Secured Intranet Messenger using MSMQ in C#

The code present in form_load of Startup form is

// To create a Message Queue if it doesn't exist...
try
{
    if (!MessageQueue.Exists(@".\queuemsgs"))
    {
        MessageQueue.Create(@".\queuemsgs", false);
        MessageBox.Show("Queue named queuemsgs is created on your machine");
    }
}
catch (InvalidOperationException ex)
{
    MessageBox.Show("Message Queuing has not been installed on this computer. Please install it by going to Control Panel -> Add/Remove Programs -> Add Windows Components and select Message Queuing and start this application...");
    System.Diagnostics.EventLog.WriteEntry("DOTNET Messenger Error", ex.Message + "::" + ex.StackTrace);
    Application.Exit();
    return;
}

// To load all public queues...
try
{
    MessageQueue[] queues = MessageQueue.GetPublicQueues();
    foreach (MessageQueue queue in MessageQueue.GetPublicQueues())
    {
        drppublicqueues.Items.Add(queue.Path);
    }
}
catch (Exception ex)
{
    MessageBox.Show(ex.Message);
}

// To create an XML file for storing contact details entered using AddNewUser window and bind it to a combobox...
try
{
    filename = @"c:\contactslist.xml";
    if (!File.Exists(filename))
    {
        File.Create(filename).Close();
        StreamWriter writer = new StreamWriter(filename);
        writer.Write("<?xml version=\"1.0\"?>");
        writer.Write("<users>");
        writer.Write("</users>");
        writer.Close();
        return;
    }
    else
    {
        DataSet ds = new DataSet();
        StreamReader reader = new StreamReader(filename);
        string tmpfilecontents = reader.ReadToEnd();
        reader.Close();
        if (tmpfilecontents.IndexOf("<machinename>") != -1)
        {
            ds.ReadXml(filename);
            drpuserslist.DataSource = ds.Tables[0];
            drpuserslist.DisplayMember = "name";
            drpuserslist.ValueMember = "machinename";
        }
    }
}
catch { }

// To load all unread messages...
try
{
    string queuepath = "";
    queuepath = @"FormatName:DIRECT=OS:" + System.Environment.MachineName + @"\queuemsgs";
    lblunread.Text = "Unread Messages in Queue " + System.Environment.MachineName + @"\queuemsgs";
    MessageQueue tmpqueue = new MessageQueue(queuepath);
    Type[] target = new Type[1];
    target[0] = typeof(string);
    foreach (System.Messaging.Message msg in tmpqueue.GetAllMessages())
    {
        msg.Formatter = new System.Messaging.XmlMessageFormatter(target);
        txtprevmsgs.Text += msg.Body.ToString() + " Received from " + msg.Label.ToString().Substring(msg.Label.ToString().LastIndexOf(":::") + 3) + " at " + msg.Label.ToString().Substring(0, msg.Label.ToString().LastIndexOf(":::")) + "\r\n";
    }
}
catch (Exception ex)
{
    System.Diagnostics.EventLog.WriteEntry("DOTNET Messenger Error", ex.Message + "::" + ex.StackTrace);
}

Remaining code for this form is available in the attachment.

Functionality of Chat Window

I am using Send_QueueMessages() and Get_QueueMessages() to send, receive messages from the queue and display it.

The code for Get_QueueMessages() is.

try
{
    msgqueue.Path = @"FormatName:DIRECT=OS:" + System.Environment.MachineName.ToString() + @"\queuemsgs";
    
    Type[] target = new Type[1];
    target[0] = typeof(string);
    
    System.Messaging.Message msg = msgqueue.Receive(new TimeSpan(0, 0, 2));
    msg.Formatter = new System.Messaging.XmlMessageFormatter(target);
    
    txtallmsgs.Text += "\r\n" + "HE/SHE says:" + "\r\n" + (msg.Body.ToString());
    
    if (msg.Label.ToString().Substring(msg.Label.ToString().LastIndexOf(":::") + 3) == Form1.selectedmcname.ToString())
    {
        lblreceived.Text = "Last message received at: " + msg.Label.ToString().Substring(0, msg.Label.ToString().LastIndexOf(":::"));
    }
    else
    {
        txtallmsgs.Text += " Received from " + msg.Label.ToString().Substring(msg.Label.ToString().LastIndexOf(":::") + 3) + " at " + msg.Label.ToString().Substring(0, msg.Label.ToString().LastIndexOf(":::")) + "\r\n";
    }
}
catch (Exception ex)
{
    if (ex.Message != "Timeout for the requested operation has expired.")
    {
        MessageBox.Show(ex.Message, "DOTNET Messenger Error");
    }
}

This method will set queue path and formatter to get message. Than, it will extract received message's body and label. Finally, it will check source m/c of message and displays its name, if chat window opened is not belonging to selected user else it will display just message and its sent time.

The code for Send_QueueMessages().

try
{
    string queuepath = "";

    if (Form1.selectedconact != "")
    {
        queuepath = @"FormatName:DIRECT=OS:" + Form1.selectedmcname.ToString() + @"\queuemsgs";
    }
    else
    {
        queuepath = @"FormatName:DIRECT=OS:" + Form1.selectedmcname;
    }

    msgqueue.Path = queuepath;
    msgqueue.Send(txtsentmsg.Text, DateTime.Now.ToLongTimeString() + ":::" + System.Environment.MachineName);

    txtallmsgs.Text += "\r\n" + "You Said :" + "\r\n" + txtsentmsg.Text;
    txtsentmsg.Text = "";

    lblsenttime.Text = "Last message sent at: " + DateTime.Now.ToLongTimeString();
}
catch (Exception ex)
{
    MessageBox.Show(ex.Message, "DOTNET Messenger Error");
    System.Diagnostics.EventLog.WriteEntry("DOTNET Messenger Error", ex.Message + "::" + ex.StackTrace);
}

This code will set destination's queue path and send message along with time of sending, m/c name and message body.

If Auto Monitor menuitem is checked, than a timer will check message queue for every 3 seconds for new messages and displays it in chat window without manually clicking on receive button.

Finally, history window will load the selected contact's history, which is stored in a text file.

On Form_load, It will open selected contact's history file and load it into a textbox.

try
{
    System.IO.StreamReader reader = new System.IO.StreamReader(@"C:\" + Form1.selectedconact + ".xml");
    textBox1.Text = reader.ReadToEnd();
    reader.Close();
    textBox1.SelectionStart = 0;
    textBox1.SelectionLength = 0;
}
catch (Exception ex)
{
    MessageBox.Show(ex.Message);
}

So, by using few lines of code we can design our own messenger to chat with others present in the intranet. We can enhance this application further by adding functionality like mailing message history, good UI for displaying contacts.

I hope by using this messenger, from now onwards atleast few people can chat with other colleagues without bothering of message monitoring.

I am attaching source code for further reference. I hope this code will be useful for all.