Concurrency control has been thoroughly studied in the context of traditional database applications such as banking and airline reservations systems. There are relatively few studies, however, that address the concurrency control issues of advanced database applications such as CAD/CAM and software development environments. The concurrency control requirements in such applications are different from those in conventional database applications; in particular, there is a need to support non-serializable cooperation among users whose transactions are long-lived and interactive, and to integrate concurrency control mechanisms with version and configuration control. This paper outlines the characteristics of data and operations in some advanced database applications, discusses their concurrency control requirements, and surveys the mechanisms proposed to address these requirements.

Large scale software development processes often require cooperation among multiple teams of developers. To support such processes, SDEs must allow developers to interleave their access to the various components of the projects. This interleaving can lead to interference , which may corrupt the project components. In traditional database systems, the problem is avoided by enforcing serializability among concurrent transactions. In traditional software development, the problem has been addressed by introducing version and configuration management techniques combined with checkout/checkin mechanisms. Unfortunately, both of these solutions are too restrictive for SDEs because they enforce serialization of access to data, making cooperation unacceptably difficult. In this paper, I illustrate the problem and show how the encoding of the software development process in process-centered SDEs can be used to provide more appropriate concurrency control. I present the concurrency control mechanism I developed for the MARVEL SDE. This mechanism uses the process model in MARVEL to support the degree of cooperation specified in the development process.

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