The main objective of our research work is to contribute to the development of a modelling framework aiming at the engineering and integration of networks of firms(NoF). Referring to a state of the art on networks engineering, we first show that such a framework should provide a support for the management of networks' evolution in the future. Based on a structural study of networks of firms(NoF), in the paper we identify structural mechanisms and then configuration factors useful as a basis for networks engineering. Those configuration factors will be presented and linked to "state variables" and "contingency variables". Both kinds of variables are to be later exploited to develop an architecture and a methodology for engineering and integration of NoF.