Jochen Küster, Christian Gerth, Alexander Förster, Gregor Engels: Detecting and Resolving Process Model Differences in the Absence of a Change Log. In Proceedings of the 6th International Conference on Business Process Management (BPM'08). Springer (Berlin/Heidelberg), LNCS, vol. 5240, pp. 244--260 (2008)
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@inproceedings{DetKGFE08, author = {Jochen Küster, Christian Gerth, Alexander Förster, Gregor Engels}, title = {Detecting and Resolving Process Model Differences in the Absence of a Change Log}, booktitle = {Proceedings of the 6th International Conference on Business Process Management (BPM'08)}, year = {2008}, volume = {5240}, series = {LNCS}, pages = {244--260}, address = {Berlin/Heidelberg}, publisher = {Springer} }

Business-driven development favors the construction of process models at different abstraction levels and by different people. As a consequence, there is a demand for consolidating different versions of process models by detecting and resolving differences. Existing approaches rely on the existence of a change log which logs the changes when changing a process model. However, in several scenarios such a change log does not exist and differences must be identified by comparing process models before and after changes have been made. In this paper, we present our approach to detecting and resolving differences between process models, in the absence of a change log. It is based on computing differences and deriving change operations for resolving differences, thereby providing a foundation for variant and version management in these cases.

Tim Schattkowsky, Gregor Engels, Alexander Förster: A Model-Based Approach for Platform-Independent Binary Components with Precise Timing and Fine-Grained Concurrency. In Proceedings of the 40th Annual Hawaii International Conference on System Sciences (HICSS 2007). IEEE Computer Society (Washington, DC, USA), pp. 286ff. (2007)
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@inproceedings{Schattkowsky2007a, author = {Tim Schattkowsky, Gregor Engels, Alexander Förster}, title = {A Model-Based Approach for Platform-Independent Binary Components with Precise Timing and Fine-Grained Concurrency}, booktitle = {Proceedings of the 40th Annual Hawaii International Conference on System Sciences (HICSS 2007)}, year = {2007}, pages = {286ff.}, address = {Washington, DC, USA}, publisher = {IEEE Computer Society} }

Fine grained concurrency and accurate timing can be essential for embedded hardware and software systems. These requirements should be reflected in the specification and must be consistently enforced by the actual implementation. Automated synthesis of the implementation from such specifications appears to be a straightforward way to ensure this consistency. However, especially for software systems this is quite difficult, since software lacks the inherent timing and concurrency of a hardware system. Still, the same timing and concurrency requirements have to be fulfilled. Thus, we introduce a UML-based design approach that supports the synthesis of embedded hardware or software systems from essentially the same abstract specification. Our approach provides explicit support for specifying fine grained concurrency and microsecond accurate timing. In our approach, these properties must be ensured by the automatically derived implementation. Since this is especially hard to achieve for software systems, this paper focuses on execution on software platforms. For this, we introduce our UML Virtual Machine (UVM). It enables the direct execution of binary encoded system specifications and enforces the desired timing and concurrency. As a result, our approach enables the creation of binary encoded portable concurrent time-accurate software components.

Alexander Förster, Gregor Engels, Tim Schattkowsky, Ragnhild Van Der Straeten: Verification of Business Process Quality Constraints Based on Visual Process Patterns. In Proceedings of the First Joint IEEE/IFIP Symposium on Theoretical Aspects of Software Engineering (TASE 2007), Shanghai (China). IEEE Computer Society (Washington, DC, USA), pp. 197--208 (2007)
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@inproceedings{Forster2007, author = {Alexander Förster, Gregor Engels, Tim Schattkowsky, Ragnhild Van Der Straeten}, title = {Verification of Business Process Quality Constraints Based on Visual Process Patterns}, booktitle = {Proceedings of the First Joint IEEE/IFIP Symposium on Theoretical Aspects of Software Engineering (TASE 2007), Shanghai (China)}, year = {2007}, pages = {197--208}, address = {Washington, DC, USA}, publisher = {IEEE Computer Society} }

Business processes usually have to consider certain constraints like domain specific and quality requirements. The automated formal verification of these constraints is desirable, but requires the user to provide an unambiguous formal specification. In particular since the notations for business process modeling are usually visual flow-oriented languages, the notational gap to the languages usually employed for the formal specification of constraints, e.g., temporal logic, is significant and hard to bridge. Thus, our approach relies on UML Activities as a single language for the specification of both business processes and the corresponding constraints. For the expression of such constraints, we have provided a process pattern definition language based on specialized Activities. In this paper, we describe how model checking can be employed for formal verification of business processes against such patterns. For this, we present an automated transformation of the business process and the corresponding patterns into a transition system and temporal logic, respectively.

