1、INTERNATIONAL STANDARD ISOIIEC 14478-l First edition 1998-12-15 Information technology - Computer graphics and image processing - Presentation Environment for Multimedia Objects (PREMO) - Part 1: Fundamentals of PREMO Technologies de /information - lnfographie et traitement dimages - Environnement d
2、e pksentation dobjets multim these operations collectively characterize the objects behav- iour. 3.2.11.2 object reference: An object name which reliably denotes a particular object instance. This is a non-object. 3.2.12 state: Information encapsulated within an object that has to be remembered when
3、 one operation alters the future be- haviour of future operations. 3.2.13 identity (of objects): Objects have a unique, immutable identity which provides a means to denote or refer to the object independent of its state or behaviour. 0 ISO/IEC ISO/IEC 1447%1:1998(E) 3.2.14 attribute (of objects): A
4、pair of accessor and mutator functions, to retrieve the value of to set the value of the at- tribute. 3.2.14.1 retrieve only attribute: An object attribute where the mutator function to set the value, though conceptually present, does not change the value of the attribute, and raises an exception. 3
5、.2.15 signature (of operations): An operations signature consists of a list of parameter types, and a list of result types. 3.2.16 interface (of objects): The set of operation signatures defined for a type. 3.2.17 non-object types: Things that are not objects, e.g., integers, real numbers. 3.2.18 op
6、eration: Describes an action that can be applied to an object, using parameters. 3.2.18.1 operation invocation: Activation of an objects action, by describing its parameters, possibly causing results to be returned. 3.2.18.2 operation request: Synonym for operation invocation. 3.2.18.3 operation dis
7、patching: The selection process which selects a specific operation implementation for execution. 3.2.18.4 operation overloading: The implementation of an operation defined for a derived interface supersedes the im- plementation of the same operation defined for a base interface. This effect is calle
8、d operation overloading. 3.2.19 client: (of another object) An object issuing an operation request. 3.2.20 exception: Information returned if an error condition has occurred during the execution of a request of an operation. 3.2.21 controlling parameter: Special parameter conceptually present for al
9、1 operations, used to control the way opera- tions are dispatched. It refers to the object type on which the operation is defined. 3.2.22 subtyping: A relationship between types. It defines the rules by which objects of one type are determined to be ac- ceptable in contexts expecting another type. 3
10、.2.23 subtype: A type S is a subtype of another type T if any object of type S can be used in any context that expects an object of type T. 3.2.23.1 immediate subtype: A type S is an immediate subtype of another type T, if T is the immediate supertype of S. 3.2.24 supertype: A type T is a supertype
11、of S, if S is a subtype of T. 3.2.24.1 multiple supertype: An object type can have more than one supertype; they are referred to as multiple super- types. 3.2.24.2 immediate supertype: A type T is an immediate supertype of type S, if it is a supertype of S, and there is no type Q such that Q is a su
12、pertype of S and T is a supertype of Q. 3.2.25 direct instance: An object is a direct instance of a type T, if it is an instance of T and not an instance of any subtype of T. 3.2.26 immediate type: The type of the direct instance of an object instance. 3.2.27 type graph (of a type): The set of all s
13、upertypes of a type (including the recursively defined supertypes) plus the type itself. 3.2.28 inheritance : A notational mechanism for defining operation reuse. It is a relationship on interfaces. 3.2.28.1 multiple inheritance: A notational mechanism for defining operation reuse on multiple base i
14、nterfaces, 3.2.28.2 single inheritance: As opposed to multiple inheritance; denotes an interface having only one base interface. 3.2.29 derived interface: If the interface P inherits from Q. P may also be referred to as a derived interface. 3.2.30 base interface: If the interface P inherits from Q,
15、Q is a base interface (of P). 3.2.31 abstract object type: Non-instantiable object type. 3 ISO/IEC 14478-1: 1998(E) 0 ISO/IEC 3.2.32 operation request semantics: A finer control an object has to service an operation request. 3.2.32.1 operation receptor: A holder conceptually assigned to each operati
16、on in which operation requests are placed, 3.2.32.2 operation receptor mode: An immutable characteristics of an operation receptor. 3.32.2.1 synchronous operation receptor mode: One of the three possible modes of an operation receptor; callers are suspended on operation requests. 3.32.2.2 asynchrono
17、us operation receptor mode: One of the three possible modes of an operation receptor; call- ers are not suspended on operation requests, and the requests arguments are stored. 3.32.2.3 sampled operation receptor mode: One of the three possible modes of an operation receptor; callers are not suspende
