05 Fakultät Informatik, Elektrotechnik und Informationstechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/6
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Item Open Access REST Testbed(2013) Eisenbraun, NickWeb Services, die gemäß dem Architekturstil REST entworfen werden, zeichnen sich durch Eigenschaften wie Interoperabilität, lose Kopplung, Wiederverwendbarkeit, Leistung und Skalierbarkeit aus. In verteilten Systemen werden deswegen oft REST-basierteWeb Services eingesetzt. Verteilte Systeme haben höhere Fehleranfälligkeit als Standalone-Anwendungen und diese Erkenntnis sollte beim Entwicklungsprozess durch ausreichende Testszenarien berücksichtigt werden. Bei der Entwicklung von REST-basierten Client-Anwendungen wird ein REST-basierter Web Service benötigt, um die Funktionalitäten der Client-Anwendung zu testen. In dieser Diplomarbeit werden Anforderungen an ein Testbed zum Testen von REST-basierten Client-Anwendungen gestellt. Es wird eine Architektur zu diesem Testbed entworfen und anschließend ein Testbed prototypisch implementiert. Bei der Entwicklung des Testbeds werden die Eigenschaften wie Erweiterbarkeit und Konfigurierbarkeit der Funktionalitäten des REST-basiertenWeb Services sichergestellt. Durch die berücksichtigte Erweiterbarkeit kann das Testbed leicht um neue Funktionalitäten ergänzt werden. Die Konfigurierbarkeit erlaubt das Anpassen der funktionalen und nicht-funktionalen Eigenschaften des Testbeds, um die Erfüllbarkeit der an eine Client-Anwendung gestellten funktionalen und nicht-funktionalen Anforderungen zu überprüfen.Item Open Access Partnerübergreifende Geschäftsprozesse und ihre Realisierung in BPEL(2016) Kopp, Oliver; Leymann, Frank (Prof. Dr. Dr. h. c.)Diese Arbeit beschäftigt sich mit Geschäftsprozessen, die die Grenzen von Organisationen überspannen. Solche Geschäftsprozesse werden Choreographien genannt. In der Arbeit wird die CREAM-Methode vorgestellt, die zeigt, wie Choreographien modelliert werden können. Im Gegensatz zu Choreographien bezeichnen Orchestrierungen ausführbare Geschäftsprozesse einer einzelnen Organisation, die Dienste nutzen, um ein Geschäftsziel zu erreichen. Eine Variante der CREAM-Methode erlaubt, von einer Orchestrierung durch Aufteilung der Orchestrierung eine Choreographie zu erhalten. Um hierbei die impliziten orchestrierungsinternen Datenabhängigkeiten in Nachrichtenaustausche zu transformieren, wird der explizite Datenfluss der Orchestrierung benötigt. Die Web Services Business Process Execution Language (BPEL) ist eine verbreitete Sprache zur Modellierung von Geschäftsprozessen. In ihr wird der Datenfluss implizit modelliert und somit wird ein Verfahren benötigt, das den expliziten Datenfluss bestimmt. In dieser Arbeit wird ein solches Verfahren vorgestellt. Um eine Choreographie zu modellieren, wird eine Choreographiesprache benötigt. Zur Identifikation einer geeigneten Sprache werden in dieser Arbeit Kriterien zur Evaluation von Choreographiesprachen vorgestellt und damit Choreographiesprachen im Web-Service-Umfeld bewertet. Da keine der betrachteten Sprachen alle Kriterien erfüllt, wird die Sprache BPEL4Chor vorgestellt, die alle Kriterien erfüllt. Um die wohldefinierte Ausführungssemantik von BPEL wiederzuverwenden, verwendet BPEL4Chor die Sprache BPEL als Beschreibungssprache des Verhaltens jedes Teilnehmers in der Choreographie. BPEL4Chor verwendet analog zu BPEL XML als Serialisierungsformat und spezifiziert keine eigene graphische Repräsentation. Die Business Process Modeling Notation (BPMN) ist der de-facto Standard, um Geschäftsprozesse graphisch darzustellen. Deshalb wird in dieser Arbeit BPMN so erweitert, dass alle in BPEL4Chor verfügbaren Konstrukte mittels BPMN modelliert werden können.Item Open Access Integration of IoT devices via a blockchain-based decentralized application(2017) Ahmad, AfzaalBlockchains are shared, immutable ledgers for recording the history of transactions. They foster a new generation of transactional applications that establish trust, accountability, and transparency. It enables contract partners to secure a deal without involving a trusted third party. Initially, the focus was on financial industry for digital assets trading like Bitcoin, but with the emergence of Smart Contracts, blockchain becomes a complete programmable platform. Many research and commercial organization start diving into blockchain world, bringing new ideas of its application in different sectors like supply chain, Health, and autonomous shopping. This thesis presents an idea to integrate Internet of Things (IoT) devices via a blockchain based decentralize application based on Ethereum. The application consists of front-end application which can be deployed to any web server, and a smart contract which will be deployed on a private blockchain network comprises of Peer-to-Peer (P2P) connected IoT devices acting as full Ethereum node. The application emulates the