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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
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Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 1 to 5 of 5 (0.015 seconds)| 1 |
Einfluss von Softwarearchitektur auf den Wert eines SoftwaresystemsSchön, Hendrik 09 January 2018 (has links) (PDF)
Softwaresysteme sind ein wichtiger Bestandteil in der heutigen digitalen Welt und müssen oft als fundamentales Investitionsgut von Unternehmen betrachtet werden. Deswegen benötigen solche Systeme eine betriebswirtschaftliche Sichtweise: der Wert als operatives System sowie als langfristige finanzielle Investition bezüglich zukünftiger Anforderungen. Die Grundlage jeden guten Softwaresystems liegt in dessen Architektur, dem Zusammenhang von allen Teilen und deren Beziehungen untereinander, dem inneren Aufbau und der Organisation der Teile. Der Zusammenhang zwischen guter Architektur und resultierender guter Evolutionsfähigkeit und Zukunftsfähigkeit eines Systems ist generell in den Meinungen vertreten. Jedoch liegen dazu nur wenige Literaturstellen vor, welche die Thematik tatsächlich mehr als nur empirisch aufzeigen. Diese Arbeit soll einen möglichen Weg aufzeigen, wie mithilfe eines modellbasierten Ansatzes ein kausaler und quantitiver Zusammenhang zwischen Architektur eines Softwaresystems und dem resultierenden betriebswirtschaftlichen Wert (im Sinne der Evolutionsfähigkeit) hergestellt werden kann.
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Design and Implementation of Role-based Architectural Event Modules / Entwurf und Implementierung von rollen-basierten architektonischen Event-ModulenRohde, Frank 21 September 2016 (has links) (PDF)
This diploma thesis attempts to improve the language-support for coping with the problem of negative emergence in dynamic Systems-of-Systems (SoS). Negative emergence is understood to be the emergence of unintended behaviour among constituent systems of a SoS in response to certain changes to the composition of constituent systems in the SoS. The architecture description language (ADL) "EventArch 2.0" approaches this problem by allowing the SoS-manager to define certain rules to manipulate the original behaviour of certain constituent systems at certain critical points of execution of the SoS to prevent unintended behaviour ("coordination rules").
This thesis approaches a solution to the following problem: to prevent the introduction of unintended behaviour through overly- or underly-restrictive coordination rules, more- or less-restrictive variants of a coordination rule would have to be applied to the SoS depending on the current composition of constituent systems in the SoS. This thesis has the goal to approach this problem by devising a mechanism to dynamically exchange a coordination rule depending on the current composition of constituent systems in the SoS. To achieve that goal, the ADL "EventArch 2.0" is extended to support the dynamic application of a coordination rule to a System-of-Systems. The dynamic application is achieved by connecting coordinators and constituent systems at runtime. As a special characteristic, each coordinator is dedicated to a specific constituent system and is responsible for achieving compliance of that system with respect to a specific coordination rule. It is shown that this architectural setup can be nicely modeled using concepts from the field of "role-based modeling". The solution does therefore employ concepts that are central to the "role-based modeling"-approach: "Role", "Base", and "Compartment". The applicability of the extended language to practical coordination-problems is shown by applying it to a constructed use case in the field of energy-efficient computing. / Die vorliegende Diplomarbeit ist mit der Verbesserung der Sprachunterstützung zur Vermeidung negativer Emergenz in dynamischen Systems-of-Systems (SoS) befasst. Negative Emergenz wird dabei als unerwünschtes Verhalten von an einem SoS beteiligten Systemen verstanden, welches auf Grund von Änderungen in der Zusammensetzung des SoS (d.h. auf Grund des Eintritts oder Austritts von konstituierenden Systemen) aufgetreten ist. Die Architekturbeschreibungssprache "EventArch 2.0" unterstützt den SoS-manager bei der Lösung dieses Problems durch die Möglichkeit das Verhalten der beteiligten Systeme in bestimmten Ausführungsmomenten durch die Definition von Koordinationsregeln zu manipulieren und auf diesem Wege das Auftreten negativer Emergenz zu vermeiden.
