<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0">
  <channel>
    <title>OPUS 4 Latest Documents RSS Feed</title>
    <description>Latest documents</description>
    <link>http://opus4.kobv.de/opus4-bamberg/index/index/</link>
    <pubDate>Fri, 14 Jun 2013 11:50:07 +0200</pubDate>
    <lastBuildDate>Fri, 14 Jun 2013 11:50:07 +0200</lastBuildDate>
    <item>
      <title>BPEL Conformance in Open Source Engines</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/1928</link>
      <description>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,&#13;
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&#13;
current state of BPEL  upport. We present an evaluation of the standard conformance of five open source BPEL engines.&#13;
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&#13;
conformance in contemporary engines is still far from given.</description>
      <author>Simon Harrer; Jörg Lenhard; Guido Wirtz</author>
      <category>conferenceobject</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/1928</guid>
      <pubDate>Fri, 14 Jun 2013 11:50:07 +0200</pubDate>
    </item>
    <item>
      <title>Detecting Interoperability and Correctness Issues in BPMN 2.0 Process Models</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/3314</link>
      <description>Although BPMN 2.0 is an international standard widely used in practice, interoperability of process models is still an issue. Even between tools and engines claiming to be BPMN compliant the model exchange is often complicated or impossible as the tools produce incorrect model representations or do not support the standardized BPMN serialization format. In this position paper we present reasons for interoperability issues and show why defining a set of constraints derived from the standard is crucial to fix an important subset of those issues. We are currently developing a tool which can check this set of rules automatically.</description>
      <author>Matthias Geiger; Guido Wirtz</author>
      <category>conferenceobject</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/3314</guid>
      <pubDate>Mon, 08 Apr 2013 13:39:18 +0200</pubDate>
    </item>
    <item>
      <title>Bridging the Heterogeneity of Orchestrations – A Petri Net–based Integration of BPEL and Windows Workflow</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/1927</link>
      <description>Service orchestrations are a powerful tool for&#13;
implementing intra– and interorganizational business processes&#13;
that base on services. Several heterogeneous orchestration&#13;
languages can be found in contemporary IT landscapes. While&#13;
the Web Services Business Process Execution Language (BPEL)&#13;
is the de facto standard, others gain attention, including Windows&#13;
Workflow (WF) in the .NET segment. When integrating&#13;
orchestrations, incompatibilities between them can easily arise.&#13;
In this paper, we investigate an automated Petri net–based&#13;
integration between BPEL and WF to solve these issues with&#13;
behavioral adapter services. We provide a mapping of WF to&#13;
Open Workflow Nets (oWFNs) and implement it in a compiler.&#13;
Thereby, we integrate our approach with existing approaches&#13;
for BPEL and adapter synthesis and validate the integration&#13;
with a standards–based case study using the two languages.</description>
      <author>Stefan Kolb; Jörg Lenhard; Guido Wirtz</author>
      <category>conferenceobject</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/1927</guid>
      <pubDate>Thu, 14 Feb 2013 10:41:49 +0100</pubDate>
    </item>
    <item>
      <title>Building Orchestrations in B2Bi – The Case of BPEL 2.0 and BPMN 2.0</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/1279</link>
      <description>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.</description>
      <author>Jörg Lenhard; Guido Wirtz</author>
      <category>conferenceobject</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/1279</guid>
      <pubDate>Wed, 13 Feb 2013 10:59:49 +0100</pubDate>
    </item>
    <item>
      <title>Betsy - A BPEL Engine Test System</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/649</link>
      <description>More than five years have passed since the final release of the long-desired OASIS standard of a process language for web service orchestration, the Web Services Business Process Execution Language (BPEL). The aim of this standard is to establish a universally accepted orchestration language that forms a core part of current service-oriented architectures and, because of standardisation, avoids vendor lock-in. High expectations, in academia and practice alike, have been set on it. By now, several fully conformant and highly scalable engines should have arrived in the market. The perception of many however, is that standard conformance in current engines is far from given. It is our aim to shed light on this situation. In this study, we present the tool betsy, a BPEL Engine Test System that allows for a fully-automatic assessment of the standard conformance of a given BPEL engine. We use it to examine the five most important open source BPEL engines available today. Betsy comes with a large set of engineindependent conformance test cases for assessing BPEL standard conformance. This enables us to give a view of the state of the art in BPEL support.</description>
      <author>Simon Harrer; Jörg Lenhard</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/649</guid>
