Component-Based Adaptive Tasks Guided by Resource Contracts Peter Rigole K.U.Leuven Belgium

2 Ubiquitous Systems A Ubiquitous Computing system should commit its computing powers to support the tasks of its users should reduce user distraction to a minimal level  The Disappearing Computer

3 Context is important Context information all the information the computing system can obtain from its environment used to realize automated, proactive intelligent behaviour Context contains info about: user (preferences, mood, …) environment (location, time, temperature, …) available services platform information (hardware local and remote devices) …

4 Limited resources Ubiquitous computing environments realized by Mobile devices Small devices hidden in paintwork Occasionally supported by powerful systems Mainly resource-limited devices Tradeoff  More functionality  More resources in use

5 Adaptive Behaviour Self-managing software in an environment with Limited resources require Adaptive behaviour

6 Adaptive behaviour required Resource tradeoff: distributed cooperation must be exploited whenever possible by (self-)adaptation and foraging mechanisms  Rich and flexible computing space But: resource availability can change quite often  need to manage resource use

7 Resource aware Components Component-based applications fine-grained applications enhance self-manageability delineated entity for code analysis  Resource-Awareness per component Design-time description of resource properties by means of resource declarations for each component Resource Declaration: a parameterized description of a certain type of resource a software entity requires when for deploying its functionalities

8 Contracts proposals Resource agreements are settled at the time of instantiation between software parties  components, ports and connectors Resource Contract Proposal: contains an agreement on intended resource use by one or several software parties

9 Resource Contracts Signed Resource Contract: a resource contract proposal can become a signed resource contract when the middleware system accepts the contract and signs it Signed Resource Contract Resource Contract Proposal Resource Delaration Agreement between Several parties e.g. two component ports Negotiated and validated contract proposal gets signed Resource Delaration Resource Delaration

10 Adaptive tasks Software envisioned by ubiquitous computing should support the user’s tasks by maintaining the continuity of the softw. functionalities in a frequently changing computing environment Therefore, software adaptability becomes very important: Considering its nature we distinguish: External adaptations  driven by external forces Internal adaptations  driven by the application itself

11 External adaptations Middleware interferes with the application without guidance of the application itself Is transparent for the application Types: Component reconfiguration  changing configuration parameters Component replacement  new version Component relocation  Foraging

12 Internal adaptations Application changes itself mainly driven by context information and task models  knowledge about the evolution of the user’s task User task changes, thus functionality changes, thus application can change as well: removal of unnecessary components adding new component for new functionality adding/removing of optional components

13 Ubiquitous adaptation Coordination between: Internal adaptations External adaptations Guided by contracts to ensure the validity and integrity of Application compositions  local and  distributed

Questions ?

15 CRuMB II contract framework Contract (re-)negotiation  contract broker Contract validation  contract manager Contract monitoring  contract monitor and RAL Jess reasoning (rule engine)  validation and monitoring