Supporting SLA Provisioning in Grids by Risk Management Processes

Gridtechnologien haben heutzutage einen hohen Entwicklungsstand erreicht, aber für die Etablierung eines kommerziellen Grids ist es erforderlich, Defizite in den Bereichen Sicherheit, Vertrauenswürdigkeit und Verlässlichkeit zu beheben. Anwender fordern eine Ausführung ihrer Applikation (Grid Jobs) gemäß einer gewünschten Priorität und Qualität. Um vertraglich derartige Aspekte einzufordern, können Service Level Agreements (SLAs) zwischen Dienstbenutzern und Dienstanbietern verhandelt werden. Dienstanbieter kennen jedoch die Unzuverlässigkeit von Grid Ressourcen und sind daher vorsichtig, strenge Forderungen zu akzeptieren und entsprechende Qualitäten zu garantieren. Können strenge Forderungen jedoch nicht vertraglich vereinbart werden, so bevorzugen es viele Anwender, eigene Rechenressourcen zu verwenden. Zwar ist die Unterhaltung eigener Ressourcen in vielen Fällen teurer, aber sie haben die Kontrolle über ihre Applikation, was ihnen mehr Sicherheit bietet. Für die Etablierung eines kommerziellen Grids ist es daher unerlässlich, dass Grid Provider auch strenge SLAs akzeptieren. Damit Provider strenge SLAs akzeptieren können, benötigen sie Abschätzungen dafür, dass sie die SLA nicht erfüllen können (Risikoberechnung). Des Weiteren sollten solche Abschätzungen als Entscheidungskriterium bei der Ressourcenallokation oder Initiierung von Fehlertoleranzmaßnahmen fungieren (Risikomanagement). Diese Arbeit integriert die Betrachtung von Risiken in die Abläufe des Providers, die in die Erbringung von SLAs involviert sind. Während der SLA Verhandlung wird evaluiert welche Ressourcen für die Diensterbringung verwendet werden. Basierend darauf wird die Fehlerwahrscheinlichkeit dieser Ressourcen und der SLA Erbringung im Gesamten berechnet. Falls die mögliche Fehlerwahrscheinlichkeit zu hoch ist, können risikoreduzierende Maßnahmen durchgeführt werden, so dass die SLA akzeptiert werden kann. Die berechnete Fehlerwahrscheinlichkeit wird von Provider und Benutzer ebenfalls bei der Bestimmung des Preises und der Konventionalstrafe betrachtet. Nach dem Vertragsabschluss ist es für die Vermeidung von SLA Verletzungen aus Grid Provider Sicht essentiell, Ressourcenausfälle kompensieren zu können. Die Verwendung von Fehlertoleranzmaßnahmen in Zusammenhang mit einer Risikobetrachtung unterstützt Grid Provider bei der Bewältigung dieser Aufgabe. Risikomanagementprozesse werden dabei direkt mit dem Ressourcenmanagement verknüpft und sind nicht sichtbar für Anwender. Ein wichtiger Aspekt des entwickelten Risikomanagements sind selbstorganisierende Mechanismen, die eine Fehlertoleranzmaßnahme oder eine Kette solcher initiieren, um auf Instabilitäten oder Ausfälle von Ressourcen zu reagieren. Für kommerzielle Grid Provider ist die Betrachtung finanzieller Aspekte im Ressourcenbetrieb und in der Diensterbringung stets von hoher Bedeutung. Folglich werden alle Entscheidungen unter Berücksichtigung finanzieller Aspekte getroffen, wie zum Beispiel der Gewinnmarge, den Kosten für eine Fehlertoleranzmaßnahme sowie dem erwarteten Profit für eine Jobausführung. Zusammengefasst gilt die Integration von Risikomanagement in die Abläufe eines Grid Providers als initialer Schritt für ein risikobetrachtendes Grid. Es wird die Transparenz, Zuverlässigkeit und Vertrauenswürdigkeit steigern und dient als objektives Kriterium für Entscheidungsprozesse im Ressourcenmanagement. Ein integriertes Risikomanagement bringt enorme Vorteile sowohl während der SLA Verhandlung als auch nach Vertragsabschluss - und damit insgesamt für die Diensterbringung im Rahmen von SLAs.Grid technologies have reached a high level of development, however core shortcomings have been identified relating to security, trust, and dependability of the Grid which reduce its appeal to potential commercial adopters. Users require a job execution with a desired priority and quality. In order to stipulate such requirements, Service Level Agreements (SLA) can be negotiated. These are a powerful instrument enabling the specification of the business relationships between service providers and service users in detail. However, providers are aware of various threats for SLA violations and are reluctant to adopt a mechanism which requires them to meet strict requirements and to guarantee associated quality constraints. If strict guarantees cannot be agreed by contract, many users prefer to operate their own resources instead of using the Grid. This is more expensive but they control their applications, which removes the issues of trust and ensures dependability concerning its successful completion. To establish a commercial Grid environment, it is essential that Grid providers are prepared to accept an approach involving SLAs with associated guarantees. In order to enable providers to accept such SLAs, they need estimates of the likelihood that they are unable to fulfill an SLA, i. e. Risk Assessment. Furthermore the resource management should take into account such estimations when allocating resources or initiating fault-tolerance mechanisms, i. e. Risk Management. This work integrates risk awareness in the provider’s processes which are involved in SLA provisioning: During SLA negotiation they evaluate which resources can be used for service provisioning and estimate the Probability of Failure (PoF) of resources and of fulfilling the SLA. If the estimated PoF is too high, then, by applying risk reduction mechanisms, the provider may be able to reduce it sufficiently to accept the SLA. The estimated PoF will also be considered by the service provider and service consumer when determining the revenue and the contractual penalty. Compared to a service request requiring a relatively low quality of service, providing a more reliable service requires to receive a higher price since more guarantees have to be ensured. If a more reliable service is provided, the consumer might also define a higher contractual penalty. Thus, the PoF is an additional decision making element in the SLA negotiation since it enables end-users to compare different SLA offers by an objective measurement. When providers have accepted an SLA, they have to be able to compensate for resource failures in order to prevent SLA violations. The usage of fault-tolerance mechanisms combined with risk awareness support Grid providers in this task. The Risk Management processes are interlaced with the resource management and thereby transparent for Grid service consumers. An important aspect of the Risk Management developed for the Grid are self-organising mechanisms, which initiate a fault-tolerance action or a chain of them, in order to manage resource instabilities or resource outages. Decisions are made on the basis of financial considerations, such as the profit margin, the cost for performing fault-tolerance, and the expected profit when executing a job. Taking into account such financial factors is of high importance for commercial Grid providers. In conclusion, the integration of Risk Management in the processes of Grid providers is the initial step towards a risk aware Grid. It will increase transparency, reliability, and trust and provides an objective basis for decision processes in the resource management. Risk Management is integrated to address the SLA negotiation as well as the post-negotiation phase and thereby improves the SLA provisioning process in general

