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. 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

We introduce COWS (Calculus for Orchestration of Web Services), a new foundational language for SOC whose design has been influenced by WS-BPEL, the de facto standard language for orchestration of web services. COWS combines in an original way a number of ingredients borrowed from well-known process calculi, e.g. asynchronous communication, polyadic synchroniza-tion, pattern matching, protection, delimited receiving and killing activities, while resulting different from any of them. Several examples illustrates COWS peculiarities and show its expressiveness both for modelling imperative and orchestration constructs, e.g. web services, flow graphs, fault and compensation handlers, and for encoding other process and orchestration languages.

Abstract: Much recent research work discusses the transformation between different process modelling languages. This work, however, is mainly focussed on specific process modelling languages, and thus the general reusability of the applied transformation concepts is rather limited. In this paper, we aim to abstract from concrete transformation strategies by distinguishing two major paradigms for representing control flow in process modelling languages: block-oriented languages (such as BPEL and BPML) and graph-oriented languages (such as EPCs and YAWL). The contribution of this paper are generic strategies for transforming from block-oriented process languages to graph-oriented languages, and vice versa. 1

Web service composition refers to the creation of new (Web) services by combining functionality provided by existing ones. A number of domain-specific languages for service composition have been proposed with consensus being formed around a process-oriented language known as WS-BPEL (or BPEL). The kernel of BPEL consists of simple communication primitives that may be combined using control-flow constructs expressing sequence, branching, parallelism, synchronization, etc. We present a comprehensive and rigorously defined mapping of BPEL constructs onto Petri net structures and use this for the analysis of various dynamic properties related to unreachable activities, conflicting messages, garbage collection, conformance checking, and deadlocks and lifelocks in interaction processes. We use a mapping onto Petri nets because this allows us to use existing theoretical results and analysis tools. Unlike approaches based on finite state machines, we do not need to construct the state space and can use structural analysis (e.g., transition invariants) instead. We have implemented a tool that translates BPEL processes into Petri nets and then applies Petri-net-based analysis techniques. This tool has been tested on different examples and has been used to answer a variety of questions.

Abstract. An open workflow net is basically a workflow net extended with a message passing interface. Open workflow nets are adequate models for services or parts of inter-organizational business processes. We investigate the problem of controllability, a natural counterpart of soundness in classical workflow nets (as studied by van der Aalst). We distinguish centralized, distributed, and local controllability and provide solutions to all problems. 1

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. BPEL is currently the most widespread language for composing Web services, but it lacks formal semantics. YAWL is a workflow language with a well defined formal semantics that implements the most common workflow patterns. In this paper we provide a methodology for translating BPEL processes into YAWL workflows, thus paving the way for the formal analysis, aggregation and adaptation of BPEL processes. The approach we propose defines a YAWL pattern for each BPEL activity. The translation of a BPEL process reduces then to suitably instantiating and interconnecting the patterns of its activities. 1

Abstract: Much recent research work discusses the transformation between different process modeling languages. This work, however, is mainly focussed on specific process modeling languages, and thus the general reusability of the applied transformation concepts is rather limited. In this article, we aim to abstract from concrete transformations by distinguishing two major paradigms for representing control flow in process modeling languages: block-oriented languages (such as BPEL and BPML) and graph-oriented languages (such as BPMN, EPCs, and YAWL). The contribution of this article are generic strategies for transforming from block-oriented process languages to graph-oriented languages, and vice versa.

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.