1、BRITISH STANDARD BS ISO/IEC 13250-2:2006 Information technology Topic Maps Part 2: Data model ICS 35.240.30 BS ISO/IEC 13250-2:2006 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 September 2006 BSI 2006 ISBN 0 580 48925 6 National forewor
2、d This British Standard was published by BSI. It is the UK implementation of ISO/IEC 13250-2:2006. The UK participation in its preparation was entrusted to Technical Committee IST/41, Document description and processing language. A list of organizations represented on IST/41 can be obtained on reque
3、st to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued since publication Amd. No. Date Comment
4、s Reference number ISO/IEC 13250-2:2006(E)INTERNATIONAL STANDARD ISO/IEC 13250-2 First edition 2006-08-15 Information technology Topic Maps Part 2: Data model Technologies de linformation Plans relatifs des sujets Partie 2: Modle de donnes BS ISO/IEC 13250-2:2006ii iiiContents Page Foreword iv Intro
5、duction. v 1 Scope. 1 2 Normative references 1 3 Terms and definitions 1 4 The metamodel. 4 4.1 Introduction 4 4.2 Locators 5 4.3 The fundamental types 5 4.4 Datatypes 6 5 The data model. 6 5.1 General 6 5.2 The topic map item 7 5.3 Topic items. 8 5.3.1 Subjects and topics. 8 5.3.2 Identifying subje
6、cts. 8 5.3.3 Scope 9 5.3.4 Reification. 9 5.3.5 Properties. 10 5.4 Topic name items. 10 5.5 Variant items. 12 5.6 Occurrence items. 12 5.7 Association items 13 5.8 Association role items. 14 6 Merging. 15 6.1 General 15 6.2 Merging topic items. 15 6.3 Merging topic name items. 15 6.4 Merging variant
7、 items 15 6.5 Merging occurrence items 16 6.6 Merging association items 16 6.7 Merging association role items 16 7 Core subject identifiers. 17 7.1 General 17 7.2 The type-instance relationship. 17 7.3 The supertype-subtype relationship 17 7.4 Sort names 18 7.5 The default name type. 18 Annex A (inf
8、ormative) Subject identifiers for defined terms 19 Bibliography 21 BS ISO/IEC 13250-2:2006iv Foreword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are m
9、embers of ISO or IEC participate in the development of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international
10、organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. International Standards are drafted in accordance with the rules given in the IS
11、O/IEC Directives, Part 2. The main task of the joint technical committee is to prepare International Standards. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least
12、75 % of the national bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights. ISO/IEC 13250-2 was prepared by Joint Technical C
13、ommittee ISO/IEC JTC 1, Information technology, Subcommittee SC 34, Document description and processing languages. This first edition of ISO/IEC 13250-2 is part of a multi-part standard. The complete series will cancel and replace ISO/IEC 13250:2003. ISO/IEC 13250 consists of the following parts, un
14、der the general title Information technology Topic Maps: Part 2: Data model Part 3: XML syntax Part 4: Canonicalization BS ISO/IEC 13250-2:2006vIntroduction Topic Maps is a technology for encoding knowledge and connecting this encoded knowledge to relevant information resources. Topic maps are organ
15、ized around topics, which represent subjects of discourse; associations, representing relationships between the subjects; and occurrences, which connect the subjects to pertinent information resources. Topic maps may be represented in many ways: using Topic Maps syntaxes in files, inside databases,
16、as internal data structures in running programs, and even mentally in the minds of humans. All these forms are different ways of representing the same abstract structure. It is that structure which this part of ISO/IEC 13250 defines, in the form of a data model. NOTE The phrase “topic maps“ is used
17、in two ways in this part of ISO/IEC 13250: as a (capitalized) proper noun, “Topic Maps“, denoting the name of ISO/IEC 13250; and as the plural of a common noun “topic map“. Both terms are defined in Clause 3. BS ISO/IEC 13250-2:2006 blank1 1 Scope NOTE 1 This clause defines the scope of this part of
18、 ISO/IEC 13250. It should not be confused with the concept of “scope“ defined in 5.3.3, which only applies in the context of Topic Maps. This part of ISO/IEC 13250 specifies a data model of Topic Maps. It defines the abstract structure of Topic Maps, using the information set formalism, and to some
19、extent their interpretation, using prose. The rules for merging in Topic Maps are also defined, as are some fundamental subject identifiers. The purpose of the data model is to define the interpretation of the Topic Maps interchange syntaxes, and to serve as a foundation for the definition of suppor
20、ting standards for canonicalization, querying, constraints, and so on. All of these standards fall outside the scope of this part of ISO/IEC 13250. NOTE 2 This part of ISO/IEC 13250 does not have a conformance section since it is only a data model, and as such it has no boundary with the outside wor
21、ld in terms of which conformance can be specified. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including
22、any amendments) applies. NOTE Each of the following documents has a unique identifier that is used to cite the document in the text. The unique identifier consists of the part of the reference up to the first comma, and referenced thus: Identifier. Unicode, The Unicode Standard, Version 4.0, The Uni
23、code Consortium, Reading, Massachusetts, USA, Addison- Wesley, 2003, ISBN 0-321-18578-1 RFC 3986, Uniform Resource Identifiers (URI): Generic Syntax, Internet Standards Track Specification, January 2005, available at RFC 3987, Internationalized Resource Identifiers (IRIs), Internet Standards Track S
24、pecification, January 2005, available at XML Infoset, XML Information Set (Second Edition), World Wide Web Consortium, 4 February 2004, available atISO 10646, Information technology Universal Multiple-Octet Coded Character Set (UCS) XML, Extensible Markup Language (XML) 1.0 (Third Edition), W3C Reco
25、mmendation, 4 February 2004, available atXML Schema-2, XML Schema Part 2: Datatypes Second Edition, W3C Recommendation, 28 October 2004, available at 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. NOTE These definitions are reproduced from the b
26、ody of this document; for those unfamiliar with the terminology the definitions are best read in context. They are repeated here for reference. Information technology Topic Maps Part 2: Data model BS ISO/IEC 13250-2:20062 association representation of a relationship between one or more subjects 3.2
27、association role representation of the involvement of a subject in a relationship represented by an association 3.3 association role type subject describing the nature of the participation of an association role player in an association 3.4 association type subject describing the nature of the relat
