diff --git a/CampusAppWP8/CampusAppWP8/Feed/Departments/DepartmentFavoriteFeed.cs b/CampusAppWP8/CampusAppWP8/Feed/Departments/DepartmentFavoriteFeed.cs
index 3d844c1a..20a1a29c 100644
--- a/CampusAppWP8/CampusAppWP8/Feed/Departments/DepartmentFavoriteFeed.cs
+++ b/CampusAppWP8/CampusAppWP8/Feed/Departments/DepartmentFavoriteFeed.cs
@@ -4,7 +4,7 @@
 // </copyright>
 // <author>fiedlchr</author>
 // <sience>01.07.2013</sience>
-//----------------------------------------------------------------------using System;
+//----------------------------------------------------------------------
 namespace CampusAppWP8.Feed.Departments
 {
     using System.IO;
@@ -26,8 +26,8 @@ namespace CampusAppWP8.Feed.Departments
         public DepartmentFavoriteFeed(bool autoLoad = true)
             : base(ModelType.File, Constants.FileDepartment_Favorite_Name, string.Empty)
         {
-            this.isFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDateOnLoad);
-            this.isFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDateOnSave);
+            this.IsFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDateOnLoad);
+            this.IsFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDateOnSave);
 
             if (autoLoad == true)
             {
diff --git a/CampusAppWP8/CampusAppWP8/Feed/Departments/DepartmentFeed.cs b/CampusAppWP8/CampusAppWP8/Feed/Departments/DepartmentFeed.cs
index 93e71301..3f964c67 100644
--- a/CampusAppWP8/CampusAppWP8/Feed/Departments/DepartmentFeed.cs
+++ b/CampusAppWP8/CampusAppWP8/Feed/Departments/DepartmentFeed.cs
@@ -27,9 +27,9 @@ namespace CampusAppWP8.Feed.Departments
         public DepartmentFeed(bool autoLoad = true)
             : base(ModelType.FileAndFeed, Constants.FileDepartment_Name, Constants.UrlDepartment_Addr)
         {
-            this.isFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDateOnLoad);
-            this.isFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDateOnSave);
-            this.isModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
+            this.IsFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDateOnLoad);
+            this.IsFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDateOnSave);
+            this.IsModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
 
             if (autoLoad == true)
             {
diff --git a/CampusAppWP8/CampusAppWP8/Feed/Events/EventFeed.cs b/CampusAppWP8/CampusAppWP8/Feed/Events/EventFeed.cs
index 3151e488..60216204 100644
--- a/CampusAppWP8/CampusAppWP8/Feed/Events/EventFeed.cs
+++ b/CampusAppWP8/CampusAppWP8/Feed/Events/EventFeed.cs
@@ -25,9 +25,9 @@ namespace CampusAppWP8.Feed.Events
         public EventFeed(bool autoLoad = true)
             : base(ModelType.FileAndFeed, Constants.FileEvents_Name, Constants.UrlEvents_Addr)
         {
-            this.isFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDateOnLoad);
-            this.isFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDateOnSave);
-            this.isModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
+            this.IsFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDateOnLoad);
+            this.IsFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDateOnSave);
+            this.IsModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
 
             if (autoLoad == true)
             {
diff --git a/CampusAppWP8/CampusAppWP8/Feed/Link/ClubLinkFeed.cs b/CampusAppWP8/CampusAppWP8/Feed/Link/ClubLinkFeed.cs
index edcba0f7..e2608efa 100644
--- a/CampusAppWP8/CampusAppWP8/Feed/Link/ClubLinkFeed.cs
+++ b/CampusAppWP8/CampusAppWP8/Feed/Link/ClubLinkFeed.cs
@@ -27,9 +27,9 @@ namespace CampusAppWP8.Feed.Link
         public ClubLinkFeed()
             : base(ModelType.FileAndFeed, Constants.FileLink_ClubLinks, Constants.UrlLink_ClubLinks)
         {
-            this.isFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDate);
-            this.isModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
-            this.isFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDate);
+            this.IsFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDate);
+            this.IsModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
+            this.IsFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDate);
         }
 
         #endregion
diff --git a/CampusAppWP8/CampusAppWP8/Feed/Link/CommonLinkFeed.cs b/CampusAppWP8/CampusAppWP8/Feed/Link/CommonLinkFeed.cs
index f63e2b37..0f988eeb 100644
--- a/CampusAppWP8/CampusAppWP8/Feed/Link/CommonLinkFeed.cs
+++ b/CampusAppWP8/CampusAppWP8/Feed/Link/CommonLinkFeed.cs
@@ -27,9 +27,9 @@ namespace CampusAppWP8.Feed.Link
         public CommonLinkFeed()
             : base(ModelType.FileAndFeed, Constants.FileLink_CommonLinks, Constants.UrlLink_CommonLinks)
         {
-            this.isFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDate);
-            this.isFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDate);
-            this.isModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
+            this.IsFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDate);
+            this.IsFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDate);
+            this.IsModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
         }
 
         #endregion
diff --git a/CampusAppWP8/CampusAppWP8/Feed/Mensa/MensaFeed.cs b/CampusAppWP8/CampusAppWP8/Feed/Mensa/MensaFeed.cs
index 950fc50e..b162e5d6 100644
--- a/CampusAppWP8/CampusAppWP8/Feed/Mensa/MensaFeed.cs
+++ b/CampusAppWP8/CampusAppWP8/Feed/Mensa/MensaFeed.cs
@@ -27,9 +27,9 @@ namespace CampusAppWP8.Feed.Mensa
         protected MensaFeed(string fileName, string feedUrl)
             : base(ModelType.FileAndFeed, fileName, feedUrl)
         {
-            this.isFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDate);
-            this.isModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
-            this.isFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDate);
+            this.IsFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDate);
+            this.IsModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
+            this.IsFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDate);
         }
 
         #endregion
diff --git a/CampusAppWP8/CampusAppWP8/Feed/News/NewsFeed.cs b/CampusAppWP8/CampusAppWP8/Feed/News/NewsFeed.cs
index b194b720..2fec1634 100644
--- a/CampusAppWP8/CampusAppWP8/Feed/News/NewsFeed.cs
+++ b/CampusAppWP8/CampusAppWP8/Feed/News/NewsFeed.cs
@@ -25,9 +25,9 @@ namespace CampusAppWP8.Feed.News
         public NewsFeed(bool autoLoad = true)
             : base(ModelType.FileAndFeed, Constants.FileNews_Name, Constants.UrlNews_Addr)
         {
-            this.isFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDateOnLoad);
-            this.isFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDateOnSave);
-            this.isModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
+            this.IsFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDateOnLoad);
+            this.IsFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDateOnSave);
+            this.IsModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
 
             if (autoLoad == true)
             {
diff --git a/CampusAppWP8/CampusAppWP8/Feed/Openinghours/OpeninghoursFeed.cs b/CampusAppWP8/CampusAppWP8/Feed/Openinghours/OpeninghoursFeed.cs
index 3a6f083c..cf60760a 100644
--- a/CampusAppWP8/CampusAppWP8/Feed/Openinghours/OpeninghoursFeed.cs
+++ b/CampusAppWP8/CampusAppWP8/Feed/Openinghours/OpeninghoursFeed.cs
@@ -26,9 +26,9 @@ namespace CampusAppWP8.Feed.Openinghours
         public OpeninghoursFeed()
             : base(ModelType.FileAndFeed, Constants.FileOpeningHours_OpeningHours,  Constants.UrlOpeningHours_OpeningHours)
         {
-            this.isFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDateOnLoad);
-            this.isFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDateOnSave);
-            this.isModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
+            this.IsFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDateOnLoad);
+            this.IsFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDateOnSave);
+            this.IsModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
         }
 