18、d on operation requests, and only one requests argument is stored. 3.2.33 protected operation: An operation which can be invoked from within the object instance only; other object instanc- es cannot request this operation. 3.2.34 life cycle (of objects and references): The mechanisms whereby objects
19、 and object references are created and de- stroyed. 3.2.34.1 life cycle facilities: The boundary between PREMO and its implementation environment, providing life cycle related services. 3.2.34.2 create facility: Facility to create objects possibly using initialization variables. 3.2.34.3 copy facili
20、ty: Facility to create objects as copies of already existing objects. 3.34.3.1 shallow copy: Version of the copy facility when attribute values are set in the newly created object using the values of the attributes in the original object. 3.34.3.2 deep copy: Version of the copy facility when attribu
21、te values are set in the newly created object using the values of the attributes in the original object except for object references; in the case of object references, the referred objects are (deep) copied, and the new reference values are used to set the attributes. 3.2.34.4 cast facility: Facilit
22、y to create an object reference to an already existing object, referring to a different immediate type. 3.2.34.5 destroyReference facility: Facility to destruct an object reference. 3.2.34.6 destroyobject facility: Facility to destruct an object instance. 3.2.35 type schema: A notational convention
23、used to describe object types (see clause A.3). 3.2.36 operation schema: A notational convention used to describe an operation within a type schema, 3.2.37 component schema: A notational convention to describe components (see clause A.7). 3.2.38 profile schema: A notational convention to describe pr
24、ofiles within a component schema (see clause A.7). 3.2.39 generic type (schema): A notational convention used to describe a family of PREMO types, based on the genera notational conventions of type schema (see clause B). 3.2.40 formal types: Symbols used in generic type schemas to denote non-specifi
25、ed object or non-object types. 3.2.41 actualization: A notational convention whereby generic type schema are used to define. PREMO object types through replacing formal types by PREMO object or non-object types. The following alphabetical list gives the subclause of each definition. abstract object
26、type 3.2.3 1 actualization 3.2.41 animation 3.2.4 asynchronous operation receptor mode 3.32.2.2 4 0 ISO/IEC ISO/lEC 14478-1:1998(E) attribute (of objects) 3.2.14 audio 3.2.6 base interface 3.2.30 basic profile (of a component) 3.2.10. I cast facility 3.2.34.4 client 3.2.19 cc+representation 3.2.8 co
27、mponent 3.2.9 component schema 3.2.37 controlling parameter 3.2.21 copy facility 3.2.34.3 create facility 3.2.34.2 deep copy 3.34.3.2 derived interface 3.2.29 destroyobject facility 3.2.34.6 destroyReference facility 3.2.34.5 direct instance 3.2.25 dynamic interactive graphics 3.2.3 exception 3.2.20
28、 formal types 3.2.40 generic type (schema) 3.2.39 identity (of objects) 3.2.13 immediate subtype 3.2.23.1 immediate supertype 3.2.24.2 immediate type 3.2.26 inheritance 3.2.28 interface (of objects) 3.2.16 life cycle (of objects and references) 3.2.34 life cycle facilities 3.2.34.1 medium (plural me
29、dia) 3.2.2 multimedia 3.2.1 multimedia object 3.2.1.1 multiple inheritance 3.2.28.1 multiple supertype 3.2.24.1 non-object types 3.2.17 non-standard component 3.2.9.2 object 3.2.1 I object reference 3.2. II .2 object type 3.2.11.1 operation 3.2. I8 operation dispatching 3.2.18.3 operation invocation
30、 3.2.18.1 operation overloading 3.2.18.4 operation receptor 3.2.32.1 operation receptor mode 3.2.32.2 operation request 3.2.18.2 operation request semantics 3.2.32 5 ISO/IEC 14478-1:1998(E) 0 ISO/IEC operation schema 3.2.36 profile 3.2.10 profile schema 3.2.38 protected operation 3.2.33 retrieve onl
31、y attribute 3.2.14.1 sampled operation receptor mode 3.32.2.3 shallow copy 3.34.3.1 signature (of operations) 3.2.15 single inheritance 3.2.28.2 standard component 3.2.9.1 state 3.2.12 subtype 3.2.23 subtyping 3.2.22 wefiype 3.2.24 synchronous operation receptor mode 3.32.2. I text 3.2.5 tyPe graph
32、(of a type) 3.2.27 type schema 3.2.35 video 3.2.7 4 Symbols and abbreviations CAD/CAM: IEC: IS: ISO: JTC: PREMO: 2SD: 2D: 3D: Computer-Aided Design / Computer-Aided Manufacturing. International Electrotechnical Commission. International Standard. International Organization for Standardization. Joint
33、 Technical Committee. Presentation Environments for Multimedia Objects. Two and a half dimensional. Two-dimensional. Three-dimensional. 5 Conformance A component is defined in PREMO to be a set of related object types and non-object types and a set of profile specifications. A component is considere
