- Lehrstuhl für Praktische Informatik (112)
- Fakultät Wirtschaftsinformatik und Angewandte Informatik (2)
- Lehrstuhl für Angewandte Informatik in den Kultur-, Geschichts- und Geowissenschaften (2)
- Professur für Informatik, insbesondere Kommunikationsdienste, Telekommunikationssysteme und Rechnernetze (2)
- Lehrstuhl für Medieninformatik (1)
- Lehrstuhl für Wirtschaftsinformatik, insbesondere Industrielle Informationssysteme (1)
- Lehrstuhl für Wirtschaftsinformatik, insbesondere Systementwicklung und Datenbankanwendung (1)
- Professur für Angewandte Informatik, insbesondere Kognitive Systeme (1)
- Professur für Grundlagen der Informatik (1)
- Concealing Presence Information in Instant Messaging Systems (2006)
- Information about online presence allows participants of instant messaging (IM) systems to determine whether their prospective communication partners will be able to answer their requests in a timely manner, or not. That is why presence information, combined with the ability to send instant messages, makes IM more personal and closer than other forms of communication such as e-mail. On the other hand, revelation of presence constitutes a potential of misuse by untrustworthy entities. A possible risk is the generation of online logs disclosing user habits. This makes presence information a resource worth protecting. We argue, however, that current IM systems do not take reasonable precautions to protect presence information. We implemented an IM system designed to be robust against attacks to disclose a user’s presence. In contrast to existing systems, it stores presence information in a registry in a way that is only detectable and applicable for intended users and not comprehensible even for the registry itself. We use a distributed hash table (DHT) as registry and apply an anonymous communication network to protect the physical addresses of both senders and receivers of messages.
- Decentralized Reputation Management for Cooperating Software Agents in Open Multi-Agent Systems (2006)
- Multi-Agent Systems (MAS) promise a new advance in distributed computing. In MAS autonomous software agents flexibly cooperate, coordinate, and compete to provide the desired function(s) of such a system. If some components of a MAS fail or do not provide the desired functionality, the system is expected to autonomously deal with these situations. It is desirable to reduce occurrences of such situations by selecting trustworthy cooperation partners before cooperating with them. This becomes even more desirable and important in an open MAS where arbitrary heterogeneous software agents, deployed by different parties, participate in the MAS, as it becomes more likely that these agents fail or try to exploit the MAS for their own purposes without reciprocation. In order to monitor agent behavior and enable selection of trustworthy cooperation partners, trust or reputation management services can be applied. As there is no central control in an open MAS and it is completely distributed these services themselves have to be distributed. This paper proposes a fully distributed reputation management service for open MAS based on peer-to-peer technology (especially distributed hash tables). A Java-based implementation of that service, which is intended as a plug-in for multi-agent platforms, is also described.
- Applying Business Process Management Systems - a Case Study (2008)
- Business Process Management Systems (BPMS) aim to support the Business Process Management paradigm and to ease legacy application integration. Often, they rely on Service-oriented Architecture (SoA). However, do such systems really meet real-world requirements? This paper introduces and discusses a set of criteria which are important for BPMS and applies these criteria in comparing tools from three important vendors, namely IDS Scheer, Oracle and Intalio based on a case study.
- QoS-Enabled B2B Integration (2009)
- Business-To-Business Integration (B2Bi) is a key mechanism for enterprises to gain competitive advantage. However, developing B2Bi applications is far from trivial. Inter alia, agreement among integration partners about the business documents and the control flow of business document exchanges as well as applying suitable communication technologies for overcoming heterogeneous IT landscapes are major challenges. At the same time, choreography languages such as ebXML BPSS (ebBP), orchestration languages such as WS-BPEL and Web Services are promising to provide the foundations for seamless interactions among business partners. Automatically translating choreography agreements of integration partners into partner-specific orchestrations is an obvious idea for ensuring conformance of orchestration models to choreography models. Moreover, the application of such model-driven development methods facilitates productivity and cost-effectiveness whereas applying a service oriented architecture (SOA) based on WS-BPEL and Web Services leverages standardization and decoupling. By now, the realization of QoS attributes has not yet received the necessary attention that makes such approaches suitable for B2Bi. In this report, we describe a proof-of-concept implementation of the translation of ebBP choreographies into WS-BPEL orchestrations that respects B2Bi-relevant QoS attributes.
