Michael Spahn

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This paper discusses the quality of service (QoS)-aware composition of Web services. The work is based on the assumption that for each task in a workflow a set of alternative Web services with similar functionality is available and that these Web services have different QoS parameters and costs. This leads to the general optimization problem of how to(More)
Business users need to analyse changing sets of information to effectively support their working tasks. Due to the complexity of enterprise systems and available tools, especially technically unskilled users face considerable challenges when trying to flexibly retrieve needed data in an ad-hoc manner. As a consequence, available data is limited to(More)
The composition of Web Services to workflows is one of the major challenges in the area of service-oriented computing. To meet the business and user requirements, it is crucial to manage the quality of service (QoS) of Web Service workflows. In our approach, we calculate the execution plan of workflows on the QoS attributes ex ante based on predictions.(More)
Companies are operating in a dynamic environment, resulting in a continuous need of adapting used information systems to changing business processes and associated information needs. Viewed from a micro-perspective, business users are managing and executing business processes on a daily basis, but are not able to adapt used software to their individual(More)
Acknowledging the competition in today’s global markets demands enterprises to be resilient in order to survive. Therefore product life cycles shorten and new customer segments have to be addressed permanently. Obviously, such environments require flexible information systems, which can be adapted quickly to the enterprises’ changing needs, without spending(More)
Delivering the right information at the right time to the right persons is one of the most important requirements of today’s business world. Business users have to deal with changing information needs, but suffer from their inability of adapting the used information systems to support their changing needs. Enterprise Resource Planning (ERP) systems, which(More)
The intent of this position paper is to present the focus of interest of our end-user development (EUD) related research at SAP Research CEC Darmstadt, enabling other participants of the Dagstuhl seminar concerning end-user software engineering to prepare for fruitful and constructive discussions. As we are in an early phase of research, research topics(More)
The dynamic composition of Web Services to workflows at runtime is a major challenge in the emerging field of Serviceoriented computing. At this, preferences and constraints defined by the user have to be considered, e.g. executing a workflow with the cheapest Web Services, but not exceeding a given execution time. Due to the volatile nature of the Web(More)