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The C3-Locking-Protocol - A Concurrency Control Mechanism For Design Environments

N. Ritter

Paper as gzipped PostScript

Abstract:

The CONCORD (CONtrolling COopeRation in Design environments) approach is a processing model for cooperative design processes. It supports the different types of activities predominating in design (transactions, design flows, cooperative actions) by providing a layered activity model allowing to pre-specify design flows and wanted patterns of cooperation and to control the corresponding actions in order to enforce those specifications. CONCORD exploits conventional transactions as elementary building blocks. Although we claim that conventional transactions are needed as elementary building blocks also in cooperative design processes, we think that the corresponding concurrency control mechanism has to be adapted to special requirements of design processes. These requirements are implied by the necessity of interplay between cooperation control, design-flow management, design-tool executions, transaction management, and version management. In this paper, we introduce a locking protocol meeting these requirements. The C3-protocol controls concurrent manipulations of versioned data and provides an adequate interplay with the higher processing structures (designflow, cooperation). Furthermore, it reflects the semantics of the version model, it avoids blocking of transactions and it takes cooperative design data exchange into account.

Keywords:

In: ITG-Fachbericht 137, Softwaretechnik in Automation und Kommunikation (STAK'96), München, März 1996, S. 95-110.