A prototype and demonstrator of Akogrimo’s architecture: An approach of merging grids, SOA, and the mobile Internet

The trend of merging telecommunication infrastructures with traditional Information Technology (IT) infrastructures is ongoing and important for commercial service providers. The driver behind this development is, on one hand, the strong need for enhanced services and on the other hand, the need of telecommunication operators aiming at value-added service provisioning to a wide variety of customers. In the telecommunications sector, the IP Multimedia Subsystem (IMS) is a promising service platform, which may become a ''standard'' for supporting added-value services on top of the next generation network infrastructure. However, since its range of applicability is bound to SIP- enabled services, IMS extensions are being proposed by ''SIPifying'' applications. In parallel to these developments within the traditional IT sector, the notion of Virtual Organizations (VO) enabling collaborative businesses across organizational boundaries is addressed in the framework of Web Services (WS) standards implementing a Service-oriented Architecture (SOA). Here, concepts for controlled resource and service sharing based on WS and Semantic Technologies have been consolidated. Since the telecommunications sector has become, in the meantime ''mobile'', all concepts brought into this infrastructure must cope with the dynamics mobility brings in. Therefore, within the Akogrimo project the VO concept has been extended towards a Mobile Dynamic Virtual Organization (MDVO) concept, additionally considering key requirements of mobile users and resources. Especial attention is given to ensure the duality of the merge of both, SOA and IMS approaches to holistically support SOA-enabled mobile added-value services and their users. This work describes major results of the Akogrimo project, paying special attention to the overall Akogrimo architecture, the prototype implemented, and the key scenario in which the instantiated Akogrimo architecture shows a very clear picture of applicability, use, and an additional functional evaluation

