1. Generic Support for Embedding Adaptive and Autonomic Behaviours Richard Anthony The University of Greenwich

2. Richard Anthony, The University of Greenwich, April 2005,1 Complexity (in large and distributed applications) From:Internal behaviour Interactions with environment Interactions between components Leads to:Complex run-time configuration and tuning Difficult to account for all behaviours at design time Increased development and test iterations → higher costs Autonomics is a possible solution to the run-time complexity issue Risk is introduced Adaptive / Autonomic approaches introduce Non-Deterministic behaviour. It is important to ensure Stability (to limit the envelope of behaviours). Testing is a particular concern Behaviour is context and environment sensitive Difficult to predict precise behaviour at any specific instant (trends ok) Testing is complex (need to capture the full range of potential behaviours) → Testing costs may increase – this is an unwelcome paradox!

3. Richard Anthony, The University of Greenwich, April 2005,2 Autonomics Research at Greenwich General approaches: Nature-inspired emergence, Layered architecture for autonomics services, Biologically-inspired concept of layered self-healing, Policy-based adaptive / autonomic systems. Underlying development approach - Generic Autonomics Common functionality developed as generic services, Development effort (end developers) focussed on the business logic, Removes some of the testing requirement (autonomic aspects), Reduces risk (of instability!, of not working!), Promotes re-use of both code and behaviour. Specific services and applications: Emergent Election Algorithm, Emergent Cluster Management, Self-configuring Parallel Application Deployment, Autonomic Application Management, Connectivity services for Wireless Devices in Grid environments.

4. Richard Anthony, The University of Greenwich, April 2005,3 Requirements Identified / Future Directions Currently, many developers think deterministically. Non-deterministic behaviour is a ‘barrier’– they don’t trust it. → Testing is an underpinning requirement for ‘complexity research’. → A sound test methodology, framework and tools should improve acceptance of Emergence / Autonomics. Adaptive systems cannot be tested simply by matching inputs to outputs. Interactions have temporal and contextual aspects: → Context and environment must be ‘mocked-up’ prior to each test. → Tests must verify internal adapting behaviour as well as output. → Each test case should be executed in many different contexts and environments so the time-complexity of testing will be dramatically worse. An eventual goal? Real-time self-diagnosis and self-testing: (What is the effect of a particular adaptation? Does it leave the system in a legal state? / stable state? / better state? Should the adaptation be rolled-back? )