Tim Schattkowsky, Alexander Förster, Christoph Loeser: Secure Storage for Physically Exposed Web- and Application Servers. In Proceedings of the 5th International Conference on Networking (ICN 2006), Morne (Mauritius). IEEE Computer Society (Washington, DC, USA), pp. 86 (2006)
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@inproceedings{Schattkowsky2006d, author = {Tim Schattkowsky, Alexander Förster, Christoph Loeser}, title = {Secure Storage for Physically Exposed Web- and Application Servers}, booktitle = {Proceedings of the 5th International Conference on Networking (ICN 2006), Morne (Mauritius)}, year = {2006}, pages = {86}, address = {Washington, DC, USA}, publisher = {IEEE Computer Society} }

Alexander Förster, Tim Schattkowsky, Gregor Engels, Ragnhild Van Der Straeten: A Pattern-driven Development Process for Quality Standard-conforming Business Process Models. In IEEE Symposium on Visual Languages and Human-Centric Computing (VL/HCC 2006), Brighton (UK). IEEE Computer Society (Washington, DC, USA), pp. 135--142 (2006)
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@inproceedings{FoersterVLHCC06, author = {Alexander Förster, Tim Schattkowsky, Gregor Engels, Ragnhild Van Der Straeten}, title = {A Pattern-driven Development Process for Quality Standard-conforming Business Process Models}, booktitle = {IEEE Symposium on Visual Languages and Human-Centric Computing (VL/HCC 2006), Brighton (UK)}, year = {2006}, pages = {135--142}, address = {Washington, DC, USA}, publisher = {IEEE Computer Society} }

Tim Schattkowsky, Alexander Förster: A Generic Component Framework for High Performance Locally Concurrent Computing Based on UML 2.0 Activities. In Proceedings of the 12th IEEE International Conference and Workshops on the Engineering of Computer-Based Systems (ECBS 2005). IEEE Computer Society (Washington, DC, USA), pp. 3--10 (2005)
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@inproceedings{Schattkowsky2005d, author = {Tim Schattkowsky, Alexander Förster}, title = {A Generic Component Framework for High Performance Locally Concurrent Computing Based on UML 2.0 Activities}, booktitle = {Proceedings of the 12th IEEE International Conference and Workshops on the Engineering of Computer-Based Systems (ECBS 2005)}, year = {2005}, pages = {3--10}, address = {Washington, DC, USA}, publisher = {IEEE Computer Society} }

Software support for multiple hardware threads like the Pentium 4's hyperthreading technology or the upcoming multi-core desktop processors is required even for traditional single processor domains like home and office systems. Although the modeling of concurrent systems is already quite advanced, the current engineering practice usually does not yield highly concurrent applications without significant extra efforts due to several limitations of most methods for concurrent systems design. Unlike other methods, we consider the problem as a deployment problem where the software components need to be deployed on different multiple execution units depending on the system configuration. To overcome this, we present a component model and design approach based on the execution semantics of UML 2.0 Activities that enables the efficient design and construction of software applications with increased inherent concurrency and scalability for multi-processor platforms. The application of the approach and its benefits are demonstrated in a real world Web server example.

Alexander Förster, Gregor Engels, Tim Schattkowsky: Activity Diagram Patterns for Modeling Quality Constraints in Business Processes. In Proceedings of the 8th International Conference on Model Driven Engineering Languages and Systems (MoDELS 2005), Montego Bay (Jamaica). Springer (Berlin/Heidelberg), LNCS, vol. 3713, pp. 2--16 (2005)
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@inproceedings{Foerster2005, author = {Alexander Förster, Gregor Engels, Tim Schattkowsky}, title = {Activity Diagram Patterns for Modeling Quality Constraints in Business Processes}, booktitle = {Proceedings of the 8th International Conference on Model Driven Engineering Languages and Systems (MoDELS 2005), Montego Bay (Jamaica)}, year = {2005}, volume = {3713}, series = {LNCS}, pages = {2--16}, address = {Berlin/Heidelberg}, publisher = {Springer} }

