D5.1.1 Models of Real-time Applications on Service Oriented Infrastructures

The IRMOS project is developing tools and techniques for modelling, simulating, analysing, and planning real-time applications on service oriented infrastructures. These tools and techniques support the processes involved in designing, developing, deploying and executing applications where guaranteed QoS is needed. The report considers the value-chain for real-time applications hosted by third-party service providers. In the context of this value chain, we analyse who might benefit from the use of models, how and why these models might be used, and when during the application lifecycle modelling is most useful. Techniques are presented for building models of real-time applications including the use of stochastic process algebras, finite state automata, workflow models (e.g. BPEL, BPMN and YAWL) and specification languages (e.g. UML MARTE). The report discusses how these models need to be supported by estimation of application resource consumption, e.g. through benchmarking and fitting, and how mapping techniques allow models to be built for different actors in the value chain, e.g. for application providers and infrastructure providers. Tool support is also discussed e.g. PRISM for probabilistic model checking and Visual Service Composition Studio for service-oriented modelling. A detailed and specific real-time application scenario is included and modelled to allow the various techniques presented in this document to be demonstrated and quantitatively evaluated. The scenario also reveals the level of detail needed in order for meaningful modelling to be achieved in practice. The modelling scenario has been carefully engineered to be as representative as possible of the broad range of application characteristics encountered in the three reference IRMOS applications (film postproduction, eLearning, virtual and augmented reality). The modelling techniques discussed and then demonstrated in this report include identifying what resources are necessary to support an application, when those resources will be required during the application workflow, what performance is needed from them (i.e. QoS) and what will happen to the application if the required performance is not delivered. All of these are essential when developing and then agreeing service level agreements between the various entities in a service oriented infrastructure

Distributed Interactive Real-time Multimedia Applications: A Sampling and Analysis Framework

The advancements in distributed computing have driven the emergence of service-based infrastructures that allow for on-demand provision of IT assets. However, the complexity of characterizing an application’s behavior, and as a result the potential offered level of Quality of Service (QoS), introduces a number of challenges in the data collection and analysis process on the Service Providers’ side, especially for real time applications. The aforementioned complexity is increased due to additional factors that influence the application’s behavior, such as real time scheduling decisions, percentage of a node assigned to the application or application-generated workload. In this paper, we present a framework developed under the IRMOS EU-funded project that enables the sampling and gathering of the necessary dataset in order to analyze an application’s behavior. Processing of the resulting dataset is also conducted in order to extract useful conclusions regarding CPU allocation and scheduling decisions effect on the QoS. We demonstrate the operation of the proposed framework and evaluate its performance and effectiveness using an interactive real-time multimedia application, namely a webbased eLearning scenario

Virtualised e-Learning on the IRMOS real-time cloud

Providing proper timeliness guarantees to distributed soft real-time applications in a virtualised infrastructure involves the careful use of various techniques at different levels, ranging from real-time scheduling mechanisms at the virtual-machine hypervisor level and QoS-aware protocols at the network level, to proper design methodologies and tools for stochastic modelling and runtime provisioning of the applications. This paper describes the way these techniques were combined to provide strong quality of service guarantees to interactive soft real-time applications in the Cloud Computing infrastructure that has been developed in the context of the IRMOS European Project. The efficiency of the developed infrastructure is demonstrated by two real interactive e-Learning applications, an e-Learning mobile content delivery application and a virtual world e-Learning application, both of which have been integrated into the IRMOS platfor

Network virtualization: The missing piece

Abstract — current service platforms or frameworks, e.g., Cloud solutions, do not take the infrastructure, necessary for the execution of the service, sufficiently into consideration. They take resources like network connectivity for granted and do not provide an integrated networking approach considering Quality of Service (QoS) or other real-time aspects of the message exchange between possibly thousands of components. This paper presents the concept of a fully managed network virtualization framework to provide the required connectivity between components within a virtualized service platform respecting all service requirements, e.g. as expressed by interactive real-time services, on transport layer

Execution and Resource Management in QoS-Aware Virtualized Infrastructures

Both real-time systems and virtualization have been important research topics for quite some time now. Having competing goals, research on the correlation of these topics has started only recently. This chapter overviews recent results in the research literature on virtualized large-scale systems and soft real-time systems. These concepts constitute the fundamental background over which the execution environment of any large-scale service-oriented real-time architecture for highly interactive, distributed, and virtualized applications will be built in the future. While many aspects covered in this chapter have already been adopted in commercial products, others are still under intensive investigation in research labs all over the world