1. A method of operation of a client computer, whereby an application may be obtained for use with a host program on the client computer, the method comprising: sending an application search request and a list of functions provided by a host program on a client computer; receiving a list of applications available from the server which can be used, at least in a basic mode of operation, with a said function provided by the host program; presenting the list of applications; receiving a selection of an application from the list; sending the selection; receiving the selected application; and activating the received application using the host program.