Yongsun Choi

Decomposition-based verification of cyclic workflows

A critical challenge in workflow analysis and design is the verification of workflow models, considering commercial workflow systems merely provide a simulation tool for validating workflow models through trial and error. As a result, the current workflow technology does not guarantee that workflow models do not fail or will behave in a manner expected by the modeler. While a couple of verification methods have been reported in the recent literature, how to verify cyclic workflow models remains an open research question. In this paper, we propose a novel integrated approach of hierarchical decomposition and verification of cyclic workflows. This result is significant since it helps close the research gap that other known workflow verification methods fail to deal with cyclic workflow models.

An Extensible Workflow Architecture through Web Services

The growing availability of Web services provides a new opportunity for enabling new ways of system integration and interoperability, which are needed to meet the needs of global e-business. In this study, we propose an extensible workflow architecture based on Web services and object-oriented techniques. The proposed architecture contains three components, the Open Kernel Framework, the Universal Resource Manager, and the Process Definition Publisher. We show how this architecture can help extend workflow systems with new features dynamically such as new workflow patterns, new process semantics, new workflow resources, and even new process languages.

Stepwise structural verification of cyclic workflow models with acyclic decomposition and reduction of loops

Abstract Existence of cycles (or loops) is one of the main sources that make the analysis of workflow models difficult. Several approaches of structural verification exist in the literature, but how to verify cyclic workflow models efficiently in a comprehensible form remains an open research question. Thus, a novel structural verification approach for cyclic workflow models by means of acyclic decomposition and reduction of loops is introduced in this paper with the following contributions. First, acyclic decomposition of natural loops, further enhanced by reduction of nested loops, enables existing verification techniques, normally dealing with acyclic models, to handle workflow models with natural loops. Second, instantiation of an irreducible loop into natural loops, altogether with reduction of concurrent loop entries, enables the proposed approach to handle workflow models with irreducible loops. Last, diagnostic information, provided by the proposed approach, helps stakeholders correct and improve their workflow models. Two examples are provided to show that the proposed approach is systematic and practical. In addition, a prototype of the proposed approach is developed. Its execution result shows that, while providing diagnostic information, the proposed approach can handle workflow models with arbitrary cycles effectively.

API and Component Based Customization of an Open Source Business Process Management System: uEngine

There is no doubt that business process management (BPM) has added tremendous value to organizations in virtually every industry. By utilizing business process management systems (BPMS), organizations can streamline and automate tasks, reduce turnaround time, and help ensure regulatory compliance. The foremost considerations when enterprises deploy BPM solutions involve supportive system functions, friendly graphical user interfaces (GUI) and maximal return on investment (ROI), based on the specific processes required, organizational management, and working style of their particular business environment. In order to address the problems associated with BPMS customization, for the flexible coverage of various requirements, this paper takes a three step approach. First, limited customization support of commercial and academic BPMS is reviewed in favor of open source BPMS. Then, advantageous features of uEngine, an open source BPMS which supports flexible customization, are introduced. Finally, API-based and component-based customization in building a BPM application utilizing uEngine is introduced with illustrative examples.

Feedback Partitioning and Decomposition-Oriented Analysis of Cyclic Workflow Graphs

This paper introduces a novel method of verifying a cyclic workflow model by partitioning it into acyclic subgraphs. The iterative classification of nodes according to the feedback structure and derivation of acyclic subgraphs are illustrated. We also introduce the concepts of two-phased verification of control flows and decomposition-oriented analysis, which is generally easier to comprehend and verify individually than the whole workflow model.