With the introduction of services, systems become more flexible as new services can easily be composed out of existing services. Services are increasingly used in mission-critical systems and applications and therefore considering Quality of Service (QoS) properties is an essential part of the service selection. Quality prediction techniques support the service provider in determining possible QoS levels that can be guaranteed to a customer or in deriving the operation costs induced by a certain QoS level. In this chapter, we present an overview on our work on modeling service-oriented systems for performance prediction using the Palladio Component Model. The prediction builds upon a model of a service-based system, and evaluates this model in order to determine the expected service quality. The presented techniques allow for early quality prediction, without the need for the system being already deployed and operating. We present the integration of our prediction approach into an SLA management framework. The emerging trend to combine event-based communication and Service-Oriented Architecture (SOA) into Event-based SOA (ESOA) induces new challenges to our approach, which are topic of a special subsection.

Event-based communication is used in different domains including telecommunications, transportation, and business information systems to build scalable distributed systems. Such systems typically have stringent requirements for performance and scalability as they provide business and mission critical services. While the use of event-based communication enables loosely-coupled interactions between components and leads to improved system scalability, it makes it much harder for developers to estimate the system's behavior and performance under load due to the decoupling of components and control flow. We present an overview on our approach enabling the modeling and performance prediction of event-based system at the architecture level. Applying a model-to-model transformation, our approach integrates platform-specific performance influences of the underlying middleware while enabling the use of different existing analytical and simulation-based prediction techniques. The results of two real world case studies demonstrate the effectiveness, practicability and accuracy of the proposed modeling and prediction approach.

Event-based communication is used in different domains including telecommunications, transportation, and business information systems to build scalable distributed systems. Such systems typically have stringent requirements for performance and scalability as they provide business and mission critical services. While the use of event-based communication enables loosely-coupled interactions between components and leads to improved system scalability, it makes it much harder for developers to estimate the system's behavior and performance under load due to the decoupling of components and control flow. In this paper, we present our approach enabling the modeling and performance prediction of event-based systems at the architecture level. Applying a model-to-model transformation, our approach integrates platform-specific performance influences of the underlying middleware while enabling the use of different existing analytical and simulation-based prediction techniques. In summary, the contributions of this paper are: (1) the development of a meta-model for event-based communication at the architecture level, (2) a platform aware model-to-model transformation, and (3) a detailed evaluation of the applicability of our approach based on two representative real-world case studies. The results demonstrate the effectiveness, practicability and accuracy of the proposed modeling and prediction approach.

Performance prediction methods can help software architects to identify potential performance problems, such as bottlenecks, in their software systems during the design phase. In such early stages of the software life-cycle, only a little information is available about the system�s implementation and execution environment. However, these details are crucial for accurate performance predictions. Performance completions close the gap between available high-level models and required low-level details. Using model-driven technologies, transformations can include details of the implementation and execution environment into abstract performance models. However, existing approaches do not consider the relation of actual implementations and performance models used for prediction. Furthermore, they neglect the broad variety of possible implementations and middleware platforms, possible configurations, and possible usage scenarios. In this paper, we (i) establish a formal relation between generated performance models and generated code, (ii) introduce a design and application process for parametric performance completions, and (iii) develop a parametric performance completion for Message-oriented Middleware according to our method. Parametric performance completions are independent of a specific platform, reflect performance-relevant software configurations, and capture the influence of different usage scenarios. To evaluate the prediction accuracy of the completion for Message-oriented Middleware, we conducted a real-world case study with the SPECjms2007 Benchmark [http://www.spec.org/jms2007/]. The observed deviation of measurements and predictions was below 10% to 15%

