1. A method of aggregating web services in generating a user interface for a computing device, the method comprising the steps of: a) receiving at least one web service description, wherein said at least one web service description comprises a plurality of web service description elements that define a web service interface to each of a plurality of web services; b) processing said at least one web service description to identify a first web service requiring one or more inputs, wherein each input to said first web service is obtainable by invoking a second web service of said plurality of web services; and c) generating a user interface for said computing device adapted to perform the substeps of i. invoking one or more second web services to obtain output data from said one or more second web services; and ii. invoking said first web service, using output data from said second web services as input data to said first web service, to obtain output data from said first web service.