      <pubDate>Fri, 21 Sep 2012 09:21:12 +0200</pubDate>
    </item>
    <item>
      <title>The CHORCH Approach: How to Model B2Bi Choreographies for Orchestration Execution</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/392</link>
      <description>The establishment and implementation of cross-organizational business processes is an implication of today's market pressure for efficiency gains.&#13;
In this context, Business-To-Business integration (B2Bi) focuses on the information integration aspects of business processes.&#13;
A core task of B2Bi is providing adequate models that capture the message exchanges between integration partners.&#13;
Following the terminology used in the SOA domain, such models will be called choreographies in the context of this work.&#13;
Despite the enormous economic importance of B2Bi, existing choreography languages fall short of fulfilling all relevant&#13;
requirements of B2Bi scenarios.&#13;
Dedicated B2Bi choreography standards allow for inconsistent outcomes of basic interactions and&#13;
do not provide unambiguous semantics for advanced interaction models.&#13;
In contrast to this, more formal or technical choreography languages may provide unambiguous modeling semantics,&#13;
but do not offer B2Bi domain concepts or an adequate level of abstraction.&#13;
Defining valid and complete B2Bi choreography models becomes a challenging task in the face of these shortcomings.&#13;
At the same time, invalid or underspecified choreography definitions are particularly costly considering the organizational&#13;
setting of B2Bi scenarios.&#13;
Models are not only needed to bridge the typical gap between business and IT,&#13;
but also as negotiation means among the business users of the integration partners on the one hand&#13;
and among the IT experts of the integration partners on the other.&#13;
Misunderstandings between any two negotiation partners potentially affect the agreements between all other negotiation partners.&#13;
&#13;
The CHORCH approach offers tailored support for B2Bi by combining the strengths of both dedicated B2Bi standards and formal rigor.&#13;
As choreography specification format, the ebXML Business Process Specification Schema (ebBP) standard is used.&#13;
ebBP provides dedicated B2Bi domain concepts such as so-called BusinessTransactions (BTs) that abstractly specify the exchange of a request business document&#13;
and an optional response business document.&#13;
In addition, ebBP provides a format for specifying the sequence of BT executions for capturing complex interaction scenarios.&#13;
&#13;
CHORCH improves the offering of ebBP in several ways.&#13;
Firstly, the execution model of BTs which allows for inconsistent outcomes among the integration partners&#13;
is redefined such that only consistent outcomes are possible.&#13;
Secondly, two binary choreography styles are defined as B2Bi implementation contract format in order to streamline implementation projects.&#13;
Both choreography styles are formalized and provided with a formal execution semantics for ensuring unambiguity.&#13;
In addition, validity criteria are defined that ensure implementability using BPEL-based orchestrations.&#13;
Thirdly, the analysis of the synchronization dependencies of complex B2Bi scenarios is supported&#13;
by means of a multi-party choreography style combined with an analysis framework.&#13;
This choreography style also is formalized and standard state machine semantics are reused in order to ensure unambiguity.&#13;
Moreover, validity criteria are defined that allow for analyzing corresponding models for typical multi-party choreography issues.&#13;
&#13;
Altogether, CHORCH provides choreography styles that are B2Bi adequate, simple, unambiguous, and implementable.&#13;
The choreography styles are B2Bi adequate in providing B2Bi domain concepts, in abstracting from low-level implementation details&#13;
and in covering the majority of real-world B2Bi scenarios.&#13;
Simplicity is fostered by using state machines as underlying specification paradigm.&#13;
This allows for thinking in the states of a B2Bi scenario and for simple control flow structures.&#13;
Unambiguity is provided by formal execution semantics whereas implementability (for the binary choreography styles) is ensured by providing&#13;
mapping rules to BPEL-based implementations.&#13;
&#13;
The validation of CHORCH's choreography styles is performed in a twofold way.&#13;
&#13;
Firstly, the implementation of the binary choreography styles based on Web Services and BPEL technology is demonstrated&#13;
which proves implementability using relatively low-cost technologies.&#13;
Moreover, the analysis algorithms for the multi-party choreography styles are validated using a Java-based prototype.&#13;
&#13;
Secondly, an abstract visualization of the choreography styles based on BPMN is provided that abstracts from&#13;
the technicalities of the ebBP standard.&#13;
This proves the amenability of CHORCH to development methods that start out with visual models.&#13;
CHORCH defines how to use BPMN choreographies for the purpose of B2Bi choreography modeling&#13;
and translates the formal rules for choreography validity into simple composition rules that&#13;
demonstrate valid ways of connecting the respective modeling constructs.&#13;
&#13;
In summary, CHORCH allows integration partners to start out with a high-level visual model of their interactions in BPMN&#13;
