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--- tanszek:oktatas:java_example_for_blocking_and_non-blocking_socket [2023/03/05 16:15] – knehez
+++ tanszek:oktatas:java_example_for_blocking_and_non-blocking_socket [2023/03/05 16:18] (current) – knehez
@@ Line 140: / Line 140: @@
 ==== Non-blocking TCP based sockets in Java ====
+The following Agent sends a message and waits for a response on port 8080, also with UDP. Older versions of the Eclipse IDE, the text you type on the console can be sent by pressing ctrl+z
+<code java>
+  package org.ait;
+  import java.io.BufferedReader;
+  import java.io.InputStreamReader;
+  import java.net.DatagramPacket;
+  import java.net.DatagramSocket;
+  import java.net.InetAddress;
+  public class UDPClient {
+	public static void main(String args[]) throws Exception {
+		BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
+		DatagramSocket clientSocket = new DatagramSocket();
+		InetAddress IPAddress = InetAddress.getByName("localhost");
+		byte[] sendData = new byte[1024];
+		byte[] receiveData = new byte[1024];
+		String sentence = inFromUser.readLine();
+		sendData = sentence.getBytes();
+		DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 8080);
+		clientSocket.send(sendPacket);
+		DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
+		clientSocket.receive(receivePacket);
+		String modifiedSentence = new String(receivePacket.getData());
+		System.out.println("converted:" + modifiedSentence);
+		clientSocket.close();
+	}
+	}
+</code>
+The UDP server waits for the agents messages on port 8080 and converts them to uppercase letters and sends them back to the client UDP socket.
+<code java>
+  package org.ait;
+  import java.net.DatagramPacket;
+  import java.net.DatagramSocket;
+  import java.net.InetAddress;
+  public class UDPServer {
+	public static void main(String args[]) throws Exception {
+		DatagramSocket serverSocket = new DatagramSocket(8080);
+		byte[] bytesReceived = new byte[1024];
+		byte[] bytesSent = new byte[1024];
+		DatagramPacket receivePacket = new DatagramPacket(bytesReceived, bytesReceived.length);
+		// here we are waiting for the packets
+		serverSocket.receive(receivePacket);
+		String textMessage = new String(receivePacket.getData());
+		System.out.println("I got: " + textMessage);
+		InetAddress IPAddress = receivePacket.getAddress();
+		int port = receivePacket.getPort();
+		String upperCaseText = textMessage.toUpperCase();
+		bytesSent = upperCaseText.getBytes();
+		// send back
+		DatagramPacket sendPacket = new DatagramPacket(bytesSent, bytesSent.length, IPAddress, port);
+		serverSocket.send(sendPacket);
+		serverSocket.close();
+	}
+  }
+</code>