digital transport ticketing system where the asset is a ticket which can be purchased and paid by the user using ether in their Ethereum account on the blockchain. Once the purchase transaction is mined, it is propagated to all the peers. Ticket can now be accessed locally without requesting any centralized system, which makes the system easily accessible and safe because of the security, data integrity and decentralization of the blockchain-based systems.Item Open Access Concept and implementation of a pluggable framework for storage, transformation, and analysis of large-scale enterprise topology graphs(2013) Todenhagen, HannesThe addition of on-demand cloud computing offerings increases the complexity of IT systems rapidly. Enterprise Topology Graphs depict all the components of enterprise IT and their relations, to regain insight into enterprise IT. The focus of this work is the research, design and implementation of a framework to store and manage these graphs in an efficient way. The difficulties are the enormous graph sizes and a lot of meta information, leading to a complex design to offer a good performing solution. The framework is based on a graph database to store the Enterprise Topology Graph efficiently and offers a pluggable architecture to be able to extend the functionality, e.g. with transformation operations the graphs. With the reference implementation of this framework, the complex structures of enterprise IT systems can be stored, managed and easily manipulated to gain a more detailed view on the IT components and their dependencies.Item Open Access Web-based application integration: advanced business process monitoring in WSO2 carbon(2011) Krein, JakobToday’s business processes tend to get more and more complex and can sometimes have hundreds of activities. Maintaining and monitoring these business processes can get hard for companies’ IT experts. Process views support those experts by providing user-defined views of a process. Complexity can be reduced by aggregating activities or leaving them out. It is also possible to highlight parts of a process that are more im-portant than others. Business Process Illustrator is an open-source, web-based business process monitoring tool, developed at the Institute of Architecture of Application Systems at the University of Stuttgart. This tool uses process views to simplify the monitoring of complex business processes. It has a built-in adapter for the Apache ODE process engine, but it can basically support any type of Workflow Management System. WSO2 Carbon is a modular open-source middleware platform which hosts a rich set of middleware components encompassing capabilities such as business process man-agement and business activity monitoring. It is extensible and allows the installation of custom components through a technology called OSGi. WSO2 Business Process Server is a WSO2 Carbon-based product that executes business processes defined using the WS-BPEL standard. The WSO2 Process Server is powered by Apache ODE and therefore predestinated for the Business Process Illustrator to be integrated with WSO2 Carbon. The goal of this student thesis is to provide an open-source integration of the Business Process Illustrator with the WSO2 Carbon platform as an OSGi bundle and to establish a connection to the Business Process Server component.Item Open Access REST compliant clients for REST APIs(2014) Jaber, MustafaIn today's distributed systems, REST services play a centric role in defining applications' architecture. Current technologies and literature focus on building server-side REST applications. But they fail to build generic and REST compliant client solutions. Therefore, most offered services and especially client applications rarely comply to the constraints that constitute the REST architecture. In this thesis, the architecture of a new generic framework for building REST compliant client applications is introduced. In addition, a new description language that conforms to REST's constraints and helps reduce development time is presented. We describe in this work the building-blocks of the proposed solutions and show a software implementation of a library that leverages the solutions' architectures. Using the proposed framework and description language, client applications that conform to the full set of REST's constraints can be built in an easy and optimized way. In addition, REST service providers can rely on the proposed description language to eliminate the complexity of repetitively building customized solutions for different technologies or platforms.Item Open Access Approach and realization of a multi-tenant service composition engine(2013) Hahn, MichaelThe support of multi-tenancy is an essential requirement to leverage the full extent of Cloud computing. Multi-tenancy enables service providers to maximize the utilization of their infrastructure and to reduce the servicing