diff --git a/Example/Example.pidb b/Example/Example.pidb
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diff --git a/Example/bin/Debug_Ubuntu/example.exe b/Example/bin/Debug_Ubuntu/example.exe
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diff --git a/Example/bin/Debug_Ubuntu/example.exe.mdb b/Example/bin/Debug_Ubuntu/example.exe.mdb
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diff --git a/Example/bin/Debug_Ubuntu/websocket-sharp.dll b/Example/bin/Debug_Ubuntu/websocket-sharp.dll
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diff --git a/Example1/bin/Debug_Ubuntu/example1.exe b/Example1/bin/Debug_Ubuntu/example1.exe
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diff --git a/Example1/bin/Debug_Ubuntu/websocket-sharp.dll b/Example1/bin/Debug_Ubuntu/websocket-sharp.dll
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diff --git a/Example2/bin/Debug_Ubuntu/example2.exe b/Example2/bin/Debug_Ubuntu/example2.exe
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diff --git a/Example2/bin/Debug_Ubuntu/websocket-sharp.dll b/Example2/bin/Debug_Ubuntu/websocket-sharp.dll
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diff --git a/Example3/bin/Debug_Ubuntu/Example3.exe b/Example3/bin/Debug_Ubuntu/Example3.exe
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index bd083aad..f390069e 100644
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diff --git a/Example3/bin/Debug_Ubuntu/websocket-sharp.dll b/Example3/bin/Debug_Ubuntu/websocket-sharp.dll
index b85f326b..0c770c1a 100755
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diff --git a/Example3/bin/Debug_Ubuntu/websocket-sharp.dll.mdb b/Example3/bin/Debug_Ubuntu/websocket-sharp.dll.mdb
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diff --git a/README.md b/README.md
index c51a4831..3ffa55d8 100644
--- a/README.md
+++ b/README.md
@@ -101,8 +101,7 @@ ws.OnClose += (sender, e) =>
 };
 ```
 
-The `e.Code` (`WebSocketSharp.CloseEventArgs.Code`, its type is `WebSocketSharp.Frame.CloseStatusCode`) contains the close status code  
-and the `e.Reason` (`WebSocketSharp.CloseEventArgs.Reason`, its type is `string`) contains the reason why closes, so you operate them.
+The `e.Code` (`WebSocketSharp.CloseEventArgs.Code`, its type is `WebSocketSharp.Frame.CloseStatusCode`) contains the close status code and the `e.Reason` (`WebSocketSharp.CloseEventArgs.Reason`, its type is `string`) contains the reason why closes, so you operate them.
 
 #### Step 4 ####
 
diff --git a/websocket-sharp/Ext.cs b/websocket-sharp/Ext.cs
index 0fba8302..8344cb8e 100644
--- a/websocket-sharp/Ext.cs
+++ b/websocket-sharp/Ext.cs
@@ -228,11 +228,11 @@ namespace WebSocketSharp {
       return false;
     }
 
-    public static bool IsValidWsUri(this Uri uri, out string message)
+    public static bool IsValidWebSocketUri(this Uri uri, out string message)
     {
       if (!uri.IsAbsoluteUri)
       {
-        message = "Not absolute uri: " + uri.ToString();
+        message = "Not absolute URI: " + uri.ToString();
         return false;
       }
 
@@ -243,11 +243,18 @@ namespace WebSocketSharp {
         return false;
       }
 
+      var original = uri.OriginalString;
+      if (original.Contains('#'))
+      {
+        message = "WebSocket URI must not contain the fragment identifier: " + original;
+        return false;
+      }
+
       var port = uri.Port;
       if (port > 0)
       {
-        if ((scheme == "wss" && port != 443) ||
-            (scheme != "wss" && port == 443))
+        if ((scheme == "ws"  && port == 443) ||
+            (scheme == "wss" && port == 80))
         {
           message = String.Format(
             "Invalid pair of WebSocket URI scheme and port: {0}, {1}", scheme, port);
@@ -255,14 +262,6 @@ namespace WebSocketSharp {
         }
       }
 
-      var host  = uri.DnsSafeHost;
-      var addrs = System.Net.Dns.GetHostAddresses(host);
-      if (addrs.Length == 0)
-      {
-        message = "Invalid WebSocket URI host: " + host;
-        return false;
-      }
-
       message = String.Empty;
       return true;
     }
diff --git a/websocket-sharp/Server/WebSocketServerBase.cs b/websocket-sharp/Server/WebSocketServerBase.cs
index 3843a421..9e1f069c 100644
--- a/websocket-sharp/Server/WebSocketServerBase.cs
+++ b/websocket-sharp/Server/WebSocketServerBase.cs
@@ -151,7 +151,7 @@ namespace WebSocketSharp.Server {
       var uri = url.ToUri();
 
       string msg;
-      if (!uri.IsValidWsUri(out msg))
+      if (!uri.IsValidWebSocketUri(out msg))
         throw new ArgumentException(msg, "url");
 
       var scheme = uri.Scheme;
diff --git a/websocket-sharp/WebSocket.cs b/websocket-sharp/WebSocket.cs
index 6578fcd1..184f89df 100644
--- a/websocket-sharp/WebSocket.cs
+++ b/websocket-sharp/WebSocket.cs
@@ -49,8 +49,7 @@ namespace WebSocketSharp {
   /// Implements the WebSocket interface.
