A GIS Interoperability Approach based on ISO RM-ODP and ISO CSMF

Arne-Jurgen Berre, Vidar Knudsen, Jon Oldevik
SINTEF Telecom and Informatics P.O.Box 124, Blindern, N-0314 Oslo, Norway
{ Arne.J.Berre | Vidar Knudsen }@informatics.sintef.no
http://www.informatics.sintef.no

Abstract

The paper will present and discuss an approach to GIS Interoperability, based on use of the ISO RM-ODP model and the ISO Conceptual Schema Modeling Facility. The practical work on this is being done in the Europan DISGIS projects. The objective of the DISGIS project, running from 7/96 until 12/98 is to provide models, methods, tools and frameworks for the development of interoperable distributed systems in general and interoperable distributed Geographical Information Systems in particular.

1. Integration and Interoperability Problems and Solutions

Basic work in systems integration, such as the ECMA/NIST "Toaster" reference model for integrated environments, provide a good basis for identifying the dif ferent technology areas that needs to be addressed in an integrated system. The "Toaster" model distinguishes 6 different areas: data, processing, communicatio n, presentation, workflow and management. In the context of interoperability g etting two or more systems to work together the notions of technical and semant ic interoperability can be discussed for each area.

The ISO reference model for Open Distributed Processing (RM-ODP) also provides a basis for discussing various aspects of interoperability, as various emphasis is given in its 5 different description viewpoints.

2. Open Distributed Processing (ISO RM-ODP)

The ISO reference model for open distributed processing ISO RM ODP is an int ernational standard that describes an architecture within which support for dist ribution, interoperability and portability can be integrated. ODP standardisati on considers distributed systems spanning many organisations and technological b oundaries. These typically lack any central point of control, and therefore show additional characteristics, such as heterogeneity, autonomy, evolution and mobi lity. In order to deal with these characteristics ODP standardisation aims to en able the building of systems with the following properties: openness, integratio n, interoperability, flexibility, modularity, federation, manageability, provisi on of QoS (Quality of Service), security and transparency.

ODP is defined based on five viewpoints: enterprise, information, computatio nal, engineering and technology. Each viewpoint is an abstraction of the whole s ystem focusing on a specific area of concern. The enterprise viewpoint is concer ned with the purpose, scope and policies of the enterprise. The information view point is concerned with the semantics of information and information processing. The computational viewpoint is concerned with the interaction patterns between the components (objects) of the system. The engineering viewpoint is concerned w ith the design of distribution-oriented aspects, i.e., the infrastructure requir ed to support distribution. Finally, the technology viewpoint is concerned with the provision of an underlying infrastructure.

3. Metadata Interoperability and the Enterprise viewpoint

We will in this section describe meta data interoperability in the context o f federations and different organisational units and information communities, ba sed on the concepts in the ODP enterprise viewpoint.

4. Data Interoperability and the Information viewpoint

We will in this section describe data interoperability based on the concept s in the ODP enterprise viewpoint, and ISO CSMF. Support for semantic data inte roperability is being addressed in a separate position statement being submitted to the workshop associated with the conference.

The purpose of the information viewpoint is to describe the information tha t flows in the system and is processed by the system. This can be captured by se mantic descriptions if objects, their properties, and their relationships. The i nformation viewpoint focuses on the structuring of semantic information, typical ly the information that will be stored in databases and communicated between sys tem components. Traditionally, this modelling have been done according to a thre e-layer schema-architecture, where a schema language (e.g. OMT) is used to descr ibe a class-model which can be instantiated. The ISO CSMF (CD ISO/IEC 14481) hav e introduced a 4-layer schema architecture.

The ISO CSMF (CD ISO/IEC 14481) defines the applicable constructs that shal l be contained in any modelling facility that is used to create a formal concept ual description of various aspects of an enterprise. The purpose of the standard is to provide a mechanism for end users and for information system analysts, de signers and constructors to communicate with each other in a formal way to agree about contents of a conceptual schema.

We will show how the ISO CSMF approach can support both a dynamic API-based specification of schema types (OGC/OpenGIS), as well as a conceptual schema lan guage based approach (ISO/TC211 and CEN/TC287).

5. Processing and Service Interoperability and the Computational viewpoint

We will in this section describe a GIS reference architecture and geoproces sing interoperability, based on concepts in the ISO RM-ODP computational viewpo int.

6. Infrastructure Interoperability and the Technology viewpoint

We will in this section describe infrastructure a interoperability, such as mapping to and interworking between different Distributed Computing Platforms (D CPs).

The intention of the RM-ODP approach is that the information and computatio nal viewpoint can focus on models which are not cluttered by details only necess ary for the mapping to a particular underlying infrastructure, such as CORBA, CO M/OLE, SQL/ODBC, Internet or others. They can thus serve as a common basis for different implementation mappings.

7. GI Standard Interoperability

There is currently many approaches to standards in the GI domain, e.g ISO/TC 211, CEN/TC287, OGC/OpenGIS and others. It is actually an area of concern how t o ensure that these standards might be "interoperable" with each other. We will argue that a common interoperability mapping soon should be established in the a reas of modeling, architecture and terminology.

With the ISO CSMF approach in the information viewpoint we will in particula r show how it is possible to ensure interoperability between the ISO/TC211 and C EN/TC287 approach of using a conceptual schema language, and the OGC/OpenGIS app roach of using an API interface for creating feature types.

8. Conclusions and future work

In this paper we will discuss an approach to GIS Interoperability based on t he use of ISO RM-ODP, including use of ISO CSMF in the information viewpoint.

A practical experiment with this approach is being undertaken in the Europea n DISGIS project. A first pilot case demonstrating this will be finished in Dece mber 1997.

References

[1] "DISGIS - Distributed Geographical Information Systems - White Paper", 3rd EC GIS workshop, Leuven, June 1997 and EUROGI GIS Interoperability workshop, October 1996

[2] A.-J. Berre, J. X. Aagedal, and A. R. Silva, "SIMOD - An ODP-extended Ro le-Modeling Methodology for Distributed Objects," presented at Thirtieth Annual Hawaii International Conference on System Sciences, Wailea, Hawaii, 1997.

[3] "An Object-Oriented Framework for Systems Integration and Interoperability", A.J. Berre, Phd-thesis, University of Trondheim, August >>93