Preservation of Integrity Constraints by Workflow

Integrity constraints on data are typically defined when workflow and business process models are developed. Keeping data consistent is vital for workflow execution. Traditionally, enforcing data integrity constraints is left for the underlying database system, while workflow system focuses primarily on performing tasks. This paper presents a new mechanism that turns a workflow into an equivalent one that will preserve integrity constraints. For a given workflow schema (or model) and a given set of data integrity constraints, an algorithm developed in this paper injects additional conditions into the workflow schema that restricts possible execution paths. The modified workflow will guarantee data consistency (i.e., satisfaction of the integrity constraints) whenever the workflow updates the database(s). In addition, we show that our injection mechanism is "conservative complete", i.e., the conditions inserted are weakest possible. By making workflow execution self-behaving, enforcing integrity constraints over multi-databases is avoided, and constraints specific to a workflow can also be enforced effectively. Mechanisms such as this enhance independence of workflow executions from the environment--a much desired property.

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