Modern software systems are becoming increasingly integrated and are required to operate over organizational boundaries through networks. The development of such distributed software systems has been shaped by the orthogonal trends of service-orientation and process-awareness. These trends put an emphasis on technological neutrality, loose coupling, independence from the execution platform, and location transparency. Execution platforms supporting these trends provide context and cross-cutting functionality to applications and are referred to as engines.
Applications and engines interface via language standards. The engine implements a standard. If an application is implemented in conformance to this standard, it can be executed on the engine. A primary motivation for the usage of standards is the portability of applications. Portability, the ability to move software among different execution platforms without the necessity for full or partial reengineering, protects from vendor lock-in and enables application migration to newer engines.
The arrival of cloud computing has made it easy to provision new and scalable execution platforms. To enable easy platform changes, existing international standards for implementing service-oriented and process-aware software name the portability of standardized artifacts as an important goal. Moreover, they provide platform-independent serialization formats that enable the portable implementation of applications. Nevertheless, practice shows that service-oriented and process-aware applications today are limited with respect to their portability. The reason for this is that engines rarely implement a complete standard, but leave out parts or differ in the interpretation of the standard. As a consequence, even applications that claim to be portable by conforming to a standard might not be so.
This thesis contributes to the development of portable service-oriented and process-aware software in two ways: Firstly, it provides evidence for the existence of portability issues and the insufficiency of standards for guaranteeing software portability. Secondly, it derives and validates a novel measurement framework for quantifying portability. We present a methodology for benchmarking the conformance of engines to a language standard and implement it in a fully automated benchmarking tool. Several test suites of conformance tests for two different languages, the Web Services Business Process Execution Language 2.0 and the Business Process Model and Notation 2.0, allow to uncover a variety of standard conformance issues in existing engines. This provides evidence that the standard-based portability of applications is a real issue. Based on these results, this thesis derives a measurement framework for portability. The framework is aligned to the ISO/IEC Systems and software Quality Requirements and Evaluation method, the recent revision of the renowned ISO/IEC software quality model and measurement methodology. This quality model separates the software quality characteristic of portability into the subcharacteristics of installability, adaptability, and replaceability. Each of these characteristics forms one part of the measurement framework. This thesis targets each characteristic with a separate analysis, metrics derivation, evaluation, and validation. We discuss existing metrics from the body of literature and derive new extensions speciffically tailored to the evaluation of service-oriented and process-aware software. Proposed metrics are defined formally and validated theoretically using an informal and a formal validation framework. Furthermore, the computation of the metrics has been prototypically implemented. This implementation is used to evaluate metrics performance in experiments based on large scale software libraries obtained from public open source software repositories.
In summary, this thesis provides evidence that contemporary standards and their implementations are not sufficient for enabling the portability of process-aware and service-oriented applications. Furthermore, it proposes, validates, and practically evaluates a framework for measuring portability.
Interface theories allow systems designers to reason about the composability and compatibility of concurrent system components. Such theories often extend both de Alfaro and Henzinger’s Interface Automata and Larsen’s Modal Transition Systems, which leads, however, to several issues that are undesirable in practice: an unintuitive treatment of specified unwanted behaviour, a binary compatibility concept that does not scale to multi-component assemblies, and compatibility guarantees that are insufficient for software product lines.
In this paper we show that communication mismatches are central to all these problems and, thus, the ability to represent such errors semantically is an important feature of an interface theory. Accordingly, we present the error-aware interface theory EMIA, where the above shortcomings are remedied by introducing explicit fatal error states. In addition, we prove via a Galois insertion that EMIA is a conservative generalisation of the established MIA (Modal Interface Automata) theory.
In 2007, OASIS finalized their Business Process Execution Language 2.0 (BPEL) specification which defines an XML-based language for orchestrations of Web Services. As the validation of BPEL processes against the official BPEL XML schema leaves room for a plethora of static errors, the specification contains 94 static analysis rules to cover all static errors. According to the specification, any violations of these rules are to be checked by a standard conformant engine at deployment time. When a violation is not detected in BPEL processes during deployment, such errors are only detectable at runtime, making them expensive to find and fix.
