Interorganizational Workflow Management

Concepts, Requirements and Approaches

Diplomarbeit / Diploma Thesis

by

Karin Pargfrieder

Linz, März 2002

Kurzfassung
Konventionelles Workflow Management beschränkt sich auf die Verbesserung der Effizienz von Geschäftsprozessen innerhalb einer Organisation. Jedoch sollten Prozesse auch dann elektronisch unterstützt werden können, wenn sie organisationale Grenzen überschreiten, wie z.B. in virtuellen Unternehmen.
Wegen der speziellen Eigenschaften von interorganisationalen Workflows kann konventionelle Workflow Technologie nicht direkt angewendet werden. Die wichtigste Anforderung an interorganisationale Workflow Systeme ist klarerweise, Interoperabilität zwischen heterogenen Systemen zu erreichen. Sehr wichtig sind auch Vertraulichkeit der internen Prozesse und Sicherheit.
Die vorliegende Diplomarbeit gibt eine Einführung in interorganisationales Workflow Management, seine Aspekte und Konzepte. Anforderungen an interorganisationale Workflow Systeme werden ausgearbeitet und die wichtigsten Ansätze, Projekte und Initiativen werden beschrieben: XML-basierte Ansätze, die Standards der WfMC, elektronische Marktplätze und elektronische Verträge.
Eine Evaluierung dieser Ansätze anhand eines Kriterienkatalogs, der aus den Anforderungen und anderen Eigenschaften der Ansätze abgeleitet wird, zeigt die verschiedenen Stärken und Schwächen. Die XML-basierten Ansätze bieten Standards für die Schnittstellen der Prozesse und eine gute Lösung bzgl. Heterogenität. Manche von ihnen ermöglichen sogar die spontane Zusammenarbeit mit neuen Geschäftspartnern ohne vorherige Absprache. Traditioneller elektronischer Datenaustausch (EDI) ist vom Prinzip her ähnlich, hat aber viele Nachteile. Die Standards der WfMC ermöglichen einen sehr geringen Aufwand bei der Systemintegration, wenn sich die Anbieter daran halten. Aber Vertraulichkeit und Sicherheit sind potentielle Problemfelder und nur einfache Kooperationsmodelle werden unterstützt. Elektronische Marktplätze und elektronische Verträge sind ideal, wenn die Anzahl der Geschäftspartner hoch ist oder die Geschäftspartner abhängig von der jeweiligen Situation dynamisch gewählt werden sollen. Dazu müssen deren Services aber leicht vergleichbar sein und einfache Schnittstellen haben.

Abstract
Conventional workflow management focuses on improving the efficiency of business processes within one organization. However, processes should not only be supported within the enterprise, but also when crossing organizational boundaries, e.g. in order to support new forms of collaborations as virtual enterprises.
Due to the different nature of interorganizational workflows, conventional workflow technology cannot be directly applied. The most important requirement specific to interorganizational workflow systems is obviously that they are able to deal with heterogeneity and that it is not too expensive to achieve interoperability. Also maintaining the privacy of internal processes is a major concern, and security issues should be addressed.
This diploma thesis gives an introduction to conventional and interorganizational workflow management, their aspects and concepts. It elaborates the requirements relevant for interorganizational workflow systems, describes the most important approaches, projects, and initiatives that currently exist in the area of interorganizational workflows, including XML-based approaches, the standards of the WfMC, electronic marketplaces and electronic contracting.
An evaluation of these approaches based on criteria derived from the requirements and other characteristics shows the differing strengths and weaknesses. The XML-based approaches provide standards for the process interfaces, and can cope with heterogeneous environments very well. Some of them even allow spontaneous commerce with new trading partners without custom integration. Traditional EDI is in principle similar, but has many disadvantages. The standards of the WfMC enable integration with a very low effort, if they are followed by software providers. But privacy and security are potential problem areas and the models of interoperability that realistically can be supported are simple. Electronic marketplaces and electronic contracting are ideal, if a high number of business partners has to be supported and the services are chosen dynamically depending on the situation. But these services have to be comparable with rather simple interfaces.

