Specifying transaction-based information systems with regular expressions

The work is about the formal specification of transaction-based, interactive information systems. A transaction is a task that the user can execute independently, and the system can be defined as a partially ordered set of transactions. The general framework is the transformational paradigm, based on the classical Waterfall development model (W.W. Royce, 1970). The stages are systems analysis, software specification, design, and implementation. The systems analysis and software specification stages are covered. An informal, transaction-oriented method for systems analysis is proposed. The resulting system specification involves two parts: a high-level specification of each transaction and a formal specification of the system´s control flow, i.e., the order of execution of the transactions. The system´s control flow is expressed in a formal language describing concurrent regular expressions built on transaction names. At the software specification stage, some operational requirements, such as connect/disconnect transactions and the application of the all-or-nothing principle, are added to the system specification. Then a serial product automaton (SPA) is used to transform the concurrent expression into a single regular expression. This result is proven to be consistent with the system specification