OASIS, a database programming environment that extends UNIX with the concept of persistent objects, is discussed. The OASIS query languages extend conventional database query languages with procedural methods and general control statements. As the complexity of the languages makes it difficult to device a query optimizer based on a universally applicable algorithm, each query in OASIS is optimized based on a collection of basic patterns for which each pattern is associated with a separation query optimization algorithm. The optimization techniques for a set of basic patterns consisting of iterative statements and a set of nested statements is described. The optimization techniques discussed include an extended decomposition algorithm, evaluation of multiple conditions, data dependence analysis, and optimization of queries with arbitrary nesting.>

In this paper, we describe a knowledge‐based software environment (KBSE) which supports concurrent programming based on the framework of object‐oriented knowledge base. The object‐oriented knowledge base framework combines an object‐oriented data model with the logic programming paradigm. In KBSE, the user can describe a concurrent process with a set of (sequential) flowcharts and a set of coordination constraints and integrity constraints specified in a high level description language. The description is then synthesized into a Petri net representation. With the Petri net representation, existing analysis tools for Petri net can be fully utilized to assist the design and analysis of concurrent processes.