1、ANSI INCITS TR-12-1993(formerly ANSI X3/TR-12-1993) Information Processing SystemsTechnical ReportRepository ContextInformation Resource Dictionary System (IRDS)Reference ModelCopyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or net
2、working permitted without license from IHS-,-,-Copyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Information Processing SystemsTechnical ReportX3/TR-12-93Repository ContextInforma
3、tion Resource Dictionary System (IRDS)Reference ModelDeveloped by American NationalStandards CommitteeX3, Information Processing SystemsCopyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or networking permitted without license from I
4、HS-,-,-iAccredited Standards CommitteeX3, Information Processing SystemsDoc. No.: X3H4.1/92-002R3X3H4/92-079R2Doc. Date: September 24, 1992Project: 570-DTReply to: Robert E. HodgesTexas Instruments, Inc.P.O. Box 869305, MS 8482Plano, TX 75086(214) 575-3442, FAX 575-Repository ContextReference ModelT
5、echnical ReportSecretariatComputer and Business Equipment Manufacturers AssociationApprovedAmerican National Standards Institute, Inc.AbstractThis Technical Report is an Accredited Standards Committee X3H4 working paperintended to provide a picture of the full strategic scope of repository functiona
6、lity as itis currently understood. This report describes the positioning of repository functionswith respect to information technologies that use repository services and those thatsupport repository implementation. The focus of this report is on the interfaces thatserve as isolation layers between t
7、he repository and these related informationtechnologies.Copyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-X3s Technical Report SeriesThis Technical Report is one in a series produ
8、ced by American National Standards Committee,X3, Information Processing Systems. The Secretariat for X3 is held by the Computer andBusiness Equipment Manufacturers Association (CBEMA), 1250 Eye Street, NW, Suite 200,Washington, DC 20005.As a by-product of the standards development process and the re
9、sources of knowledge devotedto it, X3 from time to time produces Technical Reports. Such Technical Reports are not standards,nor are they intended to be used as such. X3 Technical Reports are produced in some cases to disseminate the technical and logical con-cepts reflected in standards already pub
10、lished or under development. In other cases, they derivefrom studies in areas where it is found premature to develop a standard due to a still-changingtechnology, or inappropriate to develop a rigorous standard due to the existence of a number ofviable options, the choice of which depends on the use
11、rs particular requirements. TheseTechnical Reports, thus, provide guidelines, the use of which can result in greater consistencyand coherence of information processing systems.When the draft Technical Report is completed, the Technical Committee approval process is thesame as for a draft standard. P
12、rocessing by X3 is also similar to that for a draft standard. Published byAmerican National Standards Institute11 West 42nd Street, New York, New York 10036Copyright 1993 by American National Standards InstituteAll rights reserved.No part of this publication may be reproduced in anyform, in an elect
13、ronic retrieval system or otherwise,without prior written permission of the publisher.Printed in the United States of AmericaAPS1.5C1093/40Copyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or networking permitted without license fro
14、m IHS-,-,-ii CONTENTS 0. Foreword . 11. Introduction . 32. Scope 43. Normative References . 64. Definitions it is consistent in that the database is left in a consistent state following thetransaction; it is isolated from other transactions; and it is durable following completion ofthe transaction.
15、A transaction is uniquely identified by a transaction identifier.version:A configuration of all or part of an information system at a specific point in time.Copyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or networking permitted w
16、ithout license from IHS-,-,-125. Goals and ObjectivesThe objectives of the Repository Context Reference Model support the general goals forrepository standardization. These goals provide the motivation behind the objectives of thisdocument. This section defines the objectives for this reference mode
17、l and the broader goalsfor repository standardization that drive those objectives.5.1. Reference Model MotivationThe Repository Context Reference Model needs to support several major goals that forrepository standardization. These goals include the following : Enable information sharing. Support loc
18、ation independence. Minimize support costs. Provide controlled commit or rollback of repository work units. Allow heterogeneous facilities to cooperate. Enable information interchange between repository systems. Integrate related standards.5.1.1. Enable Information SharingThe objects managed in info
19、rmation repositories contain and represent information resourcesof an enterprise. The functions that operate the enterprise need a shared understanding ofwhat the information means, how it is used, and how to obtain or maintain it. Globallyaccessible repository objects capture meaning, behavior and
20、access methods forinformation, and thus enable the sharing of the information itself.5.1.2. Support Location IndependenceA user of a repository does not need to know where information is physically stored.Requests for repository services should identify the objects of interest by logicalcharacterist
21、ics instead of the address or location of the objects. Consistent enterprise-wideobject addressing needs to be an implicit aspect of repository standards to enable location tobe transparently accomplished by the repository system.5.1.3. Minimize Support CostsThe cost of supporting an information sys
22、tem accrues from all phases of its life cycle,including both development and operational costs. A key goal of repository standards is toallow the users of repositories to maximize benefits from current information systems in achanging environment. Repository standards must help lower costs by provid
23、ing the basis forinteroperability of existing and new information resources and maximizing potential forcontinued use and reuse of existing assets.Copyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or networking permitted without lic
24、ense from IHS-,-,-135.1.4. Provide Controlled Commit or Rollback of Work UnitsRepository users need to have control over groups of operations that can be applied withatomic, consistent, isolated and durable results. These operations may involveheterogeneous, distributed repository facilities or supp
25、ort systems. The database transactionconcept is the appropriate basis for addressing the issues of integrity, recovery, andconcurrency control for a repository system. Repository standards need to supporttransaction management for repository operations.5.1.5. Allow Heterogeneous Facilities to Cooper
