1、 International Telecommunication Union ITU-T F.750TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (02/2005) SERIES F: NON-TELEPHONE TELECOMMUNICATION SERVICES Audiovisual services Metadata framework ITU-T Recommendation F.750 ITU-T F-SERIES RECOMMENDATIONS NON-TELEPHONE TELECOMMUNICATION SERVICES TE
2、LEGRAPH SERVICE Operating methods for the international public telegram service F.1F.19 The gentex network F.20F.29 Message switching F.30F.39 The international telemessage service F.40F.58 The international telex service F.59F.89 Statistics and publications on international telegraph services F.90F
3、.99 Scheduled and leased communication services F.100F.104 Phototelegraph service F.105F.109 MOBILE SERVICE Mobile services and multidestination satellite services F.110F.159 TELEMATIC SERVICES Public facsimile service F.160F.199 Teletex service F.200F.299 Videotex service F.300F.349 General provisi
4、ons for telematic services F.350F.399 MESSAGE HANDLING SERVICES F.400F.499DIRECTORY SERVICES F.500F.549 DOCUMENT COMMUNICATION Document communication F.550F.579 Programming communication interfaces F.580F.599 DATA TRANSMISSION SERVICES F.600F.699 AUDIOVISUAL SERVICES F.700F.799 ISDN SERVICES F.800F.
5、849 UNIVERSAL PERSONAL TELECOMMUNICATION F.850F.899 HUMAN FACTORS F.900F.999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. F.750 (02/2005) i ITU-T Recommendation F.750 Metadata framework Summary A metadata framework architecture with two layers structure is defin
6、ed. The metadata gateway provides an integrated metadata retrieval capability across various metadata descriptions, and the policy-based service platform provides specific functions common to content delivery. This Recommendation provides a reference architecture of a metadata model for both content
7、 description and network control. Source ITU-T Recommendation F.750 was approved on 13 February 2005 by ITU-T Study Group 16 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. F.750 (02/2005) FOREWORD The International Telecommunication Union (ITU) is the United Nations speciali
8、zed agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a wo
9、rldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in
10、 WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication admi
11、nistration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provi
12、sions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention t
13、o the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outsi
14、de of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the lat
15、est information and are therefore strongly urged to consult the TSB patent database. ITU 2005 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. F.750 (02/2005) iii CONTENTS Page 1 Scope 1 2 References.
16、 1 2.1 Normative references 1 2.2 Non-normative references 1 3 Definition 2 4 Abbreviations 2 5 Advanced content delivery service architecture. 3 5.1 Advanced content delivery. 3 5.2 Network-related metadata 5 5.3 Role and application of metadata in network. 6 6 Metadata framework. 7 6.1 Metadata ga
17、teway. 7 6.2 Service platform using metadata 10 Appendix I Policy-based QoS control using metadata . 11 I.1 Model of policy-based QoS control using metadata 12 I.2 Implementation of QoS control 14 Appendix II Policy-based CDN management using metadata 15 II.1 Directory database as metadata retrieval
18、 infrastructure . 15 II.2 Metadata for CDN optimization. 16 II.3 Policy descriptions in CDN management. 17 II.4 Interoperability of metadata across different domains . 19 II.5 Service platform API 19 ITU-T Rec. F.750 (02/2005) 1 ITU-T Recommendation F.750 Metadata framework 1 Scope This Recommendati
19、on defines an ITU-T metadata framework architecture for policy-based content delivery over networks. Content includes multimedia Web content and digital broadcast programmes provided by real-time streaming, on-demand streaming, and downloading. In broadband ubiquitous networks, this architecture ena
20、bles content adaptation to the usage environment and content-aware QoS control, which are provided as network services by the use of policies, rules and network-related metadata. The proposed metadata framework architecture is structured in two layers: a metadata gateway and a policy-based service p
21、latform each of which provides open APIs to the next higher layer. The metadata gateway provides an integrated metadata retrieval capability across various metadata descriptions and the policy-based service platform provides specific functions common to content delivery such as compatible content di
22、scovery, session control, QoS control, authentication and charging. As implementation examples of the metadata framework architecture, policy-based QoS control and CDN management are addressed. 2 References 2.1 Normative references The following ITU-T Recommendations and other references contain pro
23、visions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possi
24、bility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recomme
25、ndation. References: None. 2.2 Non-normative references 1 IETF RFC 2327 (1998), SDP: Session Description Protocol. 2 ETSI TS 102 822-3-1 (2004), Broadcast and On-line Services: Search, select, and rightful use of content on personal storage systems (“TV-Anytime Phase 1“); Part 3: Metadata; Sub-part
26、1: Metadata schemas. 3 ISO/IEC JTC1/SC29/WG11 2002, N4980 MPEG-7 Overview (version 8). 4 W3C Recommendation (2004), Composite Capabilities/Preference Profiles (CC/PP), Structure and Vocabularies. 5 IETF RFC 2778 (2000), A Model for Presence and Instant Messaging. 6 IETF RFC 2779 (2000), Instant Mess
27、aging/Presence Protocol Requirements. 7 ISO/IEC 21000-7(2004), Information technology Multimedia framework (MPEG-21) Part 7: Digital Item Adaptation. 8 IETF RFC 1213 (1991), Management Information Base for Network Management of TCP/IP-based internets: MIB-II. 9 PAM Forum, http:/www.parlay.org/about/
28、pam/index.asp. 2 ITU-T Rec. F.750 (02/2005) 10 ITU-T Recommendation H.350 (2003), Directory services architecture for multimedia conferencing. 11 IETF RFC 3564 (2003), Requirements for Support of Differentiated Services-aware MPLS Traffic Engineering. 12 IETF RFC 3466 (2003), A Model for Content Int
29、ernetworking (CDI). 13 ETSI TS 102 822-4 (2004), Broadcast and On-line Services: Search, select, and rightful use of content on personal storage systems (“TV-Anytime Phase 1“); Part 4: Content referencing. 3 Definitions This Recommendation defines the following terms: 3.1 content delivery network (C
