Abstract: On the one hand, Petri net models have a successful history in the modeling, simulation, and verification of workflows and business processes. On the other hand, BPEL is the de facto standard for describing and implementing Web service-based business processes. With abstract BPEL processes, BPEL can also be used as modeling language. However, being a complicated language with many syntactic constraints, abstract BPEL processes impede a straightforward modeling. BPEL processes which can be easily refined to executable BPEL processes. This approach combines strengths of Petri nets in modeling and verification with the ability to execute and port BPEL processes. Furthermore, it completes the Tools4BPEL framework to synthesize BPEL processes which are correct by design. 1

Abstract. Recently, we introduced the concept of an operating guideline of a service as a structure that characterizes all its properly interacting partner services. The hitherto considered correctness criterion is deadlock freedom of the composition of both services. In practice, there are intended and unintended deadlock-freely interacting partners of a service. In this paper, we provide a formal approach to express intended and unintended behavior as behavioral constraints. With such a constraint, unintended partners can be “filtered ” yielding a customized operating guideline. Customized operating guidelines can be applied to validate a service and for service discovery. Key words: Business process modeling and analysis, Formal models in business

Abstract. We address the problem of analyzing the interaction between WS-BPEL processes. We present a technology chain that starts out with a WS-BPEL process and translates it into a Petri net model. On the model we decide controllability of the process (the existence of a partner process, such that both can interact properly) and compute its operating guideline (a characterization of all properly interacting partner processes). To manage processes of realistic size, we present a concept of a flexible model generation which allows the generation of compact Petri net models. A case study demonstrates the value of this technology chain.

Abstract. Many work has been conducted to analyze service choreographies to assert manyfold correctness criteria. While errors can be detected automatically, the correction of defective services is usually done manually. This paper introduces a graph-based approach to calculate the minimal edit distance between a given defective service and synthesized correct services. This edit distance helps to automatically fix found errors while keeping the rest of the service untouched. A prototypic implementation shows that the approach is applicable to real-life services. Key words: Choreographies, graph correction, correction of services, verification of services, service automata, operating guidelines, BPEL

Abstract. Deciding whether a service S can be substituted by another service S ′ is an important problem in practice and one of the research challenges in service-oriented computing. In this paper, we define three substitutability notions for services. Accordance specifies that S ′ cooperates with at least the environments that S cooperates with. S and S ′ are equivalent if they cooperate with the same environments. To guarantee that S ′ cooperates with a fixed subset of environments that S cooperates with, the notion of deprecation can be used. For each substitutability notion we present a decision algorithm. To this end we apply the concept of an operating guideline of a service as an abstract representation of all environments the service cooperates with.

Abstract. Controllability for service models is a similar criterion as soundness for workflow models: it establishes a necessary condition for correct behavior of a given service model. Technically, controllability is the problem to decide, for a given service, whether it can interact correctly with at least one other service. Parameters to the problem are the established correctness criterion (e.g. deadlock freedom, livelock freedom, quasi-liveness), the shape of partners (centralized partners versus independently acting partners), or the shape of communication (asynchronous versus synchronous). In this article, we survey and partly extend various recent results concerning the verification of controllability for Petri net based service models. Significant extensions include the study of livelock freedom as correctness criterion as well as the new results on autonomous multi-port controllability. 1

Behavioral adapters are a way to establish proper interaction between services that have been developed independently. We present a novel approach for specifying such adapters, based on domain-specific transformation rules that reflect the elementary operations that adapters can perform. We show how complex adapters that adhere to these rules can be generated using existing controller generation algorithms. We discuss some example applications, including real-world business processes.

Abstract. Service-oriented architectures propose loosely coupled interacting services as building blocks for distributed applications. Since distributed services differ from traditional monolithic software systems, novel testing methods are required. Based on the specification of a service, we introduce an approach to automatically generate test cases for blackbox testing to check for conformance between the specification and the implementation of a service whose internal behavior might be confidential. Due to the interacting nature of services this is a nontrivial task.

Abstract. Service-oriented computing proposes services as building blocks which can be composed to complex systems. To reason about the correctness of a service, its communication protocol needs to be analyzed. A fundamental correctness criterion for a service is the existence of a partner service, formalized in the notion of controllability. In this paper, we introduce Wendy, a Petri net-based tool to synthesize partner services. These partners are valuable artifacts to support the design, validation, verification, and adaptation of services. Furthermore, Wendy can calculate an operating guideline, a characterization of the set of all partners of a service. Operating guidelines can be used in many application scenarios from service brokerage to test case generation. Case studies show that Wendy efficiently performs on industrial service models. 1

Abstract. Compatibility of behavior, i.e. the correct ordering of messages, is one of the core aspects for the interaction between services as parts of an inter-organizational business process. In previous work, we proposed formal representations for service behavior (including Petri nets and service automata) and finite representations of sets thereof (operating guidelines). In this article, we show how the basic set operations union, intersection, and complement, as well as membership and emptiness tests, can be implemented on finite representations of (typically infinite) sets of services. We motivate the operations by three examples of applications—service substitution, selection of behavior, and navigation in a behavioral registry. 1