that identifies the types and sequences of the BusinessTransactions to be used.&#13;
For multi-party choreographies, a framework for analyzing synchronization dependencies then is available.&#13;
For binary choreographies, an ebBP refinement can be derived that fills in the technical parameters that are needed for deriving the implementation.&#13;
Finally, Web Services and BPEL based implementations can be generated.&#13;
Thus, CHORCH allows for stepwise closing the semantic gap between the information perspective of business process models&#13;
and the corresponding implementations.&#13;
&#13;
It is noteworthy that CHORCH uses international standards throughout all relevant layers, i.e., BPMN, ebBP, Web Services and BPEL,&#13;
which helps in bridging the heterogeneous IT landscapes of B2Bi partners.&#13;
In addition, the adoption of core CHORCH deliverables as international standards of the RosettaNet community&#13;
give testament to the practical relevance and promise dissemination throughout the B2Bi community.</description>
      <author>Andreas Schönberger</author>
      <category>doctoralthesis</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/392</guid>
      <pubDate>Fri, 13 Jul 2012 14:05:53 +0200</pubDate>
    </item>
    <item>
      <title>A Service Description Method for Service Ecosystems - Meta Models, Modeling Notations, and Model Transformations</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/288</link>
      <description>Globalization and rapid technological change elevates the role of the Internet in terms of business service offering and procurement. At the same time, companies specialize on core competencies on the one hand, and on the other hand, integrate with other firms into “service ecosystems” in order to serve market needs in a flexible manner. One challenge in this setting is how to develop and describe novel business services within service ecosystems for efficient trade in services over the Internet. This work proposes a method for describing business services that integrates into business service development processes. The development of such a method leads to three major challenges: Firstly, it is necessary to determine which properties are appropriate for describing business services. This work analyzes existing approaches in the marketing, information systems, and computer science domain and develops a model for a formal description that facilitates offering and discovering of business services. Secondly, business service description elicitation, documentation, and communication must be provided for the whole business service development process. This work’s approach includes the development of an appropriate modeling notation as an extension of the Unified Modeling Notation (UML). Thirdly, there is a need for transforming business service descriptions into software realization languages that are suitable for the Internet. This contribution offers an automatic transformation of business service descriptions into Web Services Description Language (WSDL) documents using model-to-model transformation scripts. The method for describing business services was evaluated by implementing an integrated modeling environment along with related transformation scripts as well as by two case studies in the insurance and IT outsourcing industry.</description>
      <author>Gregor Scheithauer</author>
      <category>doctoralthesis</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/288</guid>
      <pubDate>Fri, 15 Jul 2011 07:56:25 +0200</pubDate>
    </item>
    <item>
      <title>A Pattern-based Analysis of WS-BPEL and Windows Workflow</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/283</link>
      <description>Orchestration languages are of paramount importance for building composite services in service-oriented architectures. Pattern-based analysis is a method that allows to determine the expressiveness of existing process languages and serves as a means of comparison between different languages. The aim of this study is the analysis and comparison of important languages for building Web Services-based orchestrations, as well as the improvement of the method of pattern-based analysis. The predominant orchestration language today is the Web Services Business Process Execution Language (WS-BPEL) 2.0. This language is a standard that has been implemented by several companies and projects, such as the OpenESB BPEL Service Engine. An additional language is Windows Workflow 4 that is shipped by Microsoft as part of the .NET framework. There are various aspects, represented by pattern catalogs, for which existing languages can be analyzed. This study suggests a methodology for ordering existing pattern catalogs according to their importance for a selected problem domain which is Business-to-Business Integration. It furthermore presents an extensive evaluation of the languages at hand and assesses the degree of support they provide for several of the most important pattern catalogs. These catalogs are the workflow control-flow patterns, the service interaction patterns, the change patterns and the time patterns.</description>
      <author>Jörg Lenhard</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/283</guid>
      <pubDate>Mon, 27 Jun 2011 10:29:27 +0200</pubDate>
    </item>
    <item>
