Anja Strunk

Does Live Migration of Virtual Machines Cost Energy

Live migration, the process of moving a virtual machine (VM) interruption-free between physical hosts is a core concept in modern data centers. Power management strategies use live migration to consolidate services in a cluster environment and to switch off underutilized machines to save power. However, most migration models do not consider the energy cost of migration. This paper experimentally investigates the factors that affect the power consumption and the duration of virtual machine migration. We use the KVM platform for our experiment and show that a live migration entails an energy overhead and the size of this overhead varies with the size of the virtual machine and the available network bandwidth.

Energy-aware service execution

The energy consumption of ICT infrastructures has increased considerably in the recent years. This has resulted in extensive research on dynamic power management strategies as well as data centre design and placement. The main problem with most of the proposed or existing approaches is that they do not fully take the distributed nature of and strong logical dependencies between executed services into account. However, without a comprehensive knowledge of the wider relationships between services, local power management strategies may be ineffectual or can even result in high aggregate energy cost. Understanding this relationship is useful for fine-grained energy-aware computing. For example, services that run on underutilised servers can be stopped or seamlessly migrated to other servers, so that the underutilised servers can be turned off. Alternatively, a re-binding process can be used if the cost of service migration is high. Such advantages can be fully exploited if the dependency between services is properly understood and meaningfully modelled. This paper introduces a conceptual architecture for an energy-aware service execution platform and compares three optimisation mechanisms to support dynamic service migration and rebinding.

Investigation into the energy cost of live migration of virtual machines

One of the mechanisms to achieve energy efficiency in virtualized environments is to consolidate the workload (virtual machines) of underutilized servers and to switch-off these servers all together. Similarly, the workloads of overloaded servers can be distributed onto other servers for a load balancing reason. Central to this approach is the migration of virtual machines at runtime, which may introduce its own overhead in terms of energy consumption and service execution latency. This paper experimentally investigates the magnitude of this overhead. We use the Kernel-based Virtual Machine (KVM) hypervisor and a custom-made benchmark for our experiments. We will demonstrate that the workload of a virtual machine does not have any bearing on the power consumption of the destination server during migration but it has on the source server. Moreover, the available network bandwidth and the size of the virtual machine do indeed. introduce a non-negligible energy overhead and migration latency on both the source and the destination server.

Integrated Service Engineering workbench: service engineering for digital ecosystems

The evolution of service–oriented architectures towards digital ecosystems comprehends a number of challenges. One challenge is to develop services in a dynamic environment with high uncertainties and in collaboration with other companies. Another challenge lies in how to describe services sufficiently for trading them in digital ecosystems. This paper explores requirements of service engineering and description, and presents the ISE Framework and Workbench with its architecture and its functionality. Furthermore, this paper introduces a novel language for describing business services along with SLA management. This work concludes with a discussion about lessons learned during the development of the ISE Workbench.

Building a Flexible Service Architecture for User Controlled Hybrid Clouds

Virtualization and broadband Internet connections enabled existing technologies to form up under the nebulous term cloud. Cloud computing promises near infinite scalability and cost reduction by pay per use agreements. However for data outsourced to existing cloud solutions - which can be considered synonymous with unknown locations and potentially hostile environments - the security protection objectives can not be guaranteed. We present an approach that enables users to benefit from cloud computing and retain data sovereignty.

Zusicherung nichtfunktionaler Eigenschaften und Dienstgüte im Future Internet of Services

ZUSAMMENFASSUNG Zur Verwirklichung der Vision des Future Internet of Services werden Infrastrukturen benötigt, die eine flexible, dynamische und vertraglich garantierte Vermittlung zwischen Dienstanbietern und Dienstnutzern erlauben. Mit bisherigen Web-Service-Technologien können nichtfunktionale Eigenschaften und Dienstgüte nur für einzelne Dienste beschrieben und bewertet werden. Diese Informationen dienen als Entscheidungsgrundlage für eine dynamische Auswahl von Diensten zur Laufzeit. Sollen nichtfunktionale Eigenschaften und Dienstgüte für komplexe Geschäftsprozesse beschrieben werden, stößt man an die Grenzen gängiger Prozess- und Dienstbeschreibungssprachen. Darüber hinaus gibt es bisher keine Ansätze zur dynamischen Aushandlung dieser Dienstgüteverträge zwischen Anbieter und Nutzer, als auch zwischen Diensten, die gemeinsam in einen Geschäftsprozess integriert werden. In diesem Artikel wird vorgestellt, wie nichtfunktionale Eigenschaften im gesamten Lebenszyklus der Dienstnuzung verwendet werden können und welche Lösungen hierfür zum Einsatz kommen. Wir geben einen generellen Überblick und konzentrieren uns auf den Abschluss und die Einhaltung von Dienstgütevereinbarungen, sowie deren Überwachung und die abschließende Bewertung der Dienstqualität durch den Dienstnutzer. Die Nutzung unserer Ergebnisse erfolgt im Rahmen des Forschungsprojektes THESEUS TEXO, in dem eine Service-Plattform zur Bereitstellung und Nutzung adaptiver Dienste mit umfassender Unterstützung nichtfunktionaler Eigenschaften über den gesamten Lebenszyklus der Services entwickelt wird.

MDA applied: a task-model driven tool chain for multimodal applications

Recently, industry has adopted multimodal, context-aware applications. However, addressing various modalities on heterogeneous platforms implies a demanding development effort. Therefore, we present a task-centric methodology and a tool chain leveraging the development of adaptive multimodal applications. In order to improve efficiency the tool chain is based on the Model Driven Architecture approach emphasizing two key principles: model-to-model transformations and tool integration.

Supporting Rebinding in BPEL

The idea of the future internet of services is to combine several services of numerous service providers to new value-added services or applications. To sell these services on so-called service marketplaces the providers have to ensure a high quality of service execution. But how could a provider of a composed service ensure the quality of the whole application, if single services of other providers fail or do not reach the required level of quality? This article describes an approach for modeling adaptation in web service compositions to ensure a guaranteed quality of service for the whole composite service. A special adaptation mechanism is the rebinding of single services while the process is executed if the services fail or could not reach the needed QoS level. We will present a solution for modeling these rebinding concepts in BPEL processes and the infrastructure to support this adaptation mechanism at run-time.

Integrated service engineering workbench: service engineering for digital ecosystems

The evolution of service-oriented architectures towards digital ecosystems comprehends a number of challenges. According to Papazoglou et al., one challenge is to develop services in a dynamic environment with high uncertainties, and in collaboration with other companies. The Integrated Service Engineering (ISE) Workbench is a step in this direction in that it supports a model-driven approach and different stakeholders. This paper briefly introduces the ISE Framework, presents the ISE Workbench and its functionality, and proposes a demonstration of a conducted case study in the IT outsourcing domain.

An infrastructure for supporting rebinding in BPEL processes

The idea of the future internet of services is to combine several services of numerous service providers in new value-added services or applications. To sell these services on the so-called service marketplaces, the providers have to ensure a high quality of service execution. But how could a provider of a composed service ensure the quality of the whole application, if certain services of other providers fail or do not reach the required level of quality? This article describes an approach for an infrastructure to ensure a guaranteed quality of service for BPEL processes using rebinding. Rebinding is a special adaptation mechanism, which replaces services that fail or could not reach the needed QoS level with alternative ones.