1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU T.175 (02i98) SERIES T: TERMINALS FOR TELEMATIC SERVICES Application Programming Interface (API) for MHEG-5 ITU-T Recommendation T. 175 (Previously CCITT Recommendation) ITU-T T-SERIES RECOMMENDATIONS TERMINA
2、LS FOR TELEMATIC SERVICES For further details, please refer to ITU-T List of Recommendations. ITU-T RECOMMENDATION T.175 APPLICATION PROGRAMMING INTERFACE (API) FOR MHEGJ Summary This Recommendation specifies the Application Programming Interface (API) for the manipulation of multimedia and hypermed
3、ia information objects. MHEG part 5 (Recommendation T.172) is a standard, which specifies the coded representation of interchanged multimediahypermedia information objects (MHEG-5 objects) for base-level applications. These so-called MHEG-5 objects are handled, interpreted and presented by MHEG-5 en
4、gines. Source ITU-T Recornmendation T.175 was prepared by ITU-T Study Group 16 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 6th of February 1998. FOREWORD IT (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunic
5、ations. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the IT. The 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 Telecom
6、munication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the IT-T is covered by the procedure laid down in WT
7、SC Resolution No. 1. In some areas of information technology which fail within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. . NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication a
8、dministration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The IT takes no position concerning the evidence, validity
9、 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, the IT had not received notice of intellectual property, protected by patents, which may be requi
10、red to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. O ITU 1998 All rights reserved. No part of this publication may be reproduced or utilized in any form or b
11、y any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. 11 Recommendation T.175 (02/98) 1 2 3 3.1 3.2 4 4.1 4.2 5 6 STD-ITU-T RECMN ToL75-ENGL 1998 W 48b259L Ob45395 T32 W CONTENTS Page Scope Normative references Definitions and abbrev
12、iations . Definitions Abbreviations . Overview The DAVIC application interchange format Core set of Java APIS . The MHEG-5 API Map between MHEG-5 elementary actions and MHEG-5 API operations . Recommendation T.175 (02/98) i 1 2 4 22 . 111 Recommendation T.175 APPLICATION PROGRAMMING INTERFACE (API)
13、FOR MHEG-5 (Geneva, 1998) 1 Scope This Recommendation specifies the Application Programming Interface (MI) for the manipulation of multimedia and hypermedia information objects, i.e. the API that shall be provided by MHEG-5 engines for their control by applications running on a DAVIC 1.1 compliant t
14、erminal. MHEG part 5 (Recommendation T.172) is a standard, which specifies the coded representation of interchanged multimediahypermedia information objects (MHEG-5 objects) for base-level applications. These so-called MHEG-5 objects are handled, interpreted and presented by MHEG-5 engines. 2 Normat
15、ive references The following ITU-T Recommendations and other references contain provisions 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 revis
16、ion; all users of this Recommendation are therefore encouraged to investigate the possibility 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. Pl Pl 1131 41 3 3.1 ISOIIEC 13522-5:
17、 1997, Information technologv - Coding of multimedia and hypermedia information - Part 5: Support for base-level interactive applications. ETS 300 777-1, Terminal Equipment (TE); End-to-end protocols for multimedia information retrieval services; Part I: Coding of multimedia and hypermedia informati
18、on for basic multimedia applications (MHEG-5). ETS 300 777-2, Terminal Equipment (TE); End-to-end protocols for multimedia information retrieval services; Part 2: Use of Digital Storage Media Command and Control (DSM-CC) for basic multimedia applications. ISOIIEC DIS 13522-6, Information technology
19、- Coding of multimedia and hypermedia information - Part 6: Support for enhanced interactive applications. Definitions and abbreviations Definitions For the purposes of this Recommendation the definition of the standards referenced below apply. Should any ambiguity occur, definitions of the followin
20、g standards apply, in decreasing order: - ISOIIEC 13522-5 i MHEG-5; - 3.1.1 Application Programming Interface (API): A boundary across which a software application uses facilities of programming languages to invoke software services. These facilities may include procedures or operations, shared data
21、 objects and resolution of identifiers. any other standard part of ISOAEC 13522 MHEG. Recommendation T.175 (02/98) 1 - STD-ITU-T RECMN TeL75-ENGL 1998 4Bb257L 0645397 BO5 W 3.1.2 and is running on the considered equipment. 3.1.3 manipulation of MHEG-5 objects, as defined in this Recommendation. 3.1.
