0010. CSSocketClient

Client 소스는 좀더 간단하다. Server의 경우에는 Bind와 Listen의 절차를 거치고, Listen에서 BeginListen, EndListen으로
AsyncCallback을 통해야지 되지만, Client의 경우에는 간단히 Connect만으로 가능하고, 하나의 Client에서는 역시 하나의
연결정도만 신경을 쓰면 되기 때문에 더욱더 편한 개발이 가능하다.

솔찍한 생각으로 예제 소스이긴 하지만, UI단만 조금 붙여버리면 거의 일반 프로그램들과 큰 차이가 안보인다.
Socket의 Close시에 Shutdown으로 Socket을 정리하는 부분에 신경을 쓰면 될 것 같다.

/****************************** Module Header ******************************\
* Module Name:	Program.cs
* Project:		CSSocketClient
* Copyright (c) Microsoft Corporation.
* 
* Sockets are an application programming interface(API) in an operating system
* used for in inter-process communication. Sockets constitute a mechanism for
* delivering incoming data packets to the appropriate application process or
* thread, based on a combination of local and remote IP addresses and port
* numbers. Each socket is mapped by the operational system to a communicating
* application process or thread.
*
*
* .NET supplies a Socket class which implements the Berkeley sockets interface.
* It provides a rich set of methods and properties for network communications. 
* Socket class allows you to perform both synchronous and asynchronous data
* transfer using any of the communication protocols listed in the ProtocolType
* enumeration. It supplies the following types of socket:
*
* Stream: Supports reliable, two-way, connection-based byte streams without 
* the duplication of data and without preservation of boundaries.
*
* Dgram:Supports datagrams, which are connectionless, unreliable messages of
* a fixed (typically small) maximum length. 
*
* Raw: Supports access to the underlying transport protocol.Using the 
* SocketTypeRaw, you can communicate using protocols like Internet Control 
* Message Protocol (Icmp) and Internet Group Management Protocol (Igmp). 
*
* Rdm: Supports connectionless, message-oriented, reliably delivered messages, 
* and preserves message boundaries in data. 
*
* Seqpacket:Provides connection-oriented and reliable two-way transfer of 
* ordered byte streams across a network.
*
* Unknown:Specifies an unknown Socket type.
* 
* This source is subject to the Microsoft Public License.
* See http://www.microsoft.com/opensource/licenses.mspx#Ms-PL.
* All other rights reserved.
* 
* THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, 
* EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED 
* WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
\***************************************************************************/

#region Using directives
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Security;
using System.Security.Permissions;
#endregion


public class Program
{
    static void Main(string[] args)
    {
        // Receiving byte array 
        byte[] bytes = new byte[1024];
        try
        {
            // Create one SocketPermission for socket access restrictions
            SocketPermission permission = new SocketPermission(
                NetworkAccess.Connect,    // Connection permission
                TransportType.Tcp,        // Defines transport types
                "",                       // Gets the IP addresses
                SocketPermission.AllPorts // All ports
                );

            // Ensures the code to have permission to access a Socket
            permission.Demand();

            // Resolves a host name to an IPHostEntry instance           
            IPHostEntry ipHost = Dns.GetHostEntry("");

            // Gets first IP address associated with a localhost
            IPAddress ipAddr = ipHost.AddressList[0];

            // Creates a network endpoint
            IPEndPoint ipEndPoint = new IPEndPoint(ipAddr, 6000);

            // Create one Socket object to setup Tcp connection
            Socket sender = new Socket(
                ipAddr.AddressFamily,// Specifies the addressing scheme
                SocketType.Stream,   // The type of socket 
                ProtocolType.Tcp     // Specifies the protocols 
                );

            sender.NoDelay = true;   // Using the Nagle algorithm

            // Establishes a connection to a remote host
            sender.Connect(ipEndPoint);
            Console.WriteLine("Socket connected to {0}",
                sender.RemoteEndPoint.ToString());

            // Sending message
            // is the sign for end of data
            string theMessage = "Hello World!";
            byte[] msg = 
                Encoding.Unicode.GetBytes(theMessage +"");

            // Sends data to a connected Socket.
            int bytesSend = sender.Send(msg);

            // Receives data from a bound Socket.
            int bytesRec = sender.Receive(bytes);

            // Converts byte array to string
            theMessage = Encoding.Unicode.GetString(bytes, 0, bytesRec);

            // Continues to read the data till data isn't available
            while (sender.Available > 0)
            {
                bytesRec = sender.Receive(bytes);
                theMessage += Encoding.Unicode.GetString(bytes, 0, bytesRec);
            }
            Console.WriteLine("The server reply: {0}", theMessage);

            // Disables sends and receives on a Socket.
            sender.Shutdown(SocketShutdown.Both);

            //Closes the Socket connection and releases all resources
            sender.Close();
        }
        catch (Exception ex)
        {
            Console.WriteLine("Exception: {0}", ex.ToString());
        }
    }
}