TCP/IP applications have become increasingly important in this network generation. Their development, however, is troublesome in practice since reusable components are usually system-call-level service routines. We describe an application framework which we have developed for TCP/IP applications. The software architecture, as the model of the application framework, incorporates features of the layered and object-oriented style under the concept that a TCP/IP application consists of distributed objects communicating with one another. The architecture isolates state transition manipulation from such application logic as client user interface handling and server database access. The framework provides a large reusable component set including customizable components. We demonstrate the usefulness of this application framework through the implementation of several TCP/IP applications.