28、ionship represented by associations of that type 3.5 information resource representation of a resource as a sequence of bytes; it could thus potentially be retrieved over a network 3.6 item identifier locator assigned to an information item in order to allow it to be referred to 3.7 locator string c
29、onforming to some locator notation that references one or more information resources 3.8 merging process applied to a topic map in order to eliminate redundant topic map constructs in that topic map 3.9 occurrence representation of a relationship between a subject and an information resource 3.10 oc
30、currence type subject describing the nature of the relationship between the subjects and information resources linked by the occurrences of that type 3.11 reification making a topic represent the subject of another topic map construct in the same topic map 3.12 scope context within which a statement
31、 is valid 3.1 BS ISO/IEC 13250-2:20063 3.13 statement claim or assertion about a subject (where the subject may be a topic map construct) 3.14 subject anything whatsoever, regardless of whether it exists or has any other specific characteristics, about which anything whatsoever may be asserted by an
32、y means whatsoever 3.15 subject identifier locator that refers to a subject indicator 3.16 subject indicator information resource that is referred to from a topic map in an attempt to unambiguously identify the subject represented by a topic to a human being 3.17 subject locator locator that refers
33、to the information resource that is the subject of a topic 3.18 topic symbol used within a topic map to represent one, and only one, subject, in order to allow statements to be made about the subject 3.19 topic map set of topics and associations 3.20 topic map construct component of a topic map; tha
34、t is, a topic map, a topic, a topic name, a variant name, an occurrence, an association, or an association role. 3.21 Topic Maps technology for encoding knowledge and connecting this encoded knowledge to relevant information resources 3.22 topic name name for a topic, consisting of the base form, kn
35、own as the base name, and variants of that base form, known as variant names 3.23 topic name type subject describing the nature of the topic names of that type BS ISO/IEC 13250-2:20064 3.24 topic type subject that captures some commonality in a set of subjects 3.25 unconstrained scope scope used to
36、indicate that a statement is considered to have unlimited validity 3.26 variant name alternative form of a topic name that may be more suitable in a certain context than the corresponding base name 4 The metamodel 4.1 Introduction The metamodel used in this document is the same as that used by the X
37、ML Information Set XML Infoset. An instance of this data model consists of a number of information items, each one of which is an abstract representation of a topic map construct. Every information item is an instance of some information item type, which specifies a number of named properties which
38、the information item shall have. Throughout this part of ISO/IEC13250 the term “information item“ refers to the information item types defined in this model, while information items of particular types are referred to as “topic items“, “topic name items“, and so on. The names of properties are writt
39、en in square brackets: property name, following the convention used in XML Infoset. Every property has a type that constrains what values it may have. Properties are not allowed to have null as their value unless this is explicitly stated in the definition of the property. Certain properties in the
40、model are specified as computed properties, which means that they are specified in terms of how their values may be produced from other properties in the model. These properties are specified for reasons of convenience or to better reflect the semantics of the data model but are strictly speaking re
41、dundant. A number of constraints on the allowed instances of the model are also defined. The purpose of these constraints is to prevent inconsistencies in instances of the data model. All information item types and fundamental types defined in this part of ISO/IEC13250 have a well-defined test of eq
42、uality. This equality test is used to avoid duplicate values in properties whose values are of type set. Information items have identity, independent of their values, so items can be compared both by identity and by value. Equality throughout this part of ISO/IEC13250 should be taken to mean equalit
43、y according to the rules defined for the types of the values being compared. UML diagrams UML are used in addition to the infoset formalism for purposes of illustration. These diagrams are purely informative, and in cases of discrepancy between the diagrams and normative prose, the prose is definiti
44、ve. BS ISO/IEC 13250-2:20065 Figure 1 The class hierarchy NOTE TopicMapConstruct is the abstract superclass of all classes used in these UML diagrams. It is used here to simplify the UML diagrams using inheritance. The Reifiable class is also abstract, and is used as the common superclass of all cla
45、sses corresponding to item types which can occur in the reified property of topic items. 4.2 Locators An information resource is a a representation of a resource as a sequence of bytes; it could thus potentially be retrieved over a network. Topic maps can refer to information resources external to t
46、hemselves in order to make statements about them. These information resources are not part of the topic map; they are only referenced from it. A locator is a string conforming to some locator notation that references one or more information resources. Locators are always expressed in some locator no
47、tation, which is a definition of the formal syntax and interpretation of a class of locators. The definition of locator notations is outside the scope of this part of ISO/IEC13250. All locators in this model use the notation defined by RFC 3986 and RFC 3987. 4.3 The fundamental types The values of i
48、nformation item properties may be either other information items, or values of one of the types defined below: String Strings are sequences of Unicode scalar values (see Unicode and ISO 10646). Strings are equal if they consist of the exact same sequence of Unicode scalar values. NOTE 1 This part of
49、 ISO/IEC13250 does not require Unicode normalization to be applied to strings order to detect that syntactically different but logically equivalent strings are in fact equivalent. The application of such logic is encouraged, however. As it cannot be guaranteed that normalization will be performed reliance on normalization is strongly discouraged. Set Sets are collections of zero or more unordered elements that contain no elements that are equal to
