Echosamp consists of two subdirectories, an echo client (echoclnt)
and an echo server (echosrv), located in \TOOLKIT\SAMPLES\TCPIPTK\ECHOSAMP.

The echoclnt directory contains two samples of echo clients:

ECHOCLNT.C - is an echo client that uses one subroutine to handle
             both UDP requests and TCP requests.

ECHOCLST.C - is an echo client that uses separate subroutines to handle
             UDP requests and TCP requests.


This program implements the client side of the Echo protocol (RFC 862).  The
Echo protocol is very simple: whatever the client sends to the server, the
server will send right back to the client.  The complete RFC is reproduced
below:


Network Working Group                                          J. Postel
Request for Comments: 862                                            ISI
                                                                May 1983

                             Echo Protocol

This RFC specifies a standard for the ARPA Internet community.  Hosts on
the ARPA Internet that choose to implement an Echo Protocol are expected
to adopt and implement this standard.

A very useful debugging and measurement tool is an echo service.  An
echo service simply sends back to the originating source any data it
receives.

TCP Based Echo Service

   One echo service is defined as a connection based application on TCP.
   A server listens for TCP connections on TCP port 7.  Once a
   connection is established any data received is sent back.  This
   continues until the calling user terminates the connection.

UDP Based Echo Service

   Another echo service is defined as a datagram based application on
   UDP.  A server listens for UDP datagrams on UDP port 7.  When a
   datagram is received, the data from it is sent back in an answering
   datagram.


Following are details on building and executing the echo server samples.

   1. To compile and link the sample programs, type:

        nmake -f vacpp.mak         (to build using the VisualAge C/C++ compiler)

    2. Executing echoclnt.exe and echoc1st.exe:

       ***note before executing the an echo client, the server must be active
       on the destination host.

       a. To execute the echoclnt.exe client, type:

          echoclnt TCP hostname   (using the TCP protocol)
          echoclnt UDP hostname   (using the UDP protocol)

          Then any data typed in the client OS/2 session will be echoed from the server.

       b. To execute the echoc1st.exe client, type:

          echoc1st TCP hostname   (using the TCP protocol)
          echoc1st UDP hostname   (using the UDP protocol)

          Then, any data typed in the client OS/2 session will be echoed from the server.
