fixed Method Initializing. Setting Datafields serverAddress and serverPort.

#24

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

@@ -2,6 +2,8 @@ package ch.zhaw.pm2.multichat.client;
 
 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;
 import javafx.beans.value.ObservableValue;
@@ -34,6 +36,12 @@ public class ChatWindowController {
     @FXML private TextField filterValue;
 
 
+    @FXML
+    public void initialize() {
+        serverAddressField.setText(NetworkHandler.DEFAULT_ADDRESS.getCanonicalHostName());
+        serverPortField.setText(String.valueOf(NetworkHandler.DEFAULT_PORT));
+    }
+
     public void setMessages(ClientMessageList messages) {
         this.messages = messages;
         messageListener();
@@ -41,9 +49,6 @@ public class ChatWindowController {
 
     public void setConnectionHandler(ClientConnectionHandler connectionHandler){
         this.connectionHandler = connectionHandler;
-        startConnectionHandlerListener();
-        serverAddressField.setText(connectionHandler.getServerAddressProperty().get());
-        serverPortField.setText(String.valueOf(connectionHandler.getServerPortProperty().get()));
     }
 
     private void applicationClose() {
@@ -99,7 +104,7 @@ public class ChatWindowController {
 
     @FXML
     private void applyFilter( ) {
-        Platform.runLater(() -> this.messageArea.setText(messages.getFilteredMessages(filterValue.getText().strip())));
+    	this.redrawMessageList();
     }
 
     private void startConnectionHandler() throws IOException {
@@ -111,7 +116,7 @@ public class ChatWindowController {
             new Thread(connectionHandler).start();
 
             //register Listener
-            //startConnectionHandlerListener();
+            startListener();
 
             // register window close handler
             rootPane.getScene().getWindow().addEventHandler(WindowEvent.WINDOW_CLOSE_REQUEST, windowCloseHandler);
@@ -164,13 +169,19 @@ public class ChatWindowController {
         messages.addMessage(new Message(Message.MessageType.ERROR, null, null, message));
     }
 
+    private void redrawMessageList() {
+        this.messageArea.clear();
+        Platform.runLater(() -> this.messageArea.setText(messages.getFilteredMessages(filterValue.getText().strip())));
+    }
+
     class WindowCloseHandler implements EventHandler<WindowEvent> {
         public void handle(WindowEvent event) {
             applicationClose();
         }
+
     }
 
-    public void startConnectionHandlerListener() {
+    public void startListener() {
         connectionHandler.getStateProperty().addListener(new ChangeListener<State>() {
             @Override
             public void changed(ObservableValue<? extends State> observable, State oldValue, State newValue) {
@@ -204,7 +215,7 @@ public class ChatWindowController {
         messages.getChangedProperty().addListener(new ChangeListener<Boolean>() {
             @Override
             public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue, Boolean newValue) {
-                Platform.runLater(() -> messageArea.setText(messages.getFilteredMessages(filterValue.getText().strip())));
+                redrawMessageList();
             }
         });
     }

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

@@ -29,17 +29,21 @@ public class ClientConnectionHandler extends ConnectionHandler implements Runnab
         super();
         this.messages = messages;
         state = new SimpleObjectProperty<>(State.NEW);
-        serverAddress = new SimpleStringProperty(NetworkHandler.DEFAULT_ADDRESS.getCanonicalHostName());
-        serverPort = new SimpleIntegerProperty(NetworkHandler.DEFAULT_PORT);
-        this.userName = new SimpleStringProperty(null);
+        serverAddress = new SimpleStringProperty();
+        serverPort = new SimpleIntegerProperty();
     }
 
     public void initialize(String serverAddress, int serverPort, String userName) throws IOException {
-        state.set(NEW);
-        this.serverAddress.set(serverAddress);
-        this.serverPort.set(serverPort);
-        setConnection(NetworkHandler.openConnection(serverAddress, serverPort));
+        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; }
@@ -99,24 +103,66 @@ public class ClientConnectionHandler extends ConnectionHandler implements Runnab
 
