stream
                   component(s). When a stream is sent to a peer
                   mute status must be preserved in the stream
                   received by the peer.
   ----------------------------------------------------------------
   A10             The Web API MUST provide means for the web
                   application to cease the sending of a stream
                   to a peer.
   ----------------------------------------------------------------
   A11             The Web API MUST provide means for the web
                   application to cease processing and rendering
                   of a stream received from a peer.
   ----------------------------------------------------------------
   A12             The Web API MUST provide means for
                   informing the web application when a
                   stream from a peer is no longer received.
   ----------------------------------------------------------------
   A13             The Web API MUST provide means for
                   informing the web application when high
                   loss rates occur.
   ----------------------------------------------------------------
   A14             The Web API MUST provide means for the web
                   application to control panning, mixing and
                   other processing for streams.
   ----------------------------------------------------------------



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   A15             For each stream generated, the Web API MUST provide
                   an identifier that is accessible by the application.
                   The identifier MUST be accessible also for a peer
                   receiving that stream and MUST be unique relative
                   to all other stream identifiers in use by either party.
   ----------------------------------------------------------------
   A16             In addition to the streams listed elsewhere,
                   the Web API MUST provide a mechanism for sending
                   and receiving isolated discrete chunks of data.
   ----------------------------------------------------------------
   A17             The Web API MUST provide means for the web
                   application indicate the type of audio signal
                   (speech, audio)for audio stream(s)/stream component(s).
   ----------------------------------------------------------------
   A18             It must be possible for an initiator or a
                   responder Web application to indicate the types
                   of media he's willing to accept incoming streams
                   for when setting up a connection (audio, video,
                   other). The types of media he's willing to accept
                   can be a subset of the types of media the browser
                   is able to accept.
   ----------------------------------------------------------------


6.  IANA Considerations

   TBD


7.  Security Considerations

7.1.  Introduction

   A malicious web application might use the browser to perform Denial
   Of Service (DOS) attacks on NAT infrastructure, or on peer devices.
   Also, a malicious web application might silently establish outgoing,
   and accept incoming, streams on an already established connection.

   Based on the identified security risks, this section will describe
   security considerations for the browser and web application.

7.2.  Browser Considerations

   The browser is expected to provide mechanisms for getting user
   consent to use device resources such as camera and microphone.

   The browser is expected to provide mechanisms for informing the user
   that device resources such as camera and microphone are in use



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   ("hot").

   The browser is expected to provide mechanisms for users to revise and
   even completely revoke consent to use device resources such as camera
   and microphone.

   The browser is expected to provide mechanisms in order to assure that
   streams are the ones the recipient intended to receive.

   The browser needs to ensure that media is not sent, and that received
   media is not rendered, until the associated stream establishment and
   handshake procedures with the remote peer have been successfully
   finished.

   The browser needs to ensure that the stream negotiation procedures
   are not seen as Denial Of Service (DOS) by other entities.

7.3.  Web Application Considerations

   The web application is expected to ensure user consent in sending and
   receiving media streams.


8.  Additional use-cases

   Several additional use-cases have been discussed.  At this point
   these use-cases are not included as requirement deriving use-cases
   for different reasons (lack of documentation, overlap with existing
   use-cases, lack of consensus).  For completeness these additional
   use-cases are listed below:
   1.   Use-cases regarding different situations when being invited to a
        "session", e.g. browser open, browser open but another tab
        active, browser open but active in session, browser closed, ....
        (Matthew Kaufman); discussed at webrtc meeting
   2.   Different TURN provider scenarios (Cullen Jennings); discussed
        at the webrtc meeting.  Proposed text in http://lists.w3.org/
        Archives/Public/public-webrtc/2011Aug/0133.html
   3.   E911 (Paul Beaumont) http://www.ietf.org/mail-archive/web/
        rtcweb/current/msg00525.html, followed up by Stephan Wenger
   4.   Local Recording and Remote recording (John): Discussed a _lot_
        on the mail lists (rtcweb as well as public-webrtc) lAugust and
        September 2011.  Concrete proposal: http://www.ietf.org/
        mail-archive/web/rtcweb/current/msg01006.html (remote) and http:
        //www.ietf.org/mail-archive/web/rtcweb/current/msg00734.html
        (local)
   5.   Emergency access for disabled (Bernard Aboba) http://
        www.ietf.org/mail-archive/web/rtcweb/current/msg00478.html




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   6.   Clue use-cases (Roni Even) http://tools.ietf.org/html/
        draft-ietf-clue-telepresence-use-cases-01
   7.   Rohan red cross (Cullen Jennings); http://www.ietf.org/
        mail-archive/web/rtcweb/current/msg00323.html
   8.   Remote assistance (ala VNC or RDP) - User is helping another
        user on their computer with either view-only or view-with-
        control, either of just the browser of the the entire screen. ht
        tp://www.ietf.org/mail-archive/web/rtcweb/current/msg00543.html
   9.   Security camera/baby monitor usage http://www.ietf.org/
        mail-archive/web/rtcweb/current/msg00543.html
   10.  Large multiparty session http://www.ietf.org/mail-archive/web/
        rtcweb/current/msg00530.html


9.  Acknowledgements

   Dan Burnett has reviewed and proposed a lot of things that enhances
   the document.  Most of this has been incorporated in rev -05.

