1. A method of requesting the execution of a function in a client computer system in a client-server environment, the function being applicable to a data object processed by a server, the method comprising: obtaining an interface of the object; selecting a function from the interface; determining the types of different results sent back as a result of the execution of the function, from result type identification information, encoded in said interface; selecting at least one desired result type from said result type identification information; generating a message invoking the function, the invoking message including a selected type of result; sending the message invoking the function to said server.