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.
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.
The importance of JAVA as a programming and execution environment has grown steadily over the past decade. Furthermore, the IT industry has adapted JAVA as a major building block for the creation of new middleware as well as a technology facilitating the migration of existing applications towards web-driven environments. Parallel in time, the role of security in distributed environments has gained attention, as a large amount of middleware applications has replaced enterprise-level mainframe systems. The protection of confidentiality, integrity and availability are therefore critical for the market success of a product. The vulnerability level of every product is determined by the weakest embedded component, and selling vulnerable products can cause enormous economic damage to software vendors. An important goal of this work is to create the awareness that the usage of a programming language, which is designed as being secure, is not sufficient to create secure and trustworthy distributed applications. Moreover, the incorporation of the threat model of the programming language improves the risk analysis by allowing a better definition of the attack surface of the application. The evolution of a programming language leads towards common patterns for solutions for recurring quality aspects. Suboptimal solutions, also known as ´antipatterns´, are typical causes for quality weaknesses such as security vulnerabilities. Moreover, the exposure to a specific environment is an important parameter for threat analysis, as code considered secure in a specific scenario can cause unexpected risks when switching the environment. Antipatterns are a well-established means on the abstractional level of system modeling to inform about the effects of incomplete solutions, which are also important in the later stages of the software development process. Especially on the implementation level, we see a deficit of helpful examples, that would give programmers a better and holistic understanding. In our basic assumption, we link the missing experience of programmers regarding the security properties of patterns within their code to the creation of software vulnerabilities. Traditional software development models focus on security properties only on the meta layer. To transfer these efficiently to the practical level, we provide a three-stage approach: First, we focus on typical security problems within JAVA applications, and develop a standardized catalogue of ´antipatterns´ with examples from standard software products. Detecting and avoiding these antipatterns positively influences software quality. We therefore focus, as second element of our methodology, on possible enhancements to common models for the software development process. These help to control and identify the occurrence of antipatterns during development activities, i. e. during the coding phase and during the phase of component assembly, integrating one´s own and third party code. Within the third part, and emphasizing the practical focus of this research, we implement prototypical tools for support of the software development phase. The practical findings of this research helped to enhance the security of the standard JAVA platforms and JEE frameworks. We verified the relevance of our methods and tools by applying these to standard software products leading to a measurable reduction of vulnerabilities and an information exchange with middleware vendors (Sun Microsystems, JBoss) targeting runtime security. Our goal is to enable software architects and software developers developing end-user applications to apply our findings with embedded standard components on their environments. From a high-level perspective, software architects profit from this work through the projection of the quality-of-service goals to protection details. This supports their task of deriving security requirements when selecting standard components. In order to give implementation-near practitioners a helpful starting point to benefit from our research we provide tools and case-studies to achieve security improvements within their own code base.
