Java Networking

Java Networking

TCP/IP Socket
UDP Socket
URL(HTTP) Connection

Protocals

TCP - Transmission Control Protocol

convert data into packets or vise versa
each packet contains stream of data in bytes
ensure the connection between parties

IP - Internet Protocal

identify the destination where the packet need to be sent

UDP - User Datagram Packet

using UDP there is no connection between the client and server
there’s no guarantee the message is arrived or received by the other party
HTTP(Hypertext Transfer Protocol)
FTP(File Transfer Protocol)
SMTP(Simple Mail Transfer Protocol)

TCP/IP Socket Example

Socket <=> ServerSocket <=> Socket

Classes

ServerSocket
     - Socket accept()

Socket
     - InputStream getInputStream()
     - OutputStream getOutputStream()

InetAddress
     - InetAddress getLocalHost()
     - InetAddress getByName(String)

java.io.DataOutputStream
     - void writeUTF()
	 
java.io.DataInputStream
     - String readUTF()

Steps

Server

create and start ServerSocket, specifying which port to use
(wait for client connection, connection complete)
start communication

import java.net.*;
import java.io.*;

try {
	ServerSocket serverSocket = new ServerSocket(port);
	Socket socket = serverSocket.accept();
	
	// Server receive data from Client
	DataInputStream in = new DataInputStream(socket.getInputStream());
	System.out.println(in.readUTF());
	
	// Server send data to Client
	DataOutputStream out = new DataOutputStream(socket.getOutputStream());
	out.writeUTF("server -> client: some output data");
	
	server.close();
} catch (IOException e1 || SocketTimeoutException e2) {...}

Client

create Socket, specifying server’s name and port -> then it will keep trying to connect the Server
(Server get client’s Socket object, establish connection)
start communication

import java.net.*;
import java.io.*;

try {
	Socket socket = new Socket(serverName, port);
	
	// Client send data to Server
	DataOutputStream out = new DataOutputStream(socket.getOutputStream());
	out.writeUTF("client -> server: some output data");
	
	// Client receive data from Server
	DataInputStream in = new DataInputStream(socket.getInputStream());
	System.out.println(in.readUTF());
	
	client.close();
} catch(IOException e) {...}

Java Networking

Protocals

TCP/IP Socket Example

Classes

Steps

Links