A method for receiving a context based service includes: providing a user identifier (ID) to a service provider, the user ID being used for a recommendation of a service by a recommendation engine using a decision model; and receiving a recommended service from the service provider, the recommended service being recommended through a recommendation description (RD), the RD determined by the recommendation engine based on the decision model and at least one of a user description (UD) and a context description (CD) being obtained through the user ID.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A method for receiving a context based service, the method comprising: providing a user identifier (ID) to a service provider, the user ID being used for a recommendation of a service by a recommendation engine using a decision model; and receiving a recommended service from the service provider, the recommended service being recommended through a recommendation description (RD), the RD determined by the recommendation engine based on the decision model and at least one of a user description (UD) and a context description (CD) being obtained through the user ID. 2. The method of claim 1, wherein the user ID is provided to a manager before at least one of the UD and the CD is obtained through the user ID. 3. The method of claim 2, wherein the recommended service is determined based on a service description (SD) which is provided by the service engine and comprises the decision model and wherein the recommended service is one of services that are provided by the service engine. 4. The method of claim 1, wherein the decision model includes a decision tree used by the recommendation engine and representing a specific user type. 5. The method of claim 1, wherein the decision model is used by the recommendation engine and defines a set of user types classified for a service strategy. 6. The method of claim 1, wherein the decision model is predefined by the service provider and defines a user type included in the RD. 7. The method of claim 6, wherein the decision model defines a plurality of user type sets being used by the recommendation engine and wherein the user type is non-exclusively included in the plurality of the user type sets. 8. A method for providing a context based service, the method comprising: preparing a decision model, the decision model being used for a recommendation of a service by a recommendation engine; and providing a recommended service to a user terminal when the recommendation of the service is requested from the user terminal, the recommendation service being recommended through a recommendation description (RD) determined by the recommendation engine based on the decision model and at least one of a user description (UD) and a context description (CD) being obtained through a user identifier (ID). 9. The method of claim 8, wherein the user ID is provided from a user terminal to a manager before at least one of the UD and the CD is obtained through the user ID. 10. The method of claim 9, wherein the recommended service is determined based on a service description (SD) which is provided by the service engine and comprises the decision model and wherein the recommended service is one of services that are provided by the service engine. 11. The method of claim 8, wherein the providing the recommended service to the user terminal comprises: receiving the user ID from the user terminal; providing the user ID and the decision model to the recommendation engine; and providing the RD to the user terminal by the recommendation engine based on the decision model and at least one of the user description and the context description, wherein the RD comprises a user type in the decision model. 12. The method of claim 11, wherein the providing the recommended service to the user terminal further comprises supporting a determination of the user type by the recommendation engine according to a decision tree of the decision model. 13. The method of claim 12, wherein the providing the recommended service to the user terminal further includes checking whether the recommendation engine already has the decision model when the decision model is provided to the recommendation engine. 14. The method of claim 11, wherein providing the recommended service to the user terminal comprises determining the recommended service provided to the user terminal based on the recommendation description. 15. A method for generating a context based service, the method comprising: receiving a decision model used for determining a service to be provided from a service engine; and generating a recommendation description (RD) based on the decision model and at least one of a user description (UD) and a context description (CD). 16. The method of claim 15, wherein the generating the RD comprises analyzing a decision tree in the decision model based on at least one of the UD and the CD to infer a user type. 17. The method of claim 16, wherein the generating the RD further comprises including the user type in the RD. 18. The method of claim 15, wherein the generating the RD comprises deducing at least one of the UD and the CD through a user context being provided by a user terminal. 19. The method of claim 15, wherein the generating the RD includes providing at least one of the UD and the CD from a user-context description provider through a user ID. 20. A method for determining a context based service, the method comprising: defining a set of user type including a plurality of user types classified when a service is determined; defining a decision model to be used for determining one of the plurality of the user types through at least one of a user description and a context description; and defining the decision model comprising the set of user type and a decision tree.