Due to the large amount of rules, we have created a tag system to categorize them, allowing easier reasoning about these rules.
Next, we formalized the static rules and derived test cases based on these formalizations with the aim to evaluate the degree of support for static analysis of BPEL engines.
Hence, this work is the foundation of the static analysis capabilities of BPEL engines.
Over the last decades, large-scale assessments focusing on skills and knowledge of individuals have expanded significantly in order to obtain information about conditions for and consequences of competence acquisition. To provide valid and accurate scores of the subjects under investigation, it is necessary to thoroughly check the psychometric properties of the competence instruments that are administered and to choose appropriate scaling models for the competence data. In this thesis, various challenges in modeling competence data were addressed that arose from different recently developed competence tests in large-scale assessments. The different tests posed specific demands on the scaling of the data such as dealing with multidimensionality, incorporating different response formats, or linking competence scores. By investigating these challenges associated with each of the competence tests, the aim of the thesis was to draw implications for the specification of the scaling models for the competence data.
First, a new metacognitive knowledge test for early elementary school children was investigated. As earlier findings on metacognitive knowledge in secondary school pointed to empirically distinguishable components of metacognitive knowledge, especially the dimensionality of the newly developed test was studied. Therefore, uni- and multidimensional models were applied to the competence data and their model fit was compared. By applying multidimensional latent-change models, the homogeneity of change was observed as further indicator for dimensionality. Overall, the new test instrument exhibited good psychometric properties including fairness of the items for various subgroups. In accordance with previous studies in other age groups the results indicated a multidimensional structure of the newly developed test instrument. In the discussion, theoretical as well as empirical arguments were compiled that should be considered for the choice of a uni- or a multidimensional model for the metacognitive knowledge data.
The next objective in the thesis was to study a series of reading competence tests intended to measure the same latent trait across a large age span. The different reading competence tests, developed in a longitudinal large-scale study, were based on the same conceptual framework and were administered from fifth grade to adulthood. We specifically investigated whether the test scores were comparable across such a large age span enabling to interpret change across time. The analyses on the reading competence tests showed that the coherence of measurement could not fully be assured across the wide age range. The application of strict linking models allowing for the interpretation of developmental progress seemed to be justified within secondary school, but not between secondary school and adulthood.
The last purpose in the thesis was to find out how to adequately incorporate different response formats in a scaling model. Therefore, multiple choice (MC) and complex multiple choice (CMC) items were regarded as they are most frequently used in large-scale assessments. Specifically, we explored whether the two response formats form distinct empirical dimensions and which a priori scoring schemes for the two response formats appropriately model the competence data. The results demonstrated that the response formats built a unidimensional measure across domains, studies, and age cohorts justifying to use a unidimensional scale score. A differentiated scoring of the CMC items yielded a better discrimination between persons and was, thus, preferred. The a priori weighting scheme of giving each subtask of a CMC item half the weight of a MC item described the empirical competence data well.
The objective of the contributions presented in this volume is the investigation of authorship in pre-modern Arabic texts. From several angles and different perspectives it has been asked how the author in his various facets and aspects, and as a principle of organization and guidance, can be traced and understood. The author can be perceived as a historical individual, a singular genius, or a gifted anthologist; he can claim authority or pass it on to others. The author can be invisible, applying textual strategies for steering the reader’s perception and interpretation, trying to leave the reader oblivious to his authorial interference. Although authors can be proud to present their knowledge and their opinions, they can also be reluctant to show themselves and can even disclaim their responsibility, depending on the issue at hand. The contributions gathered in this volume provide a fresh view on the multilayered nature of authorial functions and open up new perspectives on our understanding of the rich and diverse pre-modern Arabic culture and literature.
