diff --git a/websocket-sharp/Server/IServiceHost.cs b/websocket-sharp/Server/IServiceHost.cs
index 43988ff6..5fec48b9 100644
--- a/websocket-sharp/Server/IServiceHost.cs
+++ b/websocket-sharp/Server/IServiceHost.cs
@@ -27,16 +27,25 @@
 #endregion
 
 using System;
+using System.Collections.Generic;
 using WebSocketSharp.Net.WebSockets;
 
-namespace WebSocketSharp.Server {
-
+namespace WebSocketSharp.Server
+{
   /// <summary>
   /// Exposes the methods and properties for the WebSocket service host.
   /// </summary>
   /// <remarks>
   /// </remarks>
-  public interface IServiceHost {
+  public interface IServiceHost
+  {
+    /// <summary>
+    /// Gets the connection count to the WebSocket service host.
+    /// </summary>
+    /// <value>
+    /// An <see cref="int"/> that contains the connection count.
+    /// </value>
+    int ConnectionCount { get; }
 
     /// <summary>
     /// Gets or sets a value indicating whether the WebSocket service host cleans up the inactive service
@@ -54,24 +63,101 @@ namespace WebSocketSharp.Server {
     /// <param name="context">
     /// A <see cref="WebSocketContext"/> that contains the WebSocket connection request objects to bind.
     /// </param>
-    void BindWebSocket(WebSocketContext context);
+    void BindWebSocket (WebSocketContext context);
 
     /// <summary>
-    /// Broadcasts the specified <see cref="string"/> to all service clients.
+    /// Broadcasts the specified array of <see cref="byte"/> to all clients of the WebSocket service host.
+    /// </summary>
+    /// <param name="data">
+    /// An array of <see cref="byte"/> to broadcast.
+    /// </param>
+    void Broadcast (byte [] data);
+
+    /// <summary>
+    /// Broadcasts the specified <see cref="string"/> to all clients of the WebSocket service host.
     /// </summary>
     /// <param name="data">
     /// A <see cref="string"/> to broadcast.
     /// </param>
-    void Broadcast(string data);
+    void Broadcast (string data);
+
+    /// <summary>
+    /// Sends Pings with the specified <see cref="string"/> to all clients of the WebSocket service host.
+    /// </summary>
+    /// <returns>
+    /// A Dictionary&lt;string, bool&gt; that contains the collection of session IDs and values
+    /// indicating whether the WebSocket service host received the Pongs from each clients in a time.
+    /// </returns>
+    /// <param name="message">
+    /// A <see cref="string"/> that contains a message to send.
+    /// </param>
+    Dictionary<string, bool> Broadping (string message);
+
+    /// <summary>
+    /// Sends a Ping with the specified <see cref="string"/> to the client associated with
+    /// the specified ID.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the WebSocket service host receives a Pong from the client in a time;
+    /// otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the Ping.
+    /// </param>
+    /// <param name="message">
+    /// A <see cref="string"/> that contains a message to send.
+    /// </param>
+    bool PingTo (string id, string message);
+
+    /// <summary>
+    /// Sends a binary data to the client associated with the specified ID.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the client associated with <paramref name="id"/> is successfully found;
+    /// otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the data.
+    /// </param>
+    /// <param name="data">
+    /// An array of <see cref="byte"/> that contains a binary data to send.
+    /// </param>
+    bool SendTo (string id, byte [] data);
+
+    /// <summary>
+    /// Sends a text data to the client associated with the specified ID.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the client associated with <paramref name="id"/> is successfully found;
+    /// otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the data.
+    /// </param>
+    /// <param name="data">
+    /// A <see cref="string"/> that contains a text data to send.
+    /// </param>
+    bool SendTo (string id, string data);
 
     /// <summary>
     /// Starts the WebSocket service host.
     /// </summary>
-    void Start();
+    void Start ();
 
     /// <summary>
     /// Stops the WebSocket service host.
     /// </summary>
-    void Stop();
+    void Stop ();
+
+    /// <summary>
+    /// Stops the WebSocket service host with the specified <see cref="ushort"/> and <see cref="string"/>.
+    /// </summary>
+    /// <param name="code">
+    /// A <see cref="ushort"/> that contains a status code indicating the reason for stop.
+    /// </param>
+    /// <param name="reason">
+    /// A <see cref="string"/> that contains the reason for stop.
+    /// </param>
+    void Stop (ushort code, string reason);
   }
 }
diff --git a/websocket-sharp/Server/ServiceHostManager.cs b/websocket-sharp/Server/ServiceHostManager.cs
index 76a1f6f8..5d4b760d 100644
--- a/websocket-sharp/Server/ServiceHostManager.cs
+++ b/websocket-sharp/Server/ServiceHostManager.cs
@@ -29,34 +29,56 @@
 using System;
 using System.Collections.Generic;
 
-namespace WebSocketSharp.Server {
-
-  internal class ServiceHostManager {
-  
+namespace WebSocketSharp.Server
+{
+  internal class ServiceHostManager
+  {
     #region Private Fields
 
-    private bool                             _keepClean;
-    private Dictionary<string, IServiceHost> _svcHosts;
+    private volatile bool                    _keepClean;
+    private Logger                           _logger;
+    private Dictionary<string, IServiceHost> _serviceHosts;
+    private object                           _sync;
 
     #endregion
 
     #region Public Constructors
 
-    public ServiceHostManager()
+    public ServiceHostManager ()
+      : this (new Logger ())
     {
+    }
+
+    public ServiceHostManager (Logger logger)
+    {
+      _logger = logger;
       _keepClean = true;
-      _svcHosts = new Dictionary<string, IServiceHost>();
+      _serviceHosts = new Dictionary<string, IServiceHost> ();
+      _sync = new object ();
     }
 
     #endregion
 
     #region Public Properties
 
+    public int ConnectionCount {
+      get {
+        var count = 0;
+        foreach (var host in ServiceHosts)
+          count += host.ConnectionCount;
+
+        return count;
+      }
+    }
+
     public int Count {
       get {
-        return _svcHosts.Count;
+        lock (_sync)
+        {
+          return _serviceHosts.Count;
+        }
       }
-    } 
+    }
 
     public bool KeepClean {
       get {
@@ -64,24 +86,45 @@ namespace WebSocketSharp.Server {
       }
 
       set {
-        if (_keepClean ^ value)
+        lock (_sync)
         {
-          _keepClean = value;
-          foreach (var svcHost in _svcHosts.Values)
-            svcHost.KeepClean = value;
+          if (_keepClean ^ value)
+          {
+            _keepClean = value;
+            foreach (var host in _serviceHosts.Values)
+              host.KeepClean = value;
+          }
         }
       }
     }
 
     public IEnumerable<string> Paths {
       get {
-        return _svcHosts.Keys;
+        lock (_sync)
+        {
+          return _serviceHosts.Keys;
+        }
       }
     }
 
     public IEnumerable<IServiceHost> ServiceHosts {
       get {
-        return _svcHosts.Values;
+        lock (_sync)
+        {
+          return _serviceHosts.Values;
+        }
+      }
+    }
+
+    #endregion
+
+    #region Private Methods
+
+    private Dictionary<string, IServiceHost> copy ()
+    {
+      lock (_sync)
+      {
+        return new Dictionary<string, IServiceHost> (_serviceHosts);
       }
     }
 
@@ -89,28 +132,173 @@ namespace WebSocketSharp.Server {
 
     #region Public Methods
 
-    public void Add(string absPath, IServiceHost svcHost)
+    public void Add (string servicePath, IServiceHost serviceHost)
     {
-      _svcHosts.Add(absPath.UrlDecode(), svcHost);
+      lock (_sync)
+      {
+        IServiceHost host;
+        if (_serviceHosts.TryGetValue (servicePath, out host))
+        {
+          _logger.Error (
+            "The WebSocket service host with the specified path found.\npath: " + servicePath);
+          return;
+        }
+
+        _serviceHosts.Add (servicePath.UrlDecode (), serviceHost);
+      }
     }
 
-    public void Broadcast(string data)
+    public void Broadcast (byte [] data)
     {
-      foreach (var svcHost in _svcHosts.Values)
-        svcHost.Broadcast(data);
+      foreach (var host in ServiceHosts)
+        host.Broadcast (data);
     }
 
-    public void Stop()
+    public void Broadcast (string data)
     {
-      foreach (var svcHost in _svcHosts.Values)
-        svcHost.Stop();
-
-      _svcHosts.Clear();
+      foreach (var host in ServiceHosts)
+        host.Broadcast (data);
     }
 
