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Posted 6 Aug 2006

A Remoting Event (Simple and Efficient for Enterprise Solutions)

, 21 Aug 2006
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This article contains the simplest solutions for: the security problem for DelegateSerializationHolder, the IO problem, and the messaging speed problem. Note: Messaging speed problem will appear when your application has worked for a long time.

demo project Image


I always had an interest in socket programming. I have created several chat applications and complex socket based applications. When I learned about events in Remoting I was so glad, and the first thing that I thought about was creating a chat application. But in the test, I met with some problems.

Problem 1

The first problem was a security exception:

System.Security.SecurityException: Type System.DelegateSerializationHolder 
and the types derived from it (such as System.DelegateSerializationHolder) 
are not permitted to be deserialized at this security level.

Security Exception Image

Solution 1

This problem was solved by adding the typeFilterLevel attribute with Full value to the formatter element of both configuration files.

<formatter ref="soap" typeFilterLevel="Full" />

Problem 2

But again, it did not work and an IO exception occurred:

Exception has been thrown by the target of an invocation. ---> 
System.IO.FileNotFoundException: Could not load file or assembly 
'Client, Version=, Culture=neutral, PublicKeyToken=null' 
or one of its dependencies. The system cannot find the file specified.

This exception occurs while the request is deserialized at the server. The server tries to call the event handler whereas the event handler exists in the client assembly. Because the client assembly is not available at the server, the exception is thrown.

IO exception Image

Solution 2

An intermediate wrapper class, MarshalByRefObject will solve this problem. This wrapper class is located in the shared assembly, accessible for both the client and the server; therefore, a delegate can resolve the method's signature. In the client application, we will associate the shared object event with the WrapperMessageReceivedHandler method of the wrapper class and associate an event handler on the client with the MessageReceived event of the wrapper class.

Sequense of events Image

Why [OneWay] Attribute

Without defining the remote method as [OneWay], an exception will occur when the client is unreachable or has been disconnected without disassociating the event handler. By using [OneWay], no exception will occur on the client, but it will be in the invocation list of the server and, in longtime, will make your server slower to respond.

Solution 3

Instead of using the normal event invocation mechanism, you must invoke each delegate on your own, and if an exception occurs, you must disassociate the delegate from the invocation list of the event. In the end, you can remove the [OneWay] attribute.

Shared Class

/// <span class="code-SummaryComment"><summary></span>
/// Represents the method that will handle
/// the Remotable.RemoteClass.MessageReceived event.
/// <span class="code-SummaryComment"></summary></span>
/// <span class="code-SummaryComment"><param name="message">Received message</param></span>

public delegate void MessageHandler(string message);

/// <span class="code-SummaryComment"><summary></span>
/// Shared remoting class that orchestrate messaging tasks 
/// <span class="code-SummaryComment"></summary></span>

public class RemoteClass:MarshalByRefObject

    /// <span class="code-SummaryComment"><summary></span>
    /// Occurs when a broadcast message received.
    /// <span class="code-SummaryComment"></summary></span>

    public event MessageHandler MessageReceived;
    /// <span class="code-SummaryComment"><summary></span>
    /// Initializes a new instance of the Remotable.RemoteClass class.
    /// <span class="code-SummaryComment"></summary></span>

    public RemoteClass()

    /// <span class="code-SummaryComment"><summary></span>
    /// Obtains a lifetime service object to control the lifetime policy for this
    /// instance.
    /// <span class="code-SummaryComment"></summary></span>
    /// <span class="code-SummaryComment"><returns></span>
    ///An object of type 
    ///System.Runtime.Remoting.Lifetime.ILease used to control
    ///the lifetime policy for this instance. This is the current lifetime service
    ///object for this instance if one exists; otherwise, a new lifetime service
    ///object initialized to the value of the 
    ///null value means this object has to live forever.
    /// <span class="code-SummaryComment"></returns></span>

    public override object InitializeLifetimeService()
        return null;

    /// <span class="code-SummaryComment"><summary></span>
    /// Broadcast message to all clients
    /// <span class="code-SummaryComment"></summary></span>
    /// <span class="code-SummaryComment"><param name="message">message string</param></span>

    public void Send(string message)
        if (MessageReceived != null)
            MessageHandler messageDelegate = null;
            Delegate[] invocationList_ = null;
                invocationList_ = MessageReceived.GetInvocationList();
            catch (MemberAccessException ex)
                throw ex;
            if (invocationList_ != null)
                lock (this)
                    foreach (Delegate del in invocationList_)
                            messageDelegate = (MessageHandler)del;
                        catch (Exception e)
                            MessageReceived -= messageDelegate;

Client Application

RemoteClass remoteClass;
WrapperClass wrapperClass;

private void Form1_Load(object sender, EventArgs e)
    //Configure remoting.

    RemotingConfiguration.Configure(Application.StartupPath + 

    // Create a proxy from remote object.

    remoteClass = (RemoteClass)Activator.GetObject(typeof(RemoteClass), 
    //Create an instance of wrapper class.

    wrapperClass = new WrapperClass();
    //Associate remote object event with wrapper method.

    remoteClass.MessageReceived += new 
    //Associate wrapper event with current form event handler.

    wrapperClass.WrapperMessageReceived += new 

Wrapper Class

/// <span class="code-SummaryComment"><summary></span>
/// Occurs when a broadcast message received.
/// <span class="code-SummaryComment"></summary></span>

public event MessageHandler WrapperMessageReceived;
/// <span class="code-SummaryComment"><summary></span>
/// Wrapper method for sending message to the clients.
/// <span class="code-SummaryComment"></summary></span>
/// <span class="code-SummaryComment"><param name="sender">Caller object</param></span>
/// <span class="code-SummaryComment"><param name="args">Message data</param></span>

public void WrapperMessageReceivedHandler(string message)
    // forward the message to the client

    if(WrapperMessageReceived != null)


