A service brokering apparatus which can easily build a service integration system that provides a complex service by integrating a plurality of elementary services realized on computers. This apparatus achieves a system that can easily adapt itself to expanding or changing the services. The service brokering apparatus includes a storage device that stores service description information for each elementary service, the service description information having a combination of identification information of elementary service entities, declarative description information on information needed to realize the elementary services, and declarative description information on processing results of the elementary services. Further, the service brokering apparatus includes a transmitter/receiver for transmitting and receiving messages, and a device decomposing the complex service into the elementary services using the service description information upon receipt of a request message for the complex service from the outside, and generating an elementary service request plan having strings of combinations of at least elementary service request information needed to realize the complex service, and identification information of elementary service entities.
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