7. A semantic negotiation method of a terminal that is designed by a first service provider, the method comprising: transmitting, to a service server that is designed by a second service provider, a service request message requesting an optimized service; receiving, from the service server, a constraint query message with respect to a constraint for performing the optimized service; extracting a value of the constraint, based on at least one of user ontology and terminal ontology, wherein the at least one of the user ontology and the terminal ontology enables the terminal and the service server to interact even when the first service provider is different from the second service provider; transmitting, to the service server, the value of the extracted constraint; and receiving, from the service server, information with respect to the optimized service.
7. A semantic negotiation method of a terminal that is designed by a first service provider, the method comprising: transmitting, to a service server that is designed by a second service provider, a service request message requesting an optimized service; receiving, from the service server, a constraint query message with respect to a constraint for performing the optimized service; extracting a value of the constraint, based on at least one of user ontology and terminal ontology, wherein the at least one of the user ontology and the terminal ontology enables the terminal and the service server to interact even when the first service provider is different from the second service provider; transmitting, to the service server, the value of the extracted constraint; and receiving, from the service server, information with respect to the optimized service. 8. The semantic negotiation method of claim 7 , further comprising: receiving, from the service server, a preference query message with respect to a user preference; extracting a value of the user preference, based on the at least one of the user ontology and the terminal ontology; transmitting, to the service server, the extracted value of the user preference; and receiving, from the service server, information with respect to the optimized service to which the value of the user preference is applied.