-    public bool TryGetServiceHost(string absPath, out IServiceHost svcHost)
+    public bool BroadcastTo (string servicePath, byte [] data)
     {
-      return _svcHosts.TryGetValue(absPath, out svcHost);
+      IServiceHost host;
+      if (TryGetServiceHost (servicePath, out host))
+      {
+        host.Broadcast (data);
+        return true;
+      }
+
+      _logger.Error (
+        "The WebSocket service host with the specified path not found.\npath: " + servicePath);
+      return false;
+    }
+
+    public bool BroadcastTo (string servicePath, string data)
+    {
+      IServiceHost host;
+      if (TryGetServiceHost (servicePath, out host))
+      {
+        host.Broadcast (data);
+        return true;
+      }
+
+      _logger.Error (
+        "The WebSocket service host with the specified path not found.\npath: " + servicePath);
+      return false;
+    }
+
+    public Dictionary<string, Dictionary<string, bool>> Broadping (string message)
+    {
+      var result = new Dictionary<string, Dictionary<string, bool>> ();
+      foreach (var service in copy ())
+        result.Add (service.Key, service.Value.Broadping (message));
+
+      return result;
+    }
+
+    public Dictionary<string, bool> BroadpingTo (string servicePath, string message)
+    {
+      IServiceHost host;
+      if (TryGetServiceHost (servicePath, out host))
+        return host.Broadping (message);
+
+      _logger.Error (
+        "The WebSocket service host with the specified path not found.\npath: " + servicePath);
+      return null;
+    }
+
+    public int GetConnectionCount (string servicePath)
+    {
+      IServiceHost host;
+      if (TryGetServiceHost (servicePath, out host))
+        return host.ConnectionCount;
+
+      _logger.Error (
+        "The WebSocket service host with the specified path not found.\npath: " + servicePath);
+      return -1;
+    }
+
+    public bool PingTo (string servicePath, string id, string message)
+    {
+      IServiceHost host;
+      if (TryGetServiceHost (servicePath, out host))
+        return host.PingTo (id, message);
+
+      _logger.Error (
+        "The WebSocket service host with the specified path not found.\npath: " + servicePath);
+      return false;
+    }
+
+    public bool Remove (string servicePath)
+    {
+      IServiceHost host;
+      lock (_sync)
+      {
+        if (!_serviceHosts.TryGetValue (servicePath, out host))
+        {
+          _logger.Error (
+            "The WebSocket service host with the specified path not found.\npath: " + servicePath);
+          return false;
+        }
+
+        _serviceHosts.Remove (servicePath);
+      }
+
+      host.Stop ((ushort) CloseStatusCode.AWAY, String.Empty);
+      return true;
+    }
+
+    public bool SendTo (string servicePath, string id, byte [] data)
+    {
+      IServiceHost host;
+      if (TryGetServiceHost (servicePath, out host))
+        return host.SendTo (id, data);
+
+      _logger.Error (
+        "The WebSocket service host with the specified path not found.\npath: " + servicePath);
+      return false;
+    }
+
+    public bool SendTo (string servicePath, string id, string data)
+    {
+      IServiceHost host;
+      if (TryGetServiceHost (servicePath, out host))
+        return host.SendTo (id, data);
+
+      _logger.Error (
+        "The WebSocket service host with the specified path not found.\npath: " + servicePath);
+      return false;
+    }
+
+    public void Stop ()
+    {
+      lock (_sync)
+      {
+        foreach (var host in _serviceHosts.Values)
+          host.Stop ();
+
+        _serviceHosts.Clear ();
+      }
+    }
+
+    public void Stop (ushort code, string reason)
+    {
+      lock (_sync)
+      {
+        foreach (var host in _serviceHosts.Values)
+          host.Stop (code, reason);
+
+        _serviceHosts.Clear ();
+      }
+    }
+
+    public bool TryGetServiceHost (string servicePath, out IServiceHost serviceHost)
+    {
+      lock (_sync)
+      {
+        return _serviceHosts.TryGetValue (servicePath, out serviceHost);
+      }
     }
 
     #endregion
diff --git a/websocket-sharp/Server/WebSocketServer.cs b/websocket-sharp/Server/WebSocketServer.cs
index 4f2926db..6ffae487 100644
--- a/websocket-sharp/Server/WebSocketServer.cs
+++ b/websocket-sharp/Server/WebSocketServer.cs
@@ -31,11 +31,12 @@
 using System;
 using System.Collections.Generic;
 using System.Net.Sockets;
+using System.Text;
 using WebSocketSharp.Net;
 using WebSocketSharp.Net.WebSockets;
 
-namespace WebSocketSharp.Server {
-
+namespace WebSocketSharp.Server
+{
   /// <summary>
   /// Provides the functions of the server that receives the WebSocket connection requests.
   /// </summary>
@@ -46,7 +47,7 @@ namespace WebSocketSharp.Server {
   {
     #region Private Fields
 
-    private ServiceHostManager _svcHosts;
+    private ServiceHostManager _serviceHosts;
 
     #endregion
 
@@ -55,95 +56,107 @@ namespace WebSocketSharp.Server {
     /// <summary>
     /// Initializes a new instance of the <see cref="WebSocketServer"/> class.
     /// </summary>
-    public WebSocketServer()
-      : this(80)
+    public WebSocketServer ()
+      : this (80)
     {
     }
 
     /// <summary>
-    /// Initializes a new instance of the <see cref="WebSocketServer"/> class that listens for incoming connection attempts
-    /// on the specified <paramref name="port"/>.
+    /// Initializes a new instance of the <see cref="WebSocketServer"/> class that listens for
+    /// incoming connection attempts on the specified <paramref name="port"/>.
     /// </summary>
     /// <param name="port">
     /// An <see cref="int"/> that contains a port number.
     /// </param>
-    public WebSocketServer(int port)
-      : this(System.Net.IPAddress.Any, port)
+    public WebSocketServer (int port)
+      : this (System.Net.IPAddress.Any, port)
     {
     }
 
     /// <summary>
-    /// Initializes a new instance of the <see cref="WebSocketServer"/> class that listens for incoming connection attempts
-    /// on the specified WebSocket URL.
+    /// Initializes a new instance of the <see cref="WebSocketServer"/> class that listens for
+    /// incoming connection attempts on the specified WebSocket URL.
     /// </summary>
     /// <param name="url">
     /// A <see cref="string"/> that contains a WebSocket URL.
     /// </param>
-    public WebSocketServer(string url)
-      : base(url)
+    public WebSocketServer (string url)
+      : base (url)
     {
       if (BaseUri.AbsolutePath != "/")
-      {
-        var msg = "Must not contain the path component: " + url;
-        throw new ArgumentException(msg, "url");
-      }
+        throw new ArgumentException ("Must not contain the path component: " + url, "url");
 
-      _svcHosts = new ServiceHostManager();
+      _serviceHosts = new ServiceHostManager (Log);
     }
 
     /// <summary>
-    /// Initializes a new instance of the <see cref="WebSocketServer"/> class that listens for incoming connection attempts
-    /// on the specified <paramref name="port"/> and <paramref name="secure"/>.
+    /// Initializes a new instance of the <see cref="WebSocketServer"/> class that listens for
+    /// incoming connection attempts on the specified <paramref name="port"/> and <paramref name="secure"/>.
     /// </summary>
     /// <param name="port">
-    /// An <see cref="int"/> that contains a port number. 
+    /// An <see cref="int"/> that contains a port number.
     /// </param>
     /// <param name="secure">
-    /// A <see cref="bool"/> that indicates providing a secure connection or not. (<c>true</c> indicates providing a secure connection.)
+    /// A <see cref="bool"/> that indicates providing a secure connection or not.
+    /// (<c>true</c> indicates providing a secure connection.)
     /// </param>
-    public WebSocketServer(int port, bool secure)
-      : this(System.Net.IPAddress.Any, port, secure)
+    public WebSocketServer (int port, bool secure)
+      : this (System.Net.IPAddress.Any, port, secure)
     {
     }
 
     /// <summary>
-    /// Initializes a new instance of the <see cref="WebSocketServer"/> class that listens for incoming connection attempts
-    /// on the specified <paramref name="address"/> and <paramref name="port"/>.
+    /// Initializes a new instance of the <see cref="WebSocketServer"/> class that listens for
+    /// incoming connection attempts on the specified <paramref name="address"/> and <paramref name="port"/>.
     /// </summary>
     /// <param name="address">
     /// A <see cref="System.Net.IPAddress"/> that contains a local IP address.
     /// </param>
     /// <param name="port">
-    /// An <see cref="int"/> that contains a port number. 
+    /// An <see cref="int"/> that contains a port number.
     /// </param>
-    public WebSocketServer(System.Net.IPAddress address, int port)
-      : this(address, port, port == 443 ? true : false)
+    public WebSocketServer (System.Net.IPAddress address, int port)
+      : this (address, port, port == 443 ? true : false)
     {
     }
 
     /// <summary>
-    /// Initializes a new instance of the <see cref="WebSocketServer"/> class that listens for incoming connection attempts
-    /// on the specified <paramref name="address"/>, <paramref name="port"/> and <paramref name="secure"/>.
+    /// Initializes a new instance of the <see cref="WebSocketServer"/> class that listens for
+    /// incoming connection attempts on the specified <paramref name="address"/>, <paramref name="port"/>
+    /// and <paramref name="secure"/>.
     /// </summary>
     /// <param name="address">
     /// A <see cref="System.Net.IPAddress"/> that contains a local IP address.
     /// </param>
     /// <param name="port">
-    /// An <see cref="int"/> that contains a port number. 
+    /// An <see cref="int"/> that contains a port number.
     /// </param>
     /// <param name="secure">
-    /// A <see cref="bool"/> that indicates providing a secure connection or not. (<c>true</c> indicates providing a secure connection.)
+    /// A <see cref="bool"/> that indicates providing a secure connection or not.
+    /// (<c>true</c> indicates providing a secure connection.)
     /// </param>
-    public WebSocketServer(System.Net.IPAddress address, int port, bool secure)
-      : base(address, port, "/", secure)
+    public WebSocketServer (System.Net.IPAddress address, int port, bool secure)
+      : base (address, port, "/", secure)
     {
-      _svcHosts = new ServiceHostManager();
+      _serviceHosts = new ServiceHostManager (Log);
     }
 
     #endregion
 
     #region Public Properties
 
+    /// <summary>
+    /// Gets the connection count to the <see cref="WebSocketServer"/>.
+    /// </summary>
+    /// <value>
+    /// An <see cref="int"/> that contains the connection count.
+    /// </value>
+    public int ConnectionCount {
+      get {
+        return _serviceHosts.ConnectionCount;
+      }
+    }
+
     /// <summary>
     /// Gets or sets a value indicating whether the server cleans up the inactive WebSocket service
     /// instances periodically.
@@ -154,11 +167,11 @@ namespace WebSocketSharp.Server {
     /// </value>
     public bool KeepClean {
       get {
-        return _svcHosts.KeepClean;
+        return _serviceHosts.KeepClean;
       }
 
       set {
-        _svcHosts.KeepClean = value;
+        _serviceHosts.KeepClean = value;
       }
     }
 