The focus of this dissertation lies on the brand personality (BP) and the brand relationship concept. They represent two particularly important measures of brand equity. And more importantly, both concepts still lack a comprehensive understanding. Hence, this dissertation provides deeper insight in how two manage and measure BP and how to build strong consumer-brand relationships. Thus, the purpose of this dissertation is twofold: In particular, the first objective is to discuss consumer’s perception of brand personality. In particular, the first goal is to gain an understanding of the way consumers perceive brands. The aim is to explore the amount of variance in consumer perception of brand personality. Do all customers perceive the same intended BP or do customers perceive the same intended BP differently? Reviewing the extant literature on BP reveals that there is much criticism on the existing BP scale (Aaker 1997). In order to address this issue, the research objective is to introduce an alternative conceptualization of BP by drawing upon social psychology. The aim is to analyze the role of emotions linking BP perceptions, brand attitude and purchase intentions. The second purpose of this dissertation is to illustrate how customers form relationships towards brands. Hence, in a first step, this dissertation pursues a thorough literature review. The aim is to scrutinize past research on consumer-brand relationships. This literature review will portray how the concept of consumer-brand relationships has been used in the marketing literature. The aim of this state-of-the-art review is to precisely identify the variables and concepts that deserve more attention. Subsequently, these variables will be investigated in an empirically tested model. So, the fourth aim is to identify the relevant antecedent and mediating variables of consumer-brand relationships. In doing so, this thesis seeks to provide a clear picture of the current state of BP and consumer-brand relationship research. Moreover, it aims at promoting research in these two research fields by addressing current issues in marketing. The first study (chapter 2) applies the existing BP scale. It develops a taxonomy which fills a gap in empirical knowledge about consumer perceptions of brand personalities. To the author’s knowledge, this is the first study that empirically derives a taxonomy from dimensions drawn from academic research (Aaker 1997). Overall, the results reveal that customers who perceive a strong BP perceive higher levels of performance in terms of brand attitude, preference and satisfaction. The second study (chapter 3) is the first to empirically investigate the applicability of the stereotype content model in the context of consumer goods brands. The review of extant research on BP shows a growing concern about the appropriateness of the Aaker scale. In order to address this issue, the study draws upon social psychology and the stereotype content model. The empirical study suggests that the stereotype content model is a viable alternative conceptualization of the BP concept. This study contributes to current research in two ways. First, it helps reducing complexity in BP measurement. Second, the results provide evidence that the consumer’s behavioral intention results from his stereotypes towards the brand, his emotions and his brand attitude. By providing a current state-of-the-art review, chapter 4 serves as a valuable source of information to enhance research concerning consumer-brand relationships. First, the overview shows that consumer-brand relationship research still is in its infancy. Second, it reveals that current research on consumer-brand relationships focuses on the interpersonal context. Chapter 5 proposes an alternative conceptualization of the brand relationship quality construct by integrating current knowledge from the relationship marketing literature. The results show that brand relationship quality is well captured by the dimensions relationship commitment, trust, and relationship satisfaction. Second, this study is the first to apply the Relational Exchange Theory by Macneil (1980) to the consumer goods brand context. It introduces the norm concept from a business perspective and shows that relational norms play a mediating role in actual relationships between consumers and brands. Hence, the present study approves the question by Johar (2005) whether norms are attached to brand behavior. Furthermore, this chapter advances the current knowledge on consumer-brand relationships by empirically testing a comprehensive framework of consumer-brand relationships. This framework includes not only consumer and brand characteristics, but also brand relationship characteristics as relevant drivers of the consumer-brand dyad. The findings indicate that consumer characteristics are especially related to relational norms and that brand relationship characteristics rather influence the degree of perceived brand relationship quality and brand loyalty. Brand characteristics on the other hand can be linked to both mediators and the out-come variable brand loyalty. Overall, this dissertation advances the understanding of the two key brand equity measures BP and brand relationship by reducing complexity: Whereas the first study develops a taxonomy of brand constellations, the remaining two empirical studies transfer existing knowledge originating from marketing or related disciplines to the brand context. As such, this thesis reduces complexity and enriches research in the two fields by adding knowledge which has proven of value in related contexts.
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.
In recent years a steady increase of information produced in organizations can be noticed. In order to stay competitive, companies have a growing interest in reusing existing knowledge from past projects. Furthermore, a complete picture of the available information is necessary to be able to make informed decisions. The variety and complexity of information in modern organizations often exceeds the capabilities of the currently deployed enterprise search solutions. The reasons for that are manifold and range from non-linked information from multiple software systems to missing functionality to support users during search tasks. Existing search engines often do not support the search paradigms necessary in these environments. On many occasions, users are not aware of the results they will find during the formulation of the search queries. Additionally, the aspect of knowledge building and the identification of new insights into the available data is a priority for the users. Therefore, search paradigms are useful to provide users with tools that support exploratory navigation in a data set and help them to recognize relationships between search results. The goal of this publication is the introduction of a framework that supports exploratory searches in an organizational setting. The described LFRP-framework is built on top of four pillars. 1. The multi-layer functionality allows users to formulate complex search queries referring to more than one result type. Therewith, it enables search queries that - starting from a set of relevant projects - allow selections of documents that are linked to these projects. 2. The search paradigm of faceted searching supports users in formulating search queries incrementally by offering dynamic and valid filter criteria that avoid empty result sets. 3. By combining the concept of faceted search with the capability to influence the search result order based on filter criteria, users can define in a fine-grained way which criteria values shall be weighted stronger or weaker in the search results. The interaction with the ranking is conducted transparently by the so-called user preference functions. 4. The last pillar consists of the visualization type of parallel coordinates covering two tasks in the search user interface of the LFRP-Framework. On the one hand, users formulate their search queries solely graphically in the parallel coordinates and on the other hand they obtain a visual representation of the search results and are able to discover relationships between search results and their facets. The framework is introduced formally from a query model point of view as well as a prototypical implementation. It enables users to access large linked data sets by navigation and constitutes a contribution to a comprehensive information strategy for organizations.