Die allgegenwärtige mobile Nutzung des Internets sowie die zunehmende Integration von Kommunikationsfähigkeiten in Alltagsgegenstände sowohl im Heimbereich als auch im industriellen Umfeld, besser bekannt als das Internet der Dinge, führen zu einer zunehmenden Vernetzung verschiedenster Systeme. Im Heimbereich werden Fernseher, Smartphones, aber auch Licht-, Fenster- und Heizungssteuerungen, Kühlschränke und ganze Hausautomatisierungssysteme vernetzt. Im Industrieumfeld wird die Vernetzung als Teil der vierten industriellen Revolution stark intensiviert. Die Bandbreite der eingesetzten Systeme reicht von hochleistungsfähigen Server- und PC-Systemen über Cloud-Dienste und mobile Endgeräte, wie Smartphones und Tablets, bis zu intelligenten eingebetteten mobilen oder stationären heterogenen Sensorsystemen mit eingeschränkter Energieversorgung und begrenzten Rechenkapazitäten.

With the introduction of services, software systems have become more flexible as new services can easily be composed from existing ones. Service composition frameworks offer corresponding functionality and hide the complexity of the underlying technologies from their users. However, possibilities for anticipating quality properties of com- posed services before their actual operation are limited so far. While existing approaches for model-based software quality prediction can be used by service composers for determining realizable Quality of Service (QoS) levels, integration of such techniques into composition frameworks is still missing. As a result, high effort and expert knowledge is required to build the system models required for prediction. In this paper, we present a novel service composition process that includes QoS prediction for composed services as an integral part. Furthermore, we describe how composition frameworks can be extended to support this process. With our approach, systematic consideration of service quality during the composition process is naturally achieved, without the need for de- tailed knowledge about the underlying prediction models. To evaluate our work and validate its applicability in different domains, we have integrated QoS prediction support according to our process in two com- position frameworks - a large-scale SLA management framework and a service mashup platform.

Event-based communication is used in different domains including telecommunications, transportation, and business information systems to build scalable distributed systems. The loose coupling of components in such systems makes it easy to vary the deployment. At the same time, the complexity to estimate the behavior and performance of the whole system is increased, which complicates capacity planning. In this paper, we present an automated performance prediction method supporting capacity planning for event-based systems. The performance prediction is based on an extended version of the Palladio Component Model - a performance meta-model for component-based systems. We apply this method on a real-world case study of a traffic monitoring system. In addition to the application of our performance prediction techniques for capacity planning, we evaluate the prediction results against measurements in the context of the case study. The results demonstrate the practicality and effectiveness of the proposed approach.

Today, software engineering is challenged to handle more and more large-scale distributed systems with guaranteed quality-of-service. Component-based architectures have been established to build such systems in a more structured and manageable way. Modern architectures often utilize event-based communication which enables loosely-coupled interactions between components and leads to improved system scalability. However, the loose coupling of components makes it challenging to model such architectures in order to predict their quality properties, e.g., performance and reliability, at system design time. In this paper, we present an extension of the Palladio Component Model (PCM) and the Palladio software quality prediction framework, enabling the modeling of event-based communication in component-based architectures. The contributions include: i) a meta-model extension supporting events as first class entities, ii) a model-to-model transformation from the extended to the original PCM, iii) an integration of the transformation into the Palladio tool chain allowing to use existing model solution techniques, and iv) a detailed evaluation of the reduction of the modeling effort enabled by the transformation in the context of a real-world case study.

Today, software engineering is challenged to handle more and more large-scale distributed systems with a guaranteed level of service quality. Component-based architectures have been established to build more structured and manageable software systems. However, due to time and cost constraints, it is not feasible to use a trial and error approach to ensure that an architecture meets the quality of service (QoS) requirements. In this tool demo, we present the Palladio Workbench that permits the modeling of component-based software architectures and the prediction of its quality characteristics (e.g., response time and utilization). Additional to a general tool overview, we will give some insights about a new feature to analyze the impact of event-driven communication that was added in the latest release of the Palladio Component Model (PCM)

Service-Oriented Architectures (SOA) represent an architectural shift for building business applications based on loosely-coupled services. In a multi-layered SOA environment the exact conditions under which services are to be delivered can be formally specified by Service Level Agreements (SLAs). However, typical SLAs are just specified at the customer-level and do not allow service providers to manage their IT stack accordingly as they have no insight on how customer-level SLAs translate to metrics or parameters at the various layers of the IT stack. In this paper we present a technical architecture for a multi-level SLA management framework. We discuss the fundamental components and in- terfaces in this architecture and explain the developed integrated framework. Furthermore, we show results from a qualitative evaluation of the framework in the context of an open reference case.

