When Are Two Workflows the Same?

In the area of workflow management, one is confronted with a large number of competing languages and the relations between them (e.g. relative expressiveness) are usually not clear. Moreover, even within the same language it is generally possible to express the same workflow in different ways, a feature known as variability. This paper aims at providing some of the formal groundwork for studying relative expressiveness and variability by defining notions of equivalence capturing different views on how workflow systems operate. Firstly, a notion of observational equivalence in the absence of silent steps is defined and related to classical bisimulation. Secondly, a number of equivalence notions in the presence of silent steps are defined. A distinction is made between the case where silent steps are visible (but not controllable) by the environment and the case where silent steps are not visible, i.e., there is an alternation between system events and environment interactions. It is shown that these notions of equivalence are different and do not coincide with classical notions of bisimulation with silent steps (e.g. weak and branching)

Patterns-based Evaluation of Open Source BPM Systems: The Cases of jBPM, OpenWFE, and Enhydra Shark

In keeping with the proliferation of free software development initiatives and the increased interest in the business process management domain, many open source workflow and business process management systems have appeared during the last few years and are now under active development. This upsurge gives rise to two important questions: what are the capabilities of these systems? and how do they compare to each other and to their closed source counterparts? i.e. in other words what is the state-of-the-art in the area?. To gain an insight into the area, we have conducted an in-depth analysis of three of the major open source workflow management systems - jBPM, OpenWFE and Enhydra Shark, the results of which are reported here. This analysis is based on the workflow patterns framework and provides a continuation of the series of evaluations performed using the same framework on closed source systems, business process modeling languages and web-service composition standards. The results from evaluations of the three open source systems are compared with each other and also with the results from evaluations of three representative closed source systems - Staffware, WebSphere MQ and Oracle BPEL PM, documented in earlier works. The overall conclusion is that open source systems are targeted more toward developers rather than business analysts. They generally provide less support for the patterns than closed source systems, particularly with respect to the resource perspective which describes the various ways in which work is distributed amongst business users and managed through to completion

Correctness of Business Process Models with Roles and Objects

The verification of business process models is an important step in the design phase of process-aware information systems. While a process model often describes different perspectives like control flow, object flow, and role assignment, most of the contributions in the areas of verification consider only the control flow. Hardly any work considers these three perspectives in a combined verification approach. In this paper we address this gap and introduce Integrated EPCs (iEPCs), a business process modeling language that extends EPCs with a concept of object flow and role assignment. By abstracting from the subtle differences of recent EPC semantics definitions, we show how any of these formalizations can be enhanced with transition rules that consider object existence and role availability as part of the state concept. Furthermore, we define three theorems that relate soundness of EPCs to soundness of iEPCs with different initial role and object set. These theorems provide the basis for a systematic verification approach of iEPCs that first identifies control-flow problems, then object-flow problems, and finally suitable role subsets. This way, our work contributes to a better identification of correctness issues already in conceptual process models in the early design phases

Soundness of EPC Process Models with Objects and Roles

The verification of business process models is an important step in the design phase of process-aware information systems. While a process model often describes different perspectives like control flow, object flow, and role assignment, most of the contributions in the areas of verification consider only the control flow. Hardly any work considers these three perspectives in a combined verification approach. In this paper we address this gap and introduce Integrated EPCs (iEPCs), a business process modeling language that extends EPCs with a concept of object flow and role assignment. By abstracting from the subtle differences of recent EPC semantics definitions, we show how any of these formalizations can be enhanced with transition rules that consider object existence and role availability as part of the state concept. Furthermore, we define three theorems that relate soundness of EPCs to soundness of iEPCs with different initial role and object set. These theorems provide the basis for a systematic verification approach of iEPCs that first identifies control-flow problems, then object-flow problems, and finally suitable role subsets. This way, our work contributes to a better identification of correctness issues already in conceptual process models in the early design phases

Modelling Business Process Variability

A reference process model represents multiple variants of a common business process in an inte-grated and reusable manner. It is intended to be individualized in order to fit the requirements of a specific organization or project. This practice of individualizing reference process models provides an attractive alternative with respect to designing process models from scratch. In particular, it en-ables the reuse of proven practices. This chapter introduces techniques for representing variability in the context of reference process models, as well as techniques that facilitate the individualization of reference process model with respect to a given set of requirements

Service interaction patterns : towards a reference framework for service-based business process interconnection

With increased sophistication and standardization of modeling languages and execution platforms supporting business process management (BPM) across traditional boundaries, has come the need for consolidated insights into their exploitation from a business perspective. Key technology developments in BPM bear this out, with several web services-related initiatives investing significant effort in the collection of compelling use cases to heighten the exploitation of BPM in multi-party collaborative environments. In this setting, we present a collection of patterns of service interactions which allow emerging web services functionality, especially that pertaining to choreography and orchestration, to be benchmarked against abstracted forms of representative scenarios. Beyond bilateral interactions, these patterns cover multilateral, competing, atomic and causally related interactions. Issues related to the implementation of these patterns using established and emerging web services standards, most notably BPEL, are discussed

Translating BPMN to BPEL

The Business Process Modelling Notation (BPMN) is a graph-oriented language in which control and action nodes can be connected almost arbitrarily. It is supported by various modelling tools but so far no systems can directly execute BPMN models. The Business Process Execution Language for Web Services (BPEL) on the other hand is a mainly block-structured language supported by several execution platforms. In the current setting, mapping BPMN models to BPEL code is a necessary step towards unified and standards-based business process development environments. It turns out that this mapping is challenging from a scientific viewpoint as BPMN and BPEL represent two fundamentally different classes of languages. Existing methods for mapping BPMN to BPEL impose limitations on the structure of the source model, especially with respect to cycles. This report proposes a technique that overcomes these limitations. Beyond its direct relevance in the context of BPMN and BPEL, this technique addresses difficult problems that arise generally when translating between floow-based languages with parallelism