Title: SC 21 Contribution to the Joint Workshop on Standards for the Use of Models that Define the Data and Processes of Information Systems

Author: Bryan Wood, UK

Source: SC 21 Meeting, Kansas City, US, May 1996

Reference: SC 21 N 10221: Information and Call for Participation in a Joint Workshop on Standards for the Use of Models that Define the Data and Processes of Information Systems

Background

This contribution gives an overview of the standards from, and work in progress in, SC 21 that address the concerns of the Joint Workshop, together with discussion of why this work is considered to be necessary. In addition, a number of experts from SC 21 are contributing individual papers to the Joint Workshop.

SC 21 Work on Models

The following documents represent the SC 21 work on models that is relevant to the Joint Workshop:

• SC21/WG3 N1955, Conceptual Schema Modelling Facilities (23 Feb. 1996)
• ITU-T Rec. X.901 | ISO/IEC 10746-1: Information Technology - Open Distributed Processing - Reference Model - Part 1: Overview
• ITU-T Rec. X.902 | ISO/IEC 10746-2: Information Technology - Open Distributed Processing - Reference Model - Part 2: Foundations.
• ITU-T Rec. X.903 | ISO/IEC 10746-3: Information Technology - Open Distributed Processing - Reference Model - Part 3: Architecture.
• ITU-T Rec. X.904 | ISO/IEC 10746-4: Information Technology - Open Distributed Processing - Reference Model - Part 3: Architectural semantics
• ISO 10027: Information Technology - IRDS Framework
• ISO/IEC 10032: Information Technology - Reference Model of Data Management

These models are developed in order to provide a framework for developing and applying the standards for which SC 21 is responsible. These standards relate to a context in which user needs, technology advances, and business imperatives are driving the evolution to distributed information systems that:

• are closely matched to support of enterprise objectives;
• support networked client/server and multimedia operations, flexible services, and more cost effective use of technology;
• increase the availability, accessibility and control of an increasing range of data across complete enterprises;
• exploit increased interworking between existing systems, thereby responding promptly to new business needs;
• are heterogeneous and open, to reflect the continual changes in markets and technology; and
• integrate multiple domains (administrative, management, security, etc.), allowing organizations to collaborate in the provision of goods and services.

Users expect major benefits from such systems, including:

• easier user access to each other, to public computing resources, to corporate information systems distributed over a companyÕs physical locations, and to remote diagnostics and maintenance;
• dynamic, transparent sharing, integration or partitioning of resources and applications across different systems, locations and domains in response to user needs;
• better performance through parallel operation of different applications or parts of a given application;
• higher availability, reliability and fault tolerance;
• containment of cost by allowing addition of modules to a system, load balancing within a system, and dynamic reconfiguration (to reduce, for example, communications costs); and
• decentralized management in which the owners of resources need to manage only their own resources, system structures reflect organizational structures, and local autonomy is feasible.

This evolution requires standards for connectivity, data management, application interoperation, and communications management and security. A major part of SC21 activity has been concentrated in these areas, covering standards for:

• OSI architecture and related frameworks, which are used to compare other models and technologies for communications, and to co-ordinate the development of communication standards. OSI terminology is in common use in the marketplace and in procurement specifications;
• OSI upper layers, which provide an infrastructure for interactive applications, and a set of generic applications such as file transfer and transaction processing;
• SQL and RDA, data management standards that are mature and continuing to be actively extended to meet evolving needs;
• management of communications protocols and systems;
• syntax notation, formal descriptions, and conformance testing.

These separate areas of standardization do not, however, address key issues if future computing environments are to provide solutions to enterprise needs. In such computing environments users will require systems that:

• are closely integrated with the operation of the enterprise and responsive to changing needs;
• are capable of evolving gracefully;
• accommodate heterogeneous technologies;
• are operable jointly by several autonomous organizations;
• scale to very large sizes.

Moreover, different applications will make different, conflicting demands on the infrastructure supporting the computing environment - for example:

• the need for consistency versus the need for availability;
• the need real-time guarantees from systems versus the need for convenience and openness in the use of systems;
• the need for control versus the need for transparency of distribution mechanisms.

