A Framework for the Usage of Internet Media Guides (IMGs)
RFC 4435

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Network Working Group                                          Y. Nomura
Request for Comments: 4435                                 Fujitsu Labs.
Category: Informational                                         R. Walsh
                                                              J-P. Luoma
                                                                   Nokia
                                                               H. Asaeda
                                                         Keio University
                                                          H. Schulzrinne
                                                     Columbia University
                                                              April 2006

       A Framework for the Usage of Internet Media Guides (IMGs)

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This document defines a framework for the delivery of Internet Media
   Guides (IMGs).  An IMG is a structured collection of multimedia
   session descriptions expressed using the Session Description Protocol
   (SDP), SDPng, or some similar session description format.  This
   document describes a generalized model for IMG delivery mechanisms,
   the use of existing protocols, and the need for additional work to
   create an IMG delivery infrastructure.

Nomura, et al.               Informational                      [Page 1]
RFC 4435                     IMG Framework                    April 2006

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................3
      2.1. New Terms ..................................................4
   3. IMG Common Framework Model ......................................5
      3.1. IMG Data Types .............................................5
           3.1.1. Complete IMG Description ............................5
           3.1.2. Delta IMG Description ...............................6
           3.1.3. IMG Pointer .........................................6
      3.2. IMG Entities ...............................................6
      3.3. Operation Set for IMG Delivery .............................7
           3.3.1. IMG ANNOUNCE ........................................7
           3.3.2. IMG QUERY ...........................................8
           3.3.3. IMG RESOLVE .........................................8
           3.3.4. IMG SUBSCRIBE .......................................8
           3.3.5. IMG NOTIFY ..........................................9
           3.3.6. Binding between IMG Operations and Data Types .......9
      3.4. Overview of Protocol Operations ...........................10
   4. Deployment Scenarios for IMG Entities ..........................10
      4.1. Intermediary Cases ........................................10
      4.2. One-to-Many Unidirectional Multicast ......................12
      4.3. One-to-One Bidirectional Unicast ..........................12
      4.4. Combined Operations with Common Metadata ..................13
   5. Applicability of Existing Protocols to the Proposed
      Framework Model ................................................14
      5.1. Existing Standard Fitting the IMG Framework Model .........14
      5.2. IMG Mechanism Needs Which Are Not Met by Existing
           Standards .................................................15
           5.2.1. A Multicast Transport Protocol .....................16
           5.2.2. Usage of Unicast Transport Protocols ...............16
           5.2.3. IMG Envelope .......................................17
           5.2.4. Metadata Data Model ................................18
   6. Security Considerations ........................................18
   7. Normative References ...........................................19
   8. Informative References .........................................19
   9. Acknowledgements ...............................................20

Nomura, et al.               Informational                      [Page 2]
RFC 4435                     IMG Framework                    April 2006

1.  Introduction

   Internet Media Guides (IMGs) provide and deliver structured
   collections of multimedia descriptions expressed using SDP [2], SDPng
   [3], or other description formats.  They are used to describe sets of
   multimedia services (e.g., television program schedules, content
   delivery schedules) and refer to other networked resources including
   web pages.  IMGs provide an envelope for metadata formats and session
   descriptions defined elsewhere with the aim of facilitating
   structuring, versioning, referencing, distributing, and maintaining
   (caching, updating) such information.