      <title>Analyzing the Interoperability of WS-Security and WS-ReliableMessaging Implementations</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/249</link>
      <description>Since their invention as lightweight integration technology about a decade ago, Web Services have matured significantly. Today, major middleware solution vendors as well as industry communities like RosettaNet are propagating Web services even for exchanging business-critical data and implementing inter-organizational business processes. Core enablers for using Web services in this domain are stateful interactions using the Web Services Business Process Execution Language (WS-BPEL) as well as advanced communication features like security and reliability using the WS-Security and WS-ReliableMessaging standard specifications. However, advanced communication features come at the price of complexity which challenges interoperability across different Web services stack implementations. Interoperability, in turn, is a predominant requirement for an integration technology such as Web services, in particular if inter-organizational business processes are supposed to be implemented on top of that technology. This paper approaches the problem of testing the interoperability of the so-called WS-* standards, advanced Web services communication features that are typically defined as SOAP extensions and configured using WS-Policy. Being essential to business process integration, WS-Security and WS-ReliableMessaging are selected as representatives of this group and the two major Java-based Web services stack implementations Metro and Axis2 are tested for interoperability. We operationalize the notion of interoperability for testing WS-* standards, suppose an approach for deriving test cases from WS-* specifications as well as a method for performing the test cases, and we provide a comprehensive interoperability review of the two selected Web services stack implementations.</description>
      <author>Johannes Schwalb; Andreas Schönberger</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/249</guid>
      <pubDate>Wed, 13 Oct 2010 15:51:09 +0200</pubDate>
    </item>
    <item>
      <title>Proaktives Problem Management durch Eventkorrelation - ein Best Practice Ansatz</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/245</link>
      <description>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.</description>
      <author>Werner Zirkel; Guido Wirtz</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/245</guid>
      <pubDate>Mon, 20 Sep 2010 11:01:00 +0200</pubDate>
    </item>
    <item>
      <title>A Requirements Analysis of Business-To-Business Integration</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/217</link>
      <description>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.</description>
      <author>Andreas Schönberger; Christian Wilms; Guido Wirtz</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/217</guid>
      <pubDate>Thu, 20 May 2010 13:32:46 +0200</pubDate>
    </item>
    <item>
      <title>Improving the Tor Hidden Service Protocol Aiming at Better Performances</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/211</link>
      <description>Offering services anonymously on the Internet using so-called location-hidden services requires complex protocols with many different nodes involved. These properties result in performance problems, e.g. a simple website request taking tens of seconds. This work describes a setup to measure the performance of hidden services using the worldwide Tor network. It analyzes the results and proposes changes to the protocol to improve the performance without losing anonymity.</description>
      <author>Christian Wilms</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/211</guid>
      <pubDate>Fri, 23 Apr 2010 14:42:30 +0200</pubDate>
    </item>
    <item>
      <title>A Process for Identifying Predictive Correlation Patterns in Service Management Systems</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/206</link>
      <description>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.</description>
      <author>Werner Zirkel; Guido Wirtz</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/206</guid>
      <pubDate>Thu, 25 Feb 2010 11:48:41 +0100</pubDate>
    </item>
    <item>
      <title>A Realistic Approach for the Autonomic Management of Component-Based Enterprise Systems</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/186</link>
      <description>During the last decades, information technology has been characterized by constantly increasing performance of available hardware resources. This development allows the assignment of more and more complex tasks to software systems while at the same time leading to a massive increase of inherent complexity of applied systems. The expected further increase of complexity in the future demands for an explicit addressing of complexity. The concept of Component Orientation represents an approach for complexity reduction during the development and configuration of software through functional decomposition. With the vision of Autonomic Computing there does exist an approach for addressing complexity during the operation and maintenance of software systems. In this context, the approach is based on the idea of assigning low level-management tasks to the managed system itself. The concept of Component Orientation leads to the establishment of system architectures out of clearly