diff --git a/DokterApp/ITab.cs b/DokterApp/ITab.cs
new file mode 100644
index 0000000..c01f9ad
--- /dev/null
+++ b/DokterApp/ITab.cs
@@ -0,0 +1,28 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Windows.Input;
+
+namespace DokterApp
+{
+    public interface ITab
+    {
+        string Name { get; set; }
+        ICommand CloseCommand { get; }
+        event EventHandler CloseRequested;
+    }
+
+    public abstract class Tab : ITab
+    {
+        public string Name { get; set; }
+        public ICommand CloseCommand { get; }
+        public event EventHandler CloseRequested;
+
+        public Tab()
+        {
+            //CloseCommand = 
+        }
+
+    }
+
+}
diff --git a/DokterApp/MainWindow.xaml b/DokterApp/MainWindow.xaml
index 5ce5844..1c9bce1 100644
--- a/DokterApp/MainWindow.xaml
+++ b/DokterApp/MainWindow.xaml
@@ -5,8 +5,25 @@
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
         xmlns:local="clr-namespace:DokterApp"
         mc:Ignorable="d"
-        Title="MainWindow" Height="450" Width="800">
-    <Grid>
+        WindowState="Maximized"
+        Title="Dokter App" >
+    <Grid RenderTransformOrigin="0.499,0.49">
+        <Grid.RowDefinitions>
+            <RowDefinition Height="23*"/>
+            <RowDefinition Height="31*"/>
+        </Grid.RowDefinitions>
+        <Grid.ColumnDefinitions>
+            <ColumnDefinition Width="0"/>
+            <ColumnDefinition/>
+        </Grid.ColumnDefinitions>
+        <StackPanel Grid.ColumnSpan="2" Grid.RowSpan="2" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="0,0,0,0" Orientation="Vertical">
+            <Label Content="Sensei" Margin="0,0,0,20" HorizontalAlignment="Center"/>
+            <Label Content="Username" HorizontalContentAlignment="Center"/>
+            <TextBox x:Name="Username" TextWrapping="Wrap" Width="120"/>
+            <Label Content="Password" HorizontalContentAlignment="Center"/>
+            <TextBox x:Name="Password" TextWrapping="Wrap" Width="120"/>
+            <Button x:Name="Login" Content="Login" Margin="0,20,0,0" Click="Login_Click_1" />
+        </StackPanel>
 
     </Grid>
 </Window>
diff --git a/DokterApp/MainWindow.xaml.cs b/DokterApp/MainWindow.xaml.cs
index 9215b9b..fc2bab1 100644
--- a/DokterApp/MainWindow.xaml.cs
+++ b/DokterApp/MainWindow.xaml.cs
@@ -24,5 +24,17 @@ namespace DokterApp
         {
             InitializeComponent();
         }
+
+        private void TextBox_TextChanged(object sender, TextChangedEventArgs e)
+        {
+
+        }
+
+        private void Login_Click_1(object sender, RoutedEventArgs e)
+        {
+            WindowTabs windowTabs = new WindowTabs();
+            windowTabs.Show();
+            this.Close();
+        }
     }
 }
diff --git a/DokterApp/UserControlForTab.xaml b/DokterApp/UserControlForTab.xaml
new file mode 100644
index 0000000..f45a03f
--- /dev/null
+++ b/DokterApp/UserControlForTab.xaml
@@ -0,0 +1,67 @@
+<UserControl x:Class="DokterApp.UserControlForTab"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
+             xmlns:local="clr-namespace:DokterApp"
+             mc:Ignorable="d" 
+             d:DesignHeight="450" d:DesignWidth="800">
+    <Grid Margin="15,5,15,15">
+        <Grid.ColumnDefinitions>
+            <ColumnDefinition Width="5*"/>
+            <ColumnDefinition Width="3*"/>
+        </Grid.ColumnDefinitions>
+        <Grid.RowDefinitions>
+            <RowDefinition Height="43*"/>
+            <RowDefinition Height="47*"/>
+            <RowDefinition Height="180*"/>
+            <RowDefinition Height="180*"/>
+        </Grid.RowDefinitions>
+        <StackPanel Orientation="Horizontal" Grid.RowSpan="2" Margin="0,0,0,22">
+            <StackPanel.Resources>
+                <Style TargetType="{x:Type Label}">
+                    <Setter Property="Margin" Value="0,0,20,0"/>
+                </Style>
+            </StackPanel.Resources>
+            <Label Content="UserName" Name="Username_Label"/>
+            <Label Content="Status: " Name="Status_Label"/>
+        </StackPanel>
