BS ISO/IEC 13522-6:1998

1 Scope
    1.1 Context of the scope
    1.2 Scope of this part of ISO/IEC 13522
2 Normative references
    2.1 International standards
    2.2 Referenced specifications
3 Terms and definitions
    3.1 applet
    3.2 application class
    3.3 application programming interface (API)
    3.4 attribute
    3.5 class
    3.6 exception
    3.7 hypermedia, adj
    3.8 instance
    3.9 interface
    3.10 Java Virtual Machine (JVM)
    3.11 method
    3.12 MHEG-5 API
    3.13 MHEG-5 InterchangedProgram object
    3.14 MHEG-5 object
    3.15 MHEG-6,adj
    3.16 MHEG-6 Applet object
    3.17 MHEG-6 application
    3.18 MHEG-6 engine
    3.19 MHEG-6 InterchangedProgram object
    3.20 MHEG-6 object
    3.21 MHEG-6 profile
    3.22 MHEG-6 program
    3.23 multimedia, adj
    3.24 multimedia and hypermedia application
    3.25 multimedia application
    3.26 operation
    3.27 program
    3.28 Program content interchange format
    3.29 scripting language
    3.30 stack
    3.31 system class
    3.32 virtual machine (VM)
4 Symbols and abbreviations
5 Conformance requirements
    5.1 Information object conformance
          5.1.1 Encoding and syntax
          5.1.2 Semantics
          5.1.3 Profiles
    5.2 Implementation conformance
          5.2.1 Conformance requirements
          5.2.2 Conformance documentation
6 Structure of this part of ISO/IEC 13522
7 MHEG-6 InterchangedProgram class
    7.1 InterchangedProgram class
          7.1.1 Syntax of InterchangedProgram class
                  7.1.1.1 Name attribute
                  7.1.1.2 OriginalContent attribute
                  7.1.1.3 ContentHook attribute
                  7.1.1.4 Shared attribute
          7.1.2 Syntax of elementary actions applicable
                  to InterchangeProgram objects
    7.2 InterchangedProgram object semantics
          7.2.1 Initially Available attribute
          7.2.2 Scope of InterchangedProgram objects
          7.2.3 Effect of elementary actions applicable to
                  InterchangedProgram objects
                  7.2.3.1 Preparation behaviour
                  7.2.3.2 Activation behaviour
                  7.2.3.3 Deactivation behaviour
                  7.2.3.4 Destruction behaviour
8 Applet class
    8.1 Attributes
          8.1.1 Inherited attributes
          8.1.2 Own exchanged attributes
          8.1.3 Own internal MHEG-5 attributes
    8.2 Events
    8.3 Internal behaviours
    8.4 Effect of MHEG-5 elementary actions
    8.5 Formal description
9 Virtual machine
    9.1 VM instruction set
    9.2 VM interchange format
10 Kernel API
    10.1 Specification of the kernel API
    10.2 Syntax requirement
    10.3 Semantics requirement
    10.4 Pragmatics requirement
11 MHEG-5 API
    11.1 Specification of the MHEG-5 API
          11.1.1 Design principles
          11.1.2 Grades
    11.2 Syntax requirement
    11.3 Semantics requirement
    11.4 Pragmatics requirement
    11.5 Interworking considerations
12 MHEG-5/JVM interworking provisions
    12.1 Program content interchange format
    12.2 Semantics of elementary actions
          12.2.1 Call
          12.2.2 Fork
          12.2.3 Invoke
          12.2.4 Stop
          12.2.5 MHEG-5 API operations
    12.3 Execution semantics
          12.3.1 Engine bootstrapping
          12.3.2 ClassMapper initialisation
          12.3.3 Program preparation
          12.3.4 Program activation
          12.3.5 Program deactivation
          12.3.6 Program destruction
          12.3.7 ClassMapper for Applet
Annex A (normative) ASN.1 notation
Annex B (normative) Textual notation
Annex C (normative) MHEG-5 API
Annex D (informative) Mapping elementary actions to MHEG-5
API operations
Annex E (informative) Relationships between MHEG-6 Applets
and World Wide Web applets
Annex F (informative) Main features
Annex G (informative) IPR issues

Defines the coded representation of multimedia/hypermedia information objects (MHEG objects) for interchange as final form units within or across services and applications, using any interchange including local area networks, wide area telecommunication or broadcast networks, storage media and so on.

1.1 Context of the scope

ISO/IEC13522 specifies the coded representation of multimedia/hypermedia information objects (MHEG objects) for interchange as final form units within or across services and applications, by any means of interchange including local area networks, wide area telecommunication or broadcast networks, storage media, etc.

MHEG objects can be produced by computer tools taking as source form multimedia applications designed using multimedia scripting languages. In this context, the MHEG script (or program) classes are intended to complement the other MHEG classes in expressing the functionality commonly supported by scripting languages. Script (or program) objects express more powerful control mechanisms and describe more complex relationships among MHEG objects than can be expressed by MHEG action and link objects alone. Furthermore, script (or program) objects express access to and interaction with external services provided by the run-time environment.

ISO/IEC13522-5 defines the MHEG object classes for interchange and use in base-level applications intended to be run on limited resource terminals such as set-top-boxes in such contexts as interactive broadband services.

ISO/IEC13522-5 defines the coded representation for program objects in an open manner so that program objects may encapsulate either standardised or proprietary program code. ISO/IEC13522-5 allows program objects to include or reference programs that may be encoded in any encoding format as defined by the application domain.

1.2 Scope of this part of ISO/IEC13522

The scope of this part of ISO/IEC13522 is to define the semantics and final-form coded representation for the interchange of enhanced interactive multimedia applications.

These applications extend applications covered by ISO/IEC13522-5 in incorporating functionality such as computing (data processing) and extended communication with the external environment, including servers, local devices, etc.

These applications may be exploited in any communication environment including broadcast-only mode, interactive client-server or peer-to-peer (conversational). However, the main focus is on interactive retrieval (client-server) applications running on limited resource set-top-units involving asymmetrical data interchange with real-time audiovisuals on the downstream channel.

The coded representation defined by this part of ISO/IEC13522 specialises the coded representation defined by ISO/IEC13522-5. Especially, this part of ISO/IEC13522 defines the coded representation for the OriginalContent attribute of the MHEG-5 InterchangedProgram class. In addition, this part of ISO/IEC13522 defines the Applet class; this subclass of InterchangedProgram features the ability to manage its own display and interaction, by delegation from the engine.

The resulting coded representation is

• compatible with that defined by ISO/IEC13522-5;

• appropriate for execution on a set-top-unit with the same minimal resource constraints as expressed by ISO/IEC13522-5.

This part of ISO/IEC13522 specifies

• the interchange format for the OriginalContent attribute of the MHEG-5 InterchangedProgram class;

• the semantics of this coded representation;

• the coded representation and semantics of the Applet class;

• the semantic extensions to the MHEG-5 engine behaviour described by ISO/IEC13522-5;

• the semantic restrictions on the MHEG-5 interchange format described by ISO/IEC13522-5;

• the MHEG-5 API, which allows the code of an InterchangedProgram object to call upon the MHEG-5 engine\'s presentation functionality;

• the provisions for interworking between the MHEG-5 engine execution model and the execution model that underlies the program content interchange format.

MHEG engines are system or application components that handle, interpret and present MHEG objects. This part of ISO/IEC13522 specifies the semantics of the MHEG-6 coded representation. These semantics are defined in terms of minimum requirements on the behaviour of MHEG-6 engines.

This part of ISO/IEC13522 is applicable to all applications that interchange multimedia and hypermedia information.