1、 International Telecommunication Union ITU-T J.200TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (04/2010) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Application for Interactive Digital Television Worldwide common core Application environme
2、nt for digital interactive television services Recommendation ITU-T J.200 Rec. ITU-T J.200 (04/2010) i Recommendation ITU-T J.200 Worldwide common core Application environment for digital interactive television services Summary Recommendation ITU-T J.200 identifies the structure, the origins and the
3、 specification sources for a harmonized environment, including a set of application programming interfaces (APIs) for interactive television services. History Edition Recommendation Approval Study Group 1.0 ITU-T J.200 2001-03-09 9 1.1 ITU-T J.200 (2001) Cor. 1 2004-05-14 9 2.0 ITU-T J.200 2010-04-2
4、9 9 ii Rec. ITU-T J.200 (04/2010) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of
5、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 worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics
6、 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 WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepar
7、ed on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may
8、contain certain mandatory provisions (to ensure e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to expr
9、ess 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 to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Prop
10、erty Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of
11、 intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2010 A
12、ll rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T J.200 (04/2010) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 1 4
13、 Abbreviations and acronyms 4 5 Conventions 5 6 Common application environment . 5 6.1 Basic architecture . 5 6.2 Execution engine 7 6.3 Presentation engine . 7 Appendix I Terminology relevant to specific APIs 9 Bibliography. 15 iv Rec. ITU-T J.200 (04/2010) Introduction This Recommendation is the r
14、esult of collaboration, within ITU-T and ITU-R, of organizations such as DVB, ARIB, ATSC, OpenCable, ABNT, etc., who have contributed to the process of harmonizing the application environment for a wide range of media throughout the world. This Recommendation outlines the structure of application en
15、vironments specified by organizations such as those listed above and indicates the high level of commonality which has been achieved. It includes the origin and key specification sources used to define the application environment in the normative references, as well as relevant terms, definitions, a
16、bbreviations and acronyms. Additional descriptions of terms and acronyms relating to the general subject of digital video have also been included for information. Rec. ITU-T J.200 (04/2010) 1 Recommendation ITU-T J.200 Worldwide common core Application environment for digital interactive television
17、services 1 Scope This Recommendation defines the high-level architecture for a harmonized set of interactive content formats and application programming interfaces (APIs) capable of providing the variety of functionalities required by advanced interactive applications to be delivered over television
18、 networks to end-users homes. This application environment can also be used for downloading purposes, display purposes, network control and security. This Recommendation is intended to provide the “umbrella“ for the work in progress preparing the detailed Recommendations defining the specifications
19、for the application environment for various applications and also the mechanisms provided for future extensions. There will of course be some regional or media-specific requirements which demand variation from the common structure recommended. However, this “umbrella“ Recommendation is intended to e
20、ncourage and assist continued harmonization of the work in progress in the ITU on the application environment for digital interactive television services. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provis
21、ions 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 possibility of applying the most recent edition of the Recommendation
22、s 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 Recommendation. ITU-T J.201 Recommendation ITU-T J.201 (2009), Harmoniz
23、ation of declarative content format for interactive television applications. ITU-T J.202 Recommendation ITU-T J.202 (2008), Harmonization of procedural content formats for interactive TV applications. 3 Definitions 3.1 Terms defined elsewhere None. 3.2 Terms defined in this Recommendation This Recom
24、mendation defines the following terms: 3.2.1 application: Information that expresses a specific set of observable behaviour. 3.2.2 application entity: A unit of information that expresses some portion of an application. 3.2.3 application environment (environment): The context or software environment
25、 in which an application is processed. 3.2.4 application programming interface (API): Software libraries that provide uniform access to system services. 2 Rec. ITU-T J.200 (04/2010) 3.2.5 application resource: A bit-stream serialization (a physical embodiment) of an application entity. 3.2.6 applica
26、tion resource collection: The set of application resources that embody an application entity collection. 3.2.7 broadcast markup language (BML) standard: An XML b-W3C XML application language b-ARIB STD B-24 that deals with tags and attributes for multimedia representation exclusively. 3.2.8 cascadin
27、g style sheets (CSS): Standard for the style sheet for a markup language document. 3.2.9 content: A general term that refers to any of the following: application, application resource collection, or application resource. 3.2.10 declarative application: An application which primarily makes use of dec
28、larative information to express its behaviour; an XML document instance is an example of a declarative application. 3.2.11 declarative application environment: An environment that supports the processing of declarative applications; an XML user agent (browser) is an example of a declarative applicat
29、ion environment. 3.2.12 digital storage media command and control (DSM-CC): A control method defined in b-ISO/IEC 13818-6, which provides access to files and streams for digital interactive services. 3.2.13 document object model (DOM): An API that defines the logical structure of XML b-W3C XML and H
