Quality of service and scientific workflows

The advent of high-performance computing engines and networks is bringing serious numerical and problem-solving environments (PSEs) closer to a broad base of users with widely differing needs. From the perspective of these users, a key issue will be the quality of service (QoS) PSEs offer. In the broader sense, QoS includes parameters such as network delays and throughput, as well as end-user quality factors such as system availability, system functionality, content quality, and semantic interoperability. In order to facilitate integration of the QoS and PSE we introduce scientific workflows, to mean a series of structured activities and computations that arise in scientific problem-solving. Scientific workflows are expected to coexist and cooperate with other user workflows (e.g., business workflows, educational workflows, legislative workflows). As such they must support compatible QoS. We use data from existing systems and workflows to quantitatively bound some of the PSE QoS parameters. Use of multimedia imposes additional restrictions, while end-user risks impose bounds on the security and reliability of numerical computations and algorithms. It is our belief that the next generation of PSEs must have QoS parameters designed into the system, or these PSEs will fail to live up to user needs and expectations.