A remote wireless device receives a compressed message including an application definition file. The application definition file is associated with an application executing at a computing device and contains definitions for: a user interface format; a format for network messages; and a format for storing data. Using these definitions, the wireless device may receive data generated by the application and formatted in accordance with the definitions. The wireless device may then present a user interface for the application. Preferably, the application definition file is an XML file. Similarly, application-specific network messages provided to the device are also formed using XML. Data generated by the application may be presented at the mobile device under control of a virtual machine that uses the application definition file. For efficiency, the network messages received at, and transmitted by, the wireless device may be compressed.