         #endregion
diff --git a/CampusAppWP8/CampusAppWP8/Feed/StudentCouncil/StudentCouncilFeed.cs b/CampusAppWP8/CampusAppWP8/Feed/StudentCouncil/StudentCouncilFeed.cs
index 64098618..9db17651 100644
--- a/CampusAppWP8/CampusAppWP8/Feed/StudentCouncil/StudentCouncilFeed.cs
+++ b/CampusAppWP8/CampusAppWP8/Feed/StudentCouncil/StudentCouncilFeed.cs
@@ -27,9 +27,9 @@ namespace CampusAppWP8.Feed.StudentCouncil
         public StudentCouncilFeed()
             : base(ModelType.FileAndFeed, Constants.FileStudentCouncil_StudentCouncils, Constants.UrlStudentCouncil_StudentCouncils)
         {
-            this.isFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDate);
-            this.isModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
-            this.isFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDate);
+            this.IsFileUpToDateOnLoad += new IsFileUpToDate(this.CheckIsFileUpToDate);
+            this.IsModelUpToDateOnLoad += new IsModelUpToDate(this.CheckIsModelUpToDate);
+            this.IsFileUpToDateOnSave += new IsFileUpToDate(this.CheckIsFileUpToDate);
         }
 
         #endregion
diff --git a/CampusAppWP8/CampusAppWP8/LocalizedStrings.cs b/CampusAppWP8/CampusAppWP8/LocalizedStrings.cs
index e2063778..f0a4a960 100644
--- a/CampusAppWP8/CampusAppWP8/LocalizedStrings.cs
+++ b/CampusAppWP8/CampusAppWP8/LocalizedStrings.cs
@@ -1,14 +1,27 @@
-using CampusAppWP8.Resources;
-
+//-----------------------------------------------------------------------------
+// <copyright file="LocalizedStrings.cs" company="BTU/IIT">
+//     Company copyright tag.
+// </copyright>
+// <sience>16.07.2013</sience>
+//-----------------------------------------------------------------------------
 namespace CampusAppWP8
 {
-    /// <summary>
-    /// Bietet Zugriff auf Zeichenfolgenressourcen.
-    /// </summary>
+    using CampusAppWP8.Resources;
+
+    /// <summary>Localized strings. </summary>
     public class LocalizedStrings
     {
-        private static AppResources _localizedResources = new AppResources();
+        /// <summary>The localized resources. </summary>
+        private static AppResources localizedResources = new AppResources();
 
-        public AppResources LocalizedResources { get { return _localizedResources; } }
+        /// <summary>Gets the localized resources. </summary>
+        /// <value>The localized resources. </value>
+        public AppResources LocalizedResources 
+        { 
+            get 
+            { 
+                return localizedResources; 
+            } 
+        }
     }
 }
\ No newline at end of file
diff --git a/CampusAppWP8/CampusAppWP8/Model/MainModel.cs b/CampusAppWP8/CampusAppWP8/Model/MainModel.cs
index 3942d302..8a549d87 100644
--- a/CampusAppWP8/CampusAppWP8/Model/MainModel.cs
+++ b/CampusAppWP8/CampusAppWP8/Model/MainModel.cs
@@ -97,24 +97,9 @@ namespace CampusAppWP8
         }
 
         /// <summary>
-        /// Delegate of the OnLoading callback function.
+        /// Delegate of the OnIO callback function.
         /// </summary>
-        public delegate void OnLoading();
-
-        /// <summary>
-        /// Delegate of the OnLoaded callback function.
-        /// </summary>
-        public delegate void OnLoaded();
-
-        /// <summary>
-        /// Delegate of the OnSaving callback function.
-        /// </summary>
-        public delegate void OnSaving();
-
-        /// <summary>
-        /// Delegate of the OnSaved callback function.
-        /// </summary>
-        public delegate void OnSaved();
+        public delegate void OnIO();
 
         /// <summary>
         /// Delegate of the OnFailed(File/Web) callback function.
@@ -139,64 +124,64 @@ namespace CampusAppWP8
         /// <summary>
         /// Callback pointer, called before loading.
         /// </summary>
-        public event OnLoading onLoading = null;
+        public event OnIO OnLoading = null;
 
         /// <summary>
         /// Callback pointer, called after loading.
         /// </summary>
-        public event OnLoaded onLoaded = null;
+        public event OnIO OnLoaded = null;
 
         /// <summary>
         /// Callback pointer, called before saving.
         /// </summary>
-        public event OnSaving onSaving = null;
+        public event OnIO OnSaving = null;
 
         /// <summary>
         /// Callback pointer, called after saving.
         /// </summary>
-        public event OnSaved onSaved = null;
+        public event OnIO OnSaved = null;
 
         /// <summary>
         /// Callback pointer, called after failed file loading.
         /// </summary>
-        public event OnFailed onFailedFile = null;
+        public event OnFailed OnFailedFile = null;
 
         /// <summary>
         /// Callback pointer, called after failed web loading.
         /// </summary>
-        public event OnFailed onFailedWeb = null;
+        public event OnFailed OnFailedWeb = null;
 
         /// <summary>
         /// Callback pointer, called after failed file or web loading, if there
         /// is no specialized onFailed callback set.
         /// </summary>
-        public event OnFailed onFailed = null;
+        public event OnFailed OnFailedLoad = null;
 
         /// <summary>
         /// Callback pointer, called after failed saving data to file.
         /// </summary>
-        public event OnFailed onFailedSave = null;
+        public event OnFailed OnFailedSave = null;
 
         /// <summary>
         /// Callback pointer, for checking if file is up to date at loading.
         /// </summary>
-        public event IsFileUpToDate isFileUpToDateOnLoad = null;
+        public event IsFileUpToDate IsFileUpToDateOnLoad = null;
 
         /// <summary>
         /// Callback pointer, for checking if file is up to date at saving.
         /// </summary>
-        public event IsFileUpToDate isFileUpToDateOnSave = null;
+        public event IsFileUpToDate IsFileUpToDateOnSave = null;
 
         /// <summary>
         /// Callback pointer, for checking if model is up to date at loading.
         /// </summary>
-        public event IsModelUpToDate isModelUpToDateOnLoad = null;
+        public event IsModelUpToDate IsModelUpToDateOnLoad = null;
 
         /// <summary>
         /// Callback pointer, for checking if model is up to date at saving.
         /// (currently unused)
         /// </summary>
-        public event IsModelUpToDate isModelUpToDateOnSave = null;
+        public event IsModelUpToDate IsModelUpToDateOnSave = null;
 
         /// <summary>
         /// Specifies the I/O type of the model.
@@ -224,6 +209,19 @@ namespace CampusAppWP8
             FileAndFeed = 3
         }
 
+        /// <summary>Values that represent ForceType for load function.</summary>
+        public enum ForceType
+        {
+            /// <summary>An enumeration constant representing the invalid/default/unset option.</summary>
+            INVALID = 0,
+
+            /// <summary>An enumeration constant representing the force file option.</summary>
+            FORCE_FILE = 1,
+
+            /// <summary>An enumeration constant representing the force web option.</summary>
+            FORCE_WEB = 2
+        }
+
         /// <summary>
         /// Gets or sets the Model.
         /// </summary>
@@ -253,15 +251,7 @@ namespace CampusAppWP8
         /// </summary>
         public void ForceWebUpdate()
         {
-            if (this.api != null)
-            {
-                if (this.onLoading != null)
-                {
-                    this.onLoading();
-                }
-
-                this.api.HttpGet(this.httpApiUri, this.OnLoadDataComplete);
-            }
+            this.LoadData(ForceType.FORCE_WEB);
         }
 
