Identification of host-compatible downloadable applications

A user's (client) computer sends a request for a listing of applications which can be downloaded from a server in an electronic marketplace and a list of functions provided by a host program. A description of an application, such as in an application manifest, provides a list of required functions and, preferably, a list of optional functions for a software application. The server sends a list of applications supported by those functions. Those supported applications are displayed to the user as being available for downloading. The user selects the desired application and the user's computer requests, and the server provides, a download of that application. The downloaded application will then operate on the user's computer using the required functions provided by the host programs, and may use any optional functions provided by the host programs. TIME COMPUTER SERVER SEND LOGIN 302 VERIFY LOGIN INFORMATION INFORMATION RECEIVE 304 SEND APPLICATION APPLICATION SEARCH PAGE SEARCH PAGE SEND APPLICATION RECEIVE SEARCH REQUEST 306 SEARCH AND LIST OF REQUESTAND SUPPORTED LIST RECEIVE 308 SEND LIST OF APPLICATION 4 APPLICATIONS REQUEST 310 b RECEIVE APPLICATION APPLICATION SELECTEDBY DOWNLOAD USER REQUEST RECEIVE 4 312 SEND REQUESTED REQUESTED APPLICATION APPLICATION AND MANIFEST AND MANIFEST