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Top1. Introduction
In this paper, we propose a two-fold automatic model transformation of composite service behavior specification, modeled in OWFNet (an extension of Petri Nets). The model is translated in the first step by a model to model (M2M) transformation into a LOTOS model using the TGG interpreter plugin. In the second step a model to text transformation (M2T) is performed, on the generated LOTOS model, which is transformed to a purely LOTOS text specification by the Xpand tool (http://cadp.inria.fr) tool kit for checking behavior compatibility.
The service oriented architecture (SOA) is an ideal solution to the faced problems in distributed application development especially modules interoperability; this is characterized by heterogeneous system and low coupling of system components. Despite its adoption by industrial and academic fields, the success of the SOA approach is inevitably conditioned by a successful automation of dynamic service composition, where a new service is created by combining functionalities of elementary services selected on the fly (Papazoglou, 2003). Although, software vendors cannot guarantee the safety of their services in an open interactions with other applications, such as the development, the testing and the verification of these services are done independently from other vendors peers (Bentahar, 2013), in consequence, the combination their functionalities cannot success any way. This raises the problem of subdivision of services developed by different providers. This incompatibility is on two main syntactic aspects (the compatibility on the interaction interfaces) and especially on the interaction behavior as described in (Nezhad, 2006). The latter concerns the specification of the external and observable behavior of services, which is required to achieve the composition operation, because having only a syntactic compatibility level cannot by itself guarantee the success of the interaction between two services (Papazoglou, 2003, Benatallah, 2004).
The crucial problem that was raised is whether a given selected service based on some criteria may be successfully composed with the desired services, in terms of interaction interfaces, even if they are not compatible in behavior aspects.
Non-formal approaches of composition, based on AI planning tools, have shown their limits at the expense of purely formal approaches, characterized by their mathematical basis (Ehrig, 2004, Taentzer, 2004). These formal approaches are therefore ideal candidates that can contribute to solve the problem of checking compatibility between services.
The most used formalisms for describing systems behavior are the graph-based ones, including automata, Petri net and their different variants, whose expression power is proven in several engineering area. However, their major drawback is the lack of computing possibilities that allow detecting the presence or absence of some required characteristics on the modeled system. To this end, the transformation of behavior descriptions based on graph formalisms to other ones having the computing power has a major advantage to perform analysis on an equivalent description and to validate the required characteristics of the model.
The paper is structured as follows. In section 2, we present some related works. In section 3, we introduce concepts and definitions of the graph transformation formalism based on an algebraic approach and the triple graph grammar. A state of the art on the OWFNet used as formalism for modeling services in section 4. The section 5 introduce the LOTOS language, in section 6 we present our proposed transformation approach. The approach is tested on a use case that is detailed in section 7 and finally we present a conclusion and future work.