Domesticated animals need to
be treated as fellow citizens: Only if we conceive of domesticated animals as
full members of our political communities can we do justice to their moral
standing – or so Sue Donaldson and Will Kymlicka argue in their widely discussed
book Zoopolis. In this contribution, we pursue two objectives. Firstly, we
will reject Donaldson and Kymlicka’s appeal for animal citizenship. We will do
so by submitting that far from paying due heed to their moral status, regarding
animals as citizens misinterprets their moral qualities and thus risks
treating them unjustly. Secondly, we will suggest that Donaldson and
Kymlicka’s reinforced focus on membership should draw our attention to the
moral standing of a further ‘species’ living in our midst, namely robots. Developments
within artificial intelligence have advanced rapidly in recent
years. With robots gaining ever greater capacities and abilities, we need to ask
urgent questions about the moral ramifications of these technical advances.
This dissertation derives new ways and methods on how to integrate and bind developers in Free Libre Open Source Software (FLOSS) projects. It examines how sustainable commitment of new contributors can be identified at an early stage, how developers’ geographic dispersion affects their collaboration productivity, if the presence of reputable developers increases teamwork productivity and if mentoring is an appropriate means to bind developers in FLOSS projects. To address these research questions, the thesis builds on established theories and concepts from organizational and social science such as Person-Job (P-J) and Person-Team (P-T) fit, the social practice view and self-determination theory. The results of the performed empirical evaluations suggest that: (i) the derived criteria for P-J and P-T fit are suitable to identify sustained commitment early on, (ii) developers’ offline relationships determine if their spatial and cultural distance becomes a gain or a burden for their collaboration, (iii) the presence of reputable developers increases productivity in FLOSS projects only marginally, (iv) mentoring is an appropriate means to bind developers in FLOSS projects
Introduction: The knowledge about household properties (such as number of inhabitants, living area, heating type, etc.) is highly desirable for utility companies to pave the way to targeted energy efficiency programs, products and services. Raising individual household data via surveys or purchasing it is expensive and time consuming, and often only a small fraction of customers participate.
Recently, data mining methods have been developed to automatically infer house-hold characteristics from smart meter consumption data. However, the slow smart metering rollout hampers practical implementation of these methods in many countries. In this work, we present a machine learning approach that reveals household properties from conventional annual electricity consumption data currently available at a large scale.
Introduction: Recent meta-analysis showed that diabetes seems to be a
risk factor for incident depression. This prospective study examines the role
of elevated diabetes distress on the persistence or the recovery from elevated
depressive symptoms at a 6-month follow-up.Methods: Participants
completed the CES-D. A score of >=16 indicate elevated depressive symptoms.
The Problem Areas in Diabetes Scale (PAID) assessed diabetes related
distress; a PAID score of >=30 indicate moderate diabetes related distress.
Logistic regression models were performed. Persistence and recovery from
elevated depressive symptoms were the dependent variables. The independent
variable was diabetes related distress. The models were adjusted for
potential demographic (age, gender) or medial confounders (BMI, diabetes
duration, A1C, diabetes type and late complications).Results: 351 diabetic
patients were included (age 50,8 ±11.4 yrs, 52% female, 58% type 2 diabetic
patients, diabetes duration 12.9 ±11.1 yrs, BMI 29,9 ±6,9 kg/m², A1c
7.9 ±1.5%). At baseline 125 patients (35.6%) reported elevated depressive
symptoms. At follow up 96 patients (27.3%) still had an elevated depression
score. If diabetes related distress was present at baseline the hazard ratio
of having persistent elevated depressive symptoms at follow up was 6.67
(95% CI 3.79 - 11.72). Adjusting for confounding variables did not change
the hazard ratio substantially (HR 6.02 95% CI 3.32 - 10.89). In addition the
chance for recovery from elevated depressive symptoms was signifi cantly
reduced if diabetes related distress was present (Odds ratio 0.37 95% CI
0.17 - 0.77). Controlling for possible confounders did not change the odds
ratio (0.36 95% CI 0.16 - 0.82).Conclusion: Diabetes related distress seems
to play a decisive role for an unfavorable course of depressive symptoms.
Diabetes related distress may be a mediating factor between diabetes and
depression. Addressing diabetes related distress may be able to ameliorate
depression in people with diabetes.