HP X.25/9000 Programmer's Guide

34 Chapter3

Establishing and Terminating a Socket Connection

Connection Establishment for the Client Process

Connection Establishment for the Client

Process

This section discusses the system calls which the client process must

make to establish an SVC with a server process. There are two

mandatory steps:

1. Create a socket using the socket() call.

2. Make a connection request using the connect() call.

These steps are described below.

Creating a Socket

This is similar to the server process. The client process must also use the

socket() call to create a BSD IPC socket (communications endpoint).

The socket must be created before the connect() call is executed.

For a client, the socket() call and its parameters are identical to those

used by the server when it creates a socket. See “Syntax for socket()”

above.

The socket descriptor for the newly-created socket should be included in

the connect() system call and (after the connection is established) in all

subsequent data transmission.

Refer to the socket(2) entry in your man pages for more information.

Requesting a Connection

The client process requests a connection with the connect() call. The

server must be prepared to service a CALL INDICATION packet (with

an active listen socket) when connect() is executed.

The client process speciﬁes the X.121 address, subaddress, and protocol

ID of the server with which it wants to establish an SVC using the

connect() call. HP does not provide a programmatic method for getting

this addressing information. It must be acquired from an authority

associated with the remote host. When a connect() system call is

issued, X.25 sends a CALL REQUEST packet with the speciﬁed

addressing information.

36960-90061.bk Page 34 Friday, November 10, 2000 3:42 PM