30、TML b-W3C HTML documents and the way a document is accessed and manipulated. It is also called DOM-API. It is an interface independent from platforms and languages. 3.2.14 document object model (DOM) object: An object generated by a HTML b-W3C HTML document. 3.2.15 ECMAScript: Programming language d
31、efined by b-ECMAScript. 3.2.16 execution engine: A subsystem in a receiver that evaluates and executes procedural applications consisting of computer language instructions and associated data and media content. An execution engine may be implemented with an operating system, computer language compil
32、ers, interpreters and application programming interfaces (APIs), which a procedural application may use to present audiovisual content, interact with a user, or execute other tasks that are not evident to the user. A common example of an execution engine is the JavaTV software environment, using the
33、 Java programming language and byte code interpreter, JavaTV APIs, and a Java virtual machine for program execution. 3.2.17 extensible HTML (XHTML): Reformulation of HTML b-W3C HTML as an application language of XML b-W3C XML. 3.2.18 formatter: A subsystem in a receiver that evaluates and presents d
34、eclarative applications consisting of content in multiple formats. A formatter also responds to formatting information associated with the content, to user inputs, and to script statements that control presentation behaviour and initiate other processes in response to user input and other events. An
35、 example of a formatter is a nested context language (NCL) b-NCL formatter engine. 3.2.19 function: A process which conveys or transforms data in a predictable way. It may be effected by hardware, software or a combination of both. 3.2.20 GINGA: The middleware specification for the Brazilian digital
36、 TV system. It comprises two execution environments, for both declarative and imperative applications. Rec. ITU-T J.200 (04/2010) 3 3.2.21 GINGA-J: Gingas execution environment for imperative applications written in Java. It also comprises a set of APIs for the development of interactive digital TV
37、applications. 3.2.22 interoperability: The reception and presentation of applications in a vendor-, author- and broadcaster-neutral framework. 3.2.23 Lua: Lightweight embeddable scripting language that combines simple procedural syntax with data description constructs, based on associative arrays an
38、d extensible semantics. 3.2.24 markup language: A formalism that describes a documents structure, appearance, or other aspects. An example of a markup language is XHTML b-W3C HTML1. 3.2.25 multimedia hypermedia experts group-5 (MHEG-5): A specification b-ISO/IEC 13522-5 for presentation engine appli
39、cations designed for decoding in interactive television receivers using modest resources. The UK profile b-MHEG Profile, which is recognized within the ISO standard, extends the specification. It shares common text and graphics formats, and carousel mechanism with multimedia home platform (MHP), thu
40、s allowing the use of common data between MHEG-5 and MHP applications, with only a small overhead. 3.2.26 nested context language (NCL): The nested context language b-NCL is a declarative language that is used to describe the temporal behaviour of a multimedia presentation to associate hyperlinks (u
41、ser interaction) with media objects, to define alternatives for presentation (adaptation), and to describe the layout of the presentation on multiple devices. 3.2.27 object: An identifiable entity consisting of data and/or computer code. 3.2.28 packet: A packet is a set of contiguous bytes consistin
42、g of a header followed by its payload. 3.2.29 payload: The bytes following the header byte in a packet. 3.2.30 presentation engine: A subsystem in a receiver that evaluates and presents declarative applications consisting of content, such as audio, video, graphics, and text, primarily based on prese
43、ntation rules defined in the presentation engine. A presentation engine also responds to formatting information, or “markup“, associated with the content, to user inputs, and to script statements, which control presentation behaviour and initiate other processes in response to user input and other e
44、vents. A common example of a presentation engine is an HTML browser, capable of displaying text and graphic content formatted in HTML b-W3C HTML, with interactive behaviour programmed in ECMAScript b-ECMAScript. 3.2.31 procedural application: An application which primarily makes use of procedural in
45、formation to express its behaviour. A Java program is an example of a procedural application. 3.2.32 procedural information: Information expressed in the form of procedures, e.g., do F or F( ). 3.2.33 receiver platform (platform): The receivers hardware, operating system and native software librarie
46、s of the manufacturers choice. 3.2.34 resource (system): A well-defined capability or asset of a receiver, which can be used by the application environment. Examples: MPEG decoder, graphics system. 3.2.35 return channel: The communication mechanism which provides connection between the receiver and
47、a remote server. 3.2.36 scripting language: A language to describe the program process, which is embedded in markup documents. 3.2.37 section: A syntactic structure specified in b-ITU-T H.222.0 for the embedding of data in the transport stream. A data structure comprising a portion of a b-ITU-T H.22
48、2.0 (or a 4 Rec. ITU-T J.200 (04/2010) b-ISO/IEC 13818-6) defined table, such as the program association table (PAT), conditional access table (CAT), program map table (PMT) or DSM-CC section. 3.2.38 service: Content and applications provided by network operators and broadcasters. 3.2.39 service bou
49、nd application: An application delivered as part of a broadcast stream. 3.2.40 service information (SI): Data that describes programs and services. 3.2.41 transport stream: MPEG-2 transport stream syntax for the packetization and multiplexing of video, audio, and data signals for digital broadcast systems. 3.2.42 trigger: An event that may cause a change in the behaviour of the application that registers interest in such events. Triggers may come from many sources, e.g., the broadcast stream, or may be generated from other data
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