34、d to offer a set of services, embodied by the operations on the objects, and may also depend on services provided by other components. PREMO defines conformance with respect to components as follows: a) PREMO specifies conformance rules that shall apply for any definition of a conforming component;
35、b) PREMO specifies conformance rules that shall apply for any implementation of a conforming component; c) PREMO specifies conformance rules that shall apply for any implementation of a conforming PREMO system. 0 ISO/IEC ISOAEC 14478-1:1998(E) A conforming component shall be defined according to the
36、 rules described in clause 9. It may also include additional require- ments that shall apply to implementations of the component. An implementation of a conforming component shall provide the mandatory set of functionality designated as a basic profile for that component, realize the configuration s
37、pecification defined for that component, and in addition provide for any other imple- mentation requirements that are given as part of the components definition. A standard component is a conforming component defined in one of the parts of PREMO or one that has been registered by an approved registr
38、ation authority. An implementation of a conforming PREMO system (i.e., a system implemented using PREMO components) shall obey the con- formance requirements of each of the components from which it is constituted. Requirements for PREMO 6.1 Introduction Technology has evolved to the point that digit
39、al media has become an inherent part of most applications. In addition, many ap- plications use multiple presentation media simultaneously. This combination has resulted in a large number of diverse require- ments. ISO/IEC 14478 is intended to address the presentation requirements of such diverse ap
40、plication areas as: a) medical systems, b) education/training, c) virtual reality, d) geographic information systems, e) digital publications, f) scientific visualization and data exploration, g) entertainment, h) realtime command control systems, and i) simulation; and such presentation and interac
41、tion techniques as: j) animation, k) simultaneous use of multiple media, I) multimodal user interfaces, m) realistic rendering (including various dimensionalities, such 2D, 2.5D, 3D, and incorporating various media, such as video, sound, and other non-visual data). ISO/IEC 14478 provides a common un
42、derlying functional nucleus to support these application areas and presentation techniques, as well as future areas and techniques. PREMO also enables the use of interaction techniques appropriate for specific applica- tions, such as those listed above. PREMO provides a generic framework, into which
43、 various organizations or applications may place their specialised objects with specific behaviour, thereby enabling interoperability. In this sense, PREMO is intended to serve as middleware, coordinating multimedia components. ISO/IEC 14478-1:1998(E) 0 ISO/IEC 6.2 Extensibility ISO/IEC 14478 is ext
44、ensible in that it makes provisions for extending the functionality specified in the standard via a number of standardized mechanisms. In particular, additional components may be developed which respond to the needs of specific appli- cation areas. See also clause B in ISO/IEC 14478-2 for further de
45、tails on the way PREMO objects may be extended. Many aspects of ISO/IEC 14478 are extensible by an ISO-administered registration mechanism, so that a uniform description of the extension is available to all implementations. 6.3 Configurability The need for configurability arises because different ap
46、plication areas have different demands on the task of presenting their data. PREMO embodies a configurable system design which offers a foundation from which specific requirements for object support and interrelationships can be realized. This configurable system design is based on the concepts of c
47、omponents and profiles (see clause 7.3.4 and clause 9). In a configurable system, profiles can be chosen according to the special needs of particular applica- tions. The advantages of a configurable system design are: a) Applications do not reference the whole system but only the specific component
48、profiles they require. For example, an application might need only an audio or video profile. b) When introducing new techniques, e.g., shading methods within a graphics system, or a special purpose graphics data storage, there is no need to implement a completely new graphics system for the realiza
49、tion of these new approaches. They can be integrated as new object types that fit within the existing foundation. 6.4 Incremental, separable development ISO/IEC 14478 is described and structured in such a way that it can be developed incrementally. The chosen architecture provides a foundation for an evolvable family of standards. 6.5 Simplicity Aspects, such as portability and maintenance, are greatly enhanced by keeping underlying concepts simple. Simplicity means that PREMO is based on a general architecture under which various sets of objects may be utilized. Objects are defined i