@@ -171,16 +184,36 @@ namespace WebSocketSharp.Server {
     public IEnumerable<string> ServicePaths {
       get {
         var url = BaseUri.IsAbsoluteUri
-                ? BaseUri.ToString().TrimEnd('/')
+                ? BaseUri.ToString ().TrimEnd ('/')
                 : String.Empty;
 
-        foreach (var path in _svcHosts.Paths)
+        foreach (var path in _serviceHosts.Paths)
           yield return url + path;
       }
     }
 
     #endregion
 
+    #region Private Methods
+
+    private void stop (ushort code, string reason)
+    {
+      var data = code.Append (reason);
+      if (data.Length > 125)
+      {
+        var msg = "The payload length of a Close frame must be 125 bytes or less.";
+        Log.Error (String.Format ("{0}\ncode: {1}\nreason: {2}", msg, code, reason));
+        Error (msg);
+
+        return;
+      }
+
+      base.Stop ();
+      _serviceHosts.Stop (code, reason);
+    }
+
+    #endregion
+
     #region Protected Methods
 
     /// <summary>
@@ -189,23 +222,23 @@ namespace WebSocketSharp.Server {
     /// <param name="context">
     /// A <see cref="TcpListenerWebSocketContext"/> that contains the WebSocket connection request objects.
     /// </param>
-    protected override void AcceptWebSocket(TcpListenerWebSocketContext context)
+    protected override void AcceptWebSocket (TcpListenerWebSocketContext context)
     {
       var ws = context.WebSocket;
-      var path = context.Path.UrlDecode();
+      var path = context.Path.UrlDecode ();
 
       ws.Log = Log;
-      IServiceHost svcHost;
-      if (!_svcHosts.TryGetServiceHost(path, out svcHost))
+      IServiceHost host;
+      if (!_serviceHosts.TryGetServiceHost (path, out host))
       {
-        ws.Close(HttpStatusCode.NotImplemented);
+        ws.Close (HttpStatusCode.NotImplemented);
         return;
       }
 
       if (BaseUri.IsAbsoluteUri)
-        ws.Url = new Uri(BaseUri, path);
+        ws.Url = new Uri (BaseUri, path);
 
-      svcHost.BindWebSocket(context);
+      host.BindWebSocket (context);
     }
 
     #endregion
@@ -213,35 +246,55 @@ namespace WebSocketSharp.Server {
     #region Public Methods
 
     /// <summary>
-    /// Adds the specified type WebSocket service.
+    /// Adds the specified typed WebSocket service.
     /// </summary>
-    /// <param name="absPath">
-    /// A <see cref="string"/> that contains an absolute path associated with the WebSocket service.
+    /// <param name="servicePath">
+    /// A <see cref="string"/> that contains an absolute path to the WebSocket service.
     /// </param>
     /// <typeparam name="T">
     /// The type of the WebSocket service. The T must inherit the <see cref="WebSocketService"/> class.
     /// </typeparam>
-    public void AddWebSocketService<T>(string absPath)
-      where T : WebSocketService, new()
+    public void AddWebSocketService<T> (string servicePath)
+      where T : WebSocketService, new ()
     {
       string msg;
-      if (!absPath.IsValidAbsolutePath(out msg))
+      if (!servicePath.IsValidAbsolutePath (out msg))
       {
-        Log.Error(msg);
-        Error(msg);
+        Log.Error (msg);
+        Error (msg);
 
         return;
       }
 
-      var svcHost = new WebSocketServiceHost<T>(Log);
-      svcHost.Uri = BaseUri.IsAbsoluteUri
-                  ? new Uri(BaseUri, absPath)
-                  : absPath.ToUri();
+      var host = new WebSocketServiceHost<T> (Log);
+      host.Uri = BaseUri.IsAbsoluteUri
+               ? new Uri (BaseUri, servicePath)
+               : servicePath.ToUri ();
 
       if (!KeepClean)
-        svcHost.KeepClean = false;
+        host.KeepClean = false;
 
-      _svcHosts.Add(absPath, svcHost);
+      _serviceHosts.Add (servicePath, host);
+    }
+
+    /// <summary>
+    /// Broadcasts the specified array of <see cref="byte"/> to all clients.
+    /// </summary>
+    /// <param name="data">
+    /// An array of <see cref="byte"/> to broadcast.
+    /// </param>
+    public void Broadcast (byte [] data)
+    {
+      if (data == null)
+      {
+        var msg = "'data' must not be null.";
+        Log.Error (msg);
+        Error (msg);
+
+        return;
+      }
+
+      _serviceHosts.Broadcast (data);
     }
 
     /// <summary>
@@ -250,18 +303,358 @@ namespace WebSocketSharp.Server {
     /// <param name="data">
     /// A <see cref="string"/> to broadcast.
     /// </param>
-    public void Broadcast(string data)
+    public void Broadcast (string data)
     {
-      _svcHosts.Broadcast(data);
+      if (data == null)
+      {
+        var msg = "'data' must not be null.";
+        Log.Error (msg);
+        Error (msg);
+
+        return;
+      }
+
+      _serviceHosts.Broadcast (data);
+    }
+
+    /// <summary>
+    /// Broadcasts the specified array of <see cref="byte"/> to all clients of the WebSocket service
+    /// with the specified <paramref name="servicePath"/>.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the WebSocket service is found; otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="servicePath">
+    /// A <see cref="string"/> that contains an absolute path to the WebSocket service to find.
+    /// </param>
+    /// <param name="data">
+    /// An array of <see cref="byte"/> to broadcast.
+    /// </param>
+    public bool BroadcastTo (string servicePath, byte [] data)
+    {
+      var msg = servicePath.IsNullOrEmpty ()
+              ? "'servicePath' must not be null or empty."
+              : data == null
+                ? "'data' must not be null."
+                : String.Empty;
+
+      if (msg.Length > 0)
+      {
+        Log.Error (msg);
+        Error (msg);
+
+        return false;
+      }
+
+      return _serviceHosts.BroadcastTo (servicePath, data);
+    }
+
+    /// <summary>
+    /// Broadcasts the specified <see cref="string"/> to all clients of the WebSocket service
+    /// with the specified <paramref name="servicePath"/>.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the WebSocket service is found; otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="servicePath">
+    /// A <see cref="string"/> that contains an absolute path to the WebSocket service to find.
+    /// </param>
+    /// <param name="data">
+    /// A <see cref="string"/> to broadcast.
+    /// </param>
+    public bool BroadcastTo (string servicePath, string data)
+    {
+      var msg = servicePath.IsNullOrEmpty ()
+              ? "'servicePath' must not be null or empty."
+              : data == null
+                ? "'data' must not be null."
+                : String.Empty;
+
+      if (msg.Length > 0)
+      {
+        Log.Error (msg);
+        Error (msg);
+
+        return false;
+      }
+
+      return _serviceHosts.BroadcastTo (servicePath, data);
+    }
+
+    /// <summary>
+    /// Sends Pings with the specified <see cref="string"/> to all clients.
+    /// </summary>
+    /// <returns>
+    /// A Dictionary&lt;string, Dictionary&lt;string, bool&gt;&gt; that contains the collection of
+    /// service paths and pairs of ID and value indicating whether the <see cref="WebSocketServer"/>
+    /// received the Pongs from each clients in a time.
+    /// </returns>
+    /// <param name="message">
+    /// A <see cref="string"/> that contains a message to send.
+    /// </param>
+    public Dictionary<string, Dictionary<string, bool>> Broadping (string message)
+    {
+      if (message.IsNullOrEmpty ())
+        return _serviceHosts.Broadping (String.Empty);
+
+      var len = Encoding.UTF8.GetBytes (message).Length;
+      if (len > 125)
+      {
+        var msg = "The payload length of a Ping frame must be 125 bytes or less.";
+        Log.Error (msg);
+        Error (msg);
+
+        return null;
+      }
+
+      return _serviceHosts.Broadping (message);
+    }
+
+    /// <summary>
+    /// Sends Pings with the specified <see cref="string"/> to all clients of the WebSocket service
+    /// with the specified <paramref name="servicePath"/>.
+    /// </summary>
+    /// <returns>
+    /// A Dictionary&lt;string, bool&gt; that contains the collection of session IDs and values
+    /// indicating whether the <see cref="WebSocketServer"/> received the Pongs from each clients
+    /// in a time. If the WebSocket service is not found, returns <see langword="null"/>.
+    /// </returns>
+    /// <param name="servicePath">
+    /// A <see cref="string"/> that contains an absolute path to the WebSocket service to find.
+    /// </param>
+    /// <param name="message">
+    /// A <see cref="string"/> that contains a message to send.
+    /// </param>
+    public Dictionary<string, bool> BroadpingTo (string servicePath, string message)
+    {
+      if (message == null)
+        message = String.Empty;
+
+      var msg = servicePath.IsNullOrEmpty ()
+              ? "'servicePath' must not be null or empty."
+              : Encoding.UTF8.GetBytes (message).Length > 125
+                ? "The payload length of a Ping frame must be 125 bytes or less."
+                : String.Empty;
+
+      if (msg.Length > 0)
+      {
+        Log.Error (msg);
+        Error (msg);
+
+        return null;
+      }
+
+      return _serviceHosts.BroadpingTo (servicePath, message);
+    }
+
+    /// <summary>
+    /// Gets the connection count to the WebSocket service with the specified <paramref name="servicePath"/>.
+    /// </summary>
+    /// <returns>
+    /// An <see cref="int"/> that contains the connection count if the WebSocket service is successfully found;
+    /// otherwise, <c>-1</c>.
+    /// </returns>
+    /// <param name="servicePath">
+    /// A <see cref="string"/> that contains an absolute path to the WebSocket service to find.
+    /// </param>
+    public int GetConnectionCount (string servicePath)
+    {
+      if (servicePath.IsNullOrEmpty ())
+      {
+        var msg = "'servicePath' must not be null or empty.";
+        Log.Error (msg);
+        Error (msg);
+
+        return -1;
+      }
+
+      return _serviceHosts.GetConnectionCount (servicePath);
+    }
+
+    /// <summary>
+    /// Sends a Ping with the specified <see cref="string"/> to the client associated with
+    /// the specified <paramref name="servicePath"/> and <paramref name="id"/>.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the <see cref="WebSocketServer"/> receives a Pong from the client in a time;
+    /// otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="servicePath">
+    /// A <see cref="string"/> that contains an absolute path to the WebSocket service to find.
+    /// </param>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the Ping.
+    /// </param>
+    /// <param name="message">
+    /// A <see cref="string"/> that contains a message to send.
+    /// </param>
+    public bool PingTo (string servicePath, string id, string message)
+    {
+      if (message == null)
+        message = String.Empty;
+
+      var msg = servicePath.IsNullOrEmpty ()
+              ? "'servicePath' must not be null or empty."
+              : id.IsNullOrEmpty ()
+                ? "'id' must not be null or empty."
+                : Encoding.UTF8.GetBytes (message).Length > 125
+                  ? "The payload length of a Ping frame must be 125 bytes or less."
+                  : String.Empty;
+
+      if (msg.Length > 0)
+      {
+        Log.Error (msg);
+        Error (msg);
+
+        return false;
+      }
+
+      return _serviceHosts.PingTo (servicePath, id, message);
+    }
+
+    /// <summary>
+    /// Removes the WebSocket service with the specified <paramref name="servicePath"/>.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the WebSocket service is successfully found and removed; otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="servicePath">
+    /// A <see cref="string"/> that contains an absolute path to the WebSocket service to find.
+    /// </param>
+    public bool RemoveWebSocketService (string servicePath)
+    {
+      if (servicePath.IsNullOrEmpty ())
+      {
+        var msg = "'servicePath' must not be null or empty.";
+        Log.Error (msg);
+        Error (msg);
+
+        return false;
+      }
+
+      return _serviceHosts.Remove (servicePath);
+    }
+
+    /// <summary>
+    /// Sends a binary data to the client associated with the specified <paramref name="servicePath"/> and
+    /// <paramref name="id"/>.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the client is successfully found; otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="servicePath">
+    /// A <see cref="string"/> that contains an absolute path to the WebSocket service to find.
+    /// </param>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the data.
+    /// </param>
+    /// <param name="data">
+    /// An array of <see cref="byte"/> that contains a binary data to send.
+    /// </param>
+    public bool SendTo (string servicePath, string id, byte [] data)
+    {
+      var msg = servicePath.IsNullOrEmpty ()
+              ? "'servicePath' must not be null or empty."
+              : id.IsNullOrEmpty ()
+                ? "'id' must not be null or empty."
+                : data == null
+                  ? "'data' must not be null."
+                  : String.Empty;
+
+      if (msg.Length > 0)
+      {
+        Log.Error (msg);
+        Error (msg);
+
+        return false;
+      }
+
+      return _serviceHosts.SendTo (servicePath, id, data);
+    }
+
+    /// <summary>
+    /// Sends a text data to the client associated with the specified <paramref name="servicePath"/> and
+    /// <paramref name="id"/>.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the client is successfully found; otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="servicePath">
+    /// A <see cref="string"/> that contains an absolute path to the WebSocket service to find.
+    /// </param>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the data.
+    /// </param>
+    /// <param name="data">
+    /// A <see cref="string"/> that contains a text data to send.
+    /// </param>
+    public bool SendTo (string servicePath, string id, string data)
+    {
+      var msg = servicePath.IsNullOrEmpty ()
+              ? "'servicePath' must not be null or empty."
+              : id.IsNullOrEmpty ()
+                ? "'id' must not be null or empty."
+                : data == null
+                  ? "'data' must not be null."
+                  : String.Empty;
+
+      if (msg.Length > 0)
+      {
+        Log.Error (msg);
+        Error (msg);
+
+        return false;
+      }
+
+      return _serviceHosts.SendTo (servicePath, id, data);
     }
 
