Context-Aware Service Composition in Pervasive Computing Environments

Sonia Ben Mokhtar, Damien Fournier, Nikolaos Georgantas, and Val´erie Issarny

http://www.springerlink.com.proxy.lib.sfu.ca/content/38252l8676501424/fulltext.pdf

The paper presents a context-aware service composition based on workflow integration.

Context-awareness is a property of a system that uses context to provide relevant information and or services to the user where relevant depends on user's task

They use ontologies to define context and then use this information to validate context.

They want to enable the user to perform a task anywhere and any time. Networked services are described in OWL-S extended with context information -> prec0nditions & effects + context attributes.

Context-aware service composition is done in two steps:

1. context aware service discovery provides a set of services that are candidate to composition
2. context-aware process integration provides a set of composition schemes that conform to the task behavior

Matching and discovery of services is done based on the algorithm proposed by palucci in matching the inputs and outputs of user tasks and processes with the inputs and outputs of advertised services. what is important is the fact that there can be subsumption relationship between the advertised and the required services.

During the integration process, contextual preconditions and effects of service operations have to be taken into account, and second, global task's contextual requirements have to be checked.

Filtering of components happens based on the following criteria:

1. Starting from the actual state of the path, the task's following symbols can not be reached in the global automation
2. The simulated context does not fulfill the contextual preconditions of the incoming operations.
3. some attributes of the simulated context do not meet the global contextual requirements of the user task.