22、4 according to the encoding specifications of ETS 300 777-1 2 or the MHEG-5 textual notation. local application: A piece of software which is part of the (telecommunication) application MHEG-5 API: The API provided by an MHEG-5 engine to local applications for the MHEG-5 engine: A process or a set o
23、f processes that interpret MHEG-5 objects encoded 3.2 Abbreviations This Recommendation uses the following abbreviations: API Application Programming Interface ASN. 1 Abstract Syntax Notation One DAVIC Digital Audio Visual Council DSM-CC EBNF Extended Backus-Naur Form JTC Joint Technical Committee M
24、HEG SI Service Information STU Set Top Unit VM Virtual Machine Digital Storage Media Command and Control Multimedia and Hypermedia information coding Experts Group 4 Overview The following subclause positions the API defined by this Recommendation in the framework of the DAVIC specifications. 4.1 To
25、 deliver multimedia information to STUs in an interoperable way, applications shall use the MHEG-5 final form interchange format, as defined by ISOAEC 13522-5 i. The ASN.1 notation and encoding, as defined by ETS 300 777-1 2, shall be used to interchange MHEG-5 objects. This format defines the seman
26、tics and the encoding of the multimedia and hypermedia objects. To deliver program code to STUs in an interoperable way, applications shall use the MHEG-5 InterchangedProgram class to encapsulate Java1 VM code, according to the semantics and encoding defined by ISOAEC DIS 13522-6 4. Java VM classes
27、are called from MHEG-5 objects using the MHEG-5 Call and Fork elementary actions. The Java VM code interchange unit is a Java VM class. Java VM classes shall be encoded as defined by the Class File Format section of the Java Virtual machine specijkation. A Java class encapsulates data and methods th
28、at consist of sequences of instructions. The instruction set is defined by the Java Virtual machine instruction set section of the Java Virtual machine specijkation. The DAVIC application interchange format Java is a trademark or a registered trademark of Sun Microsystems, Inc. 2 Recommendation T.17
29、5 (02/98) STD-ITU-T RECMN T.175-ENGL 1998 m 48b2591 Ob45398 741 m 4.2 Core set of Java APIs The following set of APIs are used by Java VM code in the DAVIC 1.1 specifications to express access to basic functions of the STU in an interoperable way: - the j ava . lang package; - the j ava . ut i 1 pac
30、kage; - the is0 .mheg5 package; - the davic. dsmccuu package; - the et s i. si package. NOTE 1 - The Java VM specification provides flexible mechanisms to call upon external functions whose interface is defined as a Java package. The DAVIC 1.1 specification only includes a minimum core set of packag
31、es required for Java VM code to be useful in a DAVIC environment. It is anticipated that additional Java packages will be standardised at a later stage. NOTE 2 - Especially, the java.io package, although strictly speaking not necessary to the useful performance of the VM environment, is part of the
32、Java foundation classes. It is intended that the j ava . io package be added to the DAVIC core set of Java APIs together with an adequate specification of its semantics in a DAVIC environment. The j ava . lang package, as defined by the Java API documentation, consists of the minimal set of Java VM
33、classes needed to run Java VM code, supporting the following functionality: basic data types, object, mathematic operations, security, thread management, string manipulation, exception handling. The j ava . util package, as defined by the Java API documentation, consists of Java VM classes supportin
34、g a number of utility features common to all Java VM programs. The is0 .mheg5 package, as defined by this Recommendation, provides Java VM code with access to and manipulation of the MHEG-5 multimedia presentation and interaction objects, i.e. access to the dynamic attributes of MHEG-5 objects and i
35、nvocation of elementary actions on MHEG-5 obj ects . The davic. dsmccuu package, together with the associated davic. CosNaming and davic. CosNaming . NamingContext- packages, as defined by ETS 300 777-2 3, enables Java VM code to use the DSM-CC U-U interface objects for network data access. The davi
