Abstract: An extensible client-server application platform. Execution of functions may require interactions between client-side and server-side components. Extensions may be provided as pairs of modules, one for the client and one for the server, that interact when performing an extension function. To ensure that the client-side and server-side interact appropriately, extensions modules may be initially supplied to the server and downloaded as appropriate, to the client. An enterprise business intelligence application is used as an example of the extensible client-server application platform. To enable use of third party extension modules, the server-side components may execute on a virtualized server.