Quality of Service on Grid: Architectural and methodological issues

In ten years of evolution Grid Computing has changed quickly, and the development of new middleware services makes Grid platforms increasingly used not only for best effort large scientific jobs but also in industrial and business applications. This has taken to a growing demand of Quality of Service (QoS) support, strongly driven by the requirements of the new potential applications. However, the QoS issue on Grid is not easy, as Grid has been originally designed without any QoS support, and it is a complex system. During years some solutions have been proposed to implement, usually over middleware, the functionalities needed to supply QoS for specific classes of applications. This results in a focused and heterogeneous approach, so that it is hard to evaluate both the sufficiency of the support and its robustness with respect to the large spectrum of possible Grid applications. In this context, our contribution concerns three points: first, we analyze the current approach to QoS on Grid as a relationship among QoS features, applications and architectures; second, we evaluate the QoS requirements of two recent QoS-demanding applications on Grid, namely Massive Multiplayer Online Games (MMOG) and Urgent Computing, comparing these requirements with the support provided by current QoS architectures; third, as a result of our analysis, we propose some guidelines for an alternative approach to QoS provision on Grid, based on the definition of a dedicated QoS-management layer to overcome the limitation of the current methodologies.