36、c.dsmccuu package implements a subset of the DSM-CC U-U API. Access to the following Core SetTop services is provided: - - - - - - The etsi. si package enables Java VM code to access information transmitted in the DAVIC Service Information (SI) stream. interface Base: operations Close and Destroy; i
37、nterface File: operations Read and Write; interface Directory: operations Open, Close and Get; interface ServiceGateway: operations Attach and Detach; interface CosNaming:NamingContext: operations List and Resolve; interface C0sNaming:BindingIterator: operations Next-One and Next-N. Recommendation T
38、.175 (02/98) 3 - STD=ITU-T RECMN T.375-ENGL 3998 I 4862593 Ob45399 b88 5 The MHEG-5 API /* Constructors */ public Obj ectReference ( ) ; public ObjectReference( int obj ectNumber 1 ; public ObjectReference ( byte I groupIdentifier, int objectNumber); 1 / _-_- public class ContentReference I /* Attri
39、butes */ byte reference; /* Constructors */ public ContentReference(); public ContentReference( byte reference); 1 / _- I public class MhegException extends java.lang.Exception /* Attributes */ / Constant declarations for exceptionlode public static final short TARGET NOT AVAILABLE = 1; public stati
40、c final short INVALID TARGET = 2; public static final short INVALIDIPARAMETER = 3; public short exceptioncode; public short parameterRank; /* Constructors */ protected MhegExceptionO; / Construct an MhegException with exceptioncode identified by the reason / parameter public MhegException( short rea
41、son) .I exceptioncode parameterRank 1 = reason; = -1; 4 Recommendation T.175 (02198) STD-ITU-T RECMN T-375-ENGL 1778 W 4862573 Ob45400 12T / Construct an MhegException with exceptionlode identified by the reason / parameter and parameterRank by the position parameter public MhegException( short reas
42、on, short position) t exceptionlode = reason; parameterRank = position; 1 . 1 / -_- abstract public class Root I /* Constructors */ protected Root () ; /* Methods */ / Return the reference of the Java object associated with the MHEG-5 object / whose identification is mheg50bjectReference / If the Ja
43、va object does not exist, create it first public static final Root getobject( ObjectReference mheg50bjectReference) throws MhegException; / Correspond to the GetAvailabilityCtatus MHEG-5 elementary action public Boolean getAvailabilityStatus() throws MhegException; / Correspond to the GetRunningStat
44、us MHEG-5 elementary action public Boolean getRunningCtatus0 throws MhegException; 1 / _-_- abstract public class Group extends Root I /* Constructors */ protected Group () ; /* Methods */ / Correspond to the SetCachePriority MHEG-5 elementary action / The cachepriority parameter value shall be with
45、in the range 0,2551 public void setCachePriority( byte cachepriority) throws MhegException; / Retrieve the value of the GroupCachePriority attribute public Integer getCachePriority0 throws MhegException; 1 / -_-_- public class Application extends Group I /* Constructors */ protected Application () ;
46、 /* Methods */ / Correspond to the Lockscreen MHEG-5 elementary action public void lockscreen0 throws MhegException; / Correspond to the Unlockscreen MHEG-5 elementary action public void unlockScreen() throws MhegException; Recommendation T.175 (02/98) 5 / Retrieve the value of the LockCount attribu
47、te / The wrapped returned value shall be positive or equal to zero public Integer getlockcount0 throws MhegException; / Correspond to the GetEngineSupport MHEG-5 elementary action public Boolean getEngineSupport(byte feature) throws MhegException; I / -_-_- public class Scene extends Group I /* /* /
48、 / / / / / / Constructors */ protected Scene (1 ; Methods */ Correspond to the TransitionTo MHEG-5 elementary action public void transitionTo0 throws MhegException; public void transitionTo( int connectionTag) throws MhegException; public void transitionTo( byte transitionEffect) throws MhegException; public void transitionTo( int connectionTag, byte transitionEffect) throws MhegExcept
