fixed Method Initializing. Setting Datafields serverAddress and serverPort.

#24

client/src/main/java/ch/zhaw/pm2/multichat/client/ChatWindowController.java

@@ -1,7 +1,8 @@
 package ch.zhaw.pm2.multichat.client;
 
-import ch.zhaw.pm2.multichat.client.ClientConnectionHandler.State;
+import ch.zhaw.pm2.multichat.protocol.ConnectionHandler.State;
 import ch.zhaw.pm2.multichat.protocol.ChatProtocolException;
+import ch.zhaw.pm2.multichat.protocol.ConnectionHandler;
 import ch.zhaw.pm2.multichat.protocol.NetworkHandler;
 import javafx.application.Platform;
 import javafx.beans.value.ChangeListener;
@@ -15,10 +16,8 @@ import javafx.scene.layout.Pane;
 import javafx.stage.WindowEvent;
 
 import java.io.IOException;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
-import static ch.zhaw.pm2.multichat.client.ClientConnectionHandler.State.*;
+import static ch.zhaw.pm2.multichat.protocol.ConnectionHandler.State.*;
 
 public class ChatWindowController {
     private ClientConnectionHandler connectionHandler;
@@ -48,8 +47,12 @@ public class ChatWindowController {
         messageListener();
     }
 
+    public void setConnectionHandler(ClientConnectionHandler connectionHandler){
+        this.connectionHandler = connectionHandler;
+    }
+
     private void applicationClose() {
-        connectionHandler.setState(DISCONNECTED);
+        disconnect();
     }
 
     @FXML
@@ -109,9 +112,7 @@ public class ChatWindowController {
         if(!userName.contains(" ")) {
             String serverAddress = serverAddressField.getText();
             int serverPort = Integer.parseInt(serverPortField.getText());
-            connectionHandler = new ClientConnectionHandler(
-                    NetworkHandler.openConnection(serverAddress, serverPort), userName,
-                    messages);
+            connectionHandler.initialize(serverAddress, serverPort, userName);
             new Thread(connectionHandler).start();
 
             //register Listener
@@ -124,15 +125,6 @@ public class ChatWindowController {
         }
     }
 
-    private void terminateConnectionHandler() {
-        // unregister window close handler
-        rootPane.getScene().getWindow().removeEventHandler(WindowEvent.WINDOW_CLOSE_REQUEST, windowCloseHandler);
-        if (connectionHandler != null) {
-            connectionHandler.stopReceiving();
-            connectionHandler = null;
-        }
-    }
-
     public void stateChanged(State newState) {
         // update UI (need to be run in UI thread: see Platform.runLater())
         Platform.runLater(new Runnable() {
@@ -141,8 +133,8 @@ public class ChatWindowController {
                 connectButton.setText((newState == CONNECTED || newState == CONFIRM_DISCONNECT) ? "Disconnect" : "Connect");
             }
         });
-        if (newState == DISCONNECTED) {
-            terminateConnectionHandler();
+        if(newState == DISCONNECTED){
+            connectionHandler.stopReceiving();
         }
     }
 

client/src/main/java/ch/zhaw/pm2/multichat/client/ClientConnectionHandler.java

@@ -1,6 +1,7 @@
 package ch.zhaw.pm2.multichat.client;
 
 import ch.zhaw.pm2.multichat.protocol.ChatProtocolException;
+import ch.zhaw.pm2.multichat.protocol.ConnectionHandler;
 import ch.zhaw.pm2.multichat.protocol.NetworkHandler;
 import javafx.beans.property.SimpleIntegerProperty;
 import javafx.beans.property.SimpleObjectProperty;
@@ -12,21 +13,9 @@ import java.net.SocketException;
 import java.util.Scanner;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import static ch.zhaw.pm2.multichat.protocol.ConnectionHandler.State.*;
 
-import static ch.zhaw.pm2.multichat.client.ClientConnectionHandler.State.*;
-
-public class ClientConnectionHandler implements Runnable {
-    private final NetworkHandler.NetworkConnection<String> connection;
-
-    // Data types used for the Chat Protocol
-    private static final String DATA_TYPE_CONNECT = "CONNECT";
-    private static final String DATA_TYPE_CONFIRM = "CONFIRM";
-    private static final String DATA_TYPE_DISCONNECT = "DISCONNECT";
-    private static final String DATA_TYPE_MESSAGE = "MESSAGE";
-    private static final String DATA_TYPE_ERROR = "ERROR";
-
-    public static final String USER_NONE = "";
-    public static final String USER_ALL = "*";
+public class ClientConnectionHandler extends ConnectionHandler implements Runnable {
 
     private final Pattern messagePattern = Pattern.compile( "^(?:@(\\S*))?\\s*(.*)$" );
 