The event-driven communication paradigm is used increasingly often to build loosely-coupled distributed systems in many industry domains including telecommunications, transportation, and supply chain management. However, the loose coupling of components in such systems makes it hard for developers to estimate their behaviour and performance under load. Most general purpose performance meta-models for component-based systems provide limited support for modelling event-driven communication. In this paper, we present a case study of a real-life road traffic monitoring system that shows how event-driven communication can be modelled for performance prediction and capacity planning. Our approach is based on the Palladio Component Model (PCM) which we have extended to support event-driven communication. We evaluate the accuracy of our modelling approach in a number of different workload and configuration scenarios. The results demonstrate the practicality and effectiveness of the proposed approach.

The event-based communication paradigm is becoming increasingly ubiquitous as an enabling technology for building loosely-coupled distributed systems. However, the loose coupling of components in such systems makes it hard for developers to predict their performance under load. Most general purpose performance meta-models for component-based systems provide limited support for modelling event-based communication and neglect middleware-specific influence factors. In this poster, we present an extension of our approach to modelling event-based communication in the context of the Palladio Component Model (PCM), allowing to take into account middleware-specific influence factors. The latter are captured in a separate model automatically woven into the PCM instance by means of a model-to-model transformation. As a second contribution, we present a short case study of a real-life road traffic monitoring system showing how event-based communication can be modelled for performance prediction and capacity planning.

In software engineering, performance and the integration of performance analysis methodologies gain increasing importance, especially for complex systems. Well-developed methods and tools can predict non-functional performance properties like response time or resource utilization in early design stages, thus promising time and cost savings. However, as performance modeling and performance prediction is still a young research area, the methods are not yet well-established and in wide-spread industrial use. This work is a case study of the applicability of the Palladio Component Model as a performance prediction method in an industrial environment. We model and analyze different design alternatives for storage virtualization on an IBM (Trademark of IBM in USA and/or other countries) system. The model calibration, validation and evaluation is based on data measured on a System z9 (Trademark of IBM in USA and/or other countries) as a proof of concept. The results show that performance predictions can identify performance bottlenecks and evaluate design alternatives in early stages of system development. The experiences gained were that performance modeling helps to understand and analyze a system. Hence, this case study substantiates that performance modeling is applicable in industry and a valuable method for evaluating design decisions.

In recent years continuously changing market situations required IT systems that are flexible and highly responsive to changes of the underlying business processes. The transformation to service-oriented architecture (SOA) concepts, mainly services and loose coupling, promises to meet these demands. However, elevated complexity in management and evolution processes is required for the migration of existing systems towards SOA. Studies in this area of research have revealed a gap between in continuous and actual tool support of development teams throughout the process phases of evolution processes. Thus, in this article we introduce a method that fosters evolution by an iterative approach and illustrate how each phase of this method can be tool-supported.

Today, the architectures of software systems are not stable for their whole lifetime but often adapted driven by business needs. Preserving their quality characteristics beyond each of these changes requires deep knowledge of the requirements and the systems themselves. Proper documentation reduces the risk that knowledge is lost and hence is a base for the system's maintenance in the long-run. However, the influence of architectural documentation on the maintainability of software systems is neglected in current quality assessment methods. They are limited to documentation for anticipated change scenarios and do not provide a general assessment approach. In this paper, we propose a maturity model for architecture documentation. It is shaped relative to growing quality preservation maturity and independent of specific technologies or products. It supports the weighting of necessary effort against reducing long-term risks in the maintenance phase. This allows to take product maintainability requirements into account for selecting an appropriate documentation maturity level.