         /// <summary>
@@ -269,80 +259,60 @@ namespace CampusAppWP8
         /// </summary>
         public void ForceReadFile()
         {
-            if (this.file != null)
-            {
-                if (this.onLoading != null)
-                {
-                    this.onLoading();
-                }
-
-                string data = this.file.ReadFile();
-
-                if (data == null)
-                {
-                    if (this.onFailedFile != null)
-                    {
-                        this.onFailedFile();
-                    }
-                    else if (this.onFailed != null)
-                    {
-                        this.onFailed();
-                    }
-                }
-                else if (!data.Equals(string.Empty))
-                {
-                    this.DeserializeModel(Encoding.UTF8.GetBytes(data));
-                }
-
-                if ((data != null) && (this.onLoaded != null))
-                {
-                    this.onLoaded();
-                }
-            }
+            this.LoadData(ForceType.FORCE_FILE);
         }
 
         /// <summary>
         /// Load the data if necessary, from web or from file, regarding if
         /// the file data is up to date.
         /// </summary>
-        public void LoadData()
+        /// <param name="force">if set/not invalid/not default, force to load from web or file</param>
+        public void LoadData(ForceType force = ForceType.INVALID)
         {
-            bool loadFromFile = true;
-
-            if (this.onLoading != null)
+            this.RunOnIOCallback(this.OnLoading);
+            
+            // check which source is used for loading the data
+            if (force == ForceType.INVALID)
             {
-                this.onLoading();
-            }
-
-            if (((this.isModelUpToDateOnLoad == null)
-            || (this.isModelUpToDateOnLoad(this.model) == false))
-            && ((this.file != null) || this.api != null))
-            {
-                if (this.file != null)
+                // if the model is not up to date
+                if (this.CheckIsNotUpToDate(this.IsModelUpToDateOnLoad) == true)
                 {
-                    if ((this.file.Exist() == false)
-                    || (this.file.GetFileInfo().Length == 0))
+                    force = ForceType.FORCE_FILE;
+
+                    if (this.file != null)
                     {
-                        loadFromFile = false;
+                        // if the file does not exist or is size of 0 or is not
+                        // up to date, then load from web
+                        if ((this.file.Exist() == false)
+                        || (this.file.GetFileInfo().Length == 0)
+                        || (this.CheckIsNotUpToDate(this.IsFileUpToDateOnLoad) == true))
+                        {
+                            force = ForceType.FORCE_WEB;
+                        }
+                    }
+                    else
+                    {
+                        // if the file object does not exist, load from web
+                        force = ForceType.FORCE_WEB;
                     }
 
-                    if (((this.isFileUpToDateOnLoad != null) && (this.isFileUpToDateOnLoad(this.model, this.file.GetFileInfo()) == false))
-                    || (this.isFileUpToDateOnLoad == null))
+                    // if the web object does not exist, load from file
+                    if (this.api == null)
                     {
-                        loadFromFile = false;
+                        force = ForceType.FORCE_FILE;
                     }
                 }
                 else
                 {
-                    loadFromFile = false;
+                    // if it is up to date, nothing has to be loaded
+                    this.RunOnIOCallback(this.OnLoaded);
                 }
+            }
 
-                if (this.api == null)
-                {
-                    loadFromFile = true;
-                }
-
-                if (loadFromFile == false)
+            // load from web
+            if (force == ForceType.FORCE_WEB)
+            {
+                if (this.api != null)
                 {
                     if (this.paramizedUri != null)
                     {
@@ -354,32 +324,37 @@ namespace CampusAppWP8
                     }
                 }
                 else
+                {
+                    // if web object does not exist, call OnFailed callbacks
+                    this.RunOnFailedCallback(this.OnFailedWeb, this.OnFailedLoad);
+                }
+            }
+            
+            // load from file
+            if (force == ForceType.FORCE_FILE)
+            {
+                if (this.file != null)
                 {
                     string data = this.file.ReadFile();
 
                     if (data == null)
                     {
-                        if (this.onFailedFile != null)
-                        {
-                            this.onFailedFile();
-                        }
-                        else if (this.onFailed != null)
-                        {
-                            this.onFailed();
-                        }
+                        this.RunOnFailedCallback(this.OnFailedFile, this.OnFailedLoad);
                     }
-                    else if (!data.Equals(string.Empty))
+                    else
                     {
-                        this.DeserializeModel(Encoding.UTF8.GetBytes(data));
+                        if (!data.Equals(string.Empty))
+                        {
+                            this.DeserializeModel(Encoding.UTF8.GetBytes(data));
+                        }
+
+                        this.RunOnIOCallback(this.OnLoaded);
                     }
                 }
-            }
-
-            if (loadFromFile == true)
-            {
-                if (this.onLoaded != null)
+                else
                 {
-                    this.onLoaded();
+                    // if file object does not exist, call OnFailed callbacks
+                    this.RunOnFailedCallback(this.OnFailedFile, this.OnFailedLoad);
                 }
             }
         }
@@ -391,40 +366,28 @@ namespace CampusAppWP8
         public void SaveData(bool force = false)
         {
             if ((this.file != null)
-            && ((this.isFileUpToDateOnSave == null) 
-                || (this.isFileUpToDateOnSave(this.model, this.file.GetFileInfo()) == false) 
-                || (force == true)))
+            && ((this.CheckIsNotUpToDate(this.IsFileUpToDateOnSave) == true) || (force == true)))
             {
-                if (this.onSaving != null)
-                {
-                    this.onSaving();
-                }
-
+                this.RunOnIOCallback(this.OnSaving);
+                
                 byte[] data = this.SerializeModel();
 
-                if ((this.onSaved != null) && (this.onFailedSave != null))
+                if ((this.OnSaved != null) && (this.OnFailedSave != null))
                 {
-                    this.file.WriteFile(data, delegate() { this.onSaved(); }, delegate() { this.onFailedSave(); });
+                    this.file.WriteFile(data, delegate { this.OnSaved(); }, delegate { this.OnFailedSave(); });
                 }
-                else if (this.onSaved != null)
+                else if (this.OnSaved != null)
                 {
-                    this.file.WriteFile(data, delegate() { this.onSaved(); }, null);
+                    this.file.WriteFile(data, delegate { this.OnSaved(); }, null);
                 }
-                else if (this.onFailedSave != null)
+                else if (this.OnFailedSave != null)
                 {
-                    this.file.WriteFile(data, null, delegate() { this.onFailedSave(); });
+                    this.file.WriteFile(data, null, delegate { this.OnFailedSave(); });
                 }
                 else
                 {
                     this.file.WriteFile(data, null, null);
                 }
-
-                /*
-                if (this.onSaved != null)
-                {
-                    this.onSaved();
-                }
-                */
             }
         }
 
@@ -529,7 +492,7 @@ namespace CampusAppWP8
             this.fileName = fileName;
 
             if ((this.IsFile() == true)
-                && (fileName.Equals(string.Empty) == false))
+            && (fileName.Equals(string.Empty) == false))
             {
                 this.InitFile(CampusAppWP8.Utility.File.IOTypeRead.ReadSync, CampusAppWP8.Utility.File.IOTypeWrite.WriteAsync);
             }
@@ -546,7 +509,9 @@ namespace CampusAppWP8
         /// </summary>
         /// <param name="readType">read io type (Default: sync)</param>
         /// <param name="writeType">write io type (Default: async)</param>
-        private void InitFile(CampusAppWP8.Utility.File.IOTypeRead readType = CampusAppWP8.Utility.File.IOTypeRead.ReadSync, CampusAppWP8.Utility.File.IOTypeWrite writeType = CampusAppWP8.Utility.File.IOTypeWrite.WriteAsync)
+        private void InitFile(
+            CampusAppWP8.Utility.File.IOTypeRead readType = CampusAppWP8.Utility.File.IOTypeRead.ReadSync, 
+            CampusAppWP8.Utility.File.IOTypeWrite writeType = CampusAppWP8.Utility.File.IOTypeWrite.WriteAsync)
         {
             if ((this.IsFile() == true)
             && (this.file == null))
@@ -577,28 +542,75 @@ namespace CampusAppWP8
             Exception downloadError = e.Error;
             if (downloadError != null)
             {
-                if (this.onFailedWeb != null)
+                this.RunOnFailedCallback(this.OnFailedWeb, this.OnFailedLoad);
+            }
+            else
+            {
+                string downloadResult = e.Result;
+
+                if (downloadResult != null && !downloadResult.Equals(string.Empty))
                 {
-                    this.onFailedWeb();
-                }
-                else if (this.onFailed != null)
-                {
-                    this.onFailed();
+                    this.DeserializeModel(Encoding.UTF8.GetBytes(downloadResult));
                 }
 
