Abstract. We study services modeled as open workflow nets (oWFN) and describe their behavior as service automata. Based on arbitrary finite-state service automata, we introduce the concept of an operating guideline, generalizing the work of [1,2] which was restricted to acyclic services. An operating guideline gives complete information about how to properly interact (in this paper: deadlock-freely and with limited communication) with an oWFN N. It can be executed, thus forming a properly interacting partner of N, or it can be used to support service discovery. An operating guideline for N is a particular service automaton S that is enriched with Boolean annotations. S interacts properly with the service automaton Prov, representing the behavior of N, and is able to simulate every other service that interacts properly with Prov. The attached annotations give complete information about whether or not a simulated service interacts properly with Prov, too. 1

Abstract. We present a Petri net semantics for the Business Process Execution Language for Web Services (BPEL). Our semantics covers the standard behaviour of BPEL as well as the exceptional behaviour (e.g. faults, events, compensation). The semantics is implemented as a parser that translates BPEL specifications into the input language of the Petri net model checking tool LoLA. We demonstrate that the semantics is well suited for computer aided verification purposes. Key words: Business process modeling and analysis, Formal models in business

Abstract. This paper addresses the problem of analyzing the interaction between BPEL processes. We present a technology chain that starts out with a BPEL process and transforms 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). A case study demonstrates the value of this technology chain. Key words: Business process modeling and analysis, Formal models in business

A service-oriented system is composed of independent software units, namely services, that interact with one another exclusively through message exchanges. The proper functioning of such system depends on whether or not each individual service behaves as the other services expect it to behave. Since services may be developed and operated independently, it is unrealistic to assume that this is always the case. This paper addresses the problem of checking and quantifying how much the actual behavior of a service, as recorded in message logs, conforms to the expected behavior as specified in a process model. We consider the case where the expected behavior is defined using the BPEL industry standard (Business Process Execution Language for Web Services). BPEL process definitions are translated into Petri nets and Petri net-based conformance checking techniques are applied to derive two complementary indicators of conformance: fitness and appropriateness. The approach has been implemented in a toolset for business process analysis and mining, namely ProM, and has been tested in an environment comprising multiple Oracle BPEL servers.

Abstract. Despite the popularity of web services, creating them manually is an intricate task. Composite web services are defined using the evolving standard for BPEL (Business Process Execution Logic). It is explained how CRESS (Chisel Representation Employing Systematic Specification) has been extended to meet the challenge of graphically and formally describing web services. Sample CRESS descriptions are presented of web services. These are automatically translated into LOTOS, permitting rigorous analysis and automated validation. 1

Abstract — Composition of web services is much studied to support business-to-business and enterprise application integration in e-Commerce. Current web service composition approaches range from practical languages aspiring to become standards (like BPEL, WS-CDL, OWL-S and WSMO) to theoretical models (like automata, Petri nets and process algebras). In this paper we compare these approaches w.r.t. a selected set of characteristics (like trust, security and performance) and we advocate the use of formal models, and their tool support, to increase one’s confidence in web service compositions. This paper can assist web service composition designers and developers to deliver lasting solutions, in concordance with the technology’s critical needs. I.

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

Service Oriented Architectures draw heavily on techniques for reusing and assembling off-the-shelf software components. While powerful, this programming practice is not without a cost: the software architect must ensure that the off-the-shelf components interact safely and in ways that conform with the specification. We develop a new theory for adaptable service compositions. The theory provides an effective framework for analyzing the conformance of contract-based service compositions, and for enforcing their compliance, in a uniform, and formally elegant setting. 1.

Abstract — Current approaches to service composition In this paper, we first describe and compare these range from industrial standards (like BPEL and OWL-S) to formal methods (like Petri nets and process algebras). In this paper, we survey a number of such approaches and compare them with respect to a carefully selected set of characteristics (like exception handling and quality approaches to service composition w.r.t. a selected set of main characteristics to assess their quality, much in the style of [49]. We then survey the increasing use of formal methods (mainly state-action models like Petri of services). We conclude that formal methods, often nets or process models like the π-calculus) to formally including tool support, are ideal to assist designers and developers because their use leads to increased confidence in the obtained compositions. specify, compose and verify service compositions, and also compare these w.r.t. the selected set of characteristics. Finally, we discuss the expected advantage of using

Abstract. Recent research in the area of business process management (BPM) introduced the application of a process algebra—the π-calculus— for the formal description of business processes and interactions among them. Especially in the area of service-oriented architectures, the key architecture for today’s BPM systems, the π-calculus—as well as other process algebras—have shown their benefits in representing dynamic topologies. What is missing, however, are investigations regarding the correctness, i.e. soundness, of process algebraic formalizations of business processes. Due to the fact that most existing soundness properties are given for Petri nets, these cannot be applied. This paper closes the gap by giving characterizations of invariants on the behavior of business processes in terms of bisimulation equivalence. Since bisimulation equivalence is a well known concept in the world of process algebras, the characterizations can directly be applied to π-calculus formalizations of business processes. In particular, we investigate the characterization of five major soundness properties, i.e. easy, lazy, weak, relaxed, and classical soundness. 1