Cover Page Title: the Oodb Path-method Generator (pmg) Using Access Weights and Precomputed Access Relevance the Oodb Path-method Generator (pmg) Using Access Weights and Precomputed Access Relevance Zx

1 No CR classiication for Object-Oriented Databases seems to exist, so these classiications are naturally approximations. Abstract A path-method is used as a mechanism in object-oriented databases (OODBs) to retrieve or to update information relevant to one class that is not stored with that class but with some other class. A path-method is a method which traverses from one class through a chain of connections between classes and accesses information at another class. However, it is a diicult task for a casual user or even an application programmer to write path-methods to facilitate queries. This is because it might require comprehensive knowledge of many classes of the conceptual schema, that are not directly involved in the query, and therefore may not even be included in a user's (incomplete) view about the contents of the database. We have developed a system, called Path-Method Generator (PMG), which generates path-methods automatically according to a user's database manipulating requests. The PMG ooers the user one of the possible path-methods and the user veriies from his knowledge of the intended purpose of the request whether that path-method is the desired one. If the path method is rejected, then the user can utilize his now increased knowledge about the database to request (with additional parameters given) another ooer from the PMG. The PMG is based on access weights attached to the connections between classes and precomputed access relevance between every pair of classes of the OODB. Speciic rules for access weight assignment and algorithms for computing access relevance appeared in our previous papers MGPF92, MGPF93, MGPF96]. In this paper we present a variety of traversal algorithms based on access weights and precomputed access relevance. Experiments identify some of these algorithms as very successful in generating most desired path-methods. The PMG system utilizes these successful algorithms and is thus an eecient tool for aiding the user with the diicult task of querying and updating a large OODB. z This research was (partially) done under a cooperative agreement between the National Institute of Standards and Technology (NIST) Advanced Technology Program (ATP) (under the HIIT contract, number 70NANB5H1011) and the Healthcare Open Systems and Trials (HOST), Inc consortium. x This research was (partially) done under a series of cooperative agreements with the Institute of Publication and Information Systems (IPSI) at the Gesellschaft fuer Mathematik und Datenverarbeitung (GMD) in Germany.