     private void processData(String data) {
         try {
+            // parse data content
             Scanner scanner = new Scanner(data);
-            StringBuilder sender = new StringBuilder();
-            StringBuilder reciever = new StringBuilder();
-            StringBuilder type = new StringBuilder();
-            StringBuilder payload = new StringBuilder();
-            super.processData(scanner,sender,reciever,type,payload);
-
+            String sender = null;
+            String reciever = null;
+            String type = null;
+            String payload = null;
+            if (scanner.hasNextLine()) {
+                sender = scanner.nextLine();
+            } else {
+                throw new ChatProtocolException("No Sender found");
+            }
+            if (scanner.hasNextLine()) {
+                reciever = scanner.nextLine();
+            } else {
+                throw new ChatProtocolException("No Reciever found");
+            }
+            if (scanner.hasNextLine()) {
+                type = scanner.nextLine();
+            } else {
+                throw new ChatProtocolException("No Type found");
+            }
+            if (scanner.hasNextLine()) {
+                payload = scanner.nextLine();
+            }
             // dispatch operation based on type parameter
-            if (type.toString().equals(getDataTypeConnect())) {
+            if (type.equals(getDataTypeConnect())) {
                 System.err.println("Illegal connect request from server");
-            } else if (type.toString().equals(getDataTypeConfirm())) {
-                caseConfirm(sender.toString(), reciever.toString(), payload.toString());
-            } else if (type.toString().equals(getDataTypeDisconnect())) {
-                caseDisconnect(sender.toString(),reciever.toString(),payload.toString());
-            } else if (type.toString().equals(getDataTypeMessage())) {
-                caseMessage(sender.toString(),reciever.toString(),payload.toString());
-            } else if (type.toString().equals(getDataTypeError())) {
-                caseError(sender.toString(), reciever.toString(), payload.toString());
+            } else if (type.equals(getDataTypeConfirm())) {
+                if (state.get() == CONFIRM_CONNECT) {
+                    this.userName.set(reciever);
+                    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);
+                } else if (state.get() == CONFIRM_DISCONNECT) {
+                    messages.addMessage(new Message(Message.MessageType.INFO,sender,reciever,payload));
+                    System.out.println("CONFIRM: " + payload);
+                    this.setState(DISCONNECTED);
+                } else {
+                    System.err.println("Got unexpected confirm message: " + payload);
+                }
+            } else if (type.equals(getDataTypeDisconnect())) {
+                if (state.get() == DISCONNECTED) {
+                    System.out.println("DISCONNECT: Already in disconnected: " + payload);
+                    return;
+                }
+                messages.addMessage(new Message(Message.MessageType.INFO,sender,reciever,payload));
+                System.out.println("DISCONNECT: " + payload);
+                this.setState(DISCONNECTED);
+            } 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(getDataTypeError())) {
+                messages.addMessage(new Message(Message.MessageType.ERROR,sender,reciever,payload));
+                System.out.println("ERROR: " + payload);
             } else {
                 System.out.println("Unknown data type received: " + type);
             }
@@ -126,47 +172,27 @@ public class ClientConnectionHandler extends ConnectionHandler implements Runnab
         }
     }
 
-    private void caseConfirm(String sender, String reciever, String payload) {
-        if (state.get() == CONFIRM_CONNECT) {
-            this.userName.set(reciever);
-            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);
-        } else if (state.get() == CONFIRM_DISCONNECT) {
-            messages.addMessage(new Message(Message.MessageType.INFO,sender,reciever,payload));
-            System.out.println("CONFIRM: " + payload);
-            this.setState(DISCONNECTED);
-        } else {
-            System.err.println("Got unexpected confirm message: " + payload);
+    private void sendData(String sender, String receiver, String type, String payload) {
+        if (getConnection().isAvailable()) {
+            new StringBuilder();
+            String data = new StringBuilder()
+                .append(sender+"\n")
+                .append(receiver+"\n")
+                .append(type+"\n")
+                .append(payload+"\n")
+                .toString();
+            try {
+                getConnection().send(data);
+            } catch (SocketException e) {
+                System.err.println("Connection closed: " + e.getMessage());
+            } catch (EOFException e) {
+                System.out.println("Connection terminated by remote");
+            } catch(IOException e) {
+                System.err.println("Communication error: " + e.getMessage());
+            }
         }
     }
 
