Context based behavioural verification of composed web services modeled in finite state machines

Abstract

Monitoring service execution for finding run time errors is of prime interest in achieving resilient service provisioning for users on web. Though the services are modelled and verified for structural errors still behavioural errors may occur for many practical reasons e.g undefined user network malfunctioning and computational errors. This makes a need for run time checking of service behaviour to ensure correctness in service execution. Run time system checking is always tricky for time consideration as overhead in runtime verification may discourage service user for delay in service provisioning. This paper address run-time behaviour verification with respect to the contexts, a service is designed for. A service is modelled in AFSM Finite State Machine augmented with context information. Context of a state is defined by variables and their values associated with. In case of a composed service communication among constituent services is also modeled both execution of a composed service and interactions among its constituting services. For runtime service behaviour verification, here we propose a technique that validates context sequence, context co-occurrence and context timeliness. A framework is proposed for system implementation.