NCL: A common language for achieving rule-based interoperability among heterogeneous systems

摘要

For achieving interoperability among heterogeneous computing systems, the Object Management Group (OMG) has adapted the Common Object Request Broker Architecture (CORBA) and the use of an Interface Definition Language (IDL) for specifying object properties and operations which encapsulate the data and programs of heterogeneous systems. This paper describes a common language which is an enhancement of IDL to include: 1) the semantic richness of EXPRESS, an information modeling language adapted by the ISO/STEP community for achieving product model and data exchange; and 2) the extensibility features and knowledge rule specification offered by the Object-oriented Semantic Association Model (OSAM*). This common language, named the NIIIP Common Language (NCL), is a part of the R&D effort of a project entitled the National Industrial Information Infrastructure Protocols (NIIIP). The design of NCL is standards-based, incorporating the semantic features of the two standard languages, IDL and EXPRESS, and conforming to their syntaxes as much as possible. It is an extensible language which supports the addition of new class, constraint, and association types to the language and its underlying object model in order to satisfy the diverse modeling needs of virtual enterprises. The language also contains a high-level rule specification component. Rules in NCL can be used for defining and enforcing integrity and security constraints, government or enterprise policies and regulations, and other types of semantic constraints that are local or global to heterogeneous systems. In this paper, we shall show how such a modeling language and its supporting KBMS functions can be used to achieve rule-based interoperability in an active heterogeneous system as an enhancement to OMG's CORBA.