tcp_socket, tcp_connection_server

To establish TCP socket communication, use the os_tcp_socket and os_tcp_connection_server classes. The following sequence describes how communication is established between a client and a server.

The server process constructs an os_tcp_connection_server and binds it to an address that is known to the server process' clients.
The server process creates an os_tcp_socket on an arbitrary port. This is the server endpoint for the final connection.
The os_tcp_connection_server in the server process waits for an incoming connection request using accept() and passes accept() a reference to the os_tcp_socket created in step 2.
The client process creates an os_tcp_socket on an arbitrary port.
The client process uses connect_to() to connect the os_tcp_socket to the os_tcp_connection_server.
The two os_tcp_socket objects, created in step 2 and step 4, are connected. This connection returns accept() in the server process and returns connect_to() in the client process. Any data written to the server socket appears as input to the client socket; any data written to the client socket appears as input to the server socket. Because stream communication is reliable, the sender is notified if any bytes sent are not received.

After communication is established, the server can issue another accept() command to the connection server and then wait for additional clients. A typical server often spawns a thread to service a client connection; then the server quickly returns to accept another connection.

The following example illustrates simple TCP communications between a client and a server. The first program, socket1s.cpp, is the server. The server process creates a connection server and waits for the client to request a connection. The second program, socket1c.cpp, is the client. The client process connects to the server process and sends it a simple text string.

Example <ospace/network/examples/socket1s.cpp>


  // Example socket1 server.

#include <iostream>
#include <ospace/network.h>

void
main()
  {
  os_network_toolkit initialize;

  // Create connection server with well-known port on local host.
  os_tcp_connection_server server( os_socket_address( 3000 ) );

  os_tcp_socket socket;
  server.accept( socket ); // Accept incoming connection.
  cout << "Server accepts connection from: " << endl;
  cout << "  " << socket.peer_address() << endl;

  // Echo text till end of input.
  char buffer[ 100 ];
  int result = socket.read( buffer, sizeof( buffer ) );
  buffer[ result ] = 0; // Null terminate result.
  cout << "Server read: " << buffer << endl;
  }

Server accepts connection from:
  os_socket_address( os_ip_address( 128.200.51.1 ), port 46283 )
Server read: hello there

Example <ospace/network/examples/socket1c.cpp>


  // Example socket1 client.

#include <iostream>
#include <ospace/network.h>

void
main()
  {
  os_network_toolkit initialize;

  // Create with unique system assigned port number.
  os_tcp_socket socket;

  // Connect to server on my host.
  socket.connect_to( os_socket_address( 3000 ) );
  cout << "Client connected to: " << endl;
  cout << "  " << socket.peer_address() << endl;
  cout << "Client sends: hello there" << endl;
  socket.write( "hello there", 11 );
  }

Client connected to:
  os_socket_address( os_ip_address( 128.200.51.1 ), port 3000 )
Client sends: hello there