-    private void caseDisconnect(String sender, String reciever, String payload) {
-        if (state.get() == DISCONNECTED) {
-            System.out.println("DISCONNECT: Already in disconnected: " + payload);
-            return;
-        }
-        messages.addMessage(new Message(Message.MessageType.INFO,sender,reciever,payload));
-        System.out.println("DISCONNECT: " + payload);
-        this.setState(DISCONNECTED);
-    }
-
-    private void caseMessage(String sender, String reciever, String payload) {
-        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);
-    }
-
-    private void caseError(String sender, String reciever, String payload) {
-        messages.addMessage(new Message(Message.MessageType.ERROR,sender,reciever,payload));
-        System.out.println("ERROR: " + payload);
-    }
-
     public void connect() throws ChatProtocolException {
         if (state.get() != NEW) throw new ChatProtocolException("Illegal state for connect: " + state);
         this.sendData(userName.get(), USER_NONE, getDataTypeConnect(),null);
@@ -196,4 +222,5 @@ public class ClientConnectionHandler extends ConnectionHandler implements Runnab
             return false;
         }
     }
+
 }

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

@@ -1,10 +1,5 @@
 package ch.zhaw.pm2.multichat.protocol;
 
-import java.io.EOFException;
-import java.io.IOException;
-import java.net.SocketException;
-import java.util.Scanner;
-
 public abstract class ConnectionHandler {
     private NetworkHandler.NetworkConnection<String> connection;
 
@@ -49,47 +44,4 @@ public abstract class ConnectionHandler {
     protected void setConnection(NetworkHandler.NetworkConnection<String> connection) {
         this.connection = connection;
     }
-
-    protected void processData(Scanner scanner, StringBuilder sender, StringBuilder reciever, StringBuilder type, StringBuilder payload) throws ChatProtocolException {
-        // parse data content
-        if (scanner.hasNextLine()) {
-            sender.append(scanner.nextLine());
-        } else {
-            throw new ChatProtocolException("No Sender found");
-        }
-        if (scanner.hasNextLine()) {
-            reciever.append(scanner.nextLine());
-        } else {
-            throw new ChatProtocolException("No Reciever found");
-        }
-        if (scanner.hasNextLine()) {
-            type.append(scanner.nextLine());
-        } else {
-            throw new ChatProtocolException("No Type found");
-        }
-        if (scanner.hasNextLine()) {
-            payload.append(scanner.nextLine());
-        }
-    }
-
-    protected void sendData(String sender, String receiver, String type, String payload) {
-        if (connection.isAvailable()) {
-            new StringBuilder();
-            String data = new StringBuilder()
-                    .append(sender+"\n")
-                    .append(receiver+"\n")
-                    .append(type+"\n")
-                    .append(payload+"\n")
-                    .toString();
-            try {
-                getConnection().send(data);
-            } catch (SocketException e) {
-                System.err.println("Connection closed: " + e.getMessage());
-            } catch (EOFException e) {
-                System.out.println("Connection terminated by remote");
-            } catch(IOException e) {
-                System.err.println("Communication error: " + e.getMessage());
-            }
-        }
-    }
 }

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

@@ -10,15 +10,7 @@ import java.util.Map;
 import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.ReentrantLock;
 
-/**
- * This Class represents a Server. The user can start the programm with the port number as a argument.
- * If no argument has been set the {@link NetworkHandler#DEFAULT_PORT} is used as port number.
- * After initialising the server:
- * 1. Starts a Socketserver using the logic given in {@link NetworkHandler.NetworkServer#createServer()}
- * 2. The server starts to listen for incoming connection using the Logic given in {@link NetworkHandler.NetworkServer#waitForConnection()}
- * 3. New conections will be atached to a Connectionhandler: {@link ServerConnectionHandler} and placed in a Map containing all active connections {@link Server#connections}
- *
- */
+
 public class Server {
 
     // Server connection
@@ -65,11 +57,6 @@ public class Server {
         }
     }
 
-    /**
-     * The Constructor to create a new instance.
-     * @param serverPort to listen for incoming connections.
-     * @throws IOException thrown if an I/O error occurs when opening the socket.
-     */
     public Server(int serverPort) throws IOException {
         // Open server connection
         System.out.println("Create server connection");
@@ -77,10 +64,6 @@ public class Server {
         System.out.println("Listening on " + networkServer.getHostAddress() + ":" + networkServer.getHostPort());
     }
 