     /// <summary>
     /// Stops receiving the WebSocket connection requests.
     /// </summary>
-    public override void Stop()
+    public override void Stop ()
     {
-      base.Stop();
-      _svcHosts.Stop();
+      base.Stop ();
+      _serviceHosts.Stop ();
+    }
+
+    /// <summary>
+    /// Stops receiving the WebSocket connection requests with the specified <see cref="ushort"/> and
+    /// <see cref="string"/>.
+    /// </summary>
+    /// <param name="code">
+    /// A <see cref="ushort"/> that contains a status code indicating the reason for stop.
+    /// </param>
+    /// <param name="reason">
+    /// A <see cref="string"/> that contains the reason for stop.
+    /// </param>
+    public void Stop (ushort code, string reason)
+    {
+      if (!code.IsCloseStatusCode ())
+      {
+        var msg = "Invalid status code for stop.";
+        Log.Error (String.Format ("{0}\ncode: {1}", msg, code));
+        Error (msg);
+
+        return;
+      }
+
+      stop (code, reason);
+    }
+
+    /// <summary>
+    /// Stops receiving the WebSocket connection requests with the specified <see cref="CloseStatusCode"/>
+    /// and <see cref="string"/>.
+    /// </summary>
+    /// <param name="code">
+    /// A <see cref="CloseStatusCode"/> that contains a status code indicating the reason for stop.
+    /// </param>
+    /// <param name="reason">
+    /// A <see cref="string"/> that contains the reason for stop.
+    /// </param>
+    public void Stop (CloseStatusCode code, string reason)
+    {
+      stop ((ushort) code, reason);
     }
 
     #endregion
diff --git a/websocket-sharp/Server/WebSocketService.cs b/websocket-sharp/Server/WebSocketService.cs
index e55d2b60..730ecf27 100644
--- a/websocket-sharp/Server/WebSocketService.cs
+++ b/websocket-sharp/Server/WebSocketService.cs
@@ -29,6 +29,7 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Specialized;
+using System.Text;
 using System.Threading;
 using WebSocketSharp.Net;
 using WebSocketSharp.Net.WebSockets;
@@ -94,10 +95,8 @@ namespace WebSocketSharp.Server
       }
 
       set {
-        if (!IsBound)
-          return;
-
-        _websocket.Log = value;
+        if (IsBound)
+          _websocket.Log = value;
       }
     }
 
@@ -217,6 +216,18 @@ namespace WebSocketSharp.Server
 
     #region Protected Methods
 
+    /// <summary>
+    /// Calls the <see cref="OnError"/> method with the specified <paramref name="message"/>.
+    /// </summary>
+    /// <param name="message">
+    /// A <see cref="string"/> that contains an error message.
+    /// </param>
+    protected virtual void Error (string message)
+    {
+      if (!message.IsNullOrEmpty ())
+        OnError (new ErrorEventArgs (message));
+    }
+
     /// <summary>
     /// Is called when the WebSocket connection has been closed.
     /// </summary>
@@ -229,7 +240,8 @@ namespace WebSocketSharp.Server
     }
 
     /// <summary>
-    /// Is called when the inner <see cref="WebSocket"/> gets an error.
+    /// Is called when the inner <see cref="WebSocket"/> or current <see cref="WebSocketService"/>
+    /// gets an error.
     /// </summary>
     /// <param name="e">
     /// An <see cref="ErrorEventArgs"/> that contains an event data associated with
@@ -285,29 +297,51 @@ namespace WebSocketSharp.Server
     #region Public Methods
 
     /// <summary>
-    /// Broadcasts the specified array of <see cref="byte"/> to the clients of
-    /// every <see cref="WebSocketService"/> instances in the <see cref="WebSocketService.Sessions"/>.
+    /// Broadcasts the specified array of <see cref="byte"/> to the clients of every <see cref="WebSocketService"/>
+    /// instances in the <see cref="WebSocketService.Sessions"/>.
     /// </summary>
     /// <param name="data">
     /// An array of <see cref="byte"/> to broadcast.
     /// </param>
-    public void Broadcast (byte [] data)
+    public virtual void Broadcast (byte [] data)
     {
-      if (IsBound)
-        _sessions.Broadcast (data);
+      if (!IsBound)
+        return;
+
+      if (data == null)
+      {
+        var msg = "'data' must not be null.";
+        Log.Error (msg);
+        Error (msg);
+
+        return;
+      }
+
+      _sessions.Broadcast (data);
     }
 
     /// <summary>
-    /// Broadcasts the specified <see cref="string"/> to the clients of
-    /// every <see cref="WebSocketService"/> instances in the <see cref="WebSocketService.Sessions"/>.
+    /// Broadcasts the specified <see cref="string"/> to the clients of every <see cref="WebSocketService"/>
+    /// instances in the <see cref="WebSocketService.Sessions"/>.
     /// </summary>
     /// <param name="data">
     /// A <see cref="string"/> to broadcast.
     /// </param>
-    public void Broadcast (string data)
+    public virtual void Broadcast (string data)
     {
-      if (IsBound)
-        _sessions.Broadcast (data);
+      if (!IsBound)
+        return;
+
+      if (data == null)
+      {
+        var msg = "'data' must not be null.";
+        Log.Error (msg);
+        Error (msg);
+
+        return;
+      }
+
+      _sessions.Broadcast (data);
     }
 
     /// <summary>
@@ -315,17 +349,19 @@ namespace WebSocketSharp.Server
     /// in the <see cref="WebSocketService.Sessions"/>.
     /// </summary>
     /// <returns>
-    /// A Dictionary&lt;string, bool&gt; that contains the collection of IDs and values
-    /// indicating whether the each <see cref="WebSocketService"/> instances received a Pong in a time.
+    /// A Dictionary&lt;string, bool&gt; that contains the collection of IDs and values indicating
+    /// whether the each <see cref="WebSocketService"/> instances received a Pong in a time.
     /// </returns>
-    public Dictionary<string, bool> Broadping ()
+    public virtual Dictionary<string, bool> Broadping ()
     {
-      return Broadping (String.Empty);
+      return IsBound
+             ? _sessions.Broadping (String.Empty)
+             : null;
     }
 