   Stephan Wenger has provided a lot of useful input and feedback, as
   well as editorial comments.

   Harald Alvestrand and Ted Hardie have provided comments and feedback
   on the draft.

   Harald Alvestrand and Cullen Jennings have provided additional use-
   cases.

   Thank You to everyone in the RTCWEB community that have provided
   comments, feedback and improvement proposals on the draft content.


10.  Change Log

   [RFC EDITOR NOTE: Please remove this section when publishing]

   Changes from draft-ietf-rtcweb-use-cases-and-requirements-04

   o  Most changes based on the input from Dan Burnett
      http://www.ietf.org/mail-archive/web/rtcweb/current/msg00948.html
   o  Many editorial changes
   o  4.2.1.1 Clarified
   o  Some clarification added to 4.3.1.1 as a note
   o  F-requirements updated (see reply to Dan's mail).
   o  Almost all A-requirements updated to start "The Web API MUST
      provide ..."





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   o  A8 removed, A9 rephrased to cover A8 and old A9
   o  A15 rephrased
   o  For more details, and discussion, look att the response to Dan's
      mail
      http://www.ietf.org/mail-archive/web/rtcweb/current/msg01177.html

   Changes from draft-ietf-rtcweb-use-cases-and-requirements-03

   o  Editorials
   o  Changed when the self-view is displayed in 4.2.1.1, and added
      words about allowing users to remove and re-insert it.
   o  Clarified 4.2.6.1
   o  Removed the "mono" stuff from 4.2.7.1
   o  Added that communication should not be possible to eavesdrop to
      most use cases - and req.  F17
   o  Re-phrased 4.3.3.1 to not describe the technical solution so much,
      and removed "stereo" stuff.  Solution possibilities are now in a
      note.
   o  Re-inserted API requirements after discussion in the W3C webrtc
      WG.  (Re-phrased A15 and added A18 compared to version -02).

   Changes from draft-ietf-rtcweb-use-cases-and-requirements-02

   o  Removed desrciption/list of API requirements, instead
   o  Reference to W3C webrtc_reqs document for API requirements

   Changes from draft-ietf-rtcweb-ucreqs-01

   o  Changed Intended status to Information
   o  Changed "Ipr" to "trust200902"
   o  Added use case "Simple video communication service, NAT/FW that
      blocks UDP", and derived new req F26
   o  Added use case "Distributed Music Band" and derived new req A17
   o  Added F24 as requirement derived from use case "Simple video
      communication service with inter-operator calling"
   o  Added section "Additional use cases"
   o  Added text about ID handling to multiparty with central server use
      case
   o  Re-phrased A1 slightly

   Changes from draft-ietf-rtcweb-ucreqs-00

   o  - Reshuffled: Just two main groups of use cases (b2b and b2GW/
      Server); removed some specific use cases and added them instead as
      flavors to the base use case (Simple video communciation)
   o  - Changed the fromulation of F19





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   o  - Removed the requirement on an API for DTMF
   o  - Removed "FX3: There SHOULD be a mapping of the minimum needed
      data for setting up connections into SIP, so that the restriction
      to SIP-carriable data can be verified.  Not a rew on the browser
      but rather on a document"
   o  - (see
      http://www.ietf.org/mail-archive/web/rtcweb/current/msg00227.html
      for more details)
   o  -Added text on informing user of that mic/cam is being used and
      that it must be possible to revoce permission to use them in
      section 7.
   Changes from draft-holmberg-rtcweb-ucreqs-01
   o  - Draft name changed to draft-ietf-rtcweb-ucreqs
   o  - Use-case grouping introduced
   o  - Additional use-cases added
   o  - Additional reqs added (derived from use cases): F19-F25, A16-A17

   Changes from draft-holmberg-rtcweb-ucreqs-00
   o  - Mapping between use-cases and requirements added (Harald
      Alvestrand, 090311)
   o  - Additional security considerations text (Harald Alvestrand,
      090311)
   o  - Clarification that user applications are assumed to be executed
      by a browser (Ted Hardie, 080311)
   o  - Editorial corrections and clarifications


11.  References

11.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

11.2.  Informative References

   [webrtc_reqs]
              "Webrt requirements,
              http://dev.w3.org/2011/webrtc/editor/webrtc_reqs.html".












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Authors' Addresses

   Christer Holmberg
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   Finland

   Email: christer.holmberg@ericsson.com


   Stefan Hakansson
   Ericsson
   Laboratoriegrand 11
   Lulea  97128
   Sweden

   Email: stefan.lk.hakansson@ericsson.com


   Goran AP Eriksson
   Ericsson
   Farogatan 6
   Stockholm  16480
   Sweden

   Email: goran.ap.eriksson@ericsson.com
























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