Abstract: Interapplication communication （IAC） is a means by which software process can efficiently exchange information units during runtime in a heterogeneous computer environment. It is the key technology of implementing cooperative computing and software integration. An IAC model for application in petroleum domain is presented based on the requirements. The IAC method, message type and communication paradigms are also discussed. Finally, the implementation of P IAC is detailed, which is a communication protocol for petroleum software. P IAC has been applied in an integrated framework of petroleum software.