The KLU faculty, post-docs, and PhD candidates regularly publish the results of their research in scientific journals. You will find a complete overview of all KLU publications below (e.g. articles in peer-reviewed journals, professional journals, books, working papers, and conference proceedings). Search for relevant terms and keywords, or filter the list by name, year of publication or type of publication. The references include DOIs and abstracts where available, and you can download them to your own reference database or platform. We regularly update the database with new publications.

Books

Conference Proceedings

Copy reference link   DOI: 10.5220/0005918500390047

Abstract: Utility, defined as the perceived satisfaction with a service, provides the ideal means for decision making on the level of individual entities and collectives participating in a large-scale dynamic system. Previous works have already introduced the concept into the area of collective adaptive systems, and have discussed what is the necessary infrastructure to support the realization of the involved theoretical concepts into actual decision making. In this work we focus on two aspects. First, we provide a concrete utility model for a case study that is part of a larger research project. Second, we incorporate this model into our implementation of the proposed architecture. More importantly, we design and execute an experiment that aims to empirically evaluate the use of utility for decision making by comparing it against simpler decision making mechanisms.

Export record: Citavi Endnote RIS ISI BibTeX WordXML

Copy reference link  

Abstract: With an ongoing division of labor and concentration on core competencies in logistics, the flexibility and quality in logistics services can be increased in terms of contracting specialists for each step in a supply chain. In order to participate in such an environment and act successfully on the market, it is essential for logistics service providers to follow a service oriented paradigm and modularize their service portfolio from static end-to-end solutions to a flexible set of modular services. One of the main challenges is to find a ’suitable’ level of granularity for the modularization of existing logistics services. In this paper a conceptual framework of service granularity levels is developed. A systematic literature review is conducted in order to find existing concepts of service granularity. Findings are analyzed and finally synthesized towards their suitability for logistics services. Domain specific composition is supported by the logistics service map concept that contains catalog and construction kit for modular services. The paper’s contribution is a Service Granularity Framework dedicated to specialized scholars of service science and practitioners of logistics.

Export record: Citavi Endnote RIS ISI BibTeX WordXML

Copy reference link

Abstract: ObjectivesThe significance of Logistics Service Providers (LSPs) has risen steadily during the last decades due to trends like logistics outsourcing or the structural change in the types of goods transported. From the freight transport modeller's point of view, integrating LSPs into freight transport models is essential to be capable of describing possible future developments. Especially important is the knowledge of the spatial distribution patterns of LSP locations e.g. to represent network routing of mixed cargo shipments more accurately. Moreover, attributes characterizing the LSP locations are helpful to relate them to traffic generation. Therefore, the objective of this paper is to present intermediate results of empirical work on LSP locations in Germany and their multiple attributes. Drawing on these findings we generate LTL freight for Germany.Data and methodologyFirstly, to identify spatial patterns of LSP locations, a secondary data analysis on the German LSP´s sites was conducted. Data on LSPs and their logistics locations including attributes like geolocation, employment, operations area, infrastructure access, or market segments served was collected. The resulting database was further combined with publicly accessible data e.g. to compute distances to highways. In this paper, the results of statistical analyses on the sample are presented. The sample´s representativeness and completeness of the database are discussed as well. Secondly we generate the LTL freight of LSPs based on generation rates and the location database. The model results are verified in two different ways.Expected resultsThe findings of this paper shed some light on the locations of the German LSP sector and the freight transport it generates. These insights especially include spatial configuration and are highly relevant for freight transport and land use planning policies. In addition, we show a new freight demand generation model based on data of logistics locations or, if we find a way to generate them synthetically, based on more available statistical data.

Export record: Citavi Endnote RIS ISI BibTeX WordXML

Copy reference link   DOI: 10.5220/0005342000280036

Abstract: The concept of reuse in process models is extensively studied in the literature. Sub-processes, process templates,process variants, and process reference models are employed as reusable elements for process modeling.Additionally, the notion of process fragments has been introduced to capture parts of a process model and store them for later reuse. In contrast, concepts for reuse of processes that cross the boundaries of organizations, i.e., choreographies, have not yet been studied in the appropriate level of detail. In this paper, we introduce the concept of choreography fragments as reusable elements for choreography modeling. Choreography fragments can be extracted from choreography models, adapted, stored, and inserted into new models. We provide a formal model for choreography fragments and identify a set of patterns constituting frequently occurring meaningful choreography fragments.

