12. Echo Class

The echo class implements RFC 862. An echo object, as a client, will get back what ever data it sends to an echo server. Similarly, an echo object, as a server, will echo back the data it receives from its client.

The echo class is derived from protocol class, and uses echo::echobuf as its stream buffer. echo::echobuf is in turn is derived from protocol::protcolbuf.

In what follows,

• e is a echo object.
• pname is a transport protocol name and must be either protocol::tcp or protocol::udp.

echo e (pname)

constructs the echo object, e with pname as its transport protocol name.

echo::operator -> ()

an echo object is a smart pointer for the underlying echobuf.

12.0.1 tsecho.C

// echo server. Serves clients at port 4000.
#include <echo.h>
#include <stdlib.h>

int main ()
{
  echo server (protocol::tcp);
  server->serve_clients (4000);
  return 1;
}

12.0.2 tcecho.C

// echo client. Sends "mary had a litte lamb" to the server
#include <echo.h>
#include <stdlib.h>

int main ()
{
  echo e(protocol::tcp);

  e->connect ("kelvin.seas.virginia.edu", 4000);

  cout << e->rfc_name () << ' ' << e->rfc_doc () << endl;

  e << "mary had a little lamb\r\n" << flush;

  char buf [256];
  e.getline (buf, 255);

  cout << "got back: " << buf << endl;
  return 0;
}