Run-time Verification of Behavioural Conformance for Conversational Web Services

Abstract

Abstract-Web services exposing run-time behaviour that deviates from their behavioural specifications represent a major threat to the sustainability of a service-oriented ecosystem. It is therefore critical to verify the behavioural conformance of services during run-time. This paper discusses a novel approach for run-time verification of Web services. It proposes the utilisation of Stream X-machines for constructing formal behavioural specifications of Web services which can be exploited for verifying that a service's run-time behaviour does not deviate from what is defined in the specification. Our approach allows for checking both the control flow of a Web service and the values of the data in the generated responses. The paper also proposes a classification of Web services and discusses how different types of services can be verified at run-time. Finally, it presents a run-time monitoring and verification architecture and discusses how it can be integrated into different types of service-oriented infrastructures.

Enabling Proactive Adaptation through Just-in-Time Testing of Conversational Services

“…This is because some operations may have preconditions which depend on the state of the service. The set of all acceptable invocation sequences is called the protocol (or choreography) [10] of the service. An example is the shopping basket of an online store.…”

“…The proposed technique builds on previous work on testing and monitoring of conversational services [9,10] and on online testing for proactive adaptation [13,19].…”

An extensible architecture for run-time monitoring of conversational web services

“…Each processing function, presented in Figure 2, has been specified in the complete SXM specification of the TravelAgency service, using the approach that has been presented in [8]. The complete SXM specification is beyond the scope of this paper and thus is not included.…”

“…In [8], we proposed a verification approach to run-time verification of behavioural conformance of Web services, which relies on the publication of a behavioural model for the Web service, based on the Stream X-Machines (SXM) [9] formalism described in the next section. The approach can be summarised as follows.…”

“…In [8], where we have presented a framework for run-time verification for Web services, we have classified stateful services into the non-conversational and conversational; the former accept all operations at all states, whereas the later accept only a specific protocol. We would like to underline that a conversational service may be implemented as a stateless interface with stateful behaviour.…”