1. A method for inter-application communication on a mobile device having an operating system that provides a sandboxed environment, the method comprising: retrieving, at a first application executing on the mobile device, a definition for functionality provided by another application executable on the mobile device; generating a first URL string based on the retrieved definition for the functionality; and invoking functionality of a second application installed on the mobile device by opening the first URL string using a system call of the operating system of the mobile device.