Detecting artifact anomalies in business process specifications with a formal model

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Abstract

Many business process analysis models have been proposed, however there are few discussions for artifact usages in workflow specifications. A well-structured business process with sufficient resources might fail or yield unexpected results dynamically due to inaccurate artifact specification, e.g. an inconsistency between artifact and control flow, or contradictions between artifact operations. This paper, based on our previous work, presents a model for describing the input/output of a workflow process and analyzes the artifact usages upon the model. This work identifies and formulates thirteen cases of artifact usage anomalies affecting process execution and categorizes the cases into three types. Moreover, the methods for detecting these anomalies with time complexities O(n2), less than O(n3) in previous methods, are presented. Besides, the paper uses an example to demonstrate the processing of them.

Introduction

A workflow is seemingly a set of interrelated tasks systematized to achieve certain business goals by accomplishing each task in a particular order under automatic control (The Workflow Management Coalition, 1995). Workflow implementation requires resources for supporting process execution. Resource allocation and resource constraint analysis (Senkul and Toroslu, 2005, Li et al., 2004, Liu et al., 2003, Du and Shan, 1999, Muehlen, 1999) are popular workflow research topics. However, data flow within workflow is seldom addressed (Sadiq et al., 2004, Sun and Zhao, 2004, Sun et al., 2004, Sun et al., 2006).

An artifact is a data instance within a workflow. Introducing artifact usage analysis into (control-oriented) workflow designs can help maintain consistency between execution order and data transition (Sadiq et al., 2004, Sun and Zhao, 2004, Sun et al., 2004, Sun et al., 2006), as well as prevents exceptions due to contradiction between data flow and control flow. In contrast to structural correctness, accuracy in artifact manipulation helps determine whether the execution result of a workflow is meaningful and desirable. Our earlier work (Hsu, 2005, Wang et al., 2006, Hsu and Wang, 2007) introduced the artifact usage analysis into workflow design phase and identified preliminary improper artifact usages affecting workflow execution.

This paper proposes a process model for describing the input/output of business processes and addresses three types of artifact usage anomalies. The model is based on component-based design technique (Zhuge, 2003, Hitomi and Le, 1998) and is compatible with existing control-oriented workflow design models. It provides an easier way to extract knowledge of artifact usages in a workflow. With the model, an analysis procedure of artifact usage is applied before deploying the workflow schema. On the other hand, the checking between data flow and control flow and the information of manipulating artifacts can be applied stepwise along with the specification process. An example demonstrating the contribution of our work and a comparison among related works and ours is also presented.

The remainder of this paper is organized as follows. Section 2 presents the research background and related works. Section 3 presents our process model, including the control flow and artifact flow. There are thirteen cases of artifact usage anomalies identified and then categorized into three types in Section 4. In Section 5, we present a method for detecting each type of anomalies. A comparison between our approach and some related works is given in Section 6. Finally, a conclusion and some recommendations of future work are given in Section 7.

Section snippets

Analysis in workflow specification

A workflow can be deemed as a collection of cooperating and coordinated activities designed to carry out a well-defined complex process, such as a trip planning, conference registration procedure, or business process in an enterprise. In addition, the technology is adopted further in developing service-oriented architecture in the last decade (Yau et al., 2008, Yau et al., 2007). A workflow model describes a workflow in terms of various elements, such as roles and resources, tools and

Basic concept of loop reduction

Our major concern is to find artifact usage anomalies and reduce the computation time. The basic concept of loop reduction is to transform a loop into an XOR structure. The condition(s) of a RepeatUntil structure R is evaluated after each iteration but that of a While structure W is done before each iteration. Obviously, the least time k of RepeatUntil(R)/While(W) execution is 1/0 if the evaluation result in R/W is not concerned. An artifact can be associated with a state representing the

Artifact usage anomalies

In process specification, the following three types of anomalies might occur: (1) missing production, (2) redundant write, and (3) conflict write. In the subsections, these anomalies are defined and the corresponding usage patterns that cause the anomalies are identified. Every usage pattern is given a name, description, and formulated detection conditions. Table 4.1 shows the symbols used in the usage patterns.

Missing production anomalies

A missing production anomaly occurs when an artifact is consumed before it is

The methods to detect artifact usage anomalies

The methods for detecting the artifact usage anomalies in a process specification are presented in this section. The goal in our study is to search the artifact usage anomaly only, and it is not necessary to construct the possible artifact activities in each process. Instead, loop can be replaced with a corresponding XOR structure. From the top-level view, a well-formed control flow can be deemed as one or a sequence of task(s) and/or top-level control block(s). Thus, an entire flow can be

Comparisons of anomalies identified in the approaches

The artifact usage anomalies identified in this paper are classified according to the classification proposed by Sun and Zhao, 2004, Sun et al., 2004, Sun et al., 2006 who claimed that the definition of the types of artifact usage anomalies – missing data, redundant data, and conflicting data – is sufficient in analyzing the data flow at a conceptual level. Each anomaly, addressed by the two groups, Sadiq et al. (2004) and Sun and Zhao, 2004, Sun et al., 2004, Sun et al., 2006, working on the

Conclusion and future work

Introducing an artifact usage analysis technique into workflow design phase is the main contribution of this paper. This paper presents a business process model for describing a business process and analyzes the artifact usages on this model to achieve this goal. Artifact usage in our model is characterized by its state transition diagram.

This work identifies thirteen cases of improper artifact usage affecting workflow execution and categorizes these anomalies into three types. The anomalies

Ching-Huey Wang received the MS degree in computer science from Tung Hai University, Taiwan, in 2002. She is a PhD student of computer science at Chiao Tung University, Taiwan. Her research interests include service-oriented application modeling and analysis, social network service, and pervasive workflow application. She has published several papers in international journals and conferences. She is a member of the IEEE Computer Society.

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    Ching-Huey Wang received the MS degree in computer science from Tung Hai University, Taiwan, in 2002. She is a PhD student of computer science at Chiao Tung University, Taiwan. Her research interests include service-oriented application modeling and analysis, social network service, and pervasive workflow application. She has published several papers in international journals and conferences. She is a member of the IEEE Computer Society.

    Prof. Feng-Jian Wang completed his Ph.D. program in Dept. of E.E.C.S., Northwestern University, 1988. Since then, he worked in National Chiao-Tung University, Taiwan. During his Ph.D program, he worked on incremental analysis of data flow. Thereafter, he worked on the development, reuse, and data analysis based no object-oriented programming language. Since 1995, he worked on the analysis and design of workflow programs and his laboratory constructed a workflow management system named Agentflow, where he studied a series of supporting analysis and tools associated with editing activities. Currently, he is focused on how to apply workflow and grid computing techniques on pervasive workflow systems, and developing the design patterns of FLASH programs.

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