Tech Report CS-91-64

InterActions: Multidatabase Support for Planning Applications

Marian H. Nodine

December 1991


Multidatabases attempt to provide a unified method of accessing information currently stored in multiple, autonomous, existing databases. This paper describes a global transaction model, {\em InterActions}, that supports access to a multidatabase. An InterAction is a unit of work that accomplishes a specific, coherent task. Unlike traditional transactions, an InterAction is not assumed to be atomic. Instead, it allows the user to define for the InterAction not only the steps that it takes to accomplish its task, but also the extent to which the InterAction must be isolated from other InterActions. It also allows the user to define what to do when the underlying multidatabase evolves in some way that affets the InterAction.

This paper presents a set of requirements for tasks that access and/or update information in a multidatabase. A model for defining these tasks, called InterActions, is presented. This includes specifying a language for defining InterActions, and shows how to map an InterAction specification onto a set of transactions on the local databases that form the multidatabase. In addition, it presents a definition for correct operation of a multidatabase that supports InterActions. Also, this paper presents insights into how to implement synchronization, commit, and recovery algorithms for InterActions in a multidatabase.

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