The establishment and implementation of cross-organizational business processes is an implication of today's market pressure for efficiency gains.
In this context, Business-To-Business integration (B2Bi) focuses on the information integration aspects of business processes.
A core task of B2Bi is providing adequate models that capture the message exchanges between integration partners.
Following the terminology used in the SOA domain, such models will be called choreographies in the context of this work.
Despite the enormous economic importance of B2Bi, existing choreography languages fall short of fulfilling all relevant
requirements of B2Bi scenarios.
Dedicated B2Bi choreography standards allow for inconsistent outcomes of basic interactions and
do not provide unambiguous semantics for advanced interaction models.
In contrast to this, more formal or technical choreography languages may provide unambiguous modeling semantics,
but do not offer B2Bi domain concepts or an adequate level of abstraction.
Defining valid and complete B2Bi choreography models becomes a challenging task in the face of these shortcomings.
At the same time, invalid or underspecified choreography definitions are particularly costly considering the organizational
setting of B2Bi scenarios.
Models are not only needed to bridge the typical gap between business and IT,
but also as negotiation means among the business users of the integration partners on the one hand
and among the IT experts of the integration partners on the other.
Misunderstandings between any two negotiation partners potentially affect the agreements between all other negotiation partners.
The CHORCH approach offers tailored support for B2Bi by combining the strengths of both dedicated B2Bi standards and formal rigor.
As choreography specification format, the ebXML Business Process Specification Schema (ebBP) standard is used.
ebBP provides dedicated B2Bi domain concepts such as so-called BusinessTransactions (BTs) that abstractly specify the exchange of a request business document
and an optional response business document.
In addition, ebBP provides a format for specifying the sequence of BT executions for capturing complex interaction scenarios.
CHORCH improves the offering of ebBP in several ways.
Firstly, the execution model of BTs which allows for inconsistent outcomes among the integration partners
is redefined such that only consistent outcomes are possible.
Secondly, two binary choreography styles are defined as B2Bi implementation contract format in order to streamline implementation projects.
Both choreography styles are formalized and provided with a formal execution semantics for ensuring unambiguity.
In addition, validity criteria are defined that ensure implementability using BPEL-based orchestrations.
Thirdly, the analysis of the synchronization dependencies of complex B2Bi scenarios is supported
by means of a multi-party choreography style combined with an analysis framework.
This choreography style also is formalized and standard state machine semantics are reused in order to ensure unambiguity.
Moreover, validity criteria are defined that allow for analyzing corresponding models for typical multi-party choreography issues.
Altogether, CHORCH provides choreography styles that are B2Bi adequate, simple, unambiguous, and implementable.
The choreography styles are B2Bi adequate in providing B2Bi domain concepts, in abstracting from low-level implementation details
and in covering the majority of real-world B2Bi scenarios.
Simplicity is fostered by using state machines as underlying specification paradigm.
This allows for thinking in the states of a B2Bi scenario and for simple control flow structures.
Unambiguity is provided by formal execution semantics whereas implementability (for the binary choreography styles) is ensured by providing
mapping rules to BPEL-based implementations.