     /// <summary>
-    /// Sends Pings with the specified <see cref="string"/> to the clients of
-    /// every <see cref="WebSocketService"/> instances in the <see cref="WebSocketService.Sessions"/>.
+    /// Sends Pings with the specified <see cref="string"/> to the clients of every <see cref="WebSocketService"/>
+    /// instances in the <see cref="WebSocketService.Sessions"/>.
     /// </summary>
     /// <returns>
     /// A Dictionary&lt;string, bool&gt; that contains the collection of IDs and values
@@ -334,11 +370,25 @@ namespace WebSocketSharp.Server
     /// <param name="message">
     /// A <see cref="string"/> that contains a message to send.
     /// </param>
-    public Dictionary<string, bool> Broadping (string message)
+    public virtual Dictionary<string, bool> Broadping (string message)
     {
-      return IsBound
-             ? _sessions.Broadping (message)
-             : null;
+      if (!IsBound)
+        return null;
+
+      if (message.IsNullOrEmpty ())
+        return _sessions.Broadping (String.Empty);
+
+      var len = Encoding.UTF8.GetBytes (message).Length;
+      if (len > 125)
+      {
+        var msg = "The payload length of a Ping frame must be 125 bytes or less.";
+        Log.Error (msg);
+        Error (msg);
+
+        return null;
+      }
+
+      return _sessions.Broadping (message);
     }
 
     /// <summary>
@@ -348,9 +398,11 @@ namespace WebSocketSharp.Server
     /// <c>true</c> if the current <see cref="WebSocketService"/> instance receives a Pong in a time;
     /// otherwise, <c>false</c>.
     /// </returns>
-    public bool Ping ()
+    public virtual bool Ping ()
     {
-      return Ping (String.Empty);
+      return IsBound
+             ? _websocket.Ping ()
+             : false;
     }
 
     /// <summary>
@@ -364,7 +416,7 @@ namespace WebSocketSharp.Server
     /// <param name="message">
     /// A <see cref="string"/> that contains a message to send.
     /// </param>
-    public bool Ping (string message)
+    public virtual bool Ping (string message)
     {
       return IsBound
              ? _websocket.Ping (message)
@@ -373,7 +425,7 @@ namespace WebSocketSharp.Server
 
     /// <summary>
     /// Sends a Ping to the client of the <see cref="WebSocketService"/> instance
-    /// associated with the specified <paramref name="id"/>.
+    /// with the specified ID.
     /// </summary>
     /// <returns>
     /// <c>true</c> if the <see cref="WebSocketService"/> instance receives a Pong in a time;
@@ -382,14 +434,14 @@ namespace WebSocketSharp.Server
     /// <param name="id">
     /// A <see cref="string"/> that contains an ID that represents the destination for the Ping.
     /// </param>
-    public bool PingTo (string id)
+    public virtual bool PingTo (string id)
     {
       return PingTo (id, String.Empty);
     }
 
     /// <summary>
-    /// Sends a Ping with the specified <see cref="string"/> to the client of
-    /// the <see cref="WebSocketService"/> instance associated with the specified <paramref name="id"/>.
+    /// Sends a Ping with the specified <see cref="string"/> to the client of the <see cref="WebSocketService"/>
+    /// instance with the specified ID.
     /// </summary>
     /// <returns>
     /// <c>true</c> if the <see cref="WebSocketService"/> instance receives a Pong in a time;
@@ -401,15 +453,29 @@ namespace WebSocketSharp.Server
     /// <param name="message">
     /// A <see cref="string"/> that contains a message to send.
     /// </param>
-    public bool PingTo (string id, string message)
+    public virtual bool PingTo (string id, string message)
     {
       if (!IsBound)
         return false;
 
-      WebSocketService service;
-      return _sessions.TryGetWebSocketService (id, out service)
-             ? service.Ping (message)
-             : false;
+      if (message == null)
+        message = String.Empty;
+
+      var msg = id.IsNullOrEmpty ()
+              ? "'id' must not be null or empty."
+              : Encoding.UTF8.GetBytes (message).Length > 125
+                ? "The payload length of a Ping frame must be 125 bytes or less."
+                : String.Empty;
+
+      if (msg.Length > 0)
+      {
+        Log.Error (msg);
+        Error (msg);
+
+        return false;
+      }
+
+      return _sessions.PingTo (id, message);
     }
 
     /// <summary>
@@ -418,7 +484,7 @@ namespace WebSocketSharp.Server
     /// <param name="data">
     /// An array of <see cref="byte"/> that contains a binary data to send.
     /// </param>
-    public void Send (byte [] data)
+    public virtual void Send (byte [] data)
     {
       if (IsBound)
         _websocket.Send (data);
@@ -430,7 +496,7 @@ namespace WebSocketSharp.Server
     /// <param name="data">
     /// A <see cref="string"/> that contains a text data to send.
     /// </param>
-    public void Send (string data)
+    public virtual void Send (string data)
     {
       if (IsBound)
         _websocket.Send (data);
@@ -438,42 +504,72 @@ namespace WebSocketSharp.Server
 
     /// <summary>
     /// Sends a binary data to the client of the <see cref="WebSocketService"/> instance
-    /// associated with the specified <paramref name="id"/>.
+    /// with the specified ID.
     /// </summary>
+    /// <returns>
+    /// <c>true</c> if the client is successfully found; otherwise, <c>false</c>.
+    /// </returns>
     /// <param name="id">
     /// A <see cref="string"/> that contains an ID that represents the destination for the data.
     /// </param>
     /// <param name="data">
     /// An array of <see cref="byte"/> that contains a binary data to send.
     /// </param>
-    public void SendTo (string id, byte [] data)
+    public virtual bool SendTo (string id, byte [] data)
     {
       if (!IsBound)
-        return;
+        return false;
 
-      WebSocketService service;
-      if (_sessions.TryGetWebSocketService (id, out service))
-        service.Send (data);
+      var msg = id.IsNullOrEmpty ()
+              ? "'id' must not be null or empty."
+              : data == null
+                ? "'data' must not be null."
+                : String.Empty;
+
+      if (msg.Length > 0)
+      {
+        Log.Error (msg);
+        Error (msg);
+
+        return false;
+      }
+
+      return _sessions.SendTo (id, data);
     }
 
     /// <summary>
     /// Sends a text data to the client of the <see cref="WebSocketService"/> instance
-    /// associated with the specified <paramref name="id"/>.
+    /// with the specified ID.
     /// </summary>
+    /// <returns>
+    /// <c>true</c> if the client is successfully found; otherwise, <c>false</c>.
+    /// </returns>
     /// <param name="id">
     /// A <see cref="string"/> that contains an ID that represents the destination for the data.
     /// </param>
     /// <param name="data">
     /// A <see cref="string"/> that contains a text data to send.
     /// </param>
-    public void SendTo (string id, string data)
+    public virtual bool SendTo (string id, string data)
     {
       if (!IsBound)
-        return;
+        return false;
 
-      WebSocketService service;
-      if (_sessions.TryGetWebSocketService (id, out service))
-        service.Send (data);
+      var msg = id.IsNullOrEmpty ()
+              ? "'id' must not be null or empty."
+              : data == null
+                ? "'data' must not be null."
+                : String.Empty;
+
+      if (msg.Length > 0)
+      {
+        Log.Error (msg);
+        Error (msg);
+
+        return false;
+      }
+
+      return _sessions.SendTo (id, data);
     }
 
     /// <summary>
@@ -490,10 +586,8 @@ namespace WebSocketSharp.Server
     /// </summary>
     public void Stop ()
     {
-      if (!IsBound)
-        return;
-
-      _websocket.Close ();
+      if (IsBound)
+        _websocket.Close ();
     }
 
     /// <summary>
@@ -508,10 +602,8 @@ namespace WebSocketSharp.Server
     /// </param>
     public void Stop (ushort code, string reason)
     {
-      if (!IsBound)
-        return;
-
-      _websocket.Close (code, reason);
+      if (IsBound)
+        _websocket.Close (code, reason);
     }
 
     /// <summary>
@@ -527,7 +619,8 @@ namespace WebSocketSharp.Server
     /// </param>
     public void Stop (CloseStatusCode code, string reason)
     {
-      Stop ((ushort) code, reason);
+      if (IsBound)
+        _websocket.Close (code, reason);
     }
 
     #endregion
diff --git a/websocket-sharp/Server/WebSocketServiceHost.cs b/websocket-sharp/Server/WebSocketServiceHost.cs
index 92b2db45..6dbefe98 100644
--- a/websocket-sharp/Server/WebSocketServiceHost.cs
+++ b/websocket-sharp/Server/WebSocketServiceHost.cs
@@ -31,11 +31,12 @@
 using System;
 using System.Collections.Generic;
 using System.Net.Sockets;
+using System.Text;
 using WebSocketSharp.Net;
 using WebSocketSharp.Net.WebSockets;
 
-namespace WebSocketSharp.Server {
-
+namespace WebSocketSharp.Server
+{
   /// <summary>
   /// Provides the functions of the server that receives the WebSocket connection requests.
   /// </summary>
@@ -43,10 +44,11 @@ namespace WebSocketSharp.Server {
   /// The WebSocketServiceHost&lt;T&gt; class provides the single WebSocket service.
   /// </remarks>
   /// <typeparam name="T">
-  /// The type of the WebSocket service that the server provides. The T must inherit the <see cref="WebSocketService"/> class.
+  /// The type of the WebSocket service that the server provides.
+  /// The T must inherit the <see cref="WebSocketService"/> class.
   /// </typeparam>
   public class WebSocketServiceHost<T> : WebSocketServerBase, IServiceHost
-    where T : WebSocketService, new()
+    where T : WebSocketService, new ()
   {
     #region Private Fields
 