@@ -36,21 +25,27 @@ public class ClientConnectionHandler implements Runnable {
     private SimpleStringProperty serverAddress;
     private SimpleIntegerProperty serverPort;
 
-    enum State {
-        NEW, CONFIRM_CONNECT, CONNECTED, CONFIRM_DISCONNECT, DISCONNECTED;
-    }
-
-    public ClientConnectionHandler(NetworkHandler.NetworkConnection<String> connection,
-                                   String userName,
-                                   ClientMessageList messages)  {
-        this.connection = connection;
-        this.userName = new SimpleStringProperty((userName == null || userName.isBlank())? USER_NONE : userName);
+    public ClientConnectionHandler(ClientMessageList messages)  {
+        super();
         this.messages = messages;
-        state = new SimpleObjectProperty<>(NEW);
+        state = new SimpleObjectProperty<>(State.NEW);
         serverAddress = new SimpleStringProperty();
         serverPort = new SimpleIntegerProperty();
     }
 
+    public void initialize(String serverAddress, int serverPort, String userName) throws IOException {
+        this.state = new SimpleObjectProperty<>(NEW);
+        this.serverAddress = new SimpleStringProperty(serverAddress);
+        this.serverPort = new SimpleIntegerProperty(serverPort);
+        this.userName = new SimpleStringProperty((userName == null || userName.isBlank())? USER_NONE : userName);
+        try {
+            setConnection(NetworkHandler.openConnection(this.serverAddress.get(), this.serverPort.get()));
+        } catch (IOException e) {
+            messages.addMessage(new Message(Message.MessageType.ERROR,null,null,e.getMessage()));
+            System.out.println("ERROR: " + e.getMessage());
+        }
+    }
+
     public SimpleStringProperty getServerAddressProperty() { return serverAddress; }
 
     public SimpleIntegerProperty getServerPortProperty() { return serverPort; }
@@ -69,12 +64,12 @@ public class ClientConnectionHandler implements Runnable {
         startReceiving();
     }
 
-    public void startReceiving() {
+    private void startReceiving() {
         System.out.println("Starting Connection Handler");
         try {
             System.out.println("Start receiving data...");
-            while (connection.isAvailable()) {
-                String data = connection.receive();
+            while (getConnection().isAvailable()) {
+                String data = getConnection().receive();
                 processData(data);
             }
             System.out.println("Stopped recieving data");
@@ -98,7 +93,7 @@ public class ClientConnectionHandler implements Runnable {
         System.out.println("Closing Connection Handler to Server");
         try {
             System.out.println("Stop receiving data...");
-            connection.close();
+            getConnection().close();
             System.out.println("Stopped receiving data.");
         } catch (IOException e) {
             System.err.println("Failed to close connection." + e.getMessage());
@@ -133,13 +128,13 @@ public class ClientConnectionHandler implements Runnable {
                 payload = scanner.nextLine();
             }
             // dispatch operation based on type parameter
-            if (type.equals(DATA_TYPE_CONNECT)) {
+            if (type.equals(getDataTypeConnect())) {
                 System.err.println("Illegal connect request from server");
-            } else if (type.equals(DATA_TYPE_CONFIRM)) {
+            } else if (type.equals(getDataTypeConfirm())) {
                 if (state.get() == CONFIRM_CONNECT) {
                     this.userName.set(reciever);
-                    this.serverPort.set(connection.getRemotePort());
-                    this.serverAddress.set(connection.getRemoteHost());
+                    this.serverPort.set(getConnection().getRemotePort());
+                    this.serverAddress.set(getConnection().getRemoteHost());
                     messages.addMessage(new Message(Message.MessageType.INFO,sender,reciever,payload));
                     System.out.println("CONFIRM: " + payload);
                     this.setState(CONNECTED);
@@ -150,7 +145,7 @@ public class ClientConnectionHandler implements Runnable {
                 } else {
                     System.err.println("Got unexpected confirm message: " + payload);
                 }
-            } else if (type.equals(DATA_TYPE_DISCONNECT)) {
+            } else if (type.equals(getDataTypeDisconnect())) {
                 if (state.get() == DISCONNECTED) {
                     System.out.println("DISCONNECT: Already in disconnected: " + payload);
                     return;
@@ -158,14 +153,14 @@ public class ClientConnectionHandler implements Runnable {
                 messages.addMessage(new Message(Message.MessageType.INFO,sender,reciever,payload));
                 System.out.println("DISCONNECT: " + payload);
                 this.setState(DISCONNECTED);
-            } else if (type.equals(DATA_TYPE_MESSAGE)) {
+            } else if (type.equals(getDataTypeMessage())) {
                 if (state.get() != CONNECTED) {
                     System.out.println("MESSAGE: Illegal state " + state + " for message: " + payload);
                     return;
                 }
                 messages.addMessage(new Message(Message.MessageType.MESSAGE,sender,reciever,payload));
                 System.out.println("MESSAGE: From " + sender + " to " + reciever + ": "+  payload);
-            } else if (type.equals(DATA_TYPE_ERROR)) {
+            } else if (type.equals(getDataTypeError())) {
                 messages.addMessage(new Message(Message.MessageType.ERROR,sender,reciever,payload));
                 System.out.println("ERROR: " + payload);
             } else {
@@ -173,12 +168,12 @@ public class ClientConnectionHandler implements Runnable {
             }
         } catch (ChatProtocolException e) {
             System.err.println("Error while processing data: " + e.getMessage());
-            sendData(USER_NONE, userName.get(), DATA_TYPE_ERROR, e.getMessage());
+            sendData(USER_NONE, userName.get(), getDataTypeError(), e.getMessage());
         }
     }
 