-    /**
-     * With this methode the instance waits for incoming connections. If a client tries to connect to the server.
-     * The connection will be registered in the connection registry if successful.
-     */
     private void start() {
         ReentrantLock mutex = new ReentrantLock();
         Condition nameComplete = mutex.newCondition();
@@ -90,19 +73,37 @@ public class Server {
                  NetworkHandler.NetworkConnection<String> connection = networkServer.waitForConnection();
                  ServerConnectionHandler connectionHandler = new ServerConnectionHandler(connection, connections, mutex, nameComplete);
                  new Thread(connectionHandler).start();
+                 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) {
+        }
+        catch (IOException e) {
             System.err.println("Communication error " + e);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
         }
         // close server
         System.out.println("Server Stopped.");
     }
 
-    /**
-     * This method will stop the serversocket.
-     */
     public void terminate() {
         try {
             System.out.println("Close server port.");

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

@@ -8,6 +8,7 @@ import ch.zhaw.pm2.multichat.protocol.NetworkHandler;
 import java.io.EOFException;
 import java.io.IOException;
 import java.net.SocketException;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Scanner;
@@ -16,31 +17,7 @@ import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.ReentrantLock;
 
 
-/**
- * This class represents the connection between the server and a client and offers the serverside logic.
- * The ServerConnectionHandler receives data send from the client aswell as sends data to the client.
- *
- * The ServeConnectionHandler offers following functionality:
- *
- * Evaluating connection attempts from a client by:
- * 1. Checks if Username is valid (Not used)
- * 2. Saves Username in {@link ServerConnectionHandler#userName}
- * 3. Saves the connection in the {@link ServerConnectionHandler#connectionRegistry}
- *
- * Processes disconnections from a client by:
- * 1. Removing the connection from the {@link ServerConnectionHandler#connectionRegistry}
- * 2. Terminates the socket by calling {@link NetworkHandler.NetworkConnection#close()}
- *
- * Processes Messages send from a client by:
- * 1. Evaluating the reciever by differentiating between broadcast or unicast.
- * 2. Sending the message accordingly.
- *
- * To use this class, start a new instance and start it in a thread.
- * To constructor needs following parameter:
- * 1. {@link ch.zhaw.pm2.multichat.protocol.NetworkHandler.NetworkConnection} representing the socket connection between server and client
- * 2. {@link Map<String,ServerConnectionHandler>} registry to check for all active connections
- * 3. {@link ReentrantLock @link Condition} to lock server thread to evaluate connection.
- * */
+
 public class ServerConnectionHandler extends ConnectionHandler implements Runnable{
     private static final AtomicInteger connectionCounter = new AtomicInteger(0);
     private final int connectionId = connectionCounter.incrementAndGet();
@@ -53,21 +30,11 @@ public class ServerConnectionHandler extends ConnectionHandler implements Runnab
     private String userName = "Anonymous-"+connectionId;
     private State state = NEW;
 
-    /**
-     * Called when runnable gets started in a thread.
-     */
     @Override
     public void run() {
         startReceiving();
     }
 
-    /**
-     * Constructor to intitialize the connection
-     * @param connection representing the socket connection between server and clinet
-     * @param registry map containing all active connections between server and clients
-     * @param mutex to lock thread
-     * @param nameComplete condition to call threads
-     */
     public ServerConnectionHandler(NetworkHandler.NetworkConnection<String> connection,
                                    Map<String,ServerConnectionHandler> registry, ReentrantLock mutex, Condition nameComplete) {
         super();
@@ -79,26 +46,14 @@ public class ServerConnectionHandler extends ConnectionHandler implements Runnab
         this.nameComplete = nameComplete;
     }
 
-    /**
-     *
-     * @return the username of the connected client
-     */
     public String getUserName() {
         return this.userName;
     }
 
-    /**
-     *
-     * @return state of the connection. Poosible states are see {@link ch.zhaw.pm2.multichat.protocol.ConnectionHandler.State}
-     */
     public State getState() {
         return state;
     }
 
