Orchestration and atomicity

This dissertation presents the concurrent programming language Ora, an extension of the Orc orchestration language with the capability to execute transactions. A new formal definition of transactions is given, in terms of two complementary properties: atomicity and coatomicity. These properties are described in terms of a partial order of events, rather than as properties of a totally ordered program trace. Atomicity and coatomicity are ensured in Ora programs by a novel algorithm for multiversion concurrency control.