+        <StackPanel Margin="0,10,0,0" Grid.RowSpan="2" Grid.Row="1">
+            <StackPanel.Resources>
+                <Style TargetType="{x:Type DockPanel}">
+                    <Setter Property="Margin" Value="0,20,0,0"/>
+                </Style>
+            </StackPanel.Resources>
+            <DockPanel Height="26" LastChildFill="False" HorizontalAlignment="Stretch">
+                <Label Content="Resistance" Width="110" DockPanel.Dock="Right"/>
+                <Label Content="Current Speed" Width="110" DockPanel.Dock="Left"/>
+                <Label Content="Current BPM" Width="110" DockPanel.Dock="Top"/>
+            </DockPanel>
+            <DockPanel Height="26" LastChildFill="False" HorizontalAlignment="Stretch">
+                <TextBox Name="textBox_Resistance" Text="" TextWrapping="Wrap" Width="110" DockPanel.Dock="Right" IsReadOnly="true"/>
+                <TextBox Name="textBox_CurrentSpeed" Text="" TextWrapping="Wrap" Width="110" DockPanel.Dock="Left" IsReadOnly="true"/>
+                <TextBox Name="textBox_CurrentBPM" Text="" TextWrapping="Wrap" Width="110" DockPanel.Dock="Top" Height="26" IsReadOnly="true"/>
+            </DockPanel>
+            <DockPanel Height="26" LastChildFill="False">
+                <Label Content="Distance Covered" Width="110" DockPanel.Dock="Right"/>
+                <Label Content="Current Power" Width="110" DockPanel.Dock="Left"/>
+                <Label Content="Acc. Power" Width="110" DockPanel.Dock="Top"/>
+            </DockPanel>
+            <DockPanel Height="26" LastChildFill="False">
+                <TextBox Name="textBox_DistanceCovered" Text="" TextWrapping="Wrap" Width="110" DockPanel.Dock="Right" IsReadOnly="true"/>
+                <TextBox Name="textBox_CurrentPower" Text="" TextWrapping="Wrap" Width="110" DockPanel.Dock="Left" IsReadOnly="true"/>
+                <TextBox Name="textBox_AccPower" Text="" TextWrapping="Wrap" Width="110" DockPanel.Dock="Top" Height="26" IsReadOnly="true"/>
+            </DockPanel>
+        </StackPanel>
+        <ListBox Name="ChatBox"  Grid.Column="1" Margin="59,41,0,0" SelectionChanged="ListBox_SelectionChanged" Grid.RowSpan="3"/>
+        <TextBox Name="textBox_Chat" Grid.Column="1" HorizontalAlignment="Left" Margin="59,10,0,0" Grid.Row="3" Text="TextBox" TextWrapping="Wrap" VerticalAlignment="Top" Width="235"/>
+        <Button Content="Button" Grid.Column="1" HorizontalAlignment="Left" Margin="59,33,0,0" Grid.Row="3" VerticalAlignment="Top" Click="Button_Click"/>
+        <Button Content="Start Session" Grid.Column="1" HorizontalAlignment="Left" Margin="69,86,0,0" Grid.Row="3" VerticalAlignment="Top" Width="97" Click="StartSession_Click"/>
+        <Button Content="Stop Session" Grid.Column="1" HorizontalAlignment="Left" Margin="187,86,0,0" Grid.Row="3" VerticalAlignment="Top" Width="97" Click="StopSession_Click"/>
+        <TextBox x:Name="textBox_SetResistance" Grid.Column="1" HorizontalAlignment="Left" Margin="69,128,0,0" Grid.Row="3" TextWrapping="Wrap" VerticalAlignment="Top" Width="97"/>
+        <Button Content="Set Resistance" Grid.Column="1" HorizontalAlignment="Left" Margin="187,128,0,0" Grid.Row="3" VerticalAlignment="Top" Width="97" Height="18" Click="SetResistance_Click"/>
+        <Canvas Grid.Row="3" Background="White" Margin="0,33,0,0"/>
+        <ComboBox Name="DropBox" HorizontalAlignment="Left" Margin="0,6,0,0" Grid.Row="3" VerticalAlignment="Top" Width="190"/>
+        <Button Content="Client Info" Grid.Column="1" HorizontalAlignment="Left" Margin="207,6,0,0" VerticalAlignment="Top" Height="26" Width="82" Click="ClientInfo_Click"/>
+    </Grid>
+</UserControl>
diff --git a/DokterApp/UserControlForTab.xaml.cs b/DokterApp/UserControlForTab.xaml.cs
new file mode 100644
index 0000000..443fa92
--- /dev/null
+++ b/DokterApp/UserControlForTab.xaml.cs
@@ -0,0 +1,59 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Documents;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Navigation;
+using System.Windows.Shapes;
+
+namespace DokterApp
+{
+    /// <summary>