-    public void sendData(String sender, String receiver, String type, String payload) {
-        if (connection.isAvailable()) {
+    private void sendData(String sender, String receiver, String type, String payload) {
+        if (getConnection().isAvailable()) {
             new StringBuilder();
             String data = new StringBuilder()
                 .append(sender+"\n")
@@ -187,7 +182,7 @@ public class ClientConnectionHandler implements Runnable {
                 .append(payload+"\n")
                 .toString();
             try {
-                connection.send(data);
+                getConnection().send(data);
             } catch (SocketException e) {
                 System.err.println("Connection closed: " + e.getMessage());
             } catch (EOFException e) {
@@ -200,13 +195,13 @@ public class ClientConnectionHandler implements Runnable {
 
     public void connect() throws ChatProtocolException {
         if (state.get() != NEW) throw new ChatProtocolException("Illegal state for connect: " + state);
-        this.sendData(userName.get(), USER_NONE, DATA_TYPE_CONNECT,null);
+        this.sendData(userName.get(), USER_NONE, getDataTypeConnect(),null);
         this.setState(CONFIRM_CONNECT);
     }
 
     public void disconnect() throws ChatProtocolException {
         if (state.get() != NEW && state.get() != CONNECTED) throw new ChatProtocolException("Illegal state for disconnect: " + state);
-        this.sendData(userName.get(), USER_NONE, DATA_TYPE_DISCONNECT,null);
+        this.sendData(userName.get(), USER_NONE, getDataTypeDisconnect(),null);
         this.setState(CONFIRM_DISCONNECT);
     }
 
@@ -221,7 +216,7 @@ public class ClientConnectionHandler implements Runnable {
                 return false;
             }
             if (receiver == null || receiver.isBlank()) receiver = ClientConnectionHandler.USER_ALL;
-            this.sendData(userName.get(), receiver, DATA_TYPE_MESSAGE,message);
+            this.sendData(userName.get(), receiver, getDataTypeMessage(),message);
             return true;
         } else {
             return false;

client/src/main/java/ch/zhaw/pm2/multichat/client/ClientUI.java

@@ -8,6 +8,7 @@ import javafx.stage.Stage;
 
 public class ClientUI extends Application {
     private ClientMessageList clientMessageList = new ClientMessageList();
+    private ClientConnectionHandler connectionHandler = new ClientConnectionHandler(clientMessageList);
 
     @Override
     public void start(Stage primaryStage) {
@@ -21,6 +22,7 @@ public class ClientUI extends Application {
 
             ChatWindowController chatWindowController = loader.getController();
             chatWindowController.setMessages(clientMessageList);
+            chatWindowController.setConnectionHandler(connectionHandler);
 
