HP X.25/9000 Programmer's Guide

Chapter 6 97

Extended Features

Using Fast Select

Fast Select Operation Summary

A server can respond to a fast select call in any of three ways:

• The call can be cleared immediately with no data

• The call can be cleared with user data speciﬁed

• A normal VC can be established with or without user data speciﬁed in

the call accept packet

Which of these alternatives are available depends on the design of the

client and server processes.

The actions to be taken are shown in the three scenarios below. The

initial steps for sending and receiving fast select is the same for all

scenarios. These initial steps are shown in Table 6-1, “Steps for Fast

Select.”

This section assumes that interfaces for both the client and the server

are conﬁgured to permit fast select and that the network provider allows

fast select.

Initial Steps for Fast Select

The client and server’s initial steps when fast select is initiated are

described below and shown in Table 6-1, “Steps for Fast Select.”

Step 1. The server creates an AF_CCITT listen socket.

Step 2. The server binds an

x25addrstr

structure containing the addressing

information.

Step 3. The server establishes a listen queue.

Step 4. The server prepares the call to control call acceptance.

Step 5. The server listens for a CALL REQUEST packet.

Step 6. The client creates an AF_CCITT socket.

Step 7. The client speciﬁes the fast select facilities for the CALL REQUEST

packet.

Step 8. The client speciﬁes the call user data for the CALL REQUEST packet.

Step 9. The client sends the CALL REQUEST packet.

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