40.2 The transport agent API

In real-world systems, applications typically access network services through an applications programming interface (API). The most popular of these APIs is known as ``sockets.'' In ns, we mimic the behavior of the sockets API through a set of well-defined API functions. These functions are then mapped to the appropriate internal agent functions (e.g., a call to send(numBytes) causes TCP to increment its ``send buffer'' by a corresponding number of bytes).

This section describes how agents and applications are hooked together and communicate with one another via the API.