             // fill in scene and stage setup
             Scene scene = new Scene(rootPane);

protocol/src/main/java/ch/zhaw/pm2/multichat/protocol/ConnectionHandler.java

@@ -0,0 +1,47 @@
+package ch.zhaw.pm2.multichat.protocol;
+
+public abstract class ConnectionHandler {
+    private NetworkHandler.NetworkConnection<String> connection;
+
+    // Data types used for the Chat Protocol
+    private static final String DATA_TYPE_CONNECT = "CONNECT";
+    private static final String DATA_TYPE_CONFIRM = "CONFIRM";
+    private static final String DATA_TYPE_DISCONNECT = "DISCONNECT";
+    private static final String DATA_TYPE_MESSAGE = "MESSAGE";
+    private static final String DATA_TYPE_ERROR = "ERROR";
+
+    public static final String USER_NONE = "";
+    public static final String USER_ALL = "*";
+
+    public enum State {
+        NEW, CONFIRM_CONNECT, CONNECTED, CONFIRM_DISCONNECT, DISCONNECTED, ERROR;
+    }
+
+    public static String getDataTypeConnect() {
+        return DATA_TYPE_CONNECT;
+    }
+
+    public static String getDataTypeConfirm() {
+        return DATA_TYPE_CONFIRM;
+    }
+
+    public static String getDataTypeDisconnect() {
+        return DATA_TYPE_DISCONNECT;
+    }
+
+    public static String getDataTypeMessage() {
+        return DATA_TYPE_MESSAGE;
+    }
+
+    public static String getDataTypeError() {
+        return DATA_TYPE_ERROR;
+    }
+
+    public NetworkHandler.NetworkConnection<String> getConnection() {
+        return connection;
+    }
+
+    protected void setConnection(NetworkHandler.NetworkConnection<String> connection) {
+        this.connection = connection;
+    }
+}

server/src/main/java/ch/zhaw/pm2/multichat/server/Server.java

@@ -1,11 +1,14 @@
 package ch.zhaw.pm2.multichat.server;
 
+import ch.zhaw.pm2.multichat.protocol.ConnectionHandler;
 import ch.zhaw.pm2.multichat.protocol.NetworkHandler;
 
 import java.io.IOException;
 import java.net.SocketException;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.ReentrantLock;
 
 
 public class Server {
@@ -62,23 +65,40 @@ public class Server {
     }
 
     private void start() {
+        ReentrantLock mutex = new ReentrantLock();
+        Condition nameComplete = mutex.newCondition();
         System.out.println("Server started.");
         try {
             while (true) {
                  NetworkHandler.NetworkConnection<String> connection = networkServer.waitForConnection();
-                 ServerConnectionHandler connectionHandler = new ServerConnectionHandler(connection, connections);
+                 ServerConnectionHandler connectionHandler = new ServerConnectionHandler(connection, connections, mutex, nameComplete);
                  new Thread(connectionHandler).start();
-                 System.out.println(String.format("Connected new Client %s with IP:Port <%s:%d>",
-                     connectionHandler.getUserName(),
-                     connection.getRemoteHost(),
-                     connection.getRemotePort()
-                 ));
+                 mutex.lock();
+                 try {
+                     nameComplete.await();
+                     if(connectionHandler.getState() == ConnectionHandler.State.ERROR) {
+                         System.out.println(String.format("Connecting failed for new Client with IP:Port <%s:%d>.\nReason: Name already taken.",
+                                 connection.getRemoteHost(),
+                                 connection.getRemotePort()));
+                     }
+                     else {
+                         System.out.println(String.format("Connected new Client %s with IP:Port <%s:%d>",
+                                 connectionHandler.getUserName(),
+                                 connection.getRemoteHost(),
+                                 connection.getRemotePort()));
+                     }
+                 }
+                finally {
+                     mutex.unlock();
+                 }
             }
         } catch(SocketException e) {
             System.out.println("Server connection terminated");
         }
         catch (IOException e) {
             System.err.println("Communication error " + e);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
         }
         // close server
         System.out.println("Server Stopped.");

server/src/main/java/ch/zhaw/pm2/multichat/server/ServerConnectionHandler.java

@@ -1,6 +1,8 @@
 package ch.zhaw.pm2.multichat.server;
 
 import ch.zhaw.pm2.multichat.protocol.ChatProtocolException;
+import ch.zhaw.pm2.multichat.protocol.ConnectionHandler;
+import static ch.zhaw.pm2.multichat.protocol.ConnectionHandler.State.*;
 import ch.zhaw.pm2.multichat.protocol.NetworkHandler;
 
 import java.io.EOFException;
@@ -11,24 +13,19 @@ import java.util.Map;
 import java.util.Objects;
 import java.util.Scanner;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.ReentrantLock;
 
