Nawal Guermouche

Timed Model Checking Based Approach for Web Services Analysis

Web services are the main pillar of the Service Oriented Computing (SOC) paradigm which enables the application integration within and across business organizations. One of the important features of the Web services is the choreography aspect which allows to capture collaborative processes involving multiple services. In this context, one of the important investigations is the choreography compatibility analysis. We mean by the choreography compatibility the capability of a set of Web services of actually interacting by exchanging messages in a proper manner. Whether a set of services are compatible depends not only on their sequences of messages but also on quantitative properties such as timed properties. In this paper, we investigate a model checking based approach that deals with checking the compatibility of a choreography in which the Web services support asynchronous timed communications. Particularly, in this paper we are using the model checker UPPAAL. We propose a set of required abstractions that allow to use the model checker UPPAAL to deal with timed asynchronous communicating services.

Timed Specification For Web Services Compatibility Analysis

Web services are becoming one of the main technologies for designing and building complex inter-enterprise business applications. Usually, a business application cannot be fulfilled by one Web service but by coordinating a set of them. In particular, to perform a coordination, one of the important investigations is the compatibility analysis. Two Web services are said compatible if they can interact correctly. In the literature, the proposed frameworks for the services compatibility checking rely on the supported sequences of messages. The interaction of services depends also on other properties, such that the exchanged data flow. Thus, considering only supported sequences of messages seems to be insufficient. Other properties on which the services interaction can rely on, are the temporal constraints. In this paper, we focus our interest on the compatibility analysis of Web services regarding their (1) supported sequences of messages, (2) the exchanged data flow, (3) constraints related to the exchanged data flow and (4) the temporal requirements. Based on these properties, we study three compatibility classes: (i) absolute compatibility, (ii) likely compatibility and (iii) absolute incompatibility.

Asynchronous Timed Web Service-Aware Choreography Analysis

Web services are the main pillar of the Service Oriented Computing (SOC) paradigm which enables applications integration within and across business organizations. One of the important features of the Web services is the choreography aspect which allows to capture collaborative processes involving multiple services. In this context, one of the important investigations is the choreography compatibility analysis . We mean by the choreography compatibility the capability of a set of Web services of actually interacting by exchanging messages in a proper manner. Whether a set of services are compatible depends not only on their sequences of messages but also on quantitative properties such as timed properties . In this paper, we investigate an approach that deals with checking the timed compatibility of a choreography in which the Web services support asynchronous timed communications .

Privacy-Aware Web Service Protocol Replaceability

Business protocols are becoming a necessary part of Web services description [4]. The work presented in [4] investigates mechanisms for analyzing the compatibility and the substitution (i.e., replaceability) of Web services based on their functional properties. In this paper, we focus on the replaceability analysis. Whether a service can replace another depends not only on their functional properties but also on non functional requirements (e.g., privacy policies). We propose a privacy-aware protocol replaceability approach to extend the work presented in [4] by privacy properties. We introduce a rule-based privacy model and we extend business protocols, leading to what we call private business protocols. Finally, a private replaceability analysis of private business protocols is discussed. We mainly investigate compatibility issues, that is whether one private business protocol can support the same set of conversations with respect to the privacy requirements.

A Mediator Based Approach For Services Composition

Web services are becoming one of the main technologies for designing and building complex inter-enterprise business applications. Usually, a business application cannot be fulfilled by one Web service but by a combination of several ones. Hence, there is an obvious need for mechanisms allowing Web services composition. In this paper, we are interested in the automatic composition of Web services. Our composition framework is based on the coordination of Web services having the capability to communicate via the exchange of messages. Web services are modeled as conversational automata, where transitions are possibly guarded according to the values of exchanged or produced data. If the coordination does not satisfy the business application, we synthesize a new service called mediator. The mediator aims at generating the missing messages which are required to complete the cartesian product so that it mimics the goal service representing the business application to implement.

Enhancing Formal Specification and Verification of Temporal Constraints in Business Processes

Formal specification and verification support of time-related constraints constitute fundamental challenges for any Business Process Management (BPM) system. Reluctantly, the literature on the subject of formal specification and verification of advanced temporal constraints such as absolute temporal constraints associated with relative temporal constraints is scarce. In this paper, we propose a novel approach enabling the formal specification and verification of advanced temporal constraints of business processes. The particularity of our approach is that it caters for relative and absolute related temporal constraints while relying on the dependencies that can exist between theses constraints. In fact, it is important to deal with such dependencies to handle the violations that can arise as soon as possible at design step. To do so, we propose a formal approach which relies on the timed automata formalism. In this context, we propose a set of mapping rules and algorithms where the semantic of timed automata is preserved even if we deal with absolute and relative temporal constraints. Using the defined formal model, we investigate a model checking based verification process that aims at validating business processes against their absolute and relative temporal constraints.

Timed Conversational Protocol Based Approach for Web Services Analysis

Choreography is one of the most important features of Web services. It allows to capture collaborative processes involving multiple services. In this paper, we are interested in analyzing the interoperability of Web services that support asynchronous communications which are constrained by data and timed constraints, using a model checking based approach. In particular, we deal with the compatibility problem. To do so, we have developed a set of abstractions and transformations on which we propose a set of primitives characterizing a set of compatibility classes of Web services. This paper is about the specification and implementation of this approach using the UPPAAL model checker.

BPMN4CPS: A BPMN Extension for Modeling Cyber-Physical Systems

Modeling is one of the most important topics in the domain of Cyber-Physical Systems (CPS). In the field of process modelling, Business Process Modeling and Notation (BPMN) is the most used standard. However, BPMN remains limited to cater for the specific characteristics and properties of CPS such as real world properties. In this paper, we propose BPMN4CPS, which provides a set of extensions for BPMN to properly and accurately model CPS processes. In order to illustrate the applicability of BPMN4CPS, we present a case study of an ambulance drone system.

Pruning Based Service Selection Approach Under QoS and Temporal Constraints

Dynamic selection of the best services to execute abstract tasks of business processes is very important. Indeed, it enables to cope with complex users requirements that require the collaboration of several more elementary services. However, with the increasing amount of candidate services of each business task that offer different QoS (Quality of Service) values, the selection of the optimal combination of services becomes a very hard task. This problem is more complex when dealing with temporal properties of business processes associated with time-dependent QoS parameters that can change according to the execution time. Unlike static QoS which have been deeply studied in the existing service selection approaches, time-dependent QoS are insufficiently taken into consideration. In this paper, we are interested in the problem of service selection to satisfy a given business process while considering temporal properties associated to time-dependent QoS. The selection approach that we propose relies on a new service pruning approach that is applied prior to our selection algorithm to reduce the number of candidate services while guaranteeing that the optimal solution still be found.

Timed Properties-Aware Asynchronous Web Service Composition

In the last few years, there has been an increasing interest in the Web service composition problem. In the literature, the proposed frameworks investigate mechanisms for synthesizing a composition based on operations and/or messages choreography constraints. The messages choreography constraints depend not only on messages, but also on timed properties. Specifically, we mean by timed properties the time window within which a message can be exchanged. In this paper, we present a formal composition approach to cope with timed properties of asynchronous Web services. We present how modeling the behavior of Web services augmented with timed properties. Then we present a mechanism to deal with such properties when building a composition.