@@ -56,10 +58,10 @@ namespace WebSocketSharp.Server {
 
     #region Internal Constructors
 
-    internal WebSocketServiceHost(Logger logger)
-      : base(logger)
+    internal WebSocketServiceHost (Logger logger)
+      : base (logger)
     {
-      _sessions = new WebSocketServiceManager();
+      _sessions = new WebSocketServiceManager (logger);
     }
 
     #endregion
@@ -67,116 +69,122 @@ namespace WebSocketSharp.Server {
     #region Public Constructors
 
     /// <summary>
-    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for incoming connection attempts
-    /// on the specified <paramref name="port"/>.
+    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for
+    /// incoming connection attempts on the specified <paramref name="port"/>.
     /// </summary>
-    /// <param name='port'>
+    /// <param name="port">
     /// An <see cref="int"/> that contains a port number.
     /// </param>
-    public WebSocketServiceHost(int port)
-      : this(port, "/")
+    public WebSocketServiceHost (int port)
+      : this (port, "/")
     {
     }
 
     /// <summary>
-    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for incoming connection attempts
-    /// on the specified WebSocket URL.
+    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for
+    /// incoming connection attempts on the specified WebSocket URL.
     /// </summary>
     /// <param name="url">
     /// A <see cref="string"/> that contains a WebSocket URL.
     /// </param>
-    public WebSocketServiceHost(string url)
-      : base(url)
+    public WebSocketServiceHost (string url)
+      : base (url)
     {
-      _sessions = new WebSocketServiceManager();
+      _sessions = new WebSocketServiceManager (Log);
     }
 
     /// <summary>
-    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for incoming connection attempts
-    /// on the specified <paramref name="port"/> and <paramref name="secure"/>.
+    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for
+    /// incoming connection attempts on the specified <paramref name="port"/> and <paramref name="secure"/>.
     /// </summary>
     /// <param name="port">
-    /// An <see cref="int"/> that contains a port number. 
+    /// An <see cref="int"/> that contains a port number.
     /// </param>
     /// <param name="secure">
-    /// A <see cref="bool"/> that indicates providing a secure connection or not. (<c>true</c> indicates providing a secure connection.)
+    /// A <see cref="bool"/> that indicates providing a secure connection or not.
+    /// (<c>true</c> indicates providing a secure connection.)
     /// </param>
-    public WebSocketServiceHost(int port, bool secure)
-      : this(port, "/", secure)
+    public WebSocketServiceHost (int port, bool secure)
+      : this (port, "/", secure)
     {
     }
 
     /// <summary>
-    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for incoming connection attempts
-    /// on the specified <paramref name="port"/> and <paramref name="absPath"/>.
+    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for
+    /// incoming connection attempts on the specified <paramref name="port"/> and <paramref name="absPath"/>.
     /// </summary>
     /// <param name="port">
-    /// An <see cref="int"/> that contains a port number. 
+    /// An <see cref="int"/> that contains a port number.
     /// </param>
     /// <param name="absPath">
     /// A <see cref="string"/> that contains an absolute path.
     /// </param>
-    public WebSocketServiceHost(int port, string absPath)
-      : this(System.Net.IPAddress.Any, port, absPath)
+    public WebSocketServiceHost (int port, string absPath)
+      : this (System.Net.IPAddress.Any, port, absPath)
     {
     }
 
     /// <summary>
-    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for incoming connection attempts
-    /// on the specified <paramref name="port"/>, <paramref name="absPath"/> and <paramref name="secure"/>.
+    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for
+    /// incoming connection attempts on the specified <paramref name="port"/>, <paramref name="absPath"/>
+    /// and <paramref name="secure"/>.
     /// </summary>
     /// <param name="port">
-    /// An <see cref="int"/> that contains a port number. 
+    /// An <see cref="int"/> that contains a port number.
     /// </param>
     /// <param name="absPath">
     /// A <see cref="string"/> that contains an absolute path.
     /// </param>
     /// <param name="secure">
-    /// A <see cref="bool"/> that indicates providing a secure connection or not. (<c>true</c> indicates providing a secure connection.)
+    /// A <see cref="bool"/> that indicates providing a secure connection or not.
+    /// (<c>true</c> indicates providing a secure connection.)
     /// </param>
-    public WebSocketServiceHost(int port, string absPath, bool secure)
-      : this(System.Net.IPAddress.Any, port, absPath, secure)
+    public WebSocketServiceHost (int port, string absPath, bool secure)
+      : this (System.Net.IPAddress.Any, port, absPath, secure)
     {
     }
 
     /// <summary>
-    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for incoming connection attempts
-    /// on the specified <paramref name="address"/>, <paramref name="port"/> and <paramref name="absPath"/>.
+    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for
+    /// incoming connection attempts on the specified <paramref name="address"/>, <paramref name="port"/>
+    /// and <paramref name="absPath"/>.
     /// </summary>
     /// <param name="address">
     /// A <see cref="System.Net.IPAddress"/> that contains a local IP address.
     /// </param>
     /// <param name="port">
-    /// An <see cref="int"/> that contains a port number. 
+    /// An <see cref="int"/> that contains a port number.
     /// </param>
     /// <param name="absPath">
     /// A <see cref="string"/> that contains an absolute path.
     /// </param>
-    public WebSocketServiceHost(System.Net.IPAddress address, int port, string absPath)
-      : this(address, port, absPath, port == 443 ? true : false)
+    public WebSocketServiceHost (System.Net.IPAddress address, int port, string absPath)
+      : this (address, port, absPath, port == 443 ? true : false)
     {
     }
 
     /// <summary>
-    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for incoming connection attempts
-    /// on the specified <paramref name="address"/>, <paramref name="port"/>, <paramref name="absPath"/> and <paramref name="secure"/>.
+    /// Initializes a new instance of the WebSocketServiceHost&lt;T&gt; class that listens for
+    /// incoming connection attempts on the specified <paramref name="address"/>, <paramref name="port"/>,
+    /// <paramref name="absPath"/> and <paramref name="secure"/>.
     /// </summary>
     /// <param name="address">
     /// A <see cref="System.Net.IPAddress"/> that contains a local IP address.
     /// </param>
     /// <param name="port">
-    /// An <see cref="int"/> that contains a port number. 
+    /// An <see cref="int"/> that contains a port number.
     /// </param>
     /// <param name="absPath">
     /// A <see cref="string"/> that contains an absolute path.
     /// </param>
     /// <param name="secure">
-    /// A <see cref="bool"/> that indicates providing a secure connection or not. (<c>true</c> indicates providing a secure connection.)
+    /// A <see cref="bool"/> that indicates providing a secure connection or not.
+    /// (<c>true</c> indicates providing a secure connection.)
     /// </param>
-    public WebSocketServiceHost(System.Net.IPAddress address, int port, string absPath, bool secure)
-      : base(address, port, absPath, secure)
+    public WebSocketServiceHost (System.Net.IPAddress address, int port, string absPath, bool secure)
+      : base (address, port, absPath, secure)
     {
-      _sessions = new WebSocketServiceManager();
+      _sessions = new WebSocketServiceManager (Log);
     }
 
     #endregion
@@ -184,11 +192,23 @@ namespace WebSocketSharp.Server {
     #region Public Properties
 
     /// <summary>
-    /// Gets or sets a value indicating whether the server cleans up the inactive WebSocket service
-    /// instances periodically.
+    /// Gets the connection count to the WebSocket service host.
     /// </summary>
     /// <value>
-    /// <c>true</c> if the server cleans up the inactive WebSocket service instances every 60 seconds;
+    /// An <see cref="int"/> that contains the connection count.
+    /// </value>
+    public int ConnectionCount {
+      get {
+        return _sessions.Count;
+      }
+    }
+
+    /// <summary>
+    /// Gets or sets a value indicating whether the WebSocket service host cleans up
+    /// the inactive <see cref="WebSocketService"/> instances periodically.
+    /// </summary>
+    /// <value>
+    /// <c>true</c> if the WebSocket service host cleans up the inactive WebSocket service instances every 60 seconds;
     /// otherwise, <c>false</c>. The default value is <c>true</c>.
     /// </value>
     public bool KeepClean {
@@ -219,6 +239,26 @@ namespace WebSocketSharp.Server {
 
     #endregion
 
+    #region Private Methods
+
+    private void stop (ushort code, string reason)
+    {
+      var data = code.Append (reason);
+      if (data.Length > 125)
+      {
+        var msg = "The payload length of a Close frame must be 125 bytes or less.";
+        Log.Error (String.Format ("{0}\ncode: {1}\nreason: {2}", msg, code, reason));
+        Error (msg);
+
+        return;
+      }
+
+      base.Stop ();
+      _sessions.Stop (code, reason);
+    }
+
+    #endregion
+
     #region Protected Methods
 
     /// <summary>
@@ -227,61 +267,241 @@ namespace WebSocketSharp.Server {
     /// <param name="context">
     /// A <see cref="TcpListenerWebSocketContext"/> that contains the WebSocket connection request objects.
     /// </param>
-    protected override void AcceptWebSocket(TcpListenerWebSocketContext context)
+    protected override void AcceptWebSocket (TcpListenerWebSocketContext context)
     {
       var ws = context.WebSocket;
-      var path = context.Path.UrlDecode();
+      var path = context.Path.UrlDecode ();
 
       ws.Log = Log;
-      if (path != Uri.GetAbsolutePath().UrlDecode())
+      if (path != Uri.GetAbsolutePath ().UrlDecode ())
       {
-        ws.Close(HttpStatusCode.NotImplemented);
+        ws.Close (HttpStatusCode.NotImplemented);
         return;
       }
 
       if (Uri.IsAbsoluteUri)
         ws.Url = Uri;
 
-      ((IServiceHost)this).BindWebSocket(context);
+      ((IServiceHost) this).BindWebSocket (context);
     }
 
