Formalizing Delegation Authorization of Workflow Using Graph Transformation with Variables

Supporting delegation mechanisms in workflow systems is receiving increasing interest from the research community. Using graph transformation as a formalism to specify access control has several advantages, from the intuition provided by the visual aspect to the precise semantics and the systematic verification of constraints. Using graph transformation with variables yields very expressive rules that are still comprehensible. After reviewing the basic notations of graph transformation with variables, this article presents specification formalisms for workflow delegation policies using graph transformation with variables. The authorization states are represented by graphs and state transition by graph transformation with variables. The proposed formalization provides an intuitive description for the manipulation of graph structures as they occur in workflow delegation and a precise specification of consistency conditions on graphs and graph transformations. We specifies a type graph to represents the type information in the graph transformation for workflow delegation, a set of rule schemes to build the system states and sets of positive and negative constraints to specify wanted and unwanted framework.