-                return;
+                this.RunOnIOCallback(this.OnLoaded);
+            }
+        }
+
+        /// <summary>
+        /// Executes the on i/o callback operation.
+        /// </summary>
+        /// <param name="callbackFunc">The callback function.</param>
+        private void RunOnIOCallback(OnIO callbackFunc)
+        {
+            if (callbackFunc != null)
+            {
+                callbackFunc();
+            }
+        }
+
+        /// <summary>Executes the on failed callback operation.</summary>
+        /// <param name="specialFunc">The special function.</param>
+        /// <param name="defaultFunc">The default function.</param>
+        private void RunOnFailedCallback(OnFailed specialFunc, OnFailed defaultFunc)
+        {
+            if (specialFunc != null)
+            {
+                specialFunc();
+            }
+            else if (defaultFunc != null)
+            {
+                defaultFunc();
+            }
+        }
+
+        /// <summary>Check if model or file is not up to date.</summary>
+        /// <param name="checkFunc">The check function.</param>
+        /// <returns>true if model or file is not up to date, false if it is.</returns>
+        private bool CheckIsNotUpToDate(object checkFunc)
+        {
+            bool retValue = false;
+
+            // if there is no check function, the model or file is not up to date
+            if (checkFunc == null)
+            {
+                retValue = true;
+            }
+            else
+            {
+                Type funcType = checkFunc.GetType();
+                
+                if (funcType.Equals(typeof(IsFileUpToDate)))
+                {
+                    retValue = !(checkFunc as IsFileUpToDate)(this.model, this.file.GetFileInfo());
+                }
+                else if (funcType.Equals(typeof(IsModelUpToDate)))
+                {
+                    retValue = !(checkFunc as IsModelUpToDate)(this.model);
+                }
             }
 
-            string downloadResult = e.Result;
-            if (downloadResult != null && !downloadResult.Equals(string.Empty))
-            {
-                this.DeserializeModel(Encoding.UTF8.GetBytes(downloadResult));
-            }
-
-            if (this.onLoaded != null)
-            {
-                this.onLoaded();
-            }
+            return retValue;
         }
     }
 }
\ No newline at end of file
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentFavoritePage.xaml b/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentFavoritePage.xaml
index fb8dd7df..41b7eb21 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentFavoritePage.xaml
+++ b/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentFavoritePage.xaml
@@ -20,6 +20,7 @@
             <RowDefinition Height="*"/>
         </Grid.RowDefinitions>
 
+        <ProgressBar x:Name="progressBar" Grid.Row="1" VerticalAlignment="Center" HorizontalAlignment="Center" Visibility="Collapsed" IsIndeterminate="True"/>
         <!--TitlePanel enthält den Namen der Anwendung und den Seitentitel-->
         <StackPanel Grid.Row="0" Margin="12,17,0,28">
             <TextBlock Text="{Binding Path=LocalizedResources.ApplicationTitle, Source={StaticResource LocalizedStrings}}" Style="{StaticResource PhoneTextNormalStyle}"/>
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentFavoritePage.xaml.cs b/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentFavoritePage.xaml.cs
index 533a6f04..3877c73d 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentFavoritePage.xaml.cs
+++ b/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentFavoritePage.xaml.cs
@@ -53,6 +53,7 @@ namespace CampusAppWP8.Pages.Departments
         protected override void OnNavigatedTo(NavigationEventArgs e)
         {
             base.OnNavigatedTo(e);
+            this.progressBar.Visibility = Visibility.Visible;
 
             if (this.isNewInstance)
             {
@@ -80,6 +81,8 @@ namespace CampusAppWP8.Pages.Departments
                 this.ContentPanel.ItemsSource = DepartmentIndexPage.GetFavoriteFeed().GetModel().Faculties[0].Chairs;
                 this.isSourceSet = true;
             }
+
+            this.progressBar.Visibility = Visibility.Collapsed;
         }
 
         /// <summary>
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentIndexPage.xaml b/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentIndexPage.xaml
index 6ac7f84f..b1f6f8b6 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentIndexPage.xaml
+++ b/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentIndexPage.xaml
@@ -22,6 +22,7 @@
             <RowDefinition Height="*"/>
         </Grid.RowDefinitions>
 
+        <ProgressBar x:Name="progressBar" Grid.Row="2" VerticalAlignment="Center" HorizontalAlignment="Center" Visibility="Collapsed" IsIndeterminate="True"/>
         <!--TitlePanel enthält den Namen der Anwendung und den Seitentitel-->
         <StackPanel Grid.Row="0" Margin="12,17,0,28">
             <TextBlock Text="{Binding Path=LocalizedResources.ApplicationTitle, Source={StaticResource LocalizedStrings}}" Style="{StaticResource PhoneTextNormalStyle}"/>
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentIndexPage.xaml.cs b/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentIndexPage.xaml.cs
index 7d8ee8da..3e54758a 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentIndexPage.xaml.cs
+++ b/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentIndexPage.xaml.cs
@@ -37,6 +37,7 @@ namespace CampusAppWP8.Pages.Departments
         public DepartmentIndexPage()
         {
             this.InitializeComponent();
+            this.progressBar.Visibility = Visibility.Visible;
 
             //// init feed objects
             if (DepartmentIndexPage.feed == null)
@@ -44,9 +45,9 @@ namespace CampusAppWP8.Pages.Departments
                 DepartmentIndexPage.feed = new DepartmentFeed(false);
             }
         
-            DepartmentIndexPage.feed.onLoaded += new DepartmentFeed.OnLoaded(this.SetupFacultyList);
-            DepartmentIndexPage.feed.onFailedWeb += new DepartmentFeed.OnFailed(this.FeedIsFailWeb);
-            DepartmentIndexPage.feed.onFailedFile += new DepartmentFeed.OnFailed(this.FeedIsFailFile);
+            DepartmentIndexPage.feed.OnLoaded += new DepartmentFeed.OnIO(this.SetupFacultyList);
+            DepartmentIndexPage.feed.OnFailedWeb += new DepartmentFeed.OnFailed(this.FeedIsFailedWeb);
+            DepartmentIndexPage.feed.OnFailedFile += new DepartmentFeed.OnFailed(this.FeedIsFailedFile);
             DepartmentIndexPage.feed.LoadData();
         
             if (DepartmentIndexPage.favorite == null)
@@ -54,8 +55,7 @@ namespace CampusAppWP8.Pages.Departments
                 DepartmentIndexPage.favorite = new DepartmentFavoriteFeed(false);
             }
 
-            DepartmentIndexPage.favorite.onLoaded += new DepartmentFavoriteFeed.OnLoaded(this.CheckFavoriteFeed);
-            DepartmentIndexPage.favorite.onFailedFile += new DepartmentFavoriteFeed.OnFailed(this.FeedIsFailFile);
+            DepartmentIndexPage.favorite.OnFailedFile += new DepartmentFavoriteFeed.OnFailed(this.CheckFavoriteFeed);
             DepartmentIndexPage.favorite.LoadData();
         }
 
