Model instantiation for query driven simulation in active KDL

Abstract

The focus of this paper is on how Active KDL can be used to provide a very powerful simulation support environment. Active KDL (Knowledge/Data Language) is an object-oriented database programming language, which provides access to integrated model, knowledge, and data bases. Simulation inputs and outputs can be stored by Active KDL since it supports complex objects. More importantly, Active KDL also allows users to specify rules to capture heuristic knowledge and methods to specify procedural behavior. Finally, Active KDL provides a simple mechanism for specifying concurrent execution, namely tasks embedded in active objects. These facilities provide a powerful mechanism for building simulation models out of pre-existing model components. These capabilities provide a tight coupling between a SIMODULA-like simulation system and a knowledge/database system, supporting query driven simulation, where model instantiation is used for information generation. Miller, Potter, Kochut, Weyrich tabase field involves object-oriented database systems [Beet 88, Bloo 87, Fish 87, Kim 87, Kim 88, Maie 86, Merr 87, Penn 87, Smit 871, since they provide more powerful constructs for structural and behavioral specification.]Active KDL is designed to support the complex information needs of engineering databases and expert databases. In particular, Active KDL provides an integration of model bases, knowledge bases, and databases. Simulation inputs and outputs can be stored by Active KDL since it supports complex objects. More importantly, Active KDL also allows users to specify rules to capture heuristic knowledge and methods to specify procedural behavior. Finally, Active KDL provides a simple mechanism for specifying concurrent execution, namely tasks embedded in active objects. These facilities provide a powerful mechanism for building simulation models out of preexisting model components.We designed Active KDL as an enhancement of KDL, which is a hyper-semantic data modeling language developed by Potter [Patt 86, Pott 87, Pott 88a, Pott 88b, Pott 891. Recently, a partial implementation of KDL in C++ has been completed [Kess 891. This implementation exploits the already present data (or object) modeling capabilities of C++ [Duwh 89, Lipp 89, Berr 88, Wein 88, Stro 861. KDL schema and queries are translated (via yacc) to C++, at which point they am compiled and executed. Currently, several research projects are either extending C++ to make it a database programmin g language (e.g., 0++ [Agra 891. E [Rich 871) or, as we are doing, translating a simpler and higher level language to C++ (e.g., ONTOS (new version of Vbase) [Andr 89, Duhl88, Andr 871).