- A Process for Identifying Predictive Correlation Patterns in Service Management Systems (2010)
- By using the remote functions of a modern IT service management system infrastructure, it is possible to analyze huge amounts of logfile data from complex technical equipment. This enables a service provider to predict failures of connected equipment before they happen. The problem most providers face in this context is finding a needle in a haystack - the obtained amount of data turns out to be too large to be analyzed manually. This report describes a process to find suitable predictive patterns in log files for the detection of upcoming critical situations. The identification process may serve as a hands-on guide. It describes how to connect statistical means, data mining algorithms and expert domain knowledge in the domain of service management. The process was developed in a research project which is currently being carried out within the Siemens Healthcare service organization. The project deals with two main aspects: First, the identification of predictive patterns in existing service data and second, the architecture of an autonomous agent which is able to correlate such patterns. This paper summarizes the results of the first project challenge. The identification process was tested successfully in a proof of concept for several Siemens Healthcare products.
- A Requirements Analysis of Business-To-Business Integration (2009)
- Ever fiercer competition has forced enterprises not only to optimize their own operations but also to cooperate with their suppliers and customers along their supply chains. Thus, competition today usually takes place between supply chains and not between individual enterprises. Business-To-Business integration (B2Bi) is a major task of supply chain management (SCM), and although it already has been researched for years, B2Bi is still an area of active research with a plethora of research questions and according approaches. Hence, management of B2Bi projects necessitates the identification of relevant requirements which is a far from trivial task. This paper identifies a core set of B2Bi challenges and deduces a comprehensive set of B2Bi requirements that are particularly useful for tackling the challenges identified. The derivation of B2Bi requirements follows an inductive approach that is based on the analysis of integration standards, reference architectures and related literature. In order to operationalize the B2Bi requirements for further analysis and concrete B2Bi projects, the requirements are classified according to the abstraction layers of a B2Bi schema. Thus, this report not only offers a requirements check list for B2Bi projects but also helps in deciding when to address which requirements during the course of a B2Bi project.
- Proaktives Problem Management durch Eventkorrelation - ein Best Practice Ansatz (2010)
- Im Servicegeschäft werden Eventkorrelationssysteme verwendet, um bevorstehende Systemzustände vorherzusagen und damit Anlagenausfälle zu vermeiden. Aus strategischer Sicht kann dies zu höherer Anlagenverfügbarkeit und bessere Planbarkeit beitragen. Unternehmen, die von diesem Wettbewerbsvorteil profitieren wollen, begegnen dabei häufig zwei grundlegenden Problemen: die Komplexität im Service steigt mit der Anzahl der Korrelationen. Gleichzeitig geht die Kostentransparenz für den Gesamtprozess verloren. Die vorliegende Arbeit zeigt, warum diese beiden Probleme entstehen und wie sie weitgehend vermieden werden können.
- Building Orchestrations in B2Bi – The Case of BPEL 2.0 and BPMN 2.0 (2012)
- Various approaches for service-oriented business-to-business integration (B2Bi) rely on a top-down development methodology. The starting point is a choreography model which is subsequently partitioned into multiple orchestrations. Most current approaches use the Web Services Business Process Execution Language (BPEL) for implementing the latter. At the same time, a plethora of other languages, such as Business Process Model and Notation (BPMN) 2.0 process diagrams, is available. As integration partners are free to select the orchestration language of their choice, it should be easy to integrate different orchestration languages with current choreography technology. Language transformation, starting from a suitable format, is a means to achieve this. In this paper, we assess BPEL 2.0 and BPMN 2.0 process diagrams for their suitability for this transformation in a services-based B2Bi setting using a requirements framework identified through a literature study.
- Bridging the Heterogeneity of Orchestrations – A Petri Net–based Integration of BPEL and Windows Workflow (2012)
- Service orchestrations are a powerful tool for implementing intra– and interorganizational business processes that base on services. Several heterogeneous orchestration languages can be found in contemporary IT landscapes. While the Web Services Business Process Execution Language (BPEL) is the de facto standard, others gain attention, including Windows Workflow (WF) in the .NET segment. When integrating orchestrations, incompatibilities between them can easily arise. In this paper, we investigate an automated Petri net–based integration between BPEL and WF to solve these issues with behavioral adapter services. We provide a mapping of WF to Open Workflow Nets (oWFNs) and implement it in a compiler. Thereby, we integrate our approach with existing approaches for BPEL and adapter synthesis and validate the integration with a standards–based case study using the two languages.
- BPEL Conformance in Open Source Engines (2012)
- More than five years have passed since the final release of the long-desired OASIS standard of a process language for Web Services orchestration, the Web Services Business Process Execution Language (BPEL). The aim of this standard was to establish a universally accepted Web Services orchestration language that forms a core part of service-oriented architectures and, because of standardization, avoids vendor lock-in. By now, several fully conformant engines should have arrived in the market. It is our aim to shed light on this situation and to provide a comprehensive picture of the current state of BPEL upport. We present an evaluation of the standard conformance of five open source BPEL engines. To obtain these results we have developed betsy, a tool that allows for a fully-automatic standard conformance testing of BPEL engines. The results demonstrate that full standard conformance in contemporary engines is still far from given.