Table of Contents

1 Introduction 1

2 Workflow Management 4
2.1. Requirements on WfMSs 6
2.2. Workflow Modeling 8
2.2.1. The Functional Aspect: Workflows and Activities 8
2.2.2 The Operational Aspect: Applications 9
2.2.3. The Behavioral Aspect: Control Flow 10
2.2.4. The Informational Aspect: Data Structures and Data Flow 12
2.2.5. The Organizational Aspect: Structure and Population 13
2.2.6. The Causal Aspect: Regulations and Dependencies 14
2.2.7. The Historical Aspect: Logging 15
2.2.8 The Transactional Aspect: Workflow Consistency 15
2.3. Workflow Analysis 16
2.4. Workflow Enactment 17
2.5. Architecture of WfMSs 19
2.5.1. Generic Workflow Product Structure of the WfMC 20
2.6. Limitations 24

3 Introduction to Interorganizational Workflows 26
3.1. Concepts for Interorganizational Workflows derived from Conventional Workflow Management 27
3.1.1. Task Assignment 27
3.1.2. Interorganizational Control Flow 27
3.1.3. Interorganizational Data Flow 28
3.2. Business Scenario 29
3.3. Partitioning of Workflows 31
3.4. Models of Workflow Interoperability 32
3.4.1. Centralized Process Management or Capacity Sharing 33
3.4.2. Chained Subprocesses or Chained Execution 34
3.4.3. Nested Subprocesses, Subcontracting or Service Outsourcing 35
3.4.4. Transaction Group 36
3.4.5. Parallel Synchronized Model or Multi-Processes Interoperation / Federation 36
3.4.6. Case Transfer 37
3.4.7. Extended Case Transfer 38
3.4.8. Loosely Coupled Processes 39
3.4.9. Peer-to-Peer Collaborative Process Management 40
3.4.10. Summary 42

4 Standardization for Interorganizational Workflows 44
4.1. Open-edi Reference Model 45
4.2. Levels of Standardization 46

5 Requirements for Interorganizational Workflow Management 48
5.1. Relevance of Requirements for Conventional Workflow Systems 49
5.2. Requirements Catalog 50
5.2.1. Build-Time 51
5.2.2. Run-Time 52
5.2.3. Requirements Independent of the Phases 55

6 Approaches, Projects and Initiatives 57
6.1. Traditional EDI 58
6.2. Workflow Management Coalition (WfMC) 59
6.3. OO-edi 64
6.4. Electronic Workflow Trading 66
6.4.1. Electronic Marketplace, ACE-Flow 66
6.4.2. Electronic Contracts, Cross Flow Project 73
6.4.3. Event-Services, EVE 82
6.4.4. Process Model Fragments 88
6.5. XML-based Commerce Languages 91
6.5.1. RosettaNet 94
6.5.2. BizTalk 96
6.5.3. eCo 98
6.5.4. ebXML 103

7 Evaluation 108
7.1. Supported Models of Interoperability 108
7.2. BOV or FSV? 110
7.3. Build-Time 111
7.3.1. Automation 111
7.3.2. Support for Collaborative Process Definition 111
7.3.3. Privacy of Internal Processes 112
7.3.4. Being able to cope with Heterogeneous Workflow Environments 112
7.3.5. Integration Effort and Integration Know-How 113
7.3.6. Support for a High Number of Partners 114
7.4. Run-Time 115
7.4.1. Automated Selection of Optimal Service 115
7.4.2. Ensure Quality of the Outsourced Operation 115
7.4.3. Security 116
7.4.4. Flexibility 116
7.4.5. Document Management 116
7.5. Autonomy of Partners 117
7.5.1. Design Autonomy 117
7.5.2. Communication Autonomy 117
7.5.3. Execution Autonomy 118
7.5.4. Association Autonomy 118
7.6. Transparency 118
7.7. Distribution 118
7.8. Summary of Evaluation 119

8 Summary, Contribution and Outlook 122

Appendix - Glossary 125

References 137

List of Figures
Figure 2-1. Types of Data in Workflow Management Systems [WfMC99a] 12
Figure 2-2. Generic Workflow Product Structure [Holl95] 20
Figure 3-1. Interorganizational Control Flow [DDDE00] 28
Figure 3-2. Processes at Telco and Logis [DDDE00] 30
Figure 3-3. Horizontal and Vertical Partitioning 31
Figure 3-4. Centralized Process Management [Aals00b] 33
Figure 3-5. Chained Subprocesses [Aals00b] 34
Figure 3-6. Nested Subprocesses [Aals00b] 35
Figure 3-7. The Parallel Synchronized Model of Interoperability [WfMC96] 37
Figure 3-8. Case Transfer [Aals00b] 38
Figure 3-9. Example (Extended) Case Transfer 38
Figure 3-10. Loosely Coupled Processes [Aals00b] 40
Figure 3-11. Example Loosely Coupled Processes 40
Figure 3-12. Peer-to-Peer Collaborative Process Management [ChHs01] 41
Figure 3-13. Partitioning Dimensions of the Models of Workflow Interoperability 42
Figure 3-14. Models of Workflow Interoperability 43
Figure 4-1. Open-edi Reference Model [EdiI96] 45
Figure 4-2. Three Levels of Standardization [Huem01b] 46
Figure 6-1. The Workflow Reference Model [Holl95] 60
Figure 6-2. ACE-Flow System [SRKT00] 69
Figure 6-3. Sequence in Bidding and Execution [SRKT00] 72
Figure 6-4. Contract and Workflow Level [KGV00] 77
Figure 6-5. Making Contracts [KGV00] 78
Figure 6-6. The CrossFlow Architecture [KGV00] 80
Figure 6-7. Architecture of EVE and Example Workflow System [GeTo98] 87
Figure 6-8. Multiple Vertical Connection [LiDe99] 90
Figure 6-9. Horizontal Connection of Three Fragments [LiDe99] 90
Figure 6-10. Partner Interface Process (RosettaNet) [ChHs01] 95
Figure 6-11. The Common Business Library [GTM99] 101
Figure 6-12. Fragment of an XML Service Definition [GTM99] 102
Figure 6-13. Use of ebXML [Huem01b] 104
Figure 6-14. High-Level Overview of ebXML Interaction between two Companies [Mert01] 106
Figure 7-1. Supported Models of Interoperability 110
Figure 7-2. Overview 120