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Hossein Ghahvei Araghi
Program Manager System Group
Iran (Islamic Republic of) Iran (Islamic Republic of)
Hossein Ghahvei Araghi
Birth date: 1978
Birth place: Iran
Academic Credentials : BS(Tehran University)
Microsoft Credentials : MCP, MCAD, MCTS 2.0, MCTS 3.5, MCPD 2.0, MCPD 3.5

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Comments and Discussions

GeneralRequested service not found Pin
Jeetu0075-Sep-06 15:38
memberJeetu0075-Sep-06 15:38 
GeneralRe: Requested service not found Pin
Jeetu00713-Sep-06 16:34
memberJeetu00713-Sep-06 16:34 
QuestionRe: Requested service not found Pin
camariei11-Dec-06 12:40
membercamariei11-Dec-06 12:40 
GeneralVB.Net Pin
FuSe51224-Aug-06 17:19
memberFuSe51224-Aug-06 17:19 
GeneralRe: VB.Net Pin
FuSe51224-Aug-06 17:58
memberFuSe51224-Aug-06 17:58 
Questionabout the NAT Pin
yonking23-Aug-06 23:41
memberyonking23-Aug-06 23:41 
AnswerRe: about the NAT Pin
shahrul6s20-Nov-07 22:37
membershahrul6s20-Nov-07 22:37 
GeneralRe: about the NAT Pin
gio_ch28-Jul-11 8:37
membergio_ch28-Jul-11 8:37 
GeneralMissing the point Pin
Alex_112-Aug-06 17:12
memberAlex_112-Aug-06 17:12 
I received from the author of this article the message:

I see the web site,
I can do anything in Remoting,
It doesn't have anything else.

This message is about DotNetRemoting framework. Really I did not want to criticize the
solution but this message made me to write a bit more. The code is simple and elegant indeed. However it has noting to do with the real word of the network communication. It is just a demo, a good one, though the term “Enterprise” is completely misleading. Judge for yourself. Let’s add the line to the client and see how the system works

public void MessageReceivedHandler(string message)

It means that the response from the client comes with 1 second delay. Create 10 clients.
Total delay in one shot is now 10 seconds. With 500 clients the delay would be (if anyone is still waiting) is 8.5 minutes. Oops! Do we always expect that response time from the client is a Zero? If the response time is zero, the client is doing noting by the definition.
Well, we can fix that, create a new worker thread on the client, catch the server request, send ACK and invoke the processing when the client is not that busy. Now our client has multithreading and queuing mechanism. What if the delay occurs in the network?
We have to create the same queuing mechanism on the server with the pool of threads and threading managing subsystem. If we do not create this multithreading system on the server, any delay with any individual client freezes the whole server. Does it look like a server any more, if the lazy client can kill it? Oops again. I can point to dozens of more “Oops” but that is beyond the scope of this comment. The problem with bidirectional communication is not in the implementation but in the model of the Remoting. The bidirectional comms from the server side must be ASYNCROUNOUS. The Remoting is based entirely on the SYNCROUNOUS model.
The Delegates are just the callbacks
Expecting that 50 lines solution solves all the problems is a bit naïve.

GeneralRe: Missing the point Pin
Hossein eraghi16-Aug-06 1:33
memberHossein eraghi16-Aug-06 1:33 
GeneralRe: Missing the point Pin
Alex_119-Aug-06 22:24
memberAlex_119-Aug-06 22:24 
GeneralRe: It's just for you Pin
Hossein eraghi21-Aug-06 2:00
memberHossein eraghi21-Aug-06 2:00 
GeneralStill Missing the Point Pin
Alex_123-Aug-06 1:00
memberAlex_123-Aug-06 1:00 
GeneralInstructive points Pin
Hossein eraghi23-Aug-06 21:04
memberHossein eraghi23-Aug-06 21:04 
GeneralRe: Instructive points Pin
Alex_124-Aug-06 0:54
memberAlex_124-Aug-06 0:54 
GeneralAbout arrogance and professionalism Pin
Kfir.C12-Sep-07 2:41
memberKfir.C12-Sep-07 2:41 
QuestionWas anyone successful making work in v1.1 Pin
Bubba Ole10-Aug-06 6:50
memberBubba Ole10-Aug-06 6:50 
AnswerRe: Was anyone successful making work in v1.1 Pin
Hossein eraghi11-Aug-06 20:47
memberHossein eraghi11-Aug-06 20:47 
AnswerRe: Was anyone successful making work in v1.1 Pin
mihir250812-May-08 14:04
membermihir250812-May-08 14:04 
GeneralGood Pin
Obaid ur Rehman8-Aug-06 8:10
memberObaid ur Rehman8-Aug-06 8:10 
GeneralRe: Good Pin
Hossein eraghi8-Aug-06 22:44
memberHossein eraghi8-Aug-06 22:44 
GeneralSingleton versus SingleCall mode Pin
Henk van der Geld8-Aug-06 1:26
memberHenk van der Geld8-Aug-06 1:26 
AnswerRe: Singleton versus SingleCall mode Pin
Obaid ur Rehman8-Aug-06 8:04
memberObaid ur Rehman8-Aug-06 8:04 
GeneralTo make it even better... Pin
mav.northwind6-Aug-06 21:38
membermav.northwind6-Aug-06 21:38 
GeneralRe: To make it even better... Pin
Hossein eraghi6-Aug-06 22:10
memberHossein eraghi6-Aug-06 22:10 

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