Formal Modelling and Verification of Compensating Web Transactions

Abstract

Correctness of a system depends on the correct execution of transactions. For large systems, e.g., web-based, these transactions involve more than one component and hence more than one independent entity. Such transactions are called Long Running Transaction(LRT) as they coordinate complex interactions among multiple sub-systems. Well known roll-back mechanism do not suffice to handle faults in LRTs, therefore compensation mechanisms are introduced. However, introduced structures are complex and hard to understand and handle. Formal methods are well known tool for modelling, analysis and synthesis of complex systems. In this chapter we present a technique that allows modelling LRTs using Compensating CSP, then translating them to Promela language and analyzing using SPIN tool. We have modelled and verified the LRTs. We exemplify it using a web service called Air-ticket Reservation System (ATRS).