The invention enables an application program to communicate a message over a network without having information regarding a protocol employed by the network. A network library program, running independently of the application program, stores communication protocol data and procedures for establishing message transport data structures to be used in communicating over the network. Initially, the application program passes an address string to the network library program. In response, the network library program determines a network protocol to be used by analyzing the received address string. The network library program then creates a "transport address" data structure which records both the protocol and the address string. The network library program further establishes a "transport" data structure for the specific message type to be dispatched, which data structure includes a dispatch command and a socket handle to be used during the transmission. Thereafter, the application program invokes the network library program to proceed with execution of the message dispatch action by using both the transport address data structure and the transport data structure.