The validation of CHORCH's choreography styles is performed in a twofold way.
Firstly, the implementation of the binary choreography styles based on Web Services and BPEL technology is demonstrated
which proves implementability using relatively low-cost technologies.
Moreover, the analysis algorithms for the multi-party choreography styles are validated using a Java-based prototype.
Secondly, an abstract visualization of the choreography styles based on BPMN is provided that abstracts from
the technicalities of the ebBP standard.
This proves the amenability of CHORCH to development methods that start out with visual models.
CHORCH defines how to use BPMN choreographies for the purpose of B2Bi choreography modeling
and translates the formal rules for choreography validity into simple composition rules that
demonstrate valid ways of connecting the respective modeling constructs.
In summary, CHORCH allows integration partners to start out with a high-level visual model of their interactions in BPMN
that identifies the types and sequences of the BusinessTransactions to be used.
For multi-party choreographies, a framework for analyzing synchronization dependencies then is available.
For binary choreographies, an ebBP refinement can be derived that fills in the technical parameters that are needed for deriving the implementation.
Finally, Web Services and BPEL based implementations can be generated.
Thus, CHORCH allows for stepwise closing the semantic gap between the information perspective of business process models
and the corresponding implementations.
It is noteworthy that CHORCH uses international standards throughout all relevant layers, i.e., BPMN, ebBP, Web Services and BPEL,
which helps in bridging the heterogeneous IT landscapes of B2Bi partners.
In addition, the adoption of core CHORCH deliverables as international standards of the RosettaNet community
give testament to the practical relevance and promise dissemination throughout the B2Bi community.
The German cognitive science conference is an interdisciplinary event where researchers from different disciplines -- mainly from artificial intelligence, cognitive psychology, linguistics, neuroscience, philosophy of mind, and anthropology -- and application areas -- such as eduction, clinical psychology, and human-machine interaction -- bring together different theoretical and methodological perspectives to study the mind. The 11th Biannual Conference of the German Cognitive Science Society took place from September 30 to October 3 2012 at Otto-Friedrich-Universität in Bamberg. The proceedings cover all contributions to this conference, that is, five invited talks, seven invited symposia and two symposia, a satellite symposium, a doctoral symposium, three tutorials, 46 abstracts of talks and 23 poster abstracts.
The BiKS research group (“Educational processes, competence development, and selection decisions in preschool- and school age”) founded in 2005 and financed by the German Research Foundation (DFG), was established by a consortium of researchers combining expertise from the disciplines of psychology, education, and sociology. Two longitudinal studies were being conducted by the BiKS research group and followed until 2012. In the first study, a cohort of preschool children was traced until grade 4 in primary school. The second study comprises a cohort of primary school children who were followed until their 9th grade in secondary school. Besides the multidisciplinary perspective, the studies can be well characterized by their broad use of different methods, such as test data, interviews, questionnaires, and live observations of behaviour as well as a consideration of different agents, i.e. students, parents, and teachers. The book focuses on empirical research findings concerning the development of reading literacy from a longitudinal perspective and the chapters cover findings from both longitudinal studies of the BiKS research group. As authors from different academic disciplines have contributed, this volume covers a range of psychological, educational as well as sociological perspectives on causes and effects of stability and interindividual differences in the development of reading literacy.
This dissertation analyzes Open-End Turbo Certificates (OETCs), a popular class of retail derivatives. OETCs can be exercised at any time at the investor’s discretion. In order to explain the existence of the certificates jump risk must be considered. We propose and implement an optimal stopping approach to price these securities, which further allows for determining optimal exercise thresholds. They result from the trade-off between benefits from downward jump protection and financing costs. We show that early exercise right has a significant impact on their values. In an empirical analysis pertaining to the years 2007 through 2009 it turns out that certificates which could be rationally held are very rare, although the degree by which the underlying exceeds the optimal exercise thresholds continually declines over the considered period. We suggest three lines of explanation: general market movement, jump risk perception by the market, and increased competition among issuers.