distinguishable building blocks. Therefore, Component Orientation seems to provide a promising foundation for realizing the vision of Autonomic Computing. This thesis presents a realistic infrastructure for the autonomic management of component-based enterprise systems. The application area of such systems leads to special requirements for managed systems and is highly affected by the complexity problem. As a foundation for the proposed approach, a well established component standard was chosen to guarantee the practical relevance of applied concepts and techniques. The applied standard is Enterprise JavaBeans, version 3.0. The proposed infrastructure is designed and realized in a generic fashion. It provides a platform upon which solutions for different application areas of Autonomic Computing can be realized. Autonomic entities are supported through a programming interface which represents a system on three interrelated levels and allows its management: On the top-level, the underlying software of a managed system is considered. The middle layer addresses the system architecture. Runtime interactions within the system are represented on the lowest layer. On this foundation, a system can be managed in a holistic, model-based way. The runtime management of a system is enabled through a specially developed component which must be integrated into the affected environment. This component is compliant with the applied component standard and does not require any adjustment of the underlying component platform. Finally, a tool is provided which supports the establishment of manageability through the automated execution of required adjustments of components. The management of a system is realized transparently for its constituent elements during runtime. On the whole, the development of enterprise software is not affected by a potential application of the presented infrastructure.</description>
      <author>Jens Bruhn</author>
      <category>doctoralthesis</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/186</guid>
      <pubDate>Thu, 08 Oct 2009 10:35:07 +0200</pubDate>
    </item>
    <item>
      <title>QoS-Enabled B2B Integration</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/182</link>
      <description>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.</description>
      <author>Thomas Benker; Stefan Fritzemeier; Matthias Geiger; Simon Harrer; Tristan Kessner; Johannes Schwalb; Andreas Schoenberger; Guido Wirtz</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/182</guid>
      <pubDate>Mon, 14 Sep 2009 11:59:12 +0200</pubDate>
    </item>
    <item>
      <title>Privacy-enhancing Technologies for Private Services</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/170</link>
      <description>Privacy on the Internet is becoming more and more important, as an increasing part of everyday life takes place over the Internet. Internet users lose the ability to control which information they give away about themselves or are even not aware that they do so. Privacy-enhancing technologies help control private information on the Internet, for example, by anonymizing Internet communication. Up to now, work on privacy-enhancing technologies has mainly focused on privacy of users requesting public services. This thesis introduces a new privacy risk that occurs when private persons run their own services. One example are instant messaging systems which allow users to exchange presence information and text messages in real time. These systems usually do not provide protection of presence information which is stored on central servers. As an alternative, decentralized instant messaging system designs mitigate this problem by having private persons provide instant messaging services to each other. However, providing a service as a private person causes new security problems as compared to providing a service as an organization or enterprise: First, the presence of such a service reveals information about the availability of the service provider. Second, the server location needs to be concealed in order to hide the whereabouts of a person. Third, the server needs to be specifically protected from unauthorized access attempts. This thesis proposes to use pseudonymous services as a building block for private services. Pseudonymous services conceal the location of a server that provides a specific service. The contribution made here is to analyze what parts of pseudonymous services, in particular Tor hidden services, are missing in order to apply them for private services. This analysis leads to three main problems for which solutions are proposed: First, known pseudonymous service designs do not scale to the expected number of private services which might be provided in the future. This thesis proposes a new approach to store hidden service descriptors in a distributed data structure rather than on central servers. A particular focus lies on the support of private entries which are required for private services. Second, pseudonymous services leak too much information about service identity during advertisement in the network and connection establishment by clients. The approach taken in this thesis is to reduce the information that a service publishes in the network to a minimum and prevent unauthorized clients from accessing a service already during connection establishment. These changes protect service activity and usage patterns from non-authorized entities. Third, pseudonymous services exhibit worse performance than direct service access. The contribution of this thesis is to measure performance, identify possible problems, and propose improvements.</description>
