From 4a06626c8ade9b9a300681db78453245c522e442 Mon Sep 17 00:00:00 2001
From: Sebastian Rieger <sebastian.rieger@informatik.hs-fulda.de>
Date: Wed, 31 Oct 2018 17:46:32 +0100
Subject: [PATCH] reusable sockets demo

---
 .../socket/reuse/TCPServerReuse.java          | 44 +++++++++++++++++++
 .../socket/reuse/UDPServerReuse.java          | 36 +++++++++++++++
 2 files changed, 80 insertions(+)
 create mode 100644 VerteilteSysteme-Examples/src/verteiltesysteme/socket/reuse/TCPServerReuse.java
 create mode 100644 VerteilteSysteme-Examples/src/verteiltesysteme/socket/reuse/UDPServerReuse.java

diff --git a/VerteilteSysteme-Examples/src/verteiltesysteme/socket/reuse/TCPServerReuse.java b/VerteilteSysteme-Examples/src/verteiltesysteme/socket/reuse/TCPServerReuse.java
new file mode 100644
index 0000000..5eb2a52
--- /dev/null
+++ b/VerteilteSysteme-Examples/src/verteiltesysteme/socket/reuse/TCPServerReuse.java
@@ -0,0 +1,44 @@
+/* Angelehnt an Kurose/Ross Computernetzwerke (bis 5e Java, ab 6e Python) */
+
+package verteiltesysteme.socket.reuse;
+
+import java.io.*;
+import java.net.*;
+
+class TCPServerReuse {
+	public static void main(String argv[]) throws Exception {
+		int tcpPort = 36037;
+		String clientSentence;
+		String capitalizedSentence;
+
+		// Server-Socket erzeugen
+		@SuppressWarnings("resource")
+		ServerSocket welcomeSocket = new ServerSocket();
+		// erlaubt das Wiederverwenden von Sockets, die für die individuellen Clients genutzt werden, auch wenn der Port nocht im Status "TIME_WAIT" ist
+		welcomeSocket.setReuseAddress(true);
+		welcomeSocket.bind(new InetSocketAddress(tcpPort));
+		
+		System.out.println("TCP Server started. Waiting for incoming requests... (reuseAddress="+welcomeSocket.getReuseAddress()+", timeout="+welcomeSocket.getSoTimeout() +", buffersize="+welcomeSocket.getReceiveBufferSize()+")");
+		
+		while (true) {
+			Socket connectionSocket = welcomeSocket.accept();
+
+			System.out.println("Received request from client " + connectionSocket.getInetAddress() + ":" + connectionSocket.getPort() + " generating response...");
+			
+			BufferedReader inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
+			DataOutputStream outToClient = new DataOutputStream(connectionSocket.getOutputStream());
+
+			// Try/Catch hinzugefügt, nachdem bei Einsatz Amazon AWS (Healthcheck des ELB) clientSentence null war  
+			try {
+				clientSentence = inFromClient.readLine();
+				if (clientSentence != null) {
+					capitalizedSentence = clientSentence.toUpperCase() + '\n';
+					outToClient.writeBytes(capitalizedSentence);
+				}
+			} catch (IOException ioe) {
+				ioe.printStackTrace();
+			}
+			connectionSocket.close();
+		}
+	}
+}
diff --git a/VerteilteSysteme-Examples/src/verteiltesysteme/socket/reuse/UDPServerReuse.java b/VerteilteSysteme-Examples/src/verteiltesysteme/socket/reuse/UDPServerReuse.java
new file mode 100644
index 0000000..52d15b7
--- /dev/null
+++ b/VerteilteSysteme-Examples/src/verteiltesysteme/socket/reuse/UDPServerReuse.java
@@ -0,0 +1,36 @@
+/* Angelehnt an Kurose/Ross Computernetzwerke (bis 5e Java, ab 6e Python) */
+
+package verteiltesysteme.socket.reuse;
+
+import java.net.*;
+
+class UDPServerReuse {
+	public static void main(String args[]) throws Exception {
+		int udpPort = 36037;
+		@SuppressWarnings("resource")
+		DatagramSocket serverSocket = new DatagramSocket(null);
+		// erlaubt das Wiederverwenden des Ports, mehrere Server-Prozesse können gleichen Port nutzen
+		serverSocket.setReuseAddress(true);
+		serverSocket.bind(new InetSocketAddress(udpPort));
+		byte[] receiveData = new byte[1024];
+		byte[] sendData = new byte[1024];
+
+		System.out.println("UDP Server started. Waiting for incoming requests... (reuseAddress="+serverSocket.getReuseAddress()+", timeout="+serverSocket.getSoTimeout() +", buffersize="+serverSocket.getReceiveBufferSize()+")");
+		
+		while (true) {
+			DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
+			serverSocket.receive(receivePacket);
+			String sentence = new String(receivePacket.getData(), 0, receivePacket.getLength());
+
+			InetAddress IPAddress = receivePacket.getAddress();
+			int clientSrcPort = receivePacket.getPort();
+
+			System.out.println("Received request from client " + IPAddress + ":" + clientSrcPort + " generating response...");
+			
+			String capitalizedSentence = sentence.toUpperCase();
+			sendData = capitalizedSentence.getBytes();
+			DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, clientSrcPort);
+			serverSocket.send(sendPacket);
+		}
+	}
+}