We present a new software generator model for the construction of network applications. Our model is called Communicating Timed Attribute Grammars (CTAG) model, which is an extension of attribute grammars. Our CTAG model allows us to describe dynamic behaviors of network applications. We represent one application program by an attributed tree. Communication between application programs is achieved by the exchange of attribute values between connected attributed trees.Traditionally network applications are constructed by procedural programming languages, but it is not easy to produce the whole codes of network application programs. Our CTAG model allows us to construct network applications based on a set of simple computing rules instead of using complex knowledge of existing function libraries and class hierarchies.We give examples of constructing a chat system and a POP client system using our CTAG model. We give comparisons of our method with previous approaches.