27. A system for registering services for use in a domain, said system comprising: an execution environment comprising an active ontology modeling the domain, the active ontology comprising a logical arrangement of a plurality of active processing elements, wherein each active processing element is configured to receive at least one fact relating to the modeled domain and to perform at least one action responsive to at least one received fact; and a processor configured as a service broker for interfacing the at least one active ontology to a service-oriented architecture comprising a plurality of services; wherein a service registers with the at least one active ontology by specifying at least one of: one or more active processing elements that the service can accept; and one or more active processing elements that the service cannot accept and wherein the active ontology filters requests for services to the at least one of the plurality of services in accordance with the one or more active processing elements specified by the at least one of the plurality of services.
27. A system for registering services for use in a domain, said system comprising: an execution environment comprising an active ontology modeling the domain, the active ontology comprising a logical arrangement of a plurality of active processing elements, wherein each active processing element is configured to receive at least one fact relating to the modeled domain and to perform at least one action responsive to at least one received fact; and a processor configured as a service broker for interfacing the at least one active ontology to a service-oriented architecture comprising a plurality of services; wherein a service registers with the at least one active ontology by specifying at least one of: one or more active processing elements that the service can accept; and one or more active processing elements that the service cannot accept and wherein the active ontology filters requests for services to the at least one of the plurality of services in accordance with the one or more active processing elements specified by the at least one of the plurality of services. 30. The system of claim 27 , wherein at least one received fact relates to at least one event collected from a user's environment.