     #endregion
 
     #region Public Methods
 
+    /// <summary>
+    /// Broadcasts the specified array of <see cref="byte"/> to all clients.
+    /// </summary>
+    /// <param name="data">
+    /// An array of <see cref="byte"/> to broadcast.
+    /// </param>
+    public void Broadcast (byte [] data)
+    {
+      if (data == null)
+      {
+        var msg = "'data' must not be null.";
+        Log.Error (msg);
+        Error (msg);
+
+        return;
+      }
+
+      _sessions.Broadcast (data);
+    }
+
     /// <summary>
     /// Broadcasts the specified <see cref="string"/> to all clients.
     /// </summary>
     /// <param name="data">
     /// A <see cref="string"/> to broadcast.
     /// </param>
-    public void Broadcast(string data)
+    public void Broadcast (string data)
     {
-      _sessions.Broadcast(data);
+      if (data == null)
+      {
+        var msg = "'data' must not be null.";
+        Log.Error (msg);
+        Error (msg);
+
+        return;
+      }
+
+      _sessions.Broadcast (data);
     }
 
     /// <summary>
-    /// Pings with the specified <see cref="string"/> to all clients.
+    /// Sends Pings with the specified <see cref="string"/> to all clients.
     /// </summary>
     /// <returns>
     /// A Dictionary&lt;string, bool&gt; that contains the collection of session IDs and values
-    /// indicating whether the server received the Pongs from each clients in a time.
+    /// indicating whether the service host received the Pongs from each clients in a time.
     /// </returns>
     /// <param name="message">
-    /// A <see cref="string"/> that contains a message.
+    /// A <see cref="string"/> that contains a message to send.
     /// </param>
-    public Dictionary<string, bool> Broadping(string message)
+    public Dictionary<string, bool> Broadping (string message)
     {
-      return _sessions.Broadping(message);
+      if (message.IsNullOrEmpty ())
+        return _sessions.Broadping (String.Empty);
+
+      var len = Encoding.UTF8.GetBytes (message).Length;
+      if (len > 125)
+      {
+        var msg = "The payload length of a Ping frame must be 125 bytes or less.";
+        Log.Error (msg);
+        Error (msg);
+
+        return null;
+      }
+
+      return _sessions.Broadping (message);
+    }
+
+    /// <summary>
+    /// Sends a Ping with the specified <see cref="string"/> to the client associated with
+    /// the specified ID.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the service host receives a Pong from the client in a time; otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the Ping.
+    /// </param>
+    /// <param name="message">
+    /// A <see cref="string"/> that contains a message to send.
+    /// </param>
+    public bool PingTo (string id, string message)
+    {
+      if (message == null)
+        message = String.Empty;
+
+      var msg = id.IsNullOrEmpty ()
+                ? "'id' must not be null or empty."
+                : Encoding.UTF8.GetBytes (message).Length > 125
+                  ? "The payload length of a Ping frame must be 125 bytes or less."
+                  : String.Empty;
+
+      if (msg.Length > 0)
+      {
+        Log.Error (msg);
+        Error (msg);
+
+        return false;
+      }
+
+      return _sessions.PingTo (id, message);
+    }
+
+    /// <summary>
+    /// Sends a binary data to the client associated with the specified ID.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the client associated with <paramref name="id"/> is successfully found;
+    /// otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the data.
+    /// </param>
+    /// <param name="data">
+    /// An array of <see cref="byte"/> that contains a binary data to send.
+    /// </param>
+    public bool SendTo (string id, byte [] data)
+    {
+      var msg = id.IsNullOrEmpty ()
+                ? "'id' must not be null or empty."
+                : data == null
+                  ? "'data' must not be null."
+                  : String.Empty;
+
+      if (msg.Length > 0)
+      {
+        Log.Error (msg);
+        Error (msg);
+
+        return false;
+      }
+
+      return _sessions.SendTo (id, data);
+    }
+
+    /// <summary>
+    /// Sends a text data to the client associated with the specified ID.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the client associated with <paramref name="id"/> is successfully found;
+    /// otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the data.
+    /// </param>
+    /// <param name="data">
+    /// A <see cref="string"/> that contains a text data to send.
+    /// </param>
+    public bool SendTo (string id, string data)
+    {
+      var msg = id.IsNullOrEmpty ()
+                ? "'id' must not be null or empty."
+                : data == null
+                  ? "'data' must not be null."
+                  : String.Empty;
+
+      if (msg.Length > 0)
+      {
+        Log.Error (msg);
+        Error (msg);
+
+        return false;
+      }
+
+      return _sessions.SendTo (id, data);
     }
 
     /// <summary>
     /// Stops receiving the WebSocket connection requests.
     /// </summary>
-    public override void Stop()
+    public override void Stop ()
     {
-      base.Stop();
-      _sessions.Stop();
+      base.Stop ();
+      _sessions.Stop ();
+    }
+
+    /// <summary>
+    /// Stops receiving the WebSocket connection requests with the specified <see cref="ushort"/> and
+    /// <see cref="string"/>.
+    /// </summary>
+    /// <param name="code">
+    /// A <see cref="ushort"/> that contains a status code indicating the reason for stop.
+    /// </param>
+    /// <param name="reason">
+    /// A <see cref="string"/> that contains the reason for stop.
+    /// </param>
+    public void Stop (ushort code, string reason)
+    {
+      if (!code.IsCloseStatusCode ())
+      {
+        var msg = "Invalid status code for stop.";
+        Log.Error (String.Format ("{0}\ncode: {1}", msg, code));
+        Error (msg);
+
+        return;
+      }
+
+      stop (code, reason);
+    }
+
+    /// <summary>
+    /// Stops receiving the WebSocket connection requests with the specified <see cref="CloseStatusCode"/>
+    /// and <see cref="string"/>.
+    /// </summary>
+    /// <param name="code">
+    /// A <see cref="CloseStatusCode"/> that contains a status code indicating the reason for stop.
+    /// </param>
+    /// <param name="reason">
+    /// A <see cref="string"/> that contains the reason for stop.
+    /// </param>
+    public void Stop (CloseStatusCode code, string reason)
+    {
+      stop ((ushort) code, reason);
     }
 
     #endregion
@@ -294,11 +514,118 @@ namespace WebSocketSharp.Server {
     /// <param name="context">
     /// A <see cref="WebSocketContext"/> that contains the WebSocket connection request objects to bind.
     /// </param>
-    void IServiceHost.BindWebSocket(WebSocketContext context)
+    void IServiceHost.BindWebSocket (WebSocketContext context)
     {
-      T service = new T();
-      service.Bind(context, _sessions);
-      service.Start();
+      T service = new T ();
+      service.Bind (context, _sessions);
+      service.Start ();
+    }
+
+    /// <summary>
+    /// Broadcasts the specified array of <see cref="byte"/> to all clients.
+    /// </summary>
+    /// <param name="data">
+    /// An array of <see cref="byte"/> to broadcast.
+    /// </param>
+    void IServiceHost.Broadcast (byte [] data)
+    {
+      _sessions.Broadcast (data);
+    }
+
+    /// <summary>
+    /// Broadcasts the specified <see cref="string"/> to all clients.
+    /// </summary>
+    /// <param name="data">
+    /// A <see cref="string"/> to broadcast.
+    /// </param>
+    void IServiceHost.Broadcast (string data)
+    {
+      _sessions.Broadcast (data);
+    }
+
+    /// <summary>
+    /// Sends Pings with the specified <see cref="string"/> to all clients.
+    /// </summary>
+    /// <returns>
+    /// A Dictionary&lt;string, bool&gt; that contains the collection of session IDs and values
+    /// indicating whether the service host received the Pongs from each clients in a time.
+    /// </returns>
+    /// <param name="message">
+    /// A <see cref="string"/> that contains a message to send.
+    /// </param>
+    Dictionary<string, bool> IServiceHost.Broadping (string message)
+    {
+      return _sessions.Broadping (message);
+    }
+
+    /// <summary>
+    /// Sends a Ping with the specified <see cref="string"/> to the client associated with
+    /// the specified ID.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the service host receives a Pong from the client in a time; otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the Ping.
+    /// </param>
+    /// <param name="message">
+    /// A <see cref="string"/> that contains a message to send.
+    /// </param>
+    bool IServiceHost.PingTo (string id, string message)
+    {
+      return _sessions.PingTo (id, message);
+    }
+
+    /// <summary>
+    /// Sends a binary data to the client associated with the specified ID.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the client associated with <paramref name="id"/> is successfully found;
+    /// otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the data.
+    /// </param>
+    /// <param name="data">
+    /// An array of <see cref="byte"/> that contains a binary data to send.
+    /// </param>
+    bool IServiceHost.SendTo (string id, byte [] data)
+    {
+      return _sessions.SendTo (id, data);
+    }
+
+    /// <summary>
+    /// Sends a text data to the client associated with the specified ID.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the client associated with <paramref name="id"/> is successfully found;
+    /// otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the data.
+    /// </param>
+    /// <param name="data">
+    /// A <see cref="string"/> that contains a text data to send.
+    /// </param>
+    bool IServiceHost.SendTo (string id, string data)
+    {
+      return _sessions.SendTo (id, data);
+    }
+
+    /// <summary>
+    /// Stops receiving the WebSocket connection requests with the specified <see cref="ushort"/> and
+    /// <see cref="string"/>.
+    /// </summary>
+    /// <param name="code">
+    /// A <see cref="ushort"/> that contains a status code indicating the reason for stop.
+    /// </param>
+    /// <param name="reason">
+    /// A <see cref="string"/> that contains the reason for stop.
+    /// </param>
+    void IServiceHost.Stop (ushort code, string reason)
+    {
+      base.Stop ();
+      _sessions.Stop (code, reason);
     }
 