+    /// Interaction logic for UserControlForTab.xaml
+    /// </summary>
+    public partial class UserControlForTab : UserControl
+    {
+        public UserControlForTab()
+        {
+            InitializeComponent();
+            Username_Label.Content = "Bob";
+            Status_Label.Content = "Status: Dead";
+        }
+
+        private void ListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
+        {
+            
+        }
+        private void Button_Click(object sender, RoutedEventArgs e)
+        {
+            ChatBox.Items.Add(textBox_Chat.Text);
+        }
+
+        private void StartSession_Click(object sender, RoutedEventArgs e)
+        {
+
+        }
+
+        private void StopSession_Click(object sender, RoutedEventArgs e)
+        {
+
+        }
+
+        private void SetResistance_Click(object sender, RoutedEventArgs e)
+        {
+
+        }
+
+        private void ClientInfo_Click(object sender, RoutedEventArgs e)
+        {
+            MessageBox.Show("firstname:\tBob\n" +
+                "surname:\t\tde Bouwer");
+        }
+
+    }
+}
diff --git a/DokterApp/UserTab.cs b/DokterApp/UserTab.cs
new file mode 100644
index 0000000..d24e593
--- /dev/null
+++ b/DokterApp/UserTab.cs
@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace DokterApp
+{
+    class UserTab : Tab
+    {
+        public UserTab()
+        {
+            Name = "Piet";
+        }
+    }
+}
diff --git a/DokterApp/WindowTabs.xaml b/DokterApp/WindowTabs.xaml
new file mode 100644
index 0000000..0869800
--- /dev/null
+++ b/DokterApp/WindowTabs.xaml
@@ -0,0 +1,16 @@
+<Window x:Class="DokterApp.WindowTabs"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:local="clr-namespace:DokterApp"
+        mc:Ignorable="d"
+        WindowState="Maximized"
+        Title="WindowTabs" Height="450" Width="800">
+    <Grid>
+        <TabControl x:Name="tabControl" Loaded="tabControl_Load" TabStripPlacement="Left" Margin="0,23,0,0" />
+        <Button Content="Button" HorizontalAlignment="Left" Margin="578,125,0,0" VerticalAlignment="Top" Click="Button_Click"/>
+        <Button Content="Button" HorizontalAlignment="Left" Margin="10,0,0,0" VerticalAlignment="Top"/>
+
+    </Grid>
+</Window>
diff --git a/DokterApp/WindowTabs.xaml.cs b/DokterApp/WindowTabs.xaml.cs
new file mode 100644
index 0000000..7317aa9
--- /dev/null
+++ b/DokterApp/WindowTabs.xaml.cs
@@ -0,0 +1,44 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Text;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Documents;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Shapes;
+
+namespace DokterApp
+{
+    /// <summary>
+    /// Interaction logic for WindowTabs.xaml
+    /// </summary>
+    public partial class WindowTabs : Window
+    {
+        public TabControl tbControl;
+        public WindowTabs()
+        {
+            InitializeComponent();
+        }
+
+        private void tabControl_Load(object sender, RoutedEventArgs e)
+        {
+            this.tbControl = (sender as TabControl);
+        }
+
+        private void Button_Click(object sender, RoutedEventArgs e)
+        {
+            TabItem newTabItem = new TabItem
+            {
+                Header = "Test",
+                Width = 110,
+                Height = 40
+            };
+            newTabItem.Content = new UserControlForTab();
+            this.tbControl.Items.Add(newTabItem);
+        }
+    }
+}
diff --git a/Server/Client.cs b/Server/Client.cs
index 0151e87..9091295 100644
--- a/Server/Client.cs
+++ b/Server/Client.cs
@@ -76,7 +76,7 @@ namespace Server
 
 
         /// <summary>
-        /// TODO
+        /// handles all incoming data from the client
         /// </summary>
         /// <param name="message">including message length and messageId (can be changed)</param>
         private void HandleData(byte[] message)
@@ -216,10 +216,6 @@ namespace Server
             }
         }
 
-
-
-
-
         public static string ByteArrayToString(byte[] ba)
         {
             StringBuilder hex = new StringBuilder(ba.Length * 2);