@@ -159,6 +159,7 @@ namespace CampusAppWP8.Pages.Departments
         private void SetupFacultyList()
         {
             this.FacultyList.ItemsSource = DepartmentIndexPage.feed.GetModel().Faculties;
+            this.progressBar.Visibility = Visibility.Collapsed;
         }
 
         /// <summary>
@@ -213,7 +214,7 @@ namespace CampusAppWP8.Pages.Departments
         /// <summary>
         /// Method will be execute if the feed is failed
         /// </summary>
-        private void FeedIsFailWeb()
+        private void FeedIsFailedWeb()
         {
             MessageBoxResult result = MessageBoxes.ShowMainModelErrorMessageBox(AppResources.MsgBox_ErrorMainModelLoadWeb);
             DepartmentIndexPage.feed.ForceReadFile();
@@ -222,8 +223,9 @@ namespace CampusAppWP8.Pages.Departments
         /// <summary>
         /// Method will be execute if the feed is failed
         /// </summary>
-        private void FeedIsFailFile()
+        private void FeedIsFailedFile()
         {
+            this.progressBar.Visibility = Visibility.Collapsed;
             MessageBoxResult result = MessageBoxes.ShowMainModelErrorMessageBox(AppResources.MsgBox_ErrorMainModelLoadFile);
         }
     }
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentPage.xaml b/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentPage.xaml
index d39e152b..62fd0e93 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentPage.xaml
+++ b/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentPage.xaml
@@ -20,6 +20,8 @@
         <Grid.DataContext>
             <viewModel:DepartmentModel />
         </Grid.DataContext>
+
+        <ProgressBar x:Name="progressBar" VerticalAlignment="Center" HorizontalAlignment="Center" Visibility="Collapsed" IsIndeterminate="True"/>
         <!-- Pivot -->
         <phone:Pivot x:Name="DepartmentPivot" Title="{Binding Path=LocalizedResources.DepartmentApp_Title, Source={StaticResource LocalizedStrings}}" ItemsSource="{Binding Faculties}">
             <!-- Pivotitem template -->
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentPage.xaml.cs b/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentPage.xaml.cs
index d0517b3a..e5dd9428 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentPage.xaml.cs
+++ b/CampusAppWP8/CampusAppWP8/Pages/Departments/DepartmentPage.xaml.cs
@@ -54,6 +54,7 @@ namespace CampusAppWP8.Pages.Departments
         protected override void OnNavigatedTo(NavigationEventArgs e)
         {
             base.OnNavigatedTo(e);
+            this.progressBar.Visibility = Visibility.Visible;
 
             if (this.isNewInstance)
             {
@@ -99,6 +100,8 @@ namespace CampusAppWP8.Pages.Departments
                     MessageBox.Show("ERROR: pivotIndex out of range!!!");
                 }
             }
+
+            this.progressBar.Visibility = Visibility.Collapsed;
         }
 
         /// <summary>
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Events/EventIndexPage.xaml b/CampusAppWP8/CampusAppWP8/Pages/Events/EventIndexPage.xaml
index 3f4eefd8..0aac8c25 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Events/EventIndexPage.xaml
+++ b/CampusAppWP8/CampusAppWP8/Pages/Events/EventIndexPage.xaml
@@ -21,6 +21,7 @@
             <RowDefinition Height="*"/>
         </Grid.RowDefinitions>
 
+        <ProgressBar x:Name="progressBar" Grid.Row="1" VerticalAlignment="Center" HorizontalAlignment="Center" Visibility="Collapsed" IsIndeterminate="True"/>
         <!-- Title and headline -->
         <StackPanel Grid.Row="0" Margin="12,17,0,28">
             <TextBlock Text="{Binding Path=LocalizedResources.ApplicationTitle, Source={StaticResource LocalizedStrings}}" Style="{StaticResource PhoneTextNormalStyle}"/>
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Events/EventIndexPage.xaml.cs b/CampusAppWP8/CampusAppWP8/Pages/Events/EventIndexPage.xaml.cs
index d8e1bc11..bb9f2dc7 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Events/EventIndexPage.xaml.cs
+++ b/CampusAppWP8/CampusAppWP8/Pages/Events/EventIndexPage.xaml.cs
@@ -32,6 +32,7 @@ namespace CampusAppWP8.Pages.Events
         public EventIndexPage()
         {
             this.InitializeComponent();
+            this.progressBar.Visibility = Visibility.Visible;
 
             ApplicationBarIconButton updateBtn = new ApplicationBarIconButton();
             updateBtn.IconUri = new Uri(Icons.Update, UriKind.Relative);
@@ -44,9 +45,9 @@ namespace CampusAppWP8.Pages.Events
                 EventIndexPage.eventFeed = new EventFeed(false);
             }
 
-            EventIndexPage.eventFeed.onLoaded += new EventFeed.OnLoaded(this.SetupEventPageList);
-            EventIndexPage.eventFeed.onFailedWeb += new EventFeed.OnFailed(this.FeedIsFailWeb);
-            EventIndexPage.eventFeed.onFailedFile += new EventFeed.OnFailed(this.FeedIsFailFile);
+            EventIndexPage.eventFeed.OnLoaded += new EventFeed.OnIO(this.SetupEventPageList);
+            EventIndexPage.eventFeed.OnFailedWeb += new EventFeed.OnFailed(this.FeedIsFailedWeb);
+            EventIndexPage.eventFeed.OnFailedFile += new EventFeed.OnFailed(this.FeedIsFailedFile);
             EventIndexPage.eventFeed.LoadData();
         }
 
@@ -95,6 +96,7 @@ namespace CampusAppWP8.Pages.Events
         private void SetupEventPageList()
         {
             this.EventList.ItemsSource = EventIndexPage.eventFeed.Model.Channel[0].Item;
+            this.progressBar.Visibility = Visibility.Collapsed;
         }
 
         /// <summary>
@@ -105,24 +107,26 @@ namespace CampusAppWP8.Pages.Events
         /// <param name="e">event args</param>
         private void EventForceUpdate_Click(object sender, EventArgs e)
         {
+            this.progressBar.Visibility = Visibility.Visible;
             EventIndexPage.eventFeed.ForceWebUpdate();
         }
 
         /// <summary>
         /// Method will be execute if the feed is failed
         /// </summary>
-        private void FeedIsFailWeb()
+        private void FeedIsFailedWeb()
         {
             MessageBoxResult result = MessageBoxes.ShowMainModelErrorMessageBox(AppResources.MsgBox_ErrorMainModelLoadWeb);
-           EventIndexPage.eventFeed.ForceReadFile();
+            EventIndexPage.eventFeed.ForceReadFile();
         }
 