InterCloud: Utility-Oriented Federation of Cloud Computing Environments for Scaling of Application Services

Cloud computing providers have setup several data centers at different geographical locations over the Internet in order to optimally serve needs of their customers around the world. However, existing systems do not support mechanisms and policies for dynamically coordinating load distribution among different Cloud-based data centers in order to determine optimal location for hosting application services to achieve reasonable QoS levels. Further, the Cloud computing providers are unable to predict geographic distribution of users consuming their services, hence the load coordination must happen automatically, and distribution of services must change in response to changes in the load. To counter this problem, we advocate creation of federated Cloud computing environment (InterCloud) that facilitates just-in-time, opportunistic, and scalable provisioning of application services, consistently achieving QoS targets under variable workload, resource and network conditions. The overall goal is to create a computing environment that supports dynamic expansion or contraction of capabilities (VMs, services, storage, and database) for handling sudden variations in service demands. This paper presents vision, challenges, and architectural elements of InterCloud for utility-oriented federation of Cloud computing environments. The proposed InterCloud environment supports scaling of applications across multiple vendor clouds. We have validated our approach by conducting a set of rigorous performance evaluation study using the CloudSim toolkit. The results demonstrate that federated Cloud computing model has immense potential as it offers significant performance gains as regards to response time and cost saving under dynamic workload scenarios.Comment: 20 pages, 4 figures, 3 tables, conference pape

Bid-Centric Cloud Service Provisioning

Bid-centric service descriptions have the potential to offer a new cloud service provisioning model that promotes portability, diversity of choice and differentiation between providers. A bid matching model based on requirements and capabilities is presented that provides the basis for such an approach. In order to facilitate the bidding process, tenders should be specified as abstractly as possible so that the solution space is not needlessly restricted. To this end, we describe how partial TOSCA service descriptions allow for a range of diverse solutions to be proposed by multiple providers in response to tenders. Rather than adopting a lowest common denominator approach, true portability should allow for the relative strengths and differentiating features of cloud service providers to be applied to bids. With this in mind, we describe how TOSCA service descriptions could be augmented with additional information in order to facilitate heterogeneity in proposed solutions, such as the use of coprocessors and provider-specific services

Elastic Business Process Management: State of the Art and Open Challenges for BPM in the Cloud

With the advent of cloud computing, organizations are nowadays able to react rapidly to changing demands for computational resources. Not only individual applications can be hosted on virtual cloud infrastructures, but also complete business processes. This allows the realization of so-called elastic processes, i.e., processes which are carried out using elastic cloud resources. Despite the manifold benefits of elastic processes, there is still a lack of solutions supporting them. In this paper, we identify the state of the art of elastic Business Process Management with a focus on infrastructural challenges. We conceptualize an architecture for an elastic Business Process Management System and discuss existing work on scheduling, resource allocation, monitoring, decentralized coordination, and state management for elastic processes. Furthermore, we present two representative elastic Business Process Management Systems which are intended to counter these challenges. Based on our findings, we identify open issues and outline possible research directions for the realization of elastic processes and elastic Business Process Management.Comment: Please cite as: S. Schulte, C. Janiesch, S. Venugopal, I. Weber, and P. Hoenisch (2015). Elastic Business Process Management: State of the Art and Open Challenges for BPM in the Cloud. Future Generation Computer Systems, Volume NN, Number N, NN-NN., http://dx.doi.org/10.1016/j.future.2014.09.00

Business Grid Services

Grid services have come to represent the synthesis of web services and grid computing paradigms. Web services provide the means to modularize software, enabling loosely coupled and novel synthesis. Grid computing removes the binding between functional software components and specific hosting hardware, enabling software to be deployed dynamically over a network (e.g. intra-, extra- or inter-net). Applying the constructs of grid computing to the service orientation of enterprise software will allow business service networks to utilize more specialized services. An upper service ontology that enables business grid services to be described and then related to the grid hosting platform is presented. Explicit knowledge is required for enterprise software, hosting servers and the domain that can then be utilized by both SLA and reservation systems. The ontology presented is derived from and validated using a collection of web services taken from leading investment banks