-import static ch.zhaw.pm2.multichat.server.ServerConnectionHandler.State.*;
 
-public class ServerConnectionHandler implements Runnable{
+
+public class ServerConnectionHandler extends ConnectionHandler implements Runnable{
     private static final AtomicInteger connectionCounter = new AtomicInteger(0);
     private final int connectionId = connectionCounter.incrementAndGet();
-    private final NetworkHandler.NetworkConnection<String> connection;
     private final Map<String,ServerConnectionHandler> connectionRegistry;
 
-    // Data types used for the Chat Protocol
-    private static final String DATA_TYPE_CONNECT = "CONNECT";
-    private static final String DATA_TYPE_CONFIRM = "CONFIRM";
-    private static final String DATA_TYPE_DISCONNECT = "DISCONNECT";
-    private static final String DATA_TYPE_MESSAGE = "MESSAGE";
-    private static final String DATA_TYPE_ERROR = "ERROR";
+    private ReentrantLock mutex;
 
-    private static final String USER_NONE = "";
-    private static final String USER_ALL = "*";
+    private Condition nameComplete;
 
     private String userName = "Anonymous-"+connectionId;
     private State state = NEW;
@@ -38,52 +35,60 @@ public class ServerConnectionHandler implements Runnable{
         startReceiving();
     }
 
-    enum State {
-        NEW, CONNECTED, DISCONNECTED;
-    }
-
     public ServerConnectionHandler(NetworkHandler.NetworkConnection<String> connection,
-                                   Map<String,ServerConnectionHandler> registry) {
+                                   Map<String,ServerConnectionHandler> registry, ReentrantLock mutex, Condition nameComplete) {
+        super();
+        setConnection(connection);
         Objects.requireNonNull(connection, "Connection must not be null");
         Objects.requireNonNull(registry, "Registry must not be null");
-        this.connection = connection;
         this.connectionRegistry = registry;
+        this.mutex = mutex;
+        this.nameComplete = nameComplete;
     }
 
     public String getUserName() {
         return this.userName;
     }
 
-    public void startReceiving() {
-        System.out.println("Starting Connection Handler for new User");
-        try {
-            System.out.println("Start receiving data...");
-            while (connection.isAvailable()) {
-                String data = connection.receive();
-                processData(data);
-            }
-            System.out.println("Stopped recieving data");
-        } catch (SocketException e) {
-            System.out.println("Connection terminated locally");
-            connectionRegistry.remove(userName);
-            System.out.println("Unregistered because client connection terminated: " + userName + " " + e.getMessage());
-        } catch (EOFException e) {
-            System.out.println("Connection terminated by remote");
-            connectionRegistry.remove(userName);
-            System.out.println("Unregistered because client connection terminated: " + userName + " " + e.getMessage());
-        } catch(IOException e) {
-            System.err.println("Communication error: " + e);
-        } catch(ClassNotFoundException e) {
-            System.err.println("Received object of unknown type: " + e.getMessage());
-        }
-        System.out.println("Stopping Connection Handler for " + userName);
+    public State getState() {
+        return state;
     }
 
-    public void stopReceiving() {
+    private void startReceiving() {
+            System.out.println("Starting Connection Handler for new User");
+            try {
+                System.out.println("Start receiving data...");
+                while (getConnection().isAvailable() && !(state == ERROR)) {
+                    String data = getConnection().receive();
+                    processData(data);
+                }
+                System.out.println("Stopped recieving data");
+            } catch (SocketException e) {
+                System.out.println("Connection terminated locally");
+                connectionRegistry.remove(userName);
+                System.out.println("Unregistered because client connection terminated: " + userName + " " + e.getMessage());
+            } catch (EOFException e) {
+                System.out.println("Connection terminated by remote");
+                connectionRegistry.remove(userName);
+                System.out.println("Unregistered because client connection terminated: " + userName + " " + e.getMessage());
+            } catch (IOException e) {
+                System.err.println("Communication error: " + e);
+            } catch (ClassNotFoundException e) {
+                System.err.println("Received object of unknown type: " + e.getMessage());
+            }
+        if (state == ERROR) {
+            System.out.println("Stopping Connection Handler for Rejected Client");
+        } else {
+            System.out.println("Stopping Connection Handler for " + userName);
+        }
+
+    }
+
+    private void stopReceiving() {
         System.out.println("Closing Connection Handler for " + userName);
         try {
             System.out.println("Stop receiving data...");
-            connection.close();
+            getConnection().close();
             System.out.println("Stopped receiving data.");
         } catch (IOException e) {
             System.err.println("Failed to close connection." + e);
@@ -119,27 +124,43 @@ public class ServerConnectionHandler implements Runnable{
             }
 