         /// <summary>
         /// Method will be execute if the feed is failed
         /// </summary>
-        private void FeedIsFailFile()
+        private void FeedIsFailedFile()
         {
             MessageBoxResult result = MessageBoxes.ShowMainModelErrorMessageBox(AppResources.MsgBox_ErrorMainModelLoadFile);
+            this.progressBar.Visibility = Visibility.Collapsed;
         }
     }
 }
\ No newline at end of file
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Events/EventPage.xaml b/CampusAppWP8/CampusAppWP8/Pages/Events/EventPage.xaml
index 956943b7..3597dbbd 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Events/EventPage.xaml
+++ b/CampusAppWP8/CampusAppWP8/Pages/Events/EventPage.xaml
@@ -19,6 +19,8 @@
     </phone:PhoneApplicationPage.Resources>
     <!-- LayoutRoot -->
     <Grid x:Name="LayoutRoot" Background="Transparent">
+        
+        <ProgressBar x:Name="progressBar" VerticalAlignment="Center" HorizontalAlignment="Center" Visibility="Collapsed" IsIndeterminate="True"/>
         <!-- Pivotpage -->
         <phone:Pivot x:Name="EventPivot" Title="{Binding Path=LocalizedResources.ApplicationTitle, Source={StaticResource LocalizedStrings}}" SelectionChanged="OnPivotSelectionChange">
             <!-- Pivotitem template -->
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Events/EventPage.xaml.cs b/CampusAppWP8/CampusAppWP8/Pages/Events/EventPage.xaml.cs
index 78a5493e..893982e6 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Events/EventPage.xaml.cs
+++ b/CampusAppWP8/CampusAppWP8/Pages/Events/EventPage.xaml.cs
@@ -64,6 +64,7 @@ namespace CampusAppWP8.Pages.Events
         protected override void OnNavigatedTo(NavigationEventArgs e)
         {
             base.OnNavigatedTo(e);
+            this.progressBar.Visibility = Visibility.Visible;
 
             if (this.isNewInstance)
             {
@@ -117,6 +118,8 @@ namespace CampusAppWP8.Pages.Events
                     MessageBox.Show("ERROR: pivotIndex out of range!!! (" + o + ")");
                 }
             }
+
+            this.progressBar.Visibility = Visibility.Collapsed;
         }
 
         /// <summary>
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Lecture/LecturePage.xaml.cs b/CampusAppWP8/CampusAppWP8/Pages/Lecture/LecturePage.xaml.cs
index 27dd9d1b..a29a037d 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Lecture/LecturePage.xaml.cs
+++ b/CampusAppWP8/CampusAppWP8/Pages/Lecture/LecturePage.xaml.cs
@@ -166,8 +166,8 @@ namespace CampusAppWP8.Pages.Lecture
         private void SendRequest(object sender, RoutedEventArgs e)
         {
             this.api = new LectureApi();
-            this.api.onLoaded += new LectureApi.OnLoaded(this.ApiIsReady);
-            this.api.onFailed += new LectureApi.OnFailed(this.ApiIsFail);
+            this.api.OnLoaded += new LectureApi.OnIO(this.ApiIsReady);
+            this.api.OnFailedLoad += new LectureApi.OnFailed(this.ApiIsFail);
             this.ProgressBar.Visibility = System.Windows.Visibility.Visible;
             List<UrlParamModel> parameterList = this.CreateUrlParameter();
             this.api.SetUriParams(parameterList);
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Links/LinkPage.xaml.cs b/CampusAppWP8/CampusAppWP8/Pages/Links/LinkPage.xaml.cs
index d445116b..30ff8fa0 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Links/LinkPage.xaml.cs
+++ b/CampusAppWP8/CampusAppWP8/Pages/Links/LinkPage.xaml.cs
@@ -105,9 +105,9 @@ namespace CampusAppWP8.Pages.Links
         private void InitializeCommonLinkFeed()
         {
             this.commonLinkFeed = new CommonLinkFeed();
-            this.commonLinkFeed.onLoaded += new CommonLinkFeed.OnLoaded(this.CommonLinkFeedIsReady);
-            this.commonLinkFeed.onFailedWeb += new CommonLinkFeed.OnFailed(this.CommonLinkFeedIsFailWeb);
-            this.commonLinkFeed.onFailedFile += new CommonLinkFeed.OnFailed(this.FeedIsFailFile);
+            this.commonLinkFeed.OnLoaded += new CommonLinkFeed.OnIO(this.CommonLinkFeedIsReady);
+            this.commonLinkFeed.OnFailedWeb += new CommonLinkFeed.OnFailed(this.CommonLinkFeedIsFailWeb);
+            this.commonLinkFeed.OnFailedFile += new CommonLinkFeed.OnFailed(this.FeedIsFailFile);
         }
 
         /// <summary>
@@ -116,9 +116,9 @@ namespace CampusAppWP8.Pages.Links
         private void InitializeClubLinkFeed()
         {
             this.clubLinkFeed = new ClubLinkFeed();
-            this.clubLinkFeed.onLoaded += new ClubLinkFeed.OnLoaded(this.ClubLinkFeedIsReady);
-            this.clubLinkFeed.onFailedWeb += new ClubLinkFeed.OnFailed(this.ClubLinkFeedIsFailWeb);
-            this.clubLinkFeed.onFailedFile += new ClubLinkFeed.OnFailed(this.FeedIsFailFile);
+            this.clubLinkFeed.OnLoaded += new ClubLinkFeed.OnIO(this.ClubLinkFeedIsReady);
+            this.clubLinkFeed.OnFailedWeb += new ClubLinkFeed.OnFailed(this.ClubLinkFeedIsFailWeb);
+            this.clubLinkFeed.OnFailedFile += new ClubLinkFeed.OnFailed(this.FeedIsFailFile);
         }
 
         /// <summary>
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Mensa/MensaPage.xaml.cs b/CampusAppWP8/CampusAppWP8/Pages/Mensa/MensaPage.xaml.cs
index b1931f73..4f85b351 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Mensa/MensaPage.xaml.cs
+++ b/CampusAppWP8/CampusAppWP8/Pages/Mensa/MensaPage.xaml.cs
@@ -125,8 +125,8 @@ namespace CampusAppWP8.Pages.Mensa
         private void DeterminCurrentCampusAndLoadFeed()
         {
             this.campusApi = new CampusSpsApi();
-            this.campusApi.onLoaded += new SpsApi.OnLoaded(this.SpsApiIsReady);
-            this.campusApi.onFailed += new SpsApi.OnFailed(this.SpsApiIsFail);
+            this.campusApi.OnLoaded += new SpsApi.OnIO(this.SpsApiIsReady);
+            this.campusApi.OnFailedLoad += new SpsApi.OnFailed(this.SpsApiIsFail);
             this.campusApi.SetupCurrentCampusRequest();
             this.campusApi.LoadData();
         }
@@ -138,9 +138,9 @@ namespace CampusAppWP8.Pages.Mensa
         private void InitializeFeed(CampusAppWP8.Model.Setting.UserProfilModel.Campus campus)
         {
             this.feed = MensaFeed.CreateCampusMensaFeed(campus);
-            this.feed.onLoaded += new MensaFeed.OnLoaded(this.FeedIsReady);
-            this.feed.onFailedWeb += new MensaFeed.OnFailed(this.FeedIsFailWeb);
-            this.feed.onFailedFile += new MensaFeed.OnFailed(this.FeedIsFailFile);
+            this.feed.OnLoaded += new MensaFeed.OnIO(this.FeedIsReady);
+            this.feed.OnFailedWeb += new MensaFeed.OnFailed(this.FeedIsFailWeb);
+            this.feed.OnFailedFile += new MensaFeed.OnFailed(this.FeedIsFailFile);
             this.CalcSelectedIndex();
 
             if (this.forceLoad)
diff --git a/CampusAppWP8/CampusAppWP8/Pages/News/NewsIndexPage.xaml b/CampusAppWP8/CampusAppWP8/Pages/News/NewsIndexPage.xaml
index 1deea115..1376bfb3 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/News/NewsIndexPage.xaml
+++ b/CampusAppWP8/CampusAppWP8/Pages/News/NewsIndexPage.xaml
@@ -21,6 +21,7 @@
             <RowDefinition Height="*"/>
         </Grid.RowDefinitions>
 
