Prototyping and verifying distributed database systems using executable high-level Petri net models

In a distributed database system (DDBS), the users and the copies of the data items are distributed over the nodes of a computer network. The design of such a system requires precise concepts for the correct concurrent processing of user transactions, for the data access concurrency control (CC) and for the representation and manipulation of data. We model a generic DDBS as a parameterized formal executable high-level Petri net whose database is specified as abstract data types (ADT). A particular DDBS is generated by initial declarations (for the configuration of the network and the distribution of users and data items over its nodes) and parameters (for the chosen CC method and data types). The correctness of the model can be verified rigorously by means of formal analysis methods and by inspecting the occurrence graph. The model constitutes a (rapid) prototype whose simulation can demonstrate the functionality to the designers and the man-machine interface to prospective users. Moreover, the execution of the model allows to derive performance figures for particular applications that can be used for tuning.