1. A computer-implemented method comprising: receiving a request for a web service; comparing a description of the requested web service, the description including a first input sequence that includes inputs to the requested web service that occur during operation of the requested web service, in an ordering indicated by the first input sequence, and/or including a first output sequence that includes outputs from the requested web service that occur during operation of the requested web service, in an ordering indicated by the first output sequence, to a description of an existing web service, the description including a second input sequence that includes inputs to the existing web service that occur during operation of the existing web service, in an ordering indicated by the second input sequence, and/or a second output sequence that includes outputs from the existing web service that occur during operation of the existing web service, in an ordering indicated by the second output sequence, wherein the description of the requested web service and the description of the existing web service conform to a description logic; determining, based on logical rules of the description logic, that the second input sequence in which the inputs occur during operation of the existing web service is subsumed by the first input sequence in which the inputs occur during operation of the requested web service or determining, based on logical rules of the description logic, that the second output sequence in which the outputs occur during operation of the existing web service is subsumed by the first output sequence in which the outputs occur during operation of the requested web service; based on the determination that the second input sequence in which the inputs occur during operation of the existing web service is subsumed by the first input sequence in which the inputs occur during operation of the requested web service or based on the determination that the second output sequence in which the outputs occur during operation of the existing web service is subsumed by the first output sequence in which the outputs occur during operation of the requested web service, selecting the existing web service; and fulfilling the request with the selected existing web service.