     #endregion
diff --git a/websocket-sharp/Server/WebSocketServiceManager.cs b/websocket-sharp/Server/WebSocketServiceManager.cs
index 6f23ad28..5e00e287 100644
--- a/websocket-sharp/Server/WebSocketServiceManager.cs
+++ b/websocket-sharp/Server/WebSocketServiceManager.cs
@@ -41,6 +41,7 @@ namespace WebSocketSharp.Server
     #region Private Fields
 
     private object                               _forSweep;
+    private Logger                               _logger;
     private Dictionary<string, WebSocketService> _services;
     private volatile bool                        _stopped;
     private volatile bool                        _sweeping;
@@ -52,7 +53,13 @@ namespace WebSocketSharp.Server
     #region Internal Constructors
 
     internal WebSocketServiceManager ()
+      : this (new Logger ())
     {
+    }
+
+    internal WebSocketServiceManager (Logger logger)
+    {
+      _logger = logger;
       _forSweep = new object ();
       _services = new Dictionary<string, WebSocketService> ();
       _stopped = false;
@@ -133,6 +140,38 @@ namespace WebSocketSharp.Server
       }
     }
 
+    /// <summary>
+    /// Gets the <see cref="WebSocketService"/> instance with the specified ID
+    /// from the <see cref="WebSocketServiceManager"/>.
+    /// </summary>
+    /// <value>
+    /// A <see cref="WebSocketService"/> instance with <paramref name="id"/> if it is successfully found;
+    /// otherwise, <see langword="null"/>.
+    /// </value>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID to find.
+    /// </param>
+    public WebSocketService this [string id] {
+      get {
+        if (id.IsNullOrEmpty ())
+        {
+          _logger.Error ("'id' must not be null or empty.");
+          return null;
+        }
+
+        lock (_sync)
+        {
+          try {
+            return _services [id];
+          }
+          catch {
+            _logger.Error ("'id' not found.\nid: " + id);
+            return null;
+          }
+        }
+      }
+    }
+
     /// <summary>
     /// Gets a value indicating whether the <see cref="WebSocketServiceManager"/> cleans up
     /// the inactive <see cref="WebSocketService"/> instances periodically.
@@ -157,26 +196,37 @@ namespace WebSocketSharp.Server
       }
     }
 
+    /// <summary>
+    /// Gets the collection of the <see cref="WebSocketService"/> instances
+    /// managed by the <see cref="WebSocketServiceManager"/>.
+    /// </summary>
+    /// <value>
+    /// An IEnumerable&lt;WebSocketService&gt; that contains the collection of
+    /// the <see cref="WebSocketService"/> instances.
+    /// </value>
+    public IEnumerable<WebSocketService> ServiceInstances {
+      get {
+        lock (_sync)
+        {
+          return _services.Values;
+        }
+      }
+    }
+
     #endregion
 
     #region Private Methods
 
     private void broadcast (byte [] data)
     {
-      lock (_sync)
-      {
-        foreach (var service in _services.Values)
-          service.Send (data);
-      }
+      foreach (var service in ServiceInstances)
+        service.Send (data);
     }
 
     private void broadcast (string data)
     {
-      lock (_sync)
-      {
-        foreach (var service in _services.Values)
-          service.Send (data);
-      }
+      foreach (var service in ServiceInstances)
+        service.Send (data);
     }
 
     private void broadcastAsync (byte [] data)
@@ -280,33 +330,6 @@ namespace WebSocketSharp.Server
       }
     }
 
-    internal bool Remove (string id)
-    {
-      lock (_sync)
-      {
-        return _services.Remove (id);
-      }
-    }
-
-    internal void Stop ()
-    {
-      stop (0, null, true);
-    }
-
-    internal void Stop (ushort code, string reason)
-    {
-      stop (code, reason, false);
-    }
-
-    internal void Stop (CloseStatusCode code, string reason)
-    {
-      Stop ((ushort) code, reason);
-    }
-
-    #endregion
-
-    #region Public Methods
-
     /// <summary>
     /// Broadcasts the specified array of <see cref="byte"/> to the clients of every
     /// <see cref="WebSocketService"/> instances managed by the <see cref="WebSocketServiceManager"/>.
@@ -314,7 +337,7 @@ namespace WebSocketSharp.Server
     /// <param name="data">
     /// An array of <see cref="byte"/> to broadcast.
     /// </param>
-    public void Broadcast (byte [] data)
+    internal void Broadcast (byte [] data)
     {
       if (_stopped)
         broadcast (data);
@@ -329,7 +352,7 @@ namespace WebSocketSharp.Server
     /// <param name="data">
     /// A <see cref="string"/> to broadcast.
     /// </param>
-    public void Broadcast (string data)
+    internal void Broadcast (string data)
     {
       if (_stopped)
         broadcast (data);
@@ -348,7 +371,7 @@ namespace WebSocketSharp.Server
     /// <param name="message">
     /// A <see cref="string"/> that contains a message to send.
     /// </param>
-    public Dictionary<string, bool> Broadping (string message)
+    internal Dictionary<string, bool> Broadping (string message)
     {
       var result = new Dictionary<string, bool> ();
       foreach (var session in copy ())
@@ -357,6 +380,109 @@ namespace WebSocketSharp.Server
       return result;
     }
 
+    /// <summary>
+    /// Sends a Ping with the specified <see cref="string"/> to the client of the <see cref="WebSocketService"/>
+    /// instance with the specified ID.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the <see cref="WebSocketService"/> instance receives a Pong in a time;
+    /// otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the Ping.
+    /// </param>
+    /// <param name="message">
+    /// A <see cref="string"/> that contains a message to send.
+    /// </param>
+    internal bool PingTo (string id, string message)
+    {
+      WebSocketService service;
+      if (TryGetServiceInstance (id, out service))
+        return service.Ping (message);
+
+      _logger.Error (
+        "The WebSocket service instance with the specified ID not found.\nID: " + id);
+      return false;
+    }
+
+    internal bool Remove (string id)
+    {
+      lock (_sync)
+      {
+        return _services.Remove (id);
+      }
+    }
+
+    /// <summary>
+    /// Sends a binary data to the client of the <see cref="WebSocketService"/> instance
+    /// with the specified ID.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the <see cref="WebSocketService"/> instance with <paramref name="id"/>
+    /// is successfully found; otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the data.
+    /// </param>
+    /// <param name="data">
+    /// An array of <see cref="byte"/> that contains a binary data to send.
+    /// </param>
+    internal bool SendTo (string id, byte [] data)
+    {
+      WebSocketService service;
+      if (TryGetServiceInstance (id, out service))
+      {
+        service.Send (data);
+        return true;
+      }
+
+      _logger.Error (
+        "The WebSocket service instance with the specified ID not found.\nID: " + id);
+      return false;
+    }
+
+    /// <summary>
+    /// Sends a text data to the client of the <see cref="WebSocketService"/> instance
+    /// with the specified ID.
+    /// </summary>
+    /// <returns>
+    /// <c>true</c> if the <see cref="WebSocketService"/> instance with <paramref name="id"/>
+    /// is successfully found; otherwise, <c>false</c>.
+    /// </returns>
+    /// <param name="id">
+    /// A <see cref="string"/> that contains an ID that represents the destination for the data.
+    /// </param>
+    /// <param name="data">
+    /// A <see cref="string"/> that contains a text data to send.
+    /// </param>
+    internal bool SendTo (string id, string data)
+    {
+      WebSocketService service;
+      if (TryGetServiceInstance (id, out service))
+      {
+        service.Send (data);
+        return true;
+      }
+
+      _logger.Error (
+        "The WebSocket service instance with the specified ID not found.\nID: " + id);
+      return false;
+    }
+
+    internal void Stop ()
+    {
+      stop (0, null, true);
+    }
+
+    internal void Stop (ushort code, string reason)
+    {
+      stop (code, reason, false);
+    }
+
+    #endregion
+
+    #region Public Methods
+
     /// <summary>
     /// Cleans up the inactive <see cref="WebSocketService"/> instances.
     /// </summary>
@@ -397,20 +523,20 @@ namespace WebSocketSharp.Server
     }
 
     /// <summary>
-    /// Tries to get the <see cref="WebSocketService"/> associated with the specified ID.
+    /// Tries to get the <see cref="WebSocketService"/> instance with the specified ID.
     /// </summary>
     /// <returns>
-    /// <c>true</c> if the <see cref="WebSocketServiceManager"/> manages the <see cref="WebSocketService"/>
-    /// with <paramref name="id"/>; otherwise, <c>false</c>.
+    /// <c>true</c> if the <see cref="WebSocketService"/> instance with <paramref name="id"/>
+    /// is successfully found; otherwise, <c>false</c>.
     /// </returns>
     /// <param name="id">
     /// A <see cref="string"/> that contains an ID to find.
     /// </param>
     /// <param name="service">
-    /// When this method returns, contains a <see cref="WebSocketService"/> with <paramref name="id"/>
-    /// if it is found; otherwise, <see langword="null"/>.
+    /// When this method returns, contains a <see cref="WebSocketService"/> instance with <param name="id"/>
+    /// if it is successfully found; otherwise, <see langword="null"/>.
     /// </param>
-    public bool TryGetWebSocketService (string id, out WebSocketService service)
+    public bool TryGetServiceInstance (string id, out WebSocketService service)
     {
       lock (_sync)
       {
diff --git a/websocket-sharp/WebSocket.cs b/websocket-sharp/WebSocket.cs
index 604c59e3..bf596363 100644
--- a/websocket-sharp/WebSocket.cs
+++ b/websocket-sharp/WebSocket.cs
@@ -588,7 +588,7 @@ namespace WebSocketSharp
       if (data.Length > 125)
       {
         var msg = "The payload length of a Close frame must be 125 bytes or less.";
-        _logger.Error (msg);
+        _logger.Error (String.Format ("{0}\ncode: {1}\nreason: {2}", msg, code, reason));
         error (msg);
 
         return;
@@ -1378,8 +1378,8 @@ namespace WebSocketSharp
     {
       if (!code.IsCloseStatusCode ())
       {
-        var msg = String.Format ("Invalid close status code: {0}", code);
-        _logger.Error (msg);
+        var msg = "Invalid close status code.";
+        _logger.Error (String.Format ("{0}\ncode: {1}", msg, code));
         error (msg);
 
         return;