The use of event-based communication within a Service-Oriented Architecture promises several benefits including more loosely-coupled services and better scalability. However, the loose coupling of services makes it difficult for system developers to estimate the behavior and performance of systems composed of multiple services. Most existing performance prediction techniques for systems using event-based communication require specialized knowledge to build the necessary prediction models. Furthermore, general purpose design-oriented performance models for component-based systems provide limited support for modeling event-based communication. In this paper, we propose an extension of the Palladio Component Model (PCM) that provides natural support for modeling event-based communication. We show how this extension can be exploited to model event-driven service-oriented systems with the aim to evaluate their performance and scalability.

The event-driven communication paradigm provides a number of advantages for building loosely coupled distributed systems. However, the loose coupling of components in such systems makes it hard for developers to estimate their behavior and performance under load. Most existing performance prediction techniques for systems using event-driven communication require specialized knowledge to build the necessary prediction models. In this paper, we propose an extension of the Palladio Component Model (PCM) that provides natural support for modeling event-based communication and supports different performance prediction techniques.

Web service compositions (WSC), as part of a service-oriented architecture (SOA), have to be managed to ensure compliance with guaranteed service levels. In this context, a high degree of automation is desired, which can be achieved by applying autonomic computing concepts. This paper particularly focuses the autonomic management of semi-dynamic compositions. Here, for each included service several variants are available that differ with regard to the service level they offer. Given this scenario, we first show how to instrument WSC in order to allow a controlling of the service level through switching the employed service variant. Second, we show how the desired self-manageability can be designed and implemented by means of a WSC manageability infrastructure. The presented approach is based on widely accepted methodologies and standards from the area of application and web service management, in particular the WBEM standards.

The implementation of an enterprise-wide Service Oriented Architecture (SOA) is a complex task. In most cases, evolutional approaches are used to handle this complexity. Maturity models are a possibility to plan and control such an evolution as they allow evaluating the current maturity and identifying current shortcomings. In order to support an SOA implementation, maturity models should also support in the selection of the most adequate maturity level and the deduction of a roadmap to this level. Existing SOA maturity models provide only weak assistance with the selection of an adequate maturity level. Most of them are developed by vendors of SOA products and often used to promote their products. In this paper, we introduce our independent SOA Maturity Model (iSOAMM), which is independent of the used technologies and products. In addition to the impacts on IT systems, it reflects the implications on organizational structures and governance. Furthermore, the iSOAMM lists the challenges, benefits and risks associated with each maturity level. This enables enterprises to select the most adequate maturity level for them, which is not necessarily the highest one.

Web service compositions (WSC), as part of a service- oriented architecture (SOA), have to be managed to ensure compliance with guaranteed service levels. In this context, a high degree of automation is desired, which can be achieved by applying autonomic computing concepts. This paper particularly focuses the autonomic management of semi-dynamic compositions. Here, for each included service several variants are available that differ with regard to the service level they offer. Given this scenario, we first show how to instrument WSC in order to allow a controlling of the service level through switching the employed service variant. Second, we show how the desired self-manageability can be designed and implemented by means of a WSC manageability infrastructure. The presented approach is based on widely accepted methodologies and standards from the area of application and web service management, in particular the WBEM standards.

Service-Orientierte Architekturen (SOAs) versprechen eine bessere Unterstützung von Geschäftsprozessen. Es gibt jedoch unterschiedliche Interpretationen darüber, was eine Service-Orientierte Architektur (SOA) ist. Da die Verbesserung der Geschäftsprozessunterstützung eines der häufigsten Argumente für SOAs ist, bietet es sich an, die verschiedenen SOA-Varianten nach der damit ermöglichten Prozessunterstützung zu kategorisieren. Bisherige Ansätze zur Kategorisierung sind in vielen Fällen auf bestimmte Technologien oder Standards beschränkt und gehen nur am Rand auf die gegebene Prozessunterstützung ein. In diesem Artikel wird eine solche geschäftsprozessorientierte Kategorisierung von SOAs präsentiert.

