The context of this thesis is related to the data that are distributed over different sources of heterogeneous nature (text, audio, image, XML). The rules controlling access to data could be specified according to different paradigms using verification mechanisms that may differ from a source to another, as well. In order to allow a user to query the system, a global view of the different sources has to be defined. This view acts as a mediator between the user and the different sources.
Every data source uses its own access control policy. The global view shouldn’t allow a query from acquiring information from a source if the same information is denied by another source (even if the two sources don’t use the same specification).
The arising issue then is how to handle, at the global view level, the access control in terms of specification, integration, aggregation…? The global view should harmonize and propagate the user profile over the different sources while preserving the consistency between the returned results of each source.