31.7 Summary

Sockets are sometimes implemented using STREAMS. Four new functions are provided to access the STREAMS subsystem: getmsg, getpmsg, putmsg, and putpmsg, plus the existing ioctl function is heavily used by the STREAMS subsystem also.

TPI is the SVR4 STREAMS interface from the upper layers into the transport layer. It is used by both sockets and XTI, as shown in Figure 31.3. We developed a version of our daytime client using TPI directly as an example to show the message-based interface that TPI uses.