Computer systems integration.

A computer system comprises first and second processing environments interconnected by a gateway. The gateway emulates a terminal in the second environment, converting service requests from a client in the first environment into dialogues on the emulated terminal by executing scripts in a scripting language. This allows client applications in the first environment to communicate with server applications in the second environment in a way that is completely transparent to the clients. The client is not aware that it is communicating with the server through a dialogue on an emulated terminal; all knowledge of the dialogue is embodied in the scripts. This is of utility in integrating legacy computer sytems with new systems.