Uncertainty and Predictability: Can They Be Reconciled?

Abstract

We are faced today with the confluence of antagonistic aims, when designing and deploying distributed systems. On one hand, our applications have to achieve timeliness goals, dictated both by QoS expectations with regard to on-line services (e.g. time-bounded transactions), and by technical issues of real-time nature involved in the deployment of certain services (e.g., multimedia rendering). On the other hand, the open and large-scale environments where applications and users execute and evolve exhibit uncertain timeliness or synchrony. Likewise, services, despite their sometimes critical nature (not only money-critical, but also privacy- or even safety-critical), are more often deployed on-line or through open networks. It is required that they be resilient to intrusions, despite the elusiveness of attacks they are subject to, and the pervasiveness and subtelty of vulnerabilities in the relevant systems.

Work partially supported by the EC, through proj. IST-1999-11583 (MAFTIA), IST-FET-2000- 26031(CORTEX), andFCT, through the Large-Scale Informatic Systems Laboratory (LaSIGE) and proj. POSI/1999/CHS/33996 (DEFEATS).