User`s guide

DAK

KwikNet Overview

Client - Server Using TCP Sockets

This example illustrates the use of KwikNet's TCP/IP socket interface to establish a

connection between two end points for the reliable transfer of data. Although the end

points happen to be tasks running on the same host computer, the actions required by

each are still the same as would be required if they resided on separate hosts

interconnected by a real network.

The server's first scenario is embodied in function server1(). The corresponding

function executed by the client is client1().

The server calls kn_socket() to create a streaming socket. The server calls

kn_setsockopt() to revise the socket's attributes to permit the eventual reuse of the

unique server port number of 5001. The server calls

kn_setsockopt() again to force its

socket to be non-blocking. It then calls

kn_bind() to bind itself to the socket,

identifying itself as port 5001, but allowing

KwikNet to assign its IP address. KwikNet

assigns IP address 192.168.1.73, the IP address of the only network present in the sample

configuration. The server then calls kn_listen() to prime the socket to listen for

incoming connection requests. Finally, the server calls kn_accept() to wait for such a

connection to be established. KwikNet gives the server a new socket which corresponds to

the server's end of the connection to its client.

Once the connection with the client has been made, the server uses procedure kn_recv()

to receive a 4 byte message, a long value which defines the length of a block of data

which the client intends to send to the server.

The server uses kn_send() to echo the 4 byte value back to the client as an

acknowledgement that the server is prepared to accept that amount of data from the

client. Then the server calls kn_recv() to acquire the data block from the client and

kn_send() to echo the data block back to the client.

Once the data has been echoed to the client, the server uses kn_shutdown() to terminate

all send operations on its connected socket and then repetitively calls kn_recv() until all

unexpected data, if any, from the client has been discarded. The connected socket and

the socket used for listening are then closed using

kn_close().