      <author>Karsten Loesing</author>
      <category>doctoralthesis</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/170</guid>
      <pubDate>Wed, 27 May 2009 15:06:07 +0200</pubDate>
    </item>
    <item>
      <title>On the Application of the Service-Oriented Architectural Style to Heterogeneous Application Landscapes</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/165</link>
      <description>This thesis investigates the application of the service-oriented architectural style in the context of industrial enterprises. This style provides a commonly perceived paradigm for organizing distributed software systems. However, beyond general attention to this style, there are only few descriptions of the difference between service orientation and more mature styles, such as component orientation. This dissertation argues that the service-oriented style is an approach that centralizes control over distributed functionality that is provided by the application systems of an organization. This means that service orientation is a paradigm for application integration. Moreover, we argue that it is not possible to fully formalize the inherent principles of service orientation as part of an architectural style description. In fact, soft design principles are a differentiator of this style. These principles, however, are rarely applied in the context of industrial enterprises. This is why we analyze how such design principles could be objectively described and what attention should be paid to them. This analysis is performed by categorizing the potential benefits of this style and assigning the respective underlying principles to the identified benefits. Subsequently, a reference architecture is defined on the basis of these findings. This architecture focuses on structuring service-oriented applications - so-called composite applications. In order to apply the defined reference architecture in the context of actual projects, we describe a design methodology for composite applications. This design methodology focuses on using business processes for designing various types of services and on describing their interconnections by the reference architecture. To achieve this, a service design algorithm is included that derives services from business processes by incorporating the results of a statistical analysis of service design principles. The result of this methodology is a platform-independent design of a composite application. It considers the restrictions of the application landscape in which a composite will be deployed. To permit the realization of composite applications, we informally map the platform-independent reference architecture to a platform that is widely used in industrial enterprises. This mapping is, together with the design methodology and the reference architecture, applied to an industry-scale use case. This way, the applicability of the concepts is demonstrated.</description>
      <author>Helge Hofmeister</author>
      <category>doctoralthesis</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/165</guid>
      <pubDate>Fri, 03 Apr 2009 16:25:43 +0200</pubDate>
    </item>
    <item>
      <title>A Service Description Framework for Service Ecosystems</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/158</link>
      <description>Recently, service orientation has strongly influenced the way enterprise applications are built. Service ecosystems, which provide means to trade services between companies like goods, are an evaluation of service orientation. To allow service ordering, discovering, selection, and consumption, a common way to describe services is a necessity. This paper discusses existing approaches to describe certain service aspects. Finally, a Service Description Framework for service ecosystems is proposed and exemplified.</description>
      <author>Gregor Scheithauer; Matthias Winkler</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/158</guid>
      <pubDate>Wed, 21 Jan 2009 15:47:41 +0100</pubDate>
    </item>
    <item>
      <title>Applying Business Process Management Systems - a Case Study </title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/134</link>
      <description>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.</description>
      <author>Gregor Scheithauer; Guido Wirtz</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/134</guid>
      <pubDate>Tue, 15 Jul 2008 16:08:41 +0200</pubDate>
    </item>
    <item>
      <title>Extended Abstracts of the Second Privacy Enhancing Technologies Convention (PET-CON 2008.1)</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/122</link>
      <description>PET-CON, the Privacy Enhancing Technologies Convention, is a forum for researchers, students, developers, and other interested people to discuss novel research, current developments and techniques in the area of Privacy Enhancing Technologies. PET-CON was first conceived in June 2007 at the 7th International PET Symposium in Ottawa, Canada. The idea was to set up a bi-annual convention in or nearby Germany to be able to meet more often than only once a year at some major conference.</description>