   /// </summary>
   /// <remarks>
-  /// The WebSocket class provides methods and properties for two-way communication with a remote host
-  /// with the WebSocket protocol (RFC 6455).
+  /// The WebSocket class provides methods and properties for two-way communication using the WebSocket protocol (RFC 6455).
   /// </remarks>
   public class WebSocket : IDisposable
   {
@@ -143,52 +142,58 @@ namespace WebSocketSharp {
     /// <summary>
     /// Initializes a new instance of the <see cref="WebSocketSharp.WebSocket"/> class with the specified WebSocket URL and subprotocols.
     /// </summary>
-    /// <param name='url'>
+    /// <param name="url">
     /// A <see cref="string"/> that contains the WebSocket URL.
     /// </param>
-    /// <param name='protocols'>
+    /// <param name="protocols">
     /// An array of <see cref="string"/> that contains the WebSocket subprotocols if any.
     /// </param>
-    /// <exception cref='ArgumentException'>
+    /// <exception cref="ArgumentNullException">
+    /// <paramref name="url"/> is <see langword="null"/>.
+    /// </exception>
+    /// <exception cref="ArgumentException">
     /// <paramref name="url"/> is not valid WebSocket URL.
     /// </exception>
     public WebSocket(string url, params string[] protocols)
       : this()
     {
-      var uri = url.ToUri();
+      if (url == null)
+        throw new ArgumentNullException("url");
 
       string msg;
-      if (!uri.IsValidWsUri(out msg))
+      if (!isValidUrl(url, out msg))
         throw new ArgumentException(msg, "url");
 
-      _uri       = uri;
       _protocols = protocols.ToString(", ");
       _isClient  = true;
-      _isSecure  = uri.Scheme == "wss" ? true : false;
+      _isSecure  = _uri.Scheme == "wss" ? true : false;
     }
 
     /// <summary>
     /// Initializes a new instance of the <see cref="WebSocketSharp.WebSocket"/> class with the specified WebSocket URL, OnOpen, OnMessage, OnError, OnClose event handlers and subprotocols.
     /// </summary>
-    /// <param name='url'>
+    /// <param name="url">
     /// A <see cref="string"/> that contains the WebSocket URL.
     /// </param>
-    /// <param name='onOpen'>
+    /// <param name="onOpen">
     /// An OnOpen event handler.
     /// </param>
-    /// <param name='onMessage'>
+    /// <param name="onMessage">
     /// An OnMessage event handler.
     /// </param>
-    /// <param name='onError'>
+    /// <param name="onError">
     /// An OnError event handler.
     /// </param>
-    /// <param name='onClose'>
+    /// <param name="onClose">
     /// An OnClose event handler.
     /// </param>
-    /// <param name='protocols'>
+    /// <param name="protocols">
     /// An array of <see cref="string"/> that contains the WebSocket subprotocols if any.
     /// </param>
-    /// <exception cref='ArgumentException'>
+    /// <exception cref="ArgumentNullException">
+    /// <paramref name="url"/> is <see langword="null"/>.
+    /// </exception>
+    /// <exception cref="ArgumentException">
     /// <paramref name="url"/> is not valid WebSocket URL.