Die Diplomarbeit ist ein Beitrag zur Lösung des folgenden Problems: Um die Einführung von unerwünschtem Verhalten durch übermäßig- oder unzureichend restriktive Koordinationsregeln zu verhindern, müssten unterschiedliche Varianten einer Koordinationsregel, die sich im Grade ihrer Restriktivität unterscheiden, auf das SoS angewendet werden. Diese Anwendung müßte in Abhängigkeit der aktuellen Zusammensetzung des SoS aus konstituierenden Systemen erfolgen. In der vorliegenden Diplomarbeit wird eine Möglichkeit entwickelt um eine Koordinationsregel zur Laufzeit in Abhängigkeit der aktuellen Zusammensetzung des SoS aus konstituierenden Systemen auszutauschen. Sie leistet damit einen Beitrag zur Lösung des vorgenannten Problems. In der Arbeit wird die Architekturbeschreibungssprache "EventArch 2.0" um die Möglichkeit des dynamischen Austausches von Koordinationsregeln erweitert. Dabei werden Koordinationsregeln angewendet durch die gezielte Verbindung von Koordinatoren und konstituierenden Systemen. Die Besonderheit des Ansatzes besteht darin, dass jedem konstituierenden System ein persönlicher Koordinator zugeordnet wird, d.h. ein Koordinator der ausschließlich für die Anpassung des Verhaltens des jeweiligen Systems an eine bestimmte Koordinationsregel verantwortlich ist. In der Arbeit wird gezeigt, dass dieser architektonische Ansatz durch zentrale Konzepte des Modellierungsansatzes "rollenbasierte Modellierung" modelliert werden kann. In der entwickelten Spracherweiterung werden daher die Konzepte "Rolle", "Basis" und "Compartment" verwendet. Die Anwendbarkeit der erweiterten Sprache, wird durch deren Anwendung auf einen konstruierten Anwendungsfall aus dem Bereich der Energie-effizienten Berechnung gezeigt.
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Minimizing Overhead for Fault Tolerance in Event Stream Processing SystemsMartin, André 20 September 2016 (has links) (PDF)
Event Stream Processing (ESP) is a well-established approach for low-latency data processing enabling users to quickly react to relevant situations in soft real-time. In order to cope with the sheer amount of data being generated each day and to cope with fluctuating workloads originating from data sources such as Twitter and Facebook, such systems must be highly scalable and elastic. Hence, ESP systems are typically long running applications deployed on several hundreds of nodes in either dedicated data-centers or cloud environments such as Amazon EC2. In such environments, nodes are likely to fail due to software aging, process or hardware errors whereas the unbounded stream of data asks for continuous processing.
In order to cope with node failures, several fault tolerance approaches have been proposed in literature. Active replication and rollback recovery-based on checkpointing and in-memory logging (upstream backup) are two commonly used approaches in order to cope with such failures in the context of ESP systems. However, these approaches suffer either from a high resource footprint, low throughput or unresponsiveness due to long recovery times. Moreover, in order to recover applications in a precise manner using exactly once semantics, the use of deterministic execution is required which adds another layer of complexity and overhead.
The goal of this thesis is to lower the overhead for fault tolerance in ESP systems. We first present StreamMine3G, our ESP system we built entirely from scratch in order to study and evaluate novel approaches for fault tolerance and elasticity. We then present an approach to reduce the overhead of deterministic execution by using a weak, epoch-based rather than strict ordering scheme for commutative and tumbling windowed operators that allows applications to recover precisely using active or passive replication. Since most applications are running in cloud environments nowadays, we furthermore propose an approach to increase the system availability by efficiently utilizing spare but paid resources for fault tolerance. Finally, in order to free users from the burden of choosing the correct fault tolerance scheme for their applications that guarantees the desired recovery time while still saving resources, we present a controller-based approach that adapts fault tolerance at runtime. We furthermore showcase the applicability of our StreamMine3G approach using real world applications and examples.
