We present a new model for generating network applications. Our model is based on trees communicating with each other. Our model is simple to understand, but yet powerful enough to write complex network applications. Traditionally writing network applications require much knowledge about function libraries and class libraries which are responsible for network communications. If we have a higher level model of network applications independent of choices of programming languages and libraries, our task of writing network applications would be much easier. We implemented our prototype generator system using Java programming language. A number of network applications such as network chat systems and mail systems were successfully generated by our prototype generator.