SC21 is providing a framework for addressing these issues through the work which has begun work on conceptual modelling, the development of the Reference Model of Open Distributed Processing (RM-ODP), and the Reference Model of Data Management (RMDM), providing a base for future work on data management. This framework is intended to guide SC21 activities directed at the system integration and distribution issues that underlie the provision of enterprise solutions - taking full account of the large number of industry, consortia, government and academic initiatives that cover the same areas.

Conceptual Schema Modelling Facility (CSMF)

The purpose of this standard is to provide a mechanism for end users and for information systems analysts, designers and constructors to communicate with each other in a formal way and to agree about contents of a conceptual schema. The scope of the CSMF standard is to define a set of normative constructs that are sufficient to describe conceptual schema modelling languages. Its purpose is not primarily to define a conceptual schema modelling language. The set of constructs defined may be larger than the set found in commonly used conceptual schema languages. The set of constructs defined in CSMF is not the union of those found in CSLs but are defined so that appropriate mappings may be defined.

The CSMF, thus defined, could be used in the design of systems that:

1. compare the functionality of conceptual schema languages
2. transform conceptual models defined in one CSL to a conceptual model defined in another CSL. Note that this usage requires the services of an export/import facility such as that which is defined elsewhere in SC21/WG3.
3. allow systems built based on models developed using different CSLs to interoperate.

The work on conceptual schema modelling will provide tools for representing the enterprise and the role of IT in the enterprise, and for expressing the common semantics of processing across the IT environment of the enterprise.

Reference Model of Open Distributed Processing (RM-ODP)

The RM-ODP defines a common, object-oriented, language for describing distributed systems; and a structure for distributed systems in terms of this language that identifies the functions that enable them to be open. Thus, the RM-ODP provides a framework for integrating existing standards in support of distributed system operation and for identifying major areas of future development. Aspects of this framework have clear links with the conceptual schema work on enterprise modelling.

The RM-ODP consists of:

• ITU-T Rec. X.901 | ISO/IEC 10746-1: Overview: contains a motivational overview of ODP giving scoping, justification and explanation of key concepts, and an outline of the ODP architecture. It contains explanatory material on how this Reference Model is to be interpreted and applied by its users, who may include standards writers and architects of ODP systems. It also contains a categorisation of required areas of standardization expressed in terms of the reference points for conformance identified in ITU-T Recommendation X.903 | ISO/IEC 10746-3. This part is not normative.
• ITU-T Rec. X.902 | ISO/IEC 10746-2: Foundations: contains the definition of the concepts and analytical framework for normalised description of (arbitrary) distributed processing systems. This is only to a level of detail sufficient to support ITU-T Rec. X.903 | ISO/IEC 10746-3 and to establish requirements for new specification techniques. This part is normative.
• ITU-T Rec. X.903 | ISO/IEC 10746-3: Architecture: contains the specification of the required characteristics that qualify distributed processing as open. These are the constraints to which ODP standards must conform. It uses the descriptive techniques from ITU-T Rec. X.902 | ISO/IEC 10746-2. This part is normative.
• ITU-T Rec. X.904 | ISO 10746-4: Architectural semantics: contains a formalisation of the ODP modelling concepts defined in ITU-T Rec. X.902 | ISO/IEC 10746-2 Clauses 8 and 9. The formalisation is achieved by interpreting each concept in terms of the constructs of the different standardized formal description techniques. This part is normative.

Reference Model of Data Management (RMDM)

The Reference Model of Data Management details the requirements which are being addressed by the standards of SC21/WG3. Clause 5 of ISO 10032 specifies these requirements (such as persistent storage of information represented by a wide variety of data types, concurrent access to such data in both local and distributed processing environments, etc.) in some detail. The RMDM document then provides a model which references existing data management standards (SQL, IRDS, RDA, and Export/Import) and prescribes a model for extending such standards in order to support the defined requirements. This model is predicated on the need to address and provide solutions for both local and distributed data management requirements consistently. The RMDM proposes the use of a common data modelling facility throughout a distributed processing environment, in conjunction with protocols for accessing data maintained within facilities which utilize such a data modelling facility. Within the context provided by the RMDM, data management work within SC21/WG3 is addressing the need to extend the power and scope of data management in order to increase the availability, accessibility and control of a widening range of data across complete enterprises.