Iain Gourlay

Brokering of risk-aware service level agreements in grids

Service level agreements (SLAs) are facilitators for widening the commercial uptake of Grid technology. They provide explicit statements of expectation and obligation between service consumers and providers. However, without the ability to assess the probability that an SLA might fail, commercial uptake will be restricted, since neither party will be willing to agree. Therefore, risk assessment mechanisms are critical to increase confidence in Grid technology usage within the commercial sector. This paper presents an SLA brokering mechanism with risk assessment support, which evaluates the probability of SLA failure. WS‐Agreement and risk metrics are used to facilitate SLA creation between service consumers and providers within a typical Grid resource usage scenario. An evaluation is conducted to examine risk models, the performance of the brokers implementation as well as a comparison of its capabilities against similar SLA‐based solutions from the literature. Copyright

A SNAP-Based Community Resource Broker Using a Three-Phase Commit Protocol: A Performance Study

Resource brokering is an essential component in building effective Grid systems. Existing mechanisms employ a traditional approach for resource allocation, which is likely to run into performance problems. This paper presents the development of a broker that is designed within the SNAP (Service Negotiation and Acquisition Protocol) framework and focuses on applications that require resources on demand. The broker uses a three-phase commit protocol as the traditional advance reservation facilities cannot cater to such needs due to the prior time that it requires to schedule the reservation. Experiments have been carried out on a Grid testbed, supported by mathematical modelling and simulation. The experimental results show that the inclusion of the three-phase commit protocol results in a performance enhancement in terms of the time taken from submission of user requirements until a job begins execution. The broker is a viable contender for use in future Grid resource broker implementations.

Reliability and risk in grid resource brokering

If grid computing is to experience widespread commercial adoption, then incorporating risk assessment and management techniques is essential, both during negotiation between service provider and service requester and during run-time. This paper focuses on the role of a resource broker in this context. Specifically, techniques for evaluating the reliability of risk information received from resource providers is discussed. The performance of three algorithms are compared through simulation, showing than an odds betting-based algorithm performs better in identifying providers with highly variable risk assessments.

Assessgrid, economic issues underlying risk awareness in grids

In order to improve the attractiveness and drive the commercial uptake of Grid technologies, the establishment of Service Level Agreements (SLAs) is required. The AssessGrid project contributes to this aim by introducing risk-aware Grid architectural components. Grid service users, brokers and providers benefit from risk assessment functionalities in all phases of service provisioning and utilisation. This paper focuses on the economic issues which result from this new risk-aware approach to Grid computing. Multiple open economic research questions are discussed from the perspective of users, brokers and providers, which point out the potential impact of AssessGrid in this area.

A SNAP-based community resource broker using a three-phase commit protocol

Summary form only given. Resource brokering is an essential component in building effective grid systems. Existing mechanisms employ a traditional approach for resource allocation, which is likely to run into performance problems. We present the development of a broker that is designed within the SNAP (service negotiation and acquisition protocol) framework and focuses on applications that require resources on demand. The broker uses a three-phase commit protocol, as the traditional advance reservation facilities cannot cater for such needs due to the prior time that it requires to schedule the reservation. The experimental results show that the inclusion of the three-phase commit protocol results in a performance enhancement in terms of the time taken from submission of user requirements until a job begins execution. The broker is a viable contender for use in future grid resource broker implementations.

Supporting Bulk Synchronous Parallelism with a high‐bandwidth optical interconnect

The list of applications requiring high‐performance computing resources is constantly growing. The cost of inter‐processor communication is critical in determining the performance of massively parallel computing systems for many of these applications. This paper considers the feasibility of a commodity processor‐based system which uses a free‐space optical interconnect. A novel architecture, based on this technology, is presented. Analytical and simulation results based on an implementation of BSP (Bulk Synchronous Parallelism) are presented, indicating that a significant performance enhancement, over architectures using conventional interconnect technology, is possible. Copyright

Performance Evaluation of a SNAP-Based Grid Resource Broker

Resource brokering is an essential component in building effective Grid systems. The paper discusses the performance evaluation of a broker that is designed within the SNAP (Service Negotiation and Acquisition Protocol) framework and focuses on applications that require resources on demand. The performance evaluation is carried out using a combination of mathematical modelling and simulation. Initial results are presented, indicating that the simulation and modelling are in good agreement.

Evaluating Provider Reliability in Grid Resource Brokering

If Grid computing is to experience widespread commercial adoption, then incorporating risk assessment and management techniques is essential,both during negotiation between service provider and service requester and during run-time. This paper focuses on the role of a resource broker in this context. Specifically, an approach to evaluating the reliability of risk information received from resource providers is presented, using historical data to provide a statistical estimate of the average integrity of their risk assessments, with respect to systematic overestimation or underestimation of the probability of failure. Simulation results are presented, indicating the effectiveness of this approach.

A Monitoring and Prediction Tool for Time-Constraint Grid Application

A Grid system must integrate heterogeneous resources with varying quality and availability. For example, the load on any given resource may increase during execution of a time-constrained job. This places importance on the system’s ability to recognise the state of these resources. This paper presents an approach used as a basis for applications and resources monitoring, in which Grid jobs are maintained at runtime. A reflective technique is used to simplify the monitoring of the Grid application. The monitoring tool is described and experimentally evaluated. Reflection is incorporated into the monitoring to separate functional and non-functional aspects of the system and facilitate the implementation of non-functional properties such as job migration. Results indicate that this approach enhances the likelihood of timely job completion in a dynamic Grid system.

Risk-Aware SLA Brokering Using WS-Agreement

Service Level Agreements (SLAs) are facilitators for widening the commercial uptake of Grid technology. They provide explicit statements of expectation and obligation between service consumers and providers. However, without the ability to assess the probability that an SLA might fail, commercial uptake will be restricted, since neither party will be willing to agree. Therefore, risk assessment mechanisms are critical to increase confidence in Grid technology usage within the commercial sector. This paper presents an SLA brokering mechanism including risk assessment techniques which evaluate the probability of SLA failure. WS-Agreement and risk metrics are used to facilitate SLA creation between service consumers and providers within a typical Grid resource usage scenario.