26、ateIt must not be necessary for all repository facilities to be supplied by the same vendor tohave the services interoperate. Heterogeneous repository facilities need standards forconsistent use and exchange of common services. The facilities should react predictablywhen a service request received f
27、rom any requester.5.1.6. Enable Information Interchange between RepositoriesTo share information among cooperating repository systems, standard import/export formatsare needed. Import and export facilities are particularly important in permitting the sharing ofinformation between CASE tools and repo
28、sitory facilities. These interchange formats mustalso support the preservation of archived repository information. Interchange standards canensure that evolving repository implementations can use archived information. Objectinterchange standards should support import and export of object schemas and
29、 theinformation bearing objects themselves.5.1.7. Integrate Related StandardsRepository implementations necessarily intersect a wide range of standards focusing onspecific technologies. Repository standards must address these points of intersection tominimize redundancy and incompatibility and ensur
30、e complete coverage of the technologiesrequiring standardization. Just as repositories can help integrate enterprise information,repositories can support the effective use of separate standards by integrating theinformation models of those standards.5.2. Reference Model ObjectivesThe objectives of t
31、his Repository Context Reference Model are:1. Identify the services, facilities, interfaces, and technologies that are integrated usinga repository within an information systems environment. The role of a repositorysystem cannot be defined in isolation from the information resources it integrates an
32、dmanages. An objective of this report is to characterize not only the repository system,but the components of the information environment within which the repositoryoperates.2. Provide a context for the development of a repository services architecture. Theinternal architecture of repository service
33、s and facilities needs to be defined within aknown usage context. An objective of this report is to enable these aspects ofinternal architecture to be defined within a defined context.Copyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproductio
34、n or networking permitted without license from IHS-,-,-143. Locate impact of standards (existing, emerging and needed) in relation to repositoryservices and interfaces to facilitate the incorporation of existing standards. Thestandards that are needed to support a repository system cover a broad ran
35、ge ofstandardization domains. Another objective of this report is to provide an overview ofrelated standards that are needed to supplement the emerging repository standards.4. Introduce terms and concepts of repository functionality. Existing terminology is notalways adequate to convey new concepts
36、that support repository standardization.The term “repository“ has a general meaning, “a place where something is stored,“that is consistent with the terms usage in this report. This generic definition, however,fails to capture the growing, active role envisioned for repository systems within aninfor
37、mation system environment. An objective of this report is to help educate abroad audience about repository concepts and the role envisioned for a repositorysystem within an enterprise.5. Position the use of repository services and interfaces in terms of the total informationsystems environment. A re
38、pository can only approach its goals within an enterprise ifit encompasses the total information environment. Partial management solutions arehelpful, but fail to deliver many enterprise integration benefits that are sought. Anobjective of this report is to establish a broad definition of the enviro
39、nment served bya repository system.6. Identify interface and binding boundaries associated with repository services. A basicprinciple for repository systems is the specification of well formed interfaces. Theseinterfaces include both those that enable repository using application to obtainservices a
40、nd those that enable the repository to actively interact with support systemsto manage enterprise information. An objective of this report is to identify thoseinterface boundaries.Copyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or
41、 networking permitted without license from IHS-,-,-156. Reference Model RequirementsThe requirements for the Repository Context Reference Model are as follows: The Repository Context Reference Model shall be in harmony with related referencemodels and frameworks such as the Information Technology -
42、Reference Model ofData Management and Reference Model for Frameworks of Software EngineeringEnvironments (Second Edition). The full harmonization of the repository perspectivewith these references will involve not only this document, but also the RepositoryServices Architecture (see Figure 1 - Frame
43、work for the Evolution of RepositoryStandards). The reference model shall adapt to developments in technology. The reference model shall hold to the principles of layering for reference modeldevelopment as described in the ISO Open Systems Interconnection (OSI) referencemodel.The principles of layer
44、ing which have been considered in this report are summarizedbelow:P1: keep the total structure simple;P2: create boundaries only at points where interactions across theboundaries are minimized;P3: separate into different layers those functions that are very differentin nature and purpose;P4: Collect
45、 within a layer those functions that are similar or highly inter-related;P5: select boundaries at points that experience has shown to besuccessful;P6: create layers such that the internal mechanization of such layerscan be made independently from the functionality that it provides;P7: create boundar
46、ies where it may be useful at some time to have areal physical boundary;P8: create a layer where there is a need for a different level ofabstraction in the handling of data;P9: create layers such that changes of functions and protocols can bemade within a layer without affecting other layers;P10: cr
47、eate for each layer boundaries with its upper and lower layer only.Copyright American National Standards Institute Provided by IHS under license with ANSI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-167. AudienceThis technical report is intended for these audie
48、nces : Individuals responsible for the development of repository related standards. Implementors responsible for the development of repository products and productsthat interface with repositories. Professionals responsible for supporting the engineering, operations, andmanagement of the information environment.Standards developers will find the Repository Context Reference Model useful for positioningstandards in relation to one another. Locating an existing or proposed standard within thedefined layers of this model will help identify related standards that ma