+        <ProgressBar x:Name="progressBar" Grid.Row="1" VerticalAlignment="Center" HorizontalAlignment="Center" Visibility="Collapsed" IsIndeterminate="True"/>
         <!-- Title and headline -->
         <StackPanel Grid.Row="0" Margin="12,17,0,28">
             <TextBlock Text="{Binding Path=LocalizedResources.ApplicationTitle, Source={StaticResource LocalizedStrings}}" Style="{StaticResource PhoneTextNormalStyle}"/>
diff --git a/CampusAppWP8/CampusAppWP8/Pages/News/NewsIndexPage.xaml.cs b/CampusAppWP8/CampusAppWP8/Pages/News/NewsIndexPage.xaml.cs
index b5cb6933..7a8b5e57 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/News/NewsIndexPage.xaml.cs
+++ b/CampusAppWP8/CampusAppWP8/Pages/News/NewsIndexPage.xaml.cs
@@ -32,6 +32,7 @@ namespace CampusAppWP8.Pages.News
         public NewsIndexPage()
         {
             this.InitializeComponent();
+            this.progressBar.Visibility = Visibility.Collapsed;
 
             ApplicationBarIconButton updateBtn = new ApplicationBarIconButton();
             updateBtn.IconUri = new Uri(Icons.Update, UriKind.Relative);
@@ -44,9 +45,9 @@ namespace CampusAppWP8.Pages.News
                 NewsIndexPage.newsFeed = new NewsFeed(false);
             }
 
-            NewsIndexPage.newsFeed.onLoaded += new NewsFeed.OnLoaded(this.SetupNewsPageList);
-            NewsIndexPage.newsFeed.onFailedWeb += new NewsFeed.OnFailed(this.FeedIsFailWeb);
-            NewsIndexPage.newsFeed.onFailedFile += new NewsFeed.OnFailed(this.FeedIsFailFile);
+            NewsIndexPage.newsFeed.OnLoaded += new NewsFeed.OnIO(this.SetupNewsPageList);
+            NewsIndexPage.newsFeed.OnFailedWeb += new NewsFeed.OnFailed(this.FeedIsFailWeb);
+            NewsIndexPage.newsFeed.OnFailedFile += new NewsFeed.OnFailed(this.FeedIsFailFile);
             NewsIndexPage.newsFeed.LoadData();
         }
 
@@ -95,6 +96,7 @@ namespace CampusAppWP8.Pages.News
         private void SetupNewsPageList()
         {
             this.NewsList.ItemsSource = NewsIndexPage.newsFeed.Model.Channel[0].Item;
+            this.progressBar.Visibility = Visibility.Collapsed;
         }
 
         /// <summary>
@@ -105,6 +107,7 @@ namespace CampusAppWP8.Pages.News
         /// <param name="e">event args</param>
         private void NewsForceUpdate_Click(object sender, EventArgs e)
         {
+            this.progressBar.Visibility = Visibility.Visible;
             NewsIndexPage.newsFeed.ForceWebUpdate();
         }
 
@@ -122,6 +125,7 @@ namespace CampusAppWP8.Pages.News
         /// </summary>
         private void FeedIsFailFile()
         {
+            this.progressBar.Visibility = Visibility.Collapsed;
             MessageBoxResult result = MessageBoxes.ShowMainModelErrorMessageBox(AppResources.MsgBox_ErrorMainModelLoadFile);
         }
     }
diff --git a/CampusAppWP8/CampusAppWP8/Pages/News/NewsPage.xaml b/CampusAppWP8/CampusAppWP8/Pages/News/NewsPage.xaml
index 972abeb0..36992213 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/News/NewsPage.xaml
+++ b/CampusAppWP8/CampusAppWP8/Pages/News/NewsPage.xaml
@@ -19,7 +19,9 @@
     </phone:PhoneApplicationPage.Resources>
     <!-- LayoutRoot -->
     <Grid x:Name="LayoutRoot" Background="Transparent">
+        
         <!-- Pivotpage -->
+        <ProgressBar x:Name="progressBar" VerticalAlignment="Center" HorizontalAlignment="Center" Visibility="Collapsed" IsIndeterminate="True"/>
         <phone:Pivot x:Name="NewsPivot" Title="{Binding Path=LocalizedResources.ApplicationTitle, Source={StaticResource LocalizedStrings}}" SelectionChanged="OnPivotSelectionChange">
             <!-- Pivotitem template -->
             <phone:Pivot.HeaderTemplate>
diff --git a/CampusAppWP8/CampusAppWP8/Pages/News/NewsPage.xaml.cs b/CampusAppWP8/CampusAppWP8/Pages/News/NewsPage.xaml.cs
index 709a6b7b..3c26f7cb 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/News/NewsPage.xaml.cs
+++ b/CampusAppWP8/CampusAppWP8/Pages/News/NewsPage.xaml.cs
@@ -45,7 +45,7 @@ namespace CampusAppWP8.Pages.News
         public NewsPage()
         {
             this.InitializeComponent();
-
+            
             ApplicationBarIconButton linkBtn = new ApplicationBarIconButton();
             linkBtn.IconUri = new Uri(Icons.Link, UriKind.Relative);
             linkBtn.Text = AppResources.NewsLinkBtn;
@@ -64,6 +64,7 @@ namespace CampusAppWP8.Pages.News
         protected override void OnNavigatedTo(NavigationEventArgs e)
         {
             base.OnNavigatedTo(e);
+            this.progressBar.Visibility = Visibility.Visible;
 
             if (this.isNewInstance)
             {
@@ -110,6 +111,8 @@ namespace CampusAppWP8.Pages.News
                     MessageBox.Show("ERROR: pivotIndex out of range!!!");
                 }
             }
+
+            this.progressBar.Visibility = Visibility.Collapsed;
         }
 
         /// <summary>
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Openinghours/OpeninghoursPage.xaml b/CampusAppWP8/CampusAppWP8/Pages/Openinghours/OpeninghoursPage.xaml
index 32570e7c..744eeb92 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Openinghours/OpeninghoursPage.xaml
+++ b/CampusAppWP8/CampusAppWP8/Pages/Openinghours/OpeninghoursPage.xaml
@@ -21,13 +21,13 @@
             <RowDefinition Height="*"/>
         </Grid.RowDefinitions>
 
+        <ProgressBar x:Name="progressBar" Grid.Row="1" VerticalAlignment="Center" HorizontalAlignment="Center" Visibility="Collapsed" IsIndeterminate="True"/>
         <!-- Title and headline -->
         <StackPanel Grid.Row="0" Margin="12,17,0,28">
             <TextBlock Text="{Binding Path=LocalizedResources.ApplicationTitle, Source={StaticResource LocalizedStrings}}" Style="{StaticResource PhoneTextNormalStyle}"/>
             <TextBlock Text="{Binding Path=LocalizedResources.OpenHoursApp_Title, Source={StaticResource LocalizedStrings}}" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}" FontSize="64"/>
         </StackPanel>
         <!-- Content -->
-        <ProgressBar Name="ProgressBar" Grid.Row="1"  Visibility="Collapsed" IsIndeterminate="True"/>
         <ListBox x:Name="InstitutionPanel" Grid.Row="1">
             <ListBox.ItemContainerStyle>
                 <Style TargetType="ListBoxItem">
diff --git a/CampusAppWP8/CampusAppWP8/Pages/Openinghours/OpeninghoursPage.xaml.cs b/CampusAppWP8/CampusAppWP8/Pages/Openinghours/OpeninghoursPage.xaml.cs
index f10ebff7..16d28f4a 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/Openinghours/OpeninghoursPage.xaml.cs
+++ b/CampusAppWP8/CampusAppWP8/Pages/Openinghours/OpeninghoursPage.xaml.cs
@@ -43,13 +43,14 @@ namespace CampusAppWP8.Pages.Openinghours
         public OpeninghoursPage()
         {
             this.InitializeComponent();
+            this.progressBar.Visibility = Visibility.Visible;
 
             if (this.feed == null)
             {
                 this.feed = new OpeninghoursFeed();
-                this.feed.onLoaded += new OpeninghoursFeed.OnLoaded(this.FeedIsReady);
-                this.feed.onFailedWeb += new OpeninghoursFeed.OnFailed(this.FeedIsFailWeb);
-                this.feed.onFailedFile += new OpeninghoursFeed.OnFailed(this.FeedIsFailFile);
+                this.feed.OnLoaded += new OpeninghoursFeed.OnIO(this.FeedIsReady);
+                this.feed.OnFailedWeb += new OpeninghoursFeed.OnFailed(this.FeedIsFailedWeb);
+                this.feed.OnFailedFile += new OpeninghoursFeed.OnFailed(this.FeedIsFailedFile);
                 this.feed.LoadData();
             }
 