      <author>Dominik Herrmann; Karsten Loesing; Sebastian Pape; Johannes Renner; Rolf Wendolsky; Benedikt Westermann</author>
      <category>conferenceobject</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/122</guid>
      <pubDate>Fri, 08 Feb 2008 14:53:35 +0100</pubDate>
    </item>
    <item>
      <title>Open Chord version 1.0.4 User's Manual</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/113</link>
      <description>In recent years peer-to-peer networks have developed from unstructured to structured overlay networks. Structured peer-to-peer overlay networks facilitate a bounded number of messages in the number of peers for querying and publishing content opposed to unstructured networks, which usually flood the network with messages. To prevent the messages from overflooding the network they have a bounded life time, which may cause that some published content will be lost. Structured peer-to-peer networks guarantee that all published content can be found. One well known structured overlay network is the chord distributed hash table. An implementation of chord is only available in C, but not in Java, which is used widely and often in computer science education. This manual describes an open source implementation of chord in Java - called Open Chord - and how it can be used in Java-based applications. It provides a console-based experimentation environment to explore the functionality of chord, as well.</description>
      <author>Sven Kaffille; Karsten Loesing</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/113</guid>
      <pubDate>Tue, 13 Nov 2007 08:20:13 +0100</pubDate>
    </item>
    <item>
      <title>Decentralized Reputation Management for Cooperating Software Agents in Open Multi-Agent Systems</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/87</link>
      <description>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.</description>
      <author>Marco Fischer; Andreas Grünert; Sebastian Hudert; Stefan König; Kira Lenskaya; Gregor Scheithauer; Sven Kaffille; Guido Wirtz</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/87</guid>
      <pubDate>Fri, 18 Aug 2006 13:53:34 +0200</pubDate>
    </item>
    <item>
      <title>Concealing Presence Information in Instant Messaging Systems</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/77</link>
      <description>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.</description>
      <author>Markus Dorsch; Martin Grote; Knut Hildebrandt; Maximilian Röglinger; Matthias Sehr; Christian Wilms; Karsten Loesing; Guido Wirtz</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/77</guid>
      <pubDate>Tue, 11 Apr 2006 07:54:50 +0200</pubDate>
    </item>
    <item>
      <title>Modelling and Validating Business Collaborations: A Case Study on RosettaNet</title>
      <link>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/73</link>
      <description>The way business processes are organised heavily influences the flexibility and the expenses of enterprises. The capability to address changing market needs in a timely manner and to provide appropriate pricing is indispensable in a world of internationalisation and growing competition. Optimising processes that cross enterprise boundaries potentially is a key success factor in achieving this goal but it requires the information systems of the participating enterprises to be consistently integrated. This gives rise to some challenging tasks. The personnel involved in building up business collaborations comes from different enterprises with different business vocabulary and background which requires extensive communication support. The lack of central technical infrastructure, typically prohibited by business politics, often calls for a distributed and computer-aided collaboration structure, so that the resulting complexity must be handled somehow. Nevertheless robustness is an important factor in building business collaborations as these may exchange goods of considerable value. This technical report proposes the use of a two step modelling approach that separates business logic, modelled in the so-called centralised perspective (CP), from its distributed implementation, modelled in the so-called distributed perspective (DP). The separation of these perspectives enables business people to concentrate on business issues and to solve communication problems in the CP whereas technical staff can concentrate on distribution issues. The use of stringent modelling rules is advised in order to provide the basis for formal analysis techniques as one means to achieve robustness. Considering the choreography of RosettaNet Partner Interface Processes (PIPs) as the subject of my analysis, UML activity diagrams for modelling the CP and WSBPEL for modelling the DP are described as enabling techniques for implementing the proposed two step modelling approach. Further, model checking is applied to validate the CP and DP models in order to detect errors in early design phases. As the adequacy of model checking tools highly depends on the detailed modelling techniques as well as the properties to be checked, a major part of our discussion covers relevant properties and requirements for a model checker.</description>
      <author>Andreas Schönberger</author>
      <category>report</category>
      <guid>http://opus4.kobv.de/opus4-bamberg/frontdoor/index/index/docId/73</guid>
      <pubDate>Thu, 30 Mar 2006 12:02:10 +0200</pubDate>
    </item>
  </channel>
</rss>
