1. A method comprising: receiving a call message specifying a type of application program to be called from a calling application program that is executing on a computer system; determining whether the computer system has any application programs of the specified type available for execution; if an application program of the specified type is available for execution on the computer system, performing the following: identifying an application having a type that matches the type specified in the call message; converting the call message directly to a format recognized by the identified application; and calling the identified application program using the converted application call message.