     /// </exception>
     public WebSocket(
@@ -687,6 +692,24 @@ namespace WebSocketSharp {
       return true;
     }
 
+    private bool isValidUrl(string url, out string message)
+    {
+      if (url == String.Empty)
+      {
+        message = "'url' is empty.";
+        return false;
+      }
+
+      var uri = url.ToUri();
+      if (!uri.IsValidWebSocketUri(out message))
+        return false;
+
+      _uri    = uri;
+      message = String.Empty;
+
+      return true;
+    }
+
     private void message()
     {
       try
@@ -1082,7 +1105,7 @@ namespace WebSocketSharp {
     #region Public Methods
 
     /// <summary>
-    /// Sends a Close frame and closes the WebSocket connection and releases all associated resources.
+    /// Sends a Close frame using the connection and closes the connection and releases all associated resources.
     /// </summary>
     public void Close()
     {
@@ -1090,9 +1113,9 @@ namespace WebSocketSharp {
     }
 
     /// <summary>
-    /// Sends a Close frame and closes the WebSocket connection and releases all associated resources.
+    /// Sends a Close frame using the connection and closes the connection and releases all associated resources.
     /// </summary>
-    /// <param name='code'>
+    /// <param name="code">
     /// A <see cref="WebSocketSharp.Frame.CloseStatusCode"/>.
     /// </param>
     public void Close(CloseStatusCode code)
@@ -1101,12 +1124,12 @@ namespace WebSocketSharp {
     }
 
     /// <summary>
-    /// Sends a Close frame and closes the WebSocket connection and releases all associated resources.
+    /// Sends a Close frame using the connection and closes the connection and releases all associated resources.
     /// </summary>
-    /// <param name='code'>
+    /// <param name="code">
     /// A <see cref="WebSocketSharp.Frame.CloseStatusCode"/>.
     /// </param>
-    /// <param name='reason'>
+    /// <param name="reason">
     /// A <see cref="string"/> that contains the reason why closes.
     /// </param>
     public void Close(CloseStatusCode code, string reason)
@@ -1146,7 +1169,7 @@ namespace WebSocketSharp {
     }
 
     /// <summary>
-    /// Sends a Close frame and closes the WebSocket connection and releases all associated resources.
+    /// Sends a Close frame using the connection and closes the connection and releases all associated resources.
     /// </summary>
     /// <remarks>
     /// Call <see cref="Dispose"/> when you are finished using the <see cref="WebSocketSharp.WebSocket"/>. The
@@ -1160,7 +1183,7 @@ namespace WebSocketSharp {
     }
 
     /// <summary>
-    /// Sends a Ping frame.
+    /// Sends a Ping frame using the connection.
     /// </summary>
     /// <returns>
     /// <c>true</c> if the WebSocket receives a Pong frame in a time; otherwise, <c>false</c>.
@@ -1171,9 +1194,9 @@ namespace WebSocketSharp {
     }
 
     /// <summary>
-    /// Sends a Ping frame with a message.
+    /// Sends a Ping frame with a message using the connection.
     /// </summary>
-    /// <param name='data'>
+    /// <param name="data">
     /// A <see cref="string"/> that contains the message data to be sent.
     /// </param>
     /// <returns>
@@ -1185,9 +1208,9 @@ namespace WebSocketSharp {
     }
 
     /// <summary>
-    /// Sends a Text data frame.
+    /// Sends a text data using the connection.
     /// </summary>
-    /// <param name='data'>
+    /// <param name="data">
     /// A <see cref="string"/> that contains the text data to be sent.
     /// </param>
     public void Send(string data)
@@ -1197,9 +1220,9 @@ namespace WebSocketSharp {
     }
 
     /// <summary>
-    /// Sends a Binary data frame.
+    /// Sends a binary data using the connection.
     /// </summary>
-    /// <param name='data'>
+    /// <param name="data">
     /// An array of <see cref="byte"/> that contains the binary data to be sent.
     /// </param>
     public void Send(byte[] data)
@@ -1208,9 +1231,9 @@ namespace WebSocketSharp {
     }
 
     /// <summary>
-    /// Sends a Binary data frame.
+    /// Sends a binary data using the connection.
     /// </summary>
-    /// <param name='file'>
+    /// <param name="file">
     /// A <see cref="FileInfo"/> that contains the binary data to be sent.
     /// </param>
     public void Send(FileInfo file)
diff --git a/websocket-sharp/bin/Debug_Ubuntu/websocket-sharp.dll b/websocket-sharp/bin/Debug_Ubuntu/websocket-sharp.dll
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