Cooperative transactions for multiuser environments

This chapter surveys extended transaction models proposed to support long duration, interactive and/or cooperative activities in the context of multi-user software development and CAD/CAM environments. Many of these are variants of the checkout model, which addresses the long duration and interactive nature of the activities supported by environments but still isolates environment users, making it difficult for them to collaborate while their activities are in progress. However, a few cooperative transaction models have been proposed to facilitate collaboration, usually while maintaining some guarantees of consistency. To appear as a chapter in Won Kim (ed.), Modern Database Management: Object-Oriented and Multidatabase Technologies, ACM Press. Conventional database transactions guarantee atomicity in two senses: concurrency atomicity, for consistent concurrent access, and failure atomicity, for consistent persistence. Unfortunately, these atomicity properties severely limit the applicability of the transaction concept with respect to modern database applications such as software development and CAD/CAM environments, even though thes