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Extending the Functionality of Score-P through Plugins: Interfaces and Use CasesSchöne, Robert, Tschüter, Ronny, Ilsche, Thomas, Schuchart, Joseph, Hackenberg, Daniel, Nagel, Wolfgang E. 18 October 2017 (has links) (PDF)
Performance measurement and runtime tuning tools are both vital in the HPC software ecosystem and use similar techniques: the analyzed application is interrupted at specific events and information on the current system state is gathered to be either recorded or used for tuning. One of the established performance measurement tools is Score-P. It supports numerous HPC platforms and parallel programming paradigms. To extend Score-P with support for different back-ends, create a common framework for measurement and tuning of HPC applications, and to enable the re-use of common software components such as implemented instrumentation techniques, this paper makes the following contributions: (I) We describe the Score-P metric plugin interface, which enables programmers to augment the event stream with metric data from supplementary data sources that are otherwise not accessible for Score-P. (II) We introduce the flexible Score-P substrate plugin interface that can be used for custom processing of the event stream according to the specific requirements of either measurement, analysis, or runtime tuning tasks. (III) We provide examples for both interfaces that extend Score-P’s functionality for monitoring and tuning purposes.
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Well-Formed and Scalable Invasive Software Composition / Wohlgeformte und Skalierbare Invasive SoftwarekompositionKarol, Sven 26 June 2015 (has links) (PDF)
Software components provide essential means to structure and organize software effectively. However, frequently, required component abstractions are not available in a programming language or system, or are not adequately combinable with each other. Invasive software composition (ISC) is a general approach to software composition that unifies component-like abstractions such as templates, aspects and macros. ISC is based on fragment composition, and composes programs and other software artifacts at the level of syntax trees. Therefore, a unifying fragment component model is related to the context-free grammar of a language to identify extension and variation points in syntax trees as well as valid component types. By doing so, fragment components can be composed by transformations at respective extension and variation points so that always valid composition results regarding the underlying context-free grammar are yielded. However, given a language’s context-free grammar, the composition result may still be incorrect.
Context-sensitive constraints such as type constraints may be violated so that the program cannot be compiled and/or interpreted correctly. While a compiler can detect such errors after composition, it is difficult to relate them back to the original transformation step in the composition system, especially in the case of complex compositions with several hundreds of such steps. To tackle this problem, this thesis proposes well-formed ISC—an extension to ISC that uses reference attribute grammars (RAGs) to specify fragment component models and fragment contracts to guard compositions with context-sensitive constraints. Additionally, well-formed ISC provides composition strategies as a means to configure composition algorithms and handle interferences between composition steps.
Developing ISC systems for complex languages such as programming languages is a complex undertaking. Composition-system developers need to supply or develop adequate language and parser specifications that can be processed by an ISC composition engine. Moreover, the specifications may need to be extended with rules for the intended composition abstractions.
Current approaches to ISC require complete grammars to be able to compose fragments in the respective languages. Hence, the specifications need to be developed exhaustively before any component model can be supplied. To tackle this problem, this thesis introduces scalable ISC—a variant of ISC that uses island component models as a means to define component models for partially specified languages while still the whole language is supported. Additionally, a scalable workflow for agile composition-system development is proposed which supports a development of ISC systems in small increments using modular extensions.
All theoretical concepts introduced in this thesis are implemented in the Skeletons and Application Templates framework SkAT. It supports “classic”, well-formed and scalable ISC by leveraging RAGs as its main specification and implementation language. Moreover, several composition systems based on SkAT are discussed, e.g., a well-formed composition system for Java and a C preprocessor-like macro language. In turn, those composition systems are used as composers in several example applications such as a library of parallel algorithmic skeletons.
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