@@ -117,8 +118,8 @@ namespace CampusAppWP8.Pages.Openinghours
         private void FeedIsReady()
         {
             this.InstitutionPanel.ItemsSource = this.feed.Model.Institutions;
+            this.progressBar.Visibility = Visibility.Collapsed;
 
-            // this.ProgressBar.Visibility = System.Windows.Visibility.Collapsed;
             // this.feed.SaveData(true);
         }
 
@@ -130,14 +131,14 @@ namespace CampusAppWP8.Pages.Openinghours
         /// <param name="e">event args</param>
         private void OpenHoursForceUpdate_Click(object sender, EventArgs e)
         {
-            // this.ProgressBar.Visibility = System.Windows.Visibility.Visible;
+            this.progressBar.Visibility = Visibility.Visible;
             this.feed.ForceWebUpdate();
         }
 
         /// <summary>
         /// Method will be execute if the feed is failed
         /// </summary>
-        private void FeedIsFailWeb()
+        private void FeedIsFailedWeb()
         {
             MessageBoxResult result = MessageBoxes.ShowMainModelErrorMessageBox(AppResources.MsgBox_ErrorMainModelLoadWeb);
             this.feed.ForceReadFile();
@@ -146,8 +147,9 @@ namespace CampusAppWP8.Pages.Openinghours
         /// <summary>
         /// Method will be execute if the feed is failed
         /// </summary>
-        private void FeedIsFailFile()
+        private void FeedIsFailedFile()
         {
+            this.progressBar.Visibility = Visibility.Collapsed;
             MessageBoxResult result = MessageBoxes.ShowMainModelErrorMessageBox(AppResources.MsgBox_ErrorMainModelLoadFile);
         }
 
diff --git a/CampusAppWP8/CampusAppWP8/Pages/StudentCouncil/StudentCouncilPage.xaml.cs b/CampusAppWP8/CampusAppWP8/Pages/StudentCouncil/StudentCouncilPage.xaml.cs
index 86e98e14..2e548d4f 100644
--- a/CampusAppWP8/CampusAppWP8/Pages/StudentCouncil/StudentCouncilPage.xaml.cs
+++ b/CampusAppWP8/CampusAppWP8/Pages/StudentCouncil/StudentCouncilPage.xaml.cs
@@ -80,9 +80,9 @@ namespace CampusAppWP8.Pages.StudentCouncil
         private void InitializeFeed()
         {
             this.feed = new StudentCouncilFeed();
-            this.feed.onLoaded += new StudentCouncilFeed.OnLoaded(this.FeedIsReady);
-            this.feed.onFailedWeb += new StudentCouncilFeed.OnFailed(this.FeedIsFailWeb);
-            this.feed.onFailedFile += new StudentCouncilFeed.OnFailed(this.FeedIsFailFile);
+            this.feed.OnLoaded += new StudentCouncilFeed.OnIO(this.FeedIsReady);
+            this.feed.OnFailedWeb += new StudentCouncilFeed.OnFailed(this.FeedIsFailWeb);
+            this.feed.OnFailedFile += new StudentCouncilFeed.OnFailed(this.FeedIsFailFile);
         }
 
         /// <summary>
diff --git a/CampusAppWP8/CampusAppWP8/Resources/AppResources.resx b/CampusAppWP8/CampusAppWP8/Resources/AppResources.resx
index 70135f6d..a0baa5ea 100644
--- a/CampusAppWP8/CampusAppWP8/Resources/AppResources.resx
+++ b/CampusAppWP8/CampusAppWP8/Resources/AppResources.resx
@@ -406,6 +406,7 @@
   </data>
   <data name="MsgBox_ErrorMainModelLoadWeb" xml:space="preserve">
     <value>Es konnte kein neuer Inhalt aus den Web geladen werden</value>
+  </data>
   <data name="PrimCamNotSupported" xml:space="preserve">
     <value>Die primäre Kamera steht nicht zur Verfügung.</value>
   </data>
diff --git a/CampusAppWP8/CampusAppWP8/Utility/File.cs b/CampusAppWP8/CampusAppWP8/Utility/File.cs
index f03c9be8..189a7250 100644
--- a/CampusAppWP8/CampusAppWP8/Utility/File.cs
+++ b/CampusAppWP8/CampusAppWP8/Utility/File.cs
@@ -50,6 +50,11 @@ namespace CampusAppWP8.Utility
             this.writeType = write;
         }
 
+        /// <summary>
+        /// Delegation of the write callback function prototype.
+        /// </summary>
+        public delegate void WriteCallbackFunc();
+
         /// <summary>
         /// IO read type ENUM.
         /// </summary>
@@ -97,11 +102,6 @@ namespace CampusAppWP8.Utility
             ReadOnly = 3
         }
 
-        /// <summary>
-        /// Delegation of the write callback function prototype.
-        /// </summary>
-        public delegate void WriteCallbackFunc();
-
         /// <summary>
         /// Read data from file to a string.
         /// </summary>
@@ -137,8 +137,10 @@ namespace CampusAppWP8.Utility
         /// <summary>
         /// Write bytes to the file.
         /// </summary>
-        /// <param name="data">data byte array</param>
-        /// <param name="ioType">write type</param>
+        /// <param name="data">data byte array.</param>
+        /// <param name="onSavedCallback">callback function, called after writing is done.</param>
+        /// <param name="onFailedCallback">callback function, called when writing failed.</param>
+        /// <param name="ioType">write type.</param>
         public void WriteFile(byte[] data, WriteCallbackFunc onSavedCallback, WriteCallbackFunc onFailedCallback, IOTypeWrite ioType = IOTypeWrite.INVALID)
         {
             IOTypeWrite tempType = ioType;
@@ -162,7 +164,6 @@ namespace CampusAppWP8.Utility
 
             Thread th = new Thread(delegate() { this.WriteAsync(data, onSavedCallback, onFailedCallback); });
             th.Start();
-            //this.WriteAsync(data, onSavedCallback, onFailedCallback);
         }
 
         /// <summary>
@@ -229,7 +230,9 @@ namespace CampusAppWP8.Utility
         /// <summary>
         /// Write data asynchronous to file.
         /// </summary>
-        /// <param name="data">data array</param>
+        /// <param name="data">data array.</param>
+        /// <param name="onSavedCallback">callback function, called when writing is done.</param>
+        /// <param name="onFailedCallback">callback function, called when writing failed.</param>
         private async void WriteAsync(byte[] data, WriteCallbackFunc onSavedCallback, WriteCallbackFunc onFailedCallback)
         {
             Logger.LogMsg("writeasync file: " + this.filename);
@@ -257,10 +260,12 @@ namespace CampusAppWP8.Utility
                 {
                     onFailedCallback();
                 }
+
                 return;
             }
 
             counter = 0;
+
             // try to get a stream on the file
             while ((s == null) && (counter < 10))
             {
@@ -281,6 +286,7 @@ namespace CampusAppWP8.Utility
                 {
                     onFailedCallback();
                 }
+
                 return;
             }
 
@@ -296,8 +302,10 @@ namespace CampusAppWP8.Utility
                 {
                     onFailedCallback();
                 }
+
                 Logger.LogException(e);
                 s.Dispose();
+
                 return;
             }