Matthias Geiger

BPMN Conformance in Open Source Engines

More than five years have passed since the final release of the long-desired OASIS standard of a process language for Web Services orchestration, the Web Services Business Process Execution Language (BPEL). The aim of this standard was to establish a universally accepted Web Services orchestration language that forms a core part of service-oriented architectures and, because of standardization, avoids vendor lock-in. By now, several fully conformant engines should have arrived in the market. It is our aim to shed light on this situation and to provide a comprehensive picture of the current state of BPEL support. We present an evaluation of the standard conformance of five open source BPEL engines. To obtain these results we have developed betsy, a tool that allows for a fully-automatic standard conformance testing of BPEL engines. The results demonstrate that full standard conformance in contemporary engines is still far from given.

BPMN 2.0: The state of support and implementation

The Business Process Model and Notation 2.0 (BPMN) standard has been hailed as a major step in business process modeling and automation. Recently, it has also been accepted as an ISO standard. The expectation is that vendors of business process management systems (BPMS) will switch to the new standard and natively support its execution in process engines.This paper presents an analysis of the current state and evolution of BPMN2.0 support and implementation. We investigate how BPMN2.0 implementers deal with the standard, showing that native BPMN2.0 execution is an exception. Only three out of 47 BPMS considered support the execution format defined in the standard, although all of them claim to comply to the BPMN2.0 standard. Furthermore, we evaluate three process engines that do provide native BPMN support, namely camunda BPM, jBPM and activiti, and examine the evolution of their degree of support over a period of more than three years. This lets us delimit the areas of the standard that are considered important by the implementers. Since there is only a limited increase in supported features over the past years, it seems that the implementation of the standard is more or less concluded from the perspective of the implementers. Hence, it is unlikely that features which are not available by now will be implemented in the future. Only three out of 47 vendor implementations of BPMN do support the direct execution of the native BPMN format.These three implementations only support around half of the features of BPMN.The feature support is sufficient to implement at least 13 out of 20 workflow control-flow patterns.Erroneous process models are often not rejected at deployment.There is only a limited increase in feature support over the last four years.

On the Evolution of BPMN 2.0 Support and Implementation

The Business Process Model and Notation 2.0 (BPMN) standard has been hailed as a major step in business process modeling and automation. Recently, it has also been accepted as an ISO standard. The expectation is that vendors of business process management systems (BPMS) will switch to the new standard and natively support its execution in process engines. This paper presents an analysis of the current state and evolution of BPMN 2.0 support and implementation. We investigate how current BPMN 2.0 implementers deal with the standard, showing that native BPMN 2.0 execution still is an exception. Most BPMS do not support the execution format, despite claiming to be BPMN 2.0 compliant. Furthermore, building on past work, we evaluate three process engines that do provide native BPMN support and examine the evolution of their degree of support over a three-year period. This lets us delimit the areas of the standard that are considered important by the implementers. Since there is hardly an increase in supported features over the past three years, it seems that the implementation of the standard is more or less seen as finished by vendors and it is unlikely that features which are not available by now will be implemented in the future.

QoS-Enabled Business-to-Business Integration Using ebBP to WS-BPEL Translations

Business-To-Business Integration (B2Bi) is a key mechanism for enterprises to gain competitive advantage. However,developing B2Bi applications is far from trivial. Inter alia,agreement among integration partners about the business documents and the control flow of business document exchanges, applying suitable communication technologies for overcoming heterogeneous IT landscapes as well as ensuring a Quality of Service (QoS) level that is sufficient for B2Bi are major challenges.In this context, applying choreography languages like ebXML BPSS (ebBP) for agreement among integration partners, orchestration languages like WS-BPEL for specifying partner-specific behavior, and Web Services for communication promises seamless interactions among business partners. In this scenario, the conformance of orchestration models to choreography models and cost-effective development are of paramount importance.Consequently, top-down approaches that automatically translate choreography models into orchestration models have been proposed.By now, the realization of QoS attributes has not yet received the necessary attention that makes such approaches suitable for B2Bi. In this paper, we describe a proof-of-concept implementation of a translation of ebBP choreographies into WS-BPEL orchestrations that respects B2Bi relevant QoS attributes.

On the Measurement of Design-Time Adaptability for Process-Based Systems

Today, process languages are frequently used for implementing service-oriented systems and a variety of specifications for this task exist. These specifications strive for the portability of processes among different runtime environments, i.e., process engines. However, direct portability, especially of executable processes, is seldom achieved. If processes cannot be ported directly among engines, an option is to adapt them. Such an adaptation is nontrivial and hence automated support is desirable. A first step in this direction is the quantification of the design-time adaptability of a process. This quantification is the goal of this paper. We formally define software metrics for measuring the design-time adaptability of processes and validate them theoretically with respect to measurement theory and construct validity using two validation frameworks. Moreover, we implement the metrics computation for Business Process Model and Notation (BPMN) processes and demonstrate their practical applicability with an evaluation of a large set of open source processes.

Improving the Static Analysis Conformance of BPEL Engines with BPELlint

Today, process-aware systems are ubiquitous. They are built by leveraging process languages for both business and implementation perspectives. In the typical context of a Web Services-based Service-oriented Architecture, the obvious choice to implement service orchestrations is still the Business Process Execution Language (BPEL). For BPEL, a variety of open source and commercial engines have emerged. Although the BPEL standard document defines a set of static analysis rules which should be checked by engines prior to deployment to be standard conformant, previous work revealed that most engines are not capable of revealing all violations of these constraints, resulting in costly runtime errors later on. In this paper, we aim to improve the static analysis conformance of BPEL engines. We implement the tool BPELlint that validates 71 static analysis rules of the BPEL specification, show that the tool can be easily integrated into the deployment process of existing engines, and evaluate its performance to measure the effect on the time to deploy. The results demonstrate that BPELlint can improve the static analysis conformance of BPEL engines with an acceptable performance overhead.

Lessons Learned from Evaluating Workflow Management Systems

Workflow Management Systems (WfMSs) today act as service composition engines and service-oriented middleware to enable the execution of automated business processes. Automation based on WfMSs promises to enable the model-driven construction of flexible and easily maintainable services with high-performance characteristics. In the past decade, significant effort has been invested into standardizing WfMSs that compose services, with standards such as the Web Services Business Process Execution Language (WS-BPEL) or the Business Process Model and Notation (BPMN). One of the aims of standardization is to enable users of WfMSs to compare different systems and to avoid vendor lock-in. Despite these efforts, there are many expectations concerning portability, performance efficiency, usability, reliability and maintainability of WfMSs that are likely to be unfulfilled. In this work, we synthesize the findings of two research initiatives that deal with WfMSs conformance and performance benchmarking to distill a set of lessons learned and best practices. These findings provide useful advice for practitioners who plan to evaluate and use WfMSs and for WfMS vendors that would like to foster wider adoption of process-centric service composition middleware.