4. The semantic negotiation module of claim 3 , wherein: the communication manager transmits, to the terminal, a preference query message with respect to a user preference, and receives, from the terminal, a value of the user preference, and the semantic negotiator calculates a score with respect to the service searched by the constraint matching, based on the value of the user preference, and determines the optimized service based on the calculated score.
4. The semantic negotiation module of claim 3 , wherein: the communication manager transmits, to the terminal, a preference query message with respect to a user preference, and receives, from the terminal, a value of the user preference, and the semantic negotiator calculates a score with respect to the service searched by the constraint matching, based on the value of the user preference, and determines the optimized service based on the calculated score. 5. The semantic negotiation module of claim 4 , wherein: the semantic negotiator initializes the score of the service searched by the constraint matching, the semantic negotiator increases the score of an item that has a service preference property that matches the value of the user preference, from among a plurality of items with respect the user preference, and the semantic negotiator decreases the score of an item that has a service preference property that does not match the value of the user preference.