The management of web service composition, where the employed atomic web services as well as the compositions themselves are offered on basis of Service Level Agreements (SLA), implies new requirements for the management infrastructure. In this paper we introduce the conceptual design and implementation for a standard-based and flexible manageability infrastructure offering comprehensive management information for an SLAdriven management of web service compositions. Our solution thereby is based on well-understood methodologies and standards from the area of application and web service management, in particular the WBEM standards.

Die Industrialisierung der Software-Entwicklung ist ein zurzeit sehr stark diskutiertes Thema. Es geht dabei vor allem um die Efizienzsteigerung durch die Steigerung des Standardisierungsgrades, des Automatisierungsgrades sowie eine Erhöhung der Arbeitsteilung. Dies wirkt sich einerseits auf die den Software- Systemen zu Grunde liegenden Architekturen aber auch auf die Entwicklungsprozesse aus. So sind service-orientierte Architekturen ein Beispiel für eine gesteigerte Standardisierung innerhalb von Software-Systemen. Es ist zu berücksichtigen, dass sich die Software-Branche von den klassischen produzierenden Industriezweigen dadurch unterscheidet, dass Software ein immaterielles Produkt ist und so ohne hohe Produktionskosten beliebig oft vervielfältigt werden kann. Trotzdem lassen sich viele Erkenntnisse aus den klassischen Industriezweigen auf die Software-Technik übertragen. Die Inhalte dieses Berichts stammen hauptsächlich aus dem Seminar "Software- Industrialisierung welches sich mit der Professionalisierung der Software- Entwicklung und des Software-Entwurfs beschäftigte. Während die klassische Software-Entwicklung wenig strukturiert ist und weder im Bezug auf Reproduzierbarkeit oder Qualitätssicherung erhöhten Anforderungen genügt, befindet sich die Software-Entwicklung im Rahmen der Industrialisierung in einem Wandel. Dazu zählen arbeitsteiliges Arbeiten, die Einführung von Entwicklungsprozessen mit vorhersagbaren Eigenschaften (Kosten, Zeitbedarf, ...) und in der Folge die Erstellung von Produkten mit garantierbaren Eigenschaften. Das Themenspektrum des Seminars umfasste dabei unter anderem: * Software-Architekturen * Komponentenbasierte Software-Entwicklung * Modellgetriebene Entwicklung * Berücksichtigung von Qualitätseigenschaften in Entwicklungsprozessen Das Seminar wurde wie eine wissenschaftliche Konferenz organisiert: Die Einreichungen wurden in einem zweistufigen Peer-Review-Verfahren begutachtet. In der ersten Stufe wurde eine Begutachtung der studentischen Arbeiten durch Kommilitonen durchgeführt, in der zweiten Stufe eine Begutachtung durch die Betreuer. In verschiedenen Sessions wurden die Artikel an zwei Konferenztagen präsentiert. Der beste Beitrag wurde durch einen Best Paper Award ausgezeichnet. Dieser ging an Benjamin Klatt für seine Arbeit Software Extension Mechanisms, dem hiermit noch einmal herzlich zu dieser herausragenden Leistung gratuliert wird. Ergänzend zu den Vorträgen der Seminarteilnehmer wurde ein eingeladener Vortrag gehalten. Herr Florian Kaltner und Herr Tobias Pohl vom IBM-Entwicklungslabor gaben dabei dankenswerterweise in ihrem Vortrag Einblicke in die Entwicklung von Plugins für Eclipse sowie in die Build-Umgebung der Firmware für die zSeries Mainframe-Server.

The management of process-oriented service composition within a dynamic environment, where the employed core services are offered on service marketplaces and dynamically included into the composition on basis of Service Level Agreements (SLA), demands for a service management application that takes into account the specifics of processoriented compositions and supports their automated provisioning. As a first step towards such an application, in this paper we introduce the conceptual design for an architecture and implementation of an interoperable and flexible manageability infrastructure offering comprehensive monitoring and control functionality for the management of service compositions. To achieve this, our approach is based on well-understood methodologies and standards from the area of application and web service management.