-    /**
-     * This methods runs in a whileloop as long as the socket between server and client is available
-     * and the connection State is not ERROR.
-     */
     private void startReceiving() {
             System.out.println("Starting Connection Handler for new User");
             try {
@@ -129,9 +84,6 @@ public class ServerConnectionHandler extends ConnectionHandler implements Runnab
 
     }
 
-    /**
-     * This method will call {@link NetworkHandler.NetworkConnection#close()} to close the Socket.
-     */
     private void stopReceiving() {
         System.out.println("Closing Connection Handler for " + userName);
         try {
@@ -139,41 +91,93 @@ public class ServerConnectionHandler extends ConnectionHandler implements Runnab
             getConnection().close();
             System.out.println("Stopped receiving data.");
         } catch (IOException e) {
-            System.err.println("Failed to close connection." + e.getMessage());
+            System.err.println("Failed to close connection." + e);
         }
         System.out.println("Closed Connection Handler for " + userName);
     }
 
-    /**
-     * This method gets called when socket recieves data. The method checks for the data type and reacts accordingly
-     * If data type:
-     * 1. Connect => checks if username is valid. if valid sends response to client with confirmation.
-     *  If username not valid quits connection by changing status to ERROR.
-     * 2. Confirm => Server should not recieve this kind of message. STDOUT informs about it.
-     * 3. Disconnect => Disconnects connection by removing connection from registry and calling method to terminate socket.
-     * 4. Message => Checks if broadcast or unicast. Sends data accordingly
-     * 5. Error => STDERR message
-     * @param data recieved by the server
-     */
     private void processData(String data)  {
         try {
+            // parse data content
             Scanner scanner = new Scanner(data);
-            StringBuilder sender = new StringBuilder();
-            StringBuilder reciever = new StringBuilder();
-            StringBuilder type = new StringBuilder();
-            StringBuilder payload = new StringBuilder();
-            super.processData(scanner,sender,reciever,type,payload);
+            String sender = null;
+            String reciever = null;
+            String type = null;
+            String payload = null;
+            if (scanner.hasNextLine()) {
+                sender = scanner.nextLine();
+            } else {
+                throw new ChatProtocolException("No Sender found");
+            }
+            if (scanner.hasNextLine()) {
+                reciever = scanner.nextLine();
+            } else {
+                throw new ChatProtocolException("No Reciever found");
+            }
+            if (scanner.hasNextLine()) {
+                type = scanner.nextLine();
+            } else {
+                throw new ChatProtocolException("No Type found");
+            }
+            if (scanner.hasNextLine()) {
+                payload = scanner.nextLine();
+            }
 
             // dispatch operation based on type parameter
-            if (type.toString().equals(getDataTypeConnect())) {
-                caseConnect(sender.toString());
-            } else if (type.toString().equals(getDataTypeConfirm())) {
+            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)) {
+                    mutex.lock();
+                    try {
+                        state = ERROR;
+                        nameComplete.signal();
+                    }
+                    finally {
+                        mutex.unlock();
+                    }
+                    throw new ChatProtocolException("User name already taken: " + sender);
+                }
+                mutex.lock();
+                try {
+                    this.userName = sender;
+                    nameComplete.signal();
+                }
+                finally {
+                    mutex.unlock();
+                }
+                connectionRegistry.put(userName, this);
+                sendData(USER_NONE, userName, getDataTypeConfirm(), "Registration successfull for " + userName);
+                this.state = CONNECTED;
+            } else if (type.equals(getDataTypeConfirm())) {
                 System.out.println("Not expecting to receive a CONFIRM request from client");
-            } else if (type.toString().equals(getDataTypeDisconnect())) {
-                caseDisconnect();
-            } else if (type.toString().equals(getDataTypeMessage())) {
-                caseMessage(sender.toString(), reciever.toString(), type.toString(), payload.toString());
-            } else if (type.toString().equals(getDataTypeError())) {
+            } 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, getDataTypeConfirm(), "Confirm disconnect of " + userName);
+                this.state = DISCONNECTED;
+                this.stopReceiving();
+            } 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()) {
+                        handler.sendData(sender, reciever, type, payload);
+                    }
+                } else {
+                    ServerConnectionHandler handler = connectionRegistry.get(reciever);
+                    if (handler != null) {
+                        handler.sendData(sender, reciever, type, payload);
+                        if(!reciever.equals(sender)){
+                            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, getDataTypeError(), "Unknown User: " + reciever);
+                    }
+                }
+            } else if (type.equals(getDataTypeError())) {
                 System.err.println("Received error from client (" + sender + "): " + payload);
             } else {
                 System.err.println("Unknown data type received: " + type);
@@ -185,74 +189,25 @@ public class ServerConnectionHandler extends ConnectionHandler implements Runnab
         }
     }
 