Export record: Citavi Endnote RIS ISI BibTeX WordXML

Copy reference link

Abstract: The success of the Cloud computing paradigm, together with the increase of Cloud providers and optimized Infrastructure-as-a-Service (IaaS) offerings have contributed to a raise in the number of research and industry communities that are strong supporters of migrating and running their applications in the Cloud. Focusing on eScience simulation-based applications, scientific workflows have been widely adopted in the last years, and the scientific workflow management systems have become strong candidates for being migrated to the Cloud. In this research work we aim at empirically evaluating multiple Cloud providers and their corresponding optimized and non-optimized IaaS offerings with respect to their offered performance, and its impact on the incurred monetary costs when migrating and executing a workflow-based simulation environment. The experiments show significant performance improvements and reduced monetary costs when executing the simulation environment in off-premise Clouds.

Export record: Citavi Endnote RIS ISI BibTeX WordXML

Copy reference link   DOI: doi:10.1007/978-3-319-26148-5_22

Abstract: Scientists that use the workflow paradigm for the enactment of scientific experiments need support for trial-and-error modeling, as well as flexibility mechanisms that enable the ad hoc repetition of workflow logic for the convergence of results or error handling. Towards this goal, in this paper we introduce the facilities to repeat partially or completely running choreographies on demand. Choreographies are interesting for the scientific workflow community because so-called multi-scale/field (multi-*) experiments can be modeled and enacted as choreographies of scientific workflows. A prerequisite for choreography repetition is the rewinding of the involved participant instances to a previous state. For this purpose, we define a formal model representing choreography models and their instances as well as a concept to repeat choreography logic. Furthermore, we provide an algorithm for determining the rewinding points in each involved participant instance.

Export record: Citavi Endnote RIS ISI BibTeX WordXML

Copy reference link   DOI: 10.1109/CloudCom.2015.86

Abstract: The on-demand provisioning of services, a cloud-based extension for traditional service-oriented architectures, improves the handling of services in usage scenarios where they are only used rarely and irregularly. However, the standard process of service provisioning and de-provisioning shows still some shortcomings when applying it in real world. In this paper, we introduce a middleware-centric optimization approach that can be integrated in the existing on-demand provisioning middleware in a loosely coupled manner, changing the standard provisioning and de-provisioning behavior in order to improve it with respect to cost and time. We define and implement a set of optimization strategies, evaluate them based on a real world use case from the eScience domain and provide qualitative as well as quantitative decision support for effectively selecting and parametrizing a suitable strategy. Altogether, our work improves the applicability of the existing on-demand provisioning approach and system in real world, including guidance for selecting the suitable optimization strategy for specific use cases.

Export record: Citavi Endnote RIS ISI BibTeX WordXML

Copy reference link   DOI: 10.1109/ICWS.2015.96

Abstract: Reuse of service orchestrations or service compositions is extensively studied in the literature of process modeling. Sub-processes, process templates, process variants, and process reference models are employed as reusable elements for these purposes. The concept of process fragments has been previously introduced in order to capture parts of a process model and store them for later reuse. However, similar efforts on facilitating the reuse of processes that cross the boundaries of organizations expressed as service choreographies are not available yet. In this paper, we introduce the concept of choreography fragments as reusable elements for service choreography modeling. Choreography fragments can be extracted from choreography models, adapted, stored, and later inserted into new models. Based on a formal model for choreography fragments, we define methods and algorithms for the extraction and insertion of fragments from and into service choreographies. We then discuss an experimental and proof-of-concept evaluation of our proposal.

Export record: Citavi Endnote RIS ISI BibTeX WordXML

Copy reference link   DOI: 10.5220/0005377801660176

Abstract: The objective of tactical planning in logistics is the engineering and evaluation of processes within a given set of possible alternatives. Due to outsourcing and a division of labor, a high number of participants, available services and thus possible process alternatives arises within logistics networks. The additional wide range of service description and annotation methods result in a complex planning process. In order to support planning, a semi-automated approach is presented in this paper that is based on a combined catalog and construction system (for engineering) and a generic simulation approach (for evaluation) that are able to handle the variety of description and annotation methods. The basic concepts are presented and afterward associated by a model-driven approach in order to connect them and make them compatible to work with each other. Finally, a method is developed to foster a semi-automated engineering and evaluation of process alternatives.

Export record: Citavi Endnote RIS ISI BibTeX WordXML

Copy reference link  

Abstract: Due to strong interdependencies between production, logistics and traffic, a decision in one of these fields has impacts on the others. However, decision makers in and around today’s supply chains rarely consider effects of their decisions on other participants of the supply chain or the traffic system. Thus, a tool for decision support, which clearly illustrates the variety of impacts of a decision, is highly desirable. Accordingly, this paper presents a reference model in the context of production, logistics and traffic, called Interdisciplinary Decision Map (IDM). The IDM allows for describing and analyzing interdisciplinary impacts of decisions across the disciplines. Thus, it can serve as decision support tool for decision makers out of the considered domains. The IDM’s applicability is demonstrated by using it to analyze selected impacts of an heavy goods vehicles (HGV) toll’s introduction on production, logistics and traffic.