costs per customer. With regard to the fact that nowadays new applications or services are often composed out of multiple existing services or applications, a middleware is required which enables these compositions. A Service Composition Engine (SCE) provides the required functionality to enable the definition and execution of service compositions. In this diploma thesis we investigate the requirements and define an abstract architecture for the realization of a multi-tenant SCE. This architecture is prototypically realized with an open-source SCE and integrated into an existing multi-tenant aware ESB. The resulting middleware provides configurability for service compositions, tenant-aware messaging and tenant-based administration and management of the SCE and the ESB.Item Open Access Modellierung und Ausführung einer gekoppelten Festkörpersimulation mit Workflow-Choreographien(2014) Hintermayer, KerstinIm wissenschaftlichen Umfeld wird vermehrt die Workflow-Technologie eingesetzt, um Simulationen oder Berechnungen computergesteuert auszuführen. Die vorliegende Arbeit beschäftigt sich mit der Modellierung einer gekoppelten Festkörpersimulation als Workflow-Choreographie nach dem Top-Down-Ansatz. Auftauchende Herausforderungen werden identifiziert und mögliche Lösungsansätze beschrieben. Aufbauend auf dem Modellierungsergebnis werden die für die Ausführung der gekoppelten Festkörpersimulation benötigten Prozesse implementiert und vorgestellt. Die fertige Modellierung wird im Vergleich mit den Anforderungen beurteilt. Die Modellierung kann als Basis für zukünftige Arbeiten dienen und bietet Ansätze für aufbauende Untersuchungen. Dadurch wird eine Verfeinerung für zukünftige Workflowmodellierungen auf Basis einer Choreographie ermöglicht.Item Open Access Crawling hardware for OpenTOSCA(2017) Choudhury, PushpamHeterogeneity is the essence of the IoT paradigm. There is heterogeneity in communication and transport protocols, in network infrastructure, and even among the interacting devices themselves. Managing discovery of the different devices in such a paradigm is an extremely complex task. The typical solutions include an abstraction layer, commonly known as the middleware layer, that handles this complexity for the devices, thereby, allowing them to interact with one another. One major limitation of the existing middleware solutions is in their ability to allow for an easily configurable approach required to handle the tremendous scale of heterogeneous components in the IoT. The objective of this thesis is to develop such a highly configurable discovery middleware approach. The proposed approach aims to discover a variety of heterogeneous devices and services depending on a multi-level plugin layer, consisting of independent plugins that interact with each other based on the pipes and filters architectural pattern. To allow for the dynamic configuration of the middleware, a discovery configuration is developed. The output from the middleware includes a list of devices and their capabilities and is accessible via a web interface which can interact with a range of different clients. The proposed approach is validated on a scenario in a real-life environment.Item Open Access API diversity for microservices in the domain of connected vehicles(2018) Gajek, FabianWeb services in the domain of connected vehicles are subject to various requirements including high availability and large workloads. Microservices are an architectural style which can fulfill those requirements by fostering the independence and decoupling of software components as reusable services. To achieve this independence, microservices have to implement all aspects of providing the services themselves, including different API technologies for heterogeneous consumers and supporting features like authentication. In this work, we examine the use of a service proxy that externalizes these concerns into a sidecar that provides multiple APIs and common service functionality in a platform-independent manner. We look at how different kinds of API styles and technologies solve selected classes of problems and how we can translate between API technologies. We design and implement a framework for building gateways that enables the creation and composition of reusable components, in the fashion of Lego bricks, to maximize flexibility, while reducing the effort for building gateway components. We design and implement selected components of common and reusable API functionality enabling us to build a reference setup with a service proxy as a sidecar using our framework. Finally, we evaluate the proposed solution to identify benefits and drawbacks of the approach of using our framework as a service proxy. We conclude that the examined approach provides benefits for the development of many polyglot microservices, but splitting one service into two components adds additional complexity that has to be managed.