-    /**
-     * This method is called by method {@link ServerConnectionHandler#processData(String)}
-     * Checks if username is valid. if valid sends response to client with confirmation.
-     * @param sender of the payload
-     * @throws ChatProtocolException if username not valid
-     */
-    private void caseConnect(String sender) throws ChatProtocolException {
-        if (this.state != NEW) throw new ChatProtocolException("Illegal state for connect request: " + state);
-        if (sender.isBlank()) sender = this.userName;
-        //if username not valid
-        if (connectionRegistry.containsKey(sender)) {
-            state = ERROR;
-            System.out.println(String.format("Connecting failed for new Client with IP:Port <%s:%d>.\nReason: Name already taken.",
-                    getConnection().getRemoteHost(),
-                    getConnection().getRemotePort()));
-            throw new ChatProtocolException("User name already taken: " + sender);
-        }
-        //if username valid
-        this.userName = sender;
-        connectionRegistry.put(userName, this);
-        sendData(USER_NONE, userName, getDataTypeConfirm(), "Registration successfull for " + userName);
-        this.state = CONNECTED;
-        System.out.println(String.format("Connected new Client %s with IP:Port <%s:%d>",
-                userName,
-                getConnection().getRemoteHost(),
-                getConnection().getRemotePort()));
-    }
 
-    /**
-     * This method is called by method {@link ServerConnectionHandler#processData(String)}
-     * Disconnects connection by removing connection from registry and calling method {@link ServerConnectionHandler#stopReceiving()} to terminate socket.
-     * @throws ChatProtocolException if state allready DISCONNECTED.
-     */
-    private void caseDisconnect() throws ChatProtocolException {
-        if (state == DISCONNECTED)
-            throw new ChatProtocolException("Illegal state for disconnect request: " + state);
-        if (state == CONNECTED) {
-            connectionRegistry.remove(this.userName);
-        }
-        sendData(USER_NONE, userName, getDataTypeConfirm(), "Confirm disconnect of " + userName);
-        this.state = DISCONNECTED;
-        this.stopReceiving();
-    }
 
-    /**
-     * This method is called by method {@link ServerConnectionHandler#processData(String)}
-     * Checks if broadcast or unicast. Sends data accordingly
-     * @param sender who sent data
-     * @param reciever to recieve data
-     * @param type of message
-     * @param payload data to transmit
-     * @throws ChatProtocolException if state not equal to CONNECT
-     */
-    private void caseMessage(String sender, String reciever, String type, String payload) throws ChatProtocolException{
-        if (state != CONNECTED) throw new ChatProtocolException("Illegal state for message request: " + state);
-        if (USER_ALL.equals(reciever)) {
-            for (ServerConnectionHandler handler : connectionRegistry.values()) {
-                handler.sendData(sender, reciever, type, payload);
-            }
-        } else {
-            ServerConnectionHandler handler = connectionRegistry.get(reciever);
-            if (handler != null) {
-                handler.sendData(sender, reciever, type, payload);
-                if(!reciever.equals(sender)){
-                    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, getDataTypeError(), "Unknown User: " + reciever);
+    private void sendData(String sender, String receiver, String type, String payload) {
+        if (getConnection().isAvailable()) {
+            new StringBuilder();
+            String data = new StringBuilder()
+                .append(sender+"\n")
+                .append(receiver+"\n")
+                .append(type+"\n")
+                .append(payload+"\n")
+                .toString();
+            try {
+                getConnection().send(data);
+            } catch (SocketException e) {
+                System.out.println("Connection closed: " + e.getMessage());
+            } catch (EOFException e) {
+                System.out.println("Connection terminated by remote");
+            } catch(IOException e) {
+                System.out.println("Communication error: " + e.getMessage());
             }
         }
     }