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Many capabdltles that are needed for recursive apphcatlons In engmeermg and project management are not well supported by the usual formslatlons of recursionWe Identify a class of recurstons called "traversal recurslons" (which model traversals of a dtrected graph) that have tw3 Important properties they can supply the necessary capabdlttes and efficient processmg algorithms have been defined for them First we present a taxonomy of traversal recurslons based on propertles of the recursIon on graph structure and on unusual types of metadata This taxonomy IS explolted to Identify solvable recursions and to select an execution algorithmWe show how graph traversal can sometimes outperform the more general Iteration algorithm Finally we show how a conventional query optimtzer architecture can be extended to handle recurstve queries and views

Future information processing environments will consist of a vast network of heterogeneous, autonomous, and distributed computing resources, including computers (from mainframe to personal), information-intensive applications, and data (files and databases). A key challenge in this environment is providing capabilities for combining this varied collection of resources into an integrated distributed system, allowing resources to be flexibly combined, and their activities coordinated, to address challenging new information processing requirements. In this paper, we describe the concept of distributed object management, and identify its role in the development of these open, interoperable systems. We identify the key aspects of system architectures supporting distributed object management, and describe specific elements of a distributed object management system being developed at GTE Laboratories.

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