1. Adaptive Systems – Graceful Degrading System Paul Li Paul.Li@cs.cmu.edu

2. Fundamental Concept of Dependability Failure is an event that occurs when delivered service deviates from correct service. (Quality of service?) Failure is an event that occurs when delivered service deviates from correct service. (Quality of service?) Design faults? Physical faults? Or Interaction faults? Design faults? Physical faults? Or Interaction faults?

3. Fundamental Concept of Dependability Natural Acc Perm Trans Environment/System Flux

4. Software Component Detection/ Monitoring Software Component Detection/ Monitoring Software Component Detection/ Monitoring Software Component Detection/ Monitoring System-wide Graceful Degradation (Implicit Adaptation?) Software Component Detection/ Monitoring System Variables I/M O/A Updated System Vars System Updates

5. Software Component Detection/ Monitoring Software Component Detection/ Monitoring Software Component Detection/ Monitoring Software Component Detection/ Monitoring Scalable System-wide Graceful Degradation Software Component Detection/ Monitoring System Variables I/M O/A Sub-System

6. Self Healing Problem Space Rainbow Permanent/Transient Inadequate System Configuration Stress on the System Configuration in Distributed Systems Random, arbitrary, pre-defined Gauges Less than desired quality of service Perform associated repair On-line Reconfiguration Long time between occurrences Quality of service

7. Self Healing Problem Space Open Systems with defined interfaces Assumed to be complete System knows component presence Data rates System fluctuates during operation Elements of distributed systems Heterogeneous components and resources Dynamic behavior within expectations Semi-automated System quality of service Scalability assumes linearity Many clients and servers in distributed systems