Chapter 1

Introduction

Conventional workflow management focuses on improving the efficiency of business processes within one organization. However, today′s corporations are challenged to cross organizational boundaries. Besides traditional business relations, as supplier, partner or customer, new forms of collaboration between enterprises come into existence due to increased competition and globalization, e.g. virtual enterprises or the trend to outsourcing.

Until recently, given the significant effort and investment required to deploy the necessary technology, business-to-business electronic commerce was a prerogative of large enterprises with well established commercial links. Nowadays, the advent of the Internet and the proliferation of inexpensive computing power in the form of clusters of workstations or PCs has changed this situation. Small and medium enterprises can now afford to engage in business-to-business electronic commerce by using the Internet to link their information processing systems. With the hardware infrastructure in place, there is a great demand for software support.

The benefits expected from supporting not only internal, but also cross-organizational processes are e.g. reduced costs due to automation, the possibility to redesign and optimize processes and to benefit from increased competition between service providers.

But conventional workflow systems are primarily designed for intra-enterprise process management, and they can hardly be used to handle processes with tasks and data separated by enterprise boundaries, for reasons such as security, privacy, sharability, firewalls, etc.

New concepts to support cross-organizational processes are needed. There are numerous research issues in the field of interorganizational workflows, such as how to model these workflows and the virtual enterprise in which they are executed, how to deal effectively with heterogeneous workflow environments, how to provide well-specified levels of autonomy of partners in a virtual enterprise, and how to support dynamic formation and dismantling of existing collaborations (a business partnership may be created dynamically and maintained only for the required duration such as a single transaction).

The approaches to interorganizational workflow are diverse: The work of the Workflow Management Coalition (WfMC) is focused on the technical level and provides a reference architecture and standard application programming interfaces (APIs) for workflow management systems (WfMSs). Traditional EDI and XML-based approaches are interface based, and usually connect different WfMS by exchanging messages. Approaches like electronic marketplaces or electronic contracts introduce market brokers that match business partners and mediate between them.

The aim of this diploma thesis is to provide a description and evaluation of the most important approaches to interorganizational workflow management. Requirements have to be elaborated, which will be used as criteria for the evaluation.

The diploma thesis is structured as follows:
Chapter 2 gives an introduction to conventional workflow management. Chapter 3 introduces into the area of interorganizational workflows and describes the different models of workflow interoperability in order to provide an overview, what different views on interorganizational workflows exist. It also contains examples for the different models.

Chapter 4 describes reference models for standardization activities in the area of EDI, which is closely related to interorganizational workflows.

In Chapter 5, the requirements on systems that support interorganizational workflows are elaborated. They are grouped into build-time of the interorganizational workflow system and run-time.

Chapter 6 describes the most important approaches, projects, and initiatives, which are evaluated in Chapter 7.

Finally, Chapter 8 concludes the diploma thesis with a summary, conclusion and outlook. Important terms are explained in a glossary.

Chapter 2

Workflow Management

In this chapter, the term workflow management is explained and different functional and qualitative requirements for workflow management systems are discussed. The two main services each WfMS should support are workflow modeling and enactment. In order to be able to reason about and to optimize business processes, a third service has to be provided by a WfMS: workflow analysis. Modeling, analysis, and enactment of workflows are not sequentially ordered steps one following after the other, but are rather interleaved and incremental subtasks of workflow management. Afterwards, architectural issues for WfMSs will be introduced and the limitations of WfMS will be listed. 

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