             // dispatch operation based on type parameter
-            if (type.equals(DATA_TYPE_CONNECT)) {
+            if (type.equals(getDataTypeConnect())) {
                 if (this.state != NEW) throw new ChatProtocolException("Illegal state for connect request: " + state);
                 if (sender == null || sender.isBlank()) sender = this.userName;
-                if (connectionRegistry.containsKey(sender))
+                if (connectionRegistry.containsKey(sender)) {
+                    mutex.lock();
+                    try {
+                        state = ERROR;
+                        nameComplete.signal();
+                    }
+                    finally {
+                        mutex.unlock();
+                    }
                     throw new ChatProtocolException("User name already taken: " + sender);
-                this.userName = sender;
+                }
+                mutex.lock();
+                try {
+                    this.userName = sender;
+                    nameComplete.signal();
+                }
+                finally {
+                    mutex.unlock();
+                }
                 connectionRegistry.put(userName, this);
-                sendData(USER_NONE, userName, DATA_TYPE_CONFIRM, "Registration successfull for " + userName);
+                sendData(USER_NONE, userName, getDataTypeConfirm(), "Registration successfull for " + userName);
                 this.state = CONNECTED;
-            } else if (type.equals(DATA_TYPE_CONFIRM)) {
+            } else if (type.equals(getDataTypeConfirm())) {
                 System.out.println("Not expecting to receive a CONFIRM request from client");
-            } else if (type.equals(DATA_TYPE_DISCONNECT)) {
+            } else if (type.equals(getDataTypeDisconnect())) {
                 if (state == DISCONNECTED)
                     throw new ChatProtocolException("Illegal state for disconnect request: " + state);
                 if (state == CONNECTED) {
                     connectionRegistry.remove(this.userName);
                 }
-                sendData(USER_NONE, userName, DATA_TYPE_CONFIRM, "Confirm disconnect of " + userName);
+                sendData(USER_NONE, userName, getDataTypeConfirm(), "Confirm disconnect of " + userName);
                 this.state = DISCONNECTED;
                 this.stopReceiving();
-            } else if (type.equals(DATA_TYPE_MESSAGE)) {
+            } else if (type.equals(getDataTypeMessage())) {
                 if (state != CONNECTED) throw new ChatProtocolException("Illegal state for message request: " + state);
                 if (USER_ALL.equals(reciever)) {
                     for (ServerConnectionHandler handler : connectionRegistry.values()) {
@@ -153,23 +174,25 @@ public class ServerConnectionHandler implements Runnable{
                             sendData(sender, reciever, type, payload); //send message to sender if it's a direct message and sender is not receiver.
                         }
                     } else {
-                        this.sendData(USER_NONE, userName, DATA_TYPE_ERROR, "Unknown User: " + reciever);
+                        this.sendData(USER_NONE, userName, getDataTypeError(), "Unknown User: " + reciever);
                     }
                 }
-            } else if (type.equals(DATA_TYPE_ERROR)) {
+            } else if (type.equals(getDataTypeError())) {
                 System.err.println("Received error from client (" + sender + "): " + payload);
             } else {
                 System.err.println("Unknown data type received: " + type);
 
             }
         } catch(ChatProtocolException e) {
-            System.out.println("Error while processing data" + e.getMessage());
-            sendData(USER_NONE, userName, DATA_TYPE_ERROR, e.getMessage());
+            System.out.println("Error while processing data " + e.getMessage());
+            sendData(USER_NONE, userName, getDataTypeError(), e.getMessage());
         }
     }
 
-    public void sendData(String sender, String receiver, String type, String payload) {
-        if (connection.isAvailable()) {
+
+
+    private void sendData(String sender, String receiver, String type, String payload) {
+        if (getConnection().isAvailable()) {
             new StringBuilder();
             String data = new StringBuilder()
                 .append(sender+"\n")
@@ -178,7 +201,7 @@ public class ServerConnectionHandler implements Runnable{
                 .append(payload+"\n")
                 .toString();
             try {
-                connection.send(data);
+                getConnection().send(data);
             } catch (SocketException e) {
                 System.out.println("Connection closed: " + e.getMessage());
             } catch (EOFException e) {