Jochen Küster, Christian Gerth, Alexander Förster, Gregor Engels: A Tool for Process Merging in Business-Driven Development. In Proceedings of the Forum at the CAiSE'08 Conference on Advanced Information Systems Engineering. CEUR-WS.org, CEUR Workshop Proceedings, vol. 344, pp. 89--92 (2008)
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@inproceedings{Kuester08, author = {Jochen Küster, Christian Gerth, Alexander Förster, Gregor Engels}, title = {A Tool for Process Merging in Business-Driven Development}, booktitle = {Proceedings of the Forum at the CAiSE'08 Conference on Advanced Information Systems Engineering}, year = {2008}, volume = {344}, series = {CEUR Workshop Proceedings}, pages = {89--92}, publisher = {CEUR-WS.org} }

Business-driven development favors the construction of process models at different abstraction levels and by different people. As a consequence, there is a demand for consolidating different versions of process models by merging them. In this paper, we study a basic scenario, derive requirements and present a prototype for detecting and resolving changes between process models.

Tim Schattkowsky, Alexander Förster: On the Pitfalls of UML Activity Modeling. In Proceedings of the ICSE workshop on Modeling in Software Engineering (MISE 2007), Minneapolis, MN (USA). IEEE Computer Society (Los Alamitos, CA, USA), pp. 8 (2007)
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@inproceedings{Schattkowsky2007, author = {Tim Schattkowsky, Alexander Förster}, title = {On the Pitfalls of UML Activity Modeling}, booktitle = {Proceedings of the ICSE workshop on Modeling in Software Engineering (MISE 2007), Minneapolis, MN (USA)}, year = {2007}, pages = {8}, address = {Los Alamitos, CA, USA}, month = {May}, publisher = {IEEE Computer Society} }

With the introduction of new Petri net-like semantics for Activities in UML 2.0, these have become a complete language for modeling behavior. Thus, UML Activities are nowadays investigated for application in many areas from embedded systems to business process modeling. However, some issues have been discovered that currently seem to limit the practical applicability of Activities. In this paper, we present an overview of the identified semantic and syntactic problems, and point at possible solutions and directions for future research.

Alexander Förster, Gregor Engels: Quality Ensuring Development of Software Processes. In Proceeding of the 9th European Workshop on Software Process Technology (EWSPT 2003), Helsinki (Finland). Springer (Berlin/Heidelberg), LNCS, vol. 2786, pp. 62--73 (2003)
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@inproceedings{Foerster2003, author = {Alexander Förster, Gregor Engels}, title = {Quality Ensuring Development of Software Processes}, booktitle = {Proceeding of the 9th European Workshop on Software Process Technology (EWSPT 2003), Helsinki (Finland)}, year = {2003}, volume = {2786}, series = {LNCS}, pages = {62--73}, address = {Berlin/Heidelberg}, publisher = {Springer} }

Gregor Engels, Alexander Förster, Reiko Heckel, Sebastian Thöne: Process Modeling using UML. In M. Dumas, W. van der Aalst, A. ter Hofstede (eds.): Process-Aware Information Systems. pp. 85-117 Wiley (New York, NY) (2005)
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@incollection{Engels2005, author = {Gregor Engels, Alexander Förster, Reiko Heckel, Sebastian Thöne}, title = {Process Modeling using UML}, booktitle = {Process-Aware Information Systems}, publisher = {Wiley}, year = {2005}, pages = {85-117}, address = {New York, NY} }

This chapter provides an introduction to the Unified Modeling Language (UML), a widely adopted object-oriented modeling standard, and shows how the language can be applied to (business) process modeling. As major perspectives of process modeling with UML 2.0, the chapter covers control flow, data objects and object flow, organizational structure, business partner interactions, and system-specific process models. Various types of UML diagrams are presented with a special focus on how these diagrams fit together and complement each other to form a coherent view of a process. Moreover, a running example is used throughout the chapter to illustrate the different facets of a process model.

Alexander Förster: Pattern based business process design and verification. Type: Phd Thesis (2009)
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@phdthesis{FoersterDiss09, author = {Alexander Förster}, title = {Pattern based business process design and verification}, school = {undefined}, year = {2009} }

Alexander Förster: Pattern-basierte Modellierung von Geschäftsprozessen. Type: Diploma Thesis, diplomathesis (2002)
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@masterthesis{Förster02, author = {Alexander Förster}, title = {Pattern-basierte Modellierung von Geschäftsprozessen}, school = {undefined}, year = {2002}, type = {diplomathesis}, month = {November } }