Export record: Citavi Endnote RIS ISI BibTeX WordXML

Copy reference link   DOI: 10.1007/978-3-319-19027-3_23

Abstract: Global demands and emerging markets resulted in a rise of complexity in logistics over the last years. Furthermore, producing companies outsourced their logistics for reasons of flexibility. Hence, clients consult solution specialists for customer-focused end-to-end processes. The 4th party logistics business model offers an overall service management throughout an entire logistics chain by planning and controlling inherent processes. But because physical provisioning is outsourced to 3rd party providers, performance measurement is essential in order to meet service levels. Measuring sub providers poses difficulties because of different process definitions and communication standards. A relief is the growing amount of information during the process lifecycle. In this paper we present an integrated, strategically aligned provider rating model, applicable throughout the entire logistics process and capable of summing up operational information into ratios that are further aggregated into key performance indicators. Thereafter, we prove its applicability through a prototypical implementation.

Export record: Citavi Endnote RIS ISI BibTeX WordXML

Copy reference link   DOI: 10.1109/SOCA.2014.9

Abstract: The support of multi-tenancy is an essential requirement for leveraging the full capacity of Cloud computing. Multi-tenancy enables service providers to maximize the utilization of their infrastructure and to reduce the servicing costs per customer, thus indirectly benefiting also the customers. In addition, it allows both providers and consumers to reap the advantages of Cloud-based applications configurable for the needs of different tenants. Nowadays, new applications or services are typically compositions of multiple existing services. Service Composition Engines (SCEs) provide the required functionality to enable the definition and execution of such compositions. Multi-tenancy on the level of SCEs allows for both process model, as well as underlying infrastructure sharing. Towards the goal of enabling multi-tenancy of SCEs, in this paper, we investigate the requirements and define a general architecture for the realization of a multi-tenant SCE solution. This architecture is prototypically realized based on an open-source SCE implementation and integrated into an existing multi-tenant aware Enterprise Service Bus (ESB). The performance evaluation of our prototype shows promising results in terms of the degradation introduced due to processing and communication overhead.

Export record: Citavi Endnote RIS ISI BibTeX WordXML

Copy reference link   DOI: 10.1109/SOCA.2014.54

Abstract: The ability to repeat an experiment, known as replicability, is a basic concept of scientific research and also an important aspect in the field of eScience. The principles of Service Oriented Computing (SOC) and Cloud Computing, both based on high runtime dynamicity, are more and more adopted in the eScience domain. Simulation experiments exploiting these principles introduce significant challenges with respect to replicability. Current research activities mainly focus on how to exploit SOC and Cloud for eScience, while the aspect of replicability for such experiments is still an open issue. In this paper we define a general method to identify points of dynamicity in simulation experiments and to handle them in order to enable replicability. We systematically examine different types of service binding strategies, the main source of dynamicity, and derive a method and corresponding architecture to handle this dynamicity with respect to replicability. Our work enables scientists to perform simulation experiments that exploit the dynamicity and flexibility of SOC and Cloud Computing but still are repeatable.

Export record: Citavi Endnote RIS ISI BibTeX WordXML

Copy reference link   DOI: 10.1109/UCC.2014.37

Abstract: In many modern systems, applications or services are realized as compositions of multiple existing services that can be enacted by Service Composition Engines (SCEs), which provide the required functionality to enable their definition and execution. SCEs typically use the capabilities of an Enterprise Service Bus (ESB) which serves as the messaging hub between the composed services aiming at ensuring their integration. Together, an SCE and ESB solution comprise the service middleware required for the definition and execution of service-based composite applications. Offering a service middleware solution as a service creates a PaaS offering that allows the service consumers to share the service middleware solution in a multi-tenant manner. However, multi-tenancy support for service middleware solutions remains an open issue. For this purpose, in this work we introduce a general architecture for the realization of a multi-tenant service middleware PaaS solution. This architecture is prototypically realized based on open-source, multi-tenant ESB and SCE solutions. The resulting service middleware provides configurability for service compositions, tenant-aware messaging, and tenant-based administration and management of the SCE and the ESB. We also present an empirical evaluation of the multi-tenant service middleware with focus on the SCE. The results of these experiments show a performance degradation within acceptable limits when scaling the number of tenants and tenant users.

Export record: Citavi Endnote RIS ISI BibTeX WordXML