30、DN): A network optimized for delivering digital content. 3.2 differentiated service code point (DSCP): A 6-bit bit-pattern replacing the three IP-Precedence bits and other ToS (Type of Service) bits for differentiated services. 3.3 label switch paths (LSP): Virtual paths between pairs of edges prepa
31、red in MPLS. 3.4 metadata: “Metadata“ in this Recommendation refers to the attributes of not only the content but also the network. 3.5 resource description framework (RDF): A general framework for describing a Web sites metadata, or the information about the information on the site. 4 Abbreviations
32、 This Recommendation uses the following abbreviations: 3GPP 3rd Generation Partnership Project API Application Programming Interface APL Application Programming Language CC Call Control CC/PP Composite Capabilities/Preference Profiles CDN Content Delivery Network CID Content Identification DSCP Diff
33、erentiated Services Code Point DSL Digital Subscriber Line HTTP HyperText Transfer Protocol IMPP Instant Messaging and Presence Protocol LSP Label Switch Paths MIB Management Information Base MPLS Multi Protocol Label Switching OWL Web Ontology Language PAM Presence and Availability Management PBCDN
34、M Policy-based CDN Management ITU-T Rec. F.750 (02/2005) 3 PC Personal Computer PDA Personal Digital Assistant QoS Quality of Service RDB Relational Database RDF Resource Description Framework SDP Session Description Protocol SIP Session Initiation Protocol SLA Service Level Agreement SOAP Simple Ob
35、ject Access Protocol SQL Structured Query Language ToS Type of Service UI User Interaction UNI User-Network Interface W3C World Wide Web Consortium WSDL Web Services Description Language XML eXtensible Markup Language XQL XML Query Language 5 Advanced content delivery service architecture 5.1 Advanc
36、ed content delivery Owing to rapid progress in broadband and wireless Internet access technologies, various kinds of digital content are being delivered to diverse terminal devices (PDAs, PCs, cellular phones, etc.) that are connected by diverse access methods (DSL, wireless, optical-fibre, etc.). F
37、urthermore, digital broadcasting will soon arrive in such an environment. Figure 1 shows content delivery in a ubiquitous environment. In such a configuration, it is desirable that the network automatically detects the users usage environment and adapts the content delivery to allow convenient viewi
38、ng. It is also desirable that the network recognizes the users preferences for delivery method and quality and adapts to them. To achieve such advanced content delivery, the network requires context understanding and content adaptation. Figure 2 shows a mechanism for advanced content delivery by the
39、 network. Conditions on the content side, user side, and network side are described in metadata. When a user requests content, the network gathers relevant metadata to understand the conditions. Then, for those conditions, it optimizes content delivery according to pre-defined policies. This Recomme
40、ndation provides a standardized framework for achieving this mechanism. 4 ITU-T Rec. F.750 (02/2005) Figure 1/F.750 Content delivery in ubiquitous environment Figure 2/F.750 Mechanism for advanced content delivery ITU-T Rec. F.750 (02/2005) 5 5.2 Network-related metadata Originally, metadata is defi
41、ned for efficient content retrieval and for building up clear rules in secondary use of content across different providers and/or organizations. This metadata describes attribution, usage rules, and target user profiles of content for the consumer. In addition to such metadata for customer and/or co
42、ntent provider use, this Recommendation defines a new kind of metadata for network use, which will facilitate advanced content delivery. Called “network-related metadata“, it specifies various conditions for content delivery over networks such as terminal device characteristics, access network chara
43、cteristics, and user preferences. Several standardization bodies have already defined various attribute types of information for network services that are equivalent to network-related metadata: a) Content delivery metadata i) Session Description Protocol (SDP) (IETF) 1; ii) Instance description met
44、adata (TV-Anytime Forum) 2; iii) Multimedia description (MPEG-7) 3. b) User description metadata i) Composite Capability and Preference Profiles (CC/PP) (W3C) 4; ii) Consumer metadata (TV-Anytime Forum) 2; iii) User interaction (MPEG-7) 3; iv) Presence information (IETF) 5, 6; v) Usage environment (
45、MPEG-21) 7. c) Terminal description metadata i) Composite Capability and Preference Profiles (CC/PP) (W3C) 4; ii) Usage environment (MPEG-21) 7. d) Network description metadata i) Service Level Agreement (SLA); ii) Management Information Base (MIB-II) (IETF) 8. Except for SLA and MIB-II, these types
46、 of information are described by XML (or RDF) and some are interoperable. By using this information, 3GPP specifies CC/PP-based content adaptation service for cell phones, and IETF specifies SIP (Session Initiation Protocol) that establishes dynamic sessions to a target user by using presence inform
47、ation. As these types of metadata are defined by different organizations for different application domains, metadata translation and/or matching is needed to share metadata for specific services. The objective in defining this metadata framework is not to invent new metadata, but to extract existing
48、 metadata relevant to communication and make it interoperable. In a similar way to content-related metadata, network-related metadata should be interoperable within the same provider and/or across different providers. The requirements of metadata are that the total structure is clearly defined in te
49、rms of language, scheme, elements, and vocabulary and is interoperable at some levels of the metadata structure shown in Figure 3. 6 ITU-T Rec. F.750 (02/2005) Figure 3/F.750 Metadata structure 5.3 Role and application of metadata in network Figure 4 shows, as an example, a potential usage scenario of a metadata-based network service in terms of seamless content handover. This service allows easy handover of programmes between a wide range of terminals irrespective of the specific viewing site, termina
