The basic and simple architecture of .Net Remoting technology has three parts, these are –
1. Base Remoting class: This is like a bridge to communicate between Client and Server. It exists in a DLL file which shares Server and Client program.
2. Server class: It is server to server Client requests, every client connect to Server to communicate each other. This program holds a Remoting class’s DLL.
3. Client class: This is client part of Remoting architecture. This also holds a copy of Remoting base DLL. It connects to Server and via server communicates to other client.This is very simple idea of Remoting architecture, if you want to learn about this technology then you may read from MSDN site. I am not going to explain about its theory, I am focusing mainly about its application.
Now I will describe about a Global Text Chat Room application using this technology. This is very easy to develop and interesting also. In this program I have not covered about thread related issues, this is very basic type of chat application.
As Remoting architecture here has a base class and after compiling produces a DLL file with name ‘RemoteBase.dll’. This DLL has about six methods like, JoinToChatRoom, LeaveChatRoom, SendMsgToSvr (Send Message To Server), GetMsgFromSvr (Get Message From Server) etc.
Next
one is Server, this is a Windows Form (WinForm) application. This
application uses ‘RemoteBase.dll’ as its reference file for library.
Server registers a TCP channel with a port number. You may choose any
port number from 1025 to 65k. And it registers for well known type of
RemoteBase and mode type is Singleton. (Remember it should not work for
Singlecall type, details and different will found on MSDN).
When
you run server you will see a window as attached screen shot and need
to press button ‘Start’ to start server and check server status as
‘Running’. To stop the server need to press on ‘Stop’ button.
Last
one is Client part, it also a Windows form (WinForm) application with
two windows forms. As server client also take reference of
‘RemoteBase.dll’ for library. When you run this client application one
popup window will come and ask for your name which will be used to chat
room to represent you. Then press on Join button. After that chat room
window will open.
There
also has server address like ‘tcp://localhost:8080/HelloWorld’ here
‘localhost’ is server address and 8080 is port number. Server address
needs to tell where your server is running. I am using server and client
in same machine so server address is ‘localhost’ you may give any IP
address here. Port number also can be changed but server opening port
number and client requesting port number should be same. You can not
change reaming thing in address otherwise this chat application will not
work.
Chat
room window has four sections largest one to see all chat message and
below of that to type chat message, and send button to send message to
server. Just above list to display all online user.
When
you put your name then client application creates a remote base class’s
object and connects to server by registering TCP channel. Then connects
to Chat Room and seek latest message number. After that main Chat Room
window opens. From that window it seeks latest available message in
server by a timer. To get message from server it invokes
‘GetMsgFromSvr()’, and get available online user through ‘GetOnlineUser
(), and user message sends from client application to server by invoking
‘SendMsgToSvr()’. For better understanding you may go through the code.
Source code as below and full source code can download from following link:
How the code is working
Start the Server:
When users are trying start Server by clicking Start button the following code executes –
private void btnStart_Click(object sender, EventArgs e)
{if (channel == null)
{channel = new TcpChannel(8080);ChannelServices.RegisterChannel(channel, false);RemotingConfiguration.RegisterWellKnownServiceType(typeof(SampleObject), "ChatRoom", WellKnownObjectMode.Singleton);lblStatus.Text = "Running...";btnStart.Enabled = false;btnStop.Enabled = true;}}Here a TcpChannel opens with port number 8080 and register it as WellKnownServiceType. ‘ChatRoom’ it is the ‘ObjectUri’ it will require to connect to server from client.On the other hand when user press to ‘Stop’ server then unregister the channel and stop the server. Codes are below-private void btnStop_Click(object sender, EventArgs e){if (channel != null){ChannelServices.UnregisterChannel(channel);channel = null;lblStatus.Text = "Stopped.";btnStart.Enabled = true;btnStop.Enabled = false;}
}
Join to ChatRoom:
Next
coming the client, how client connect to server and user login to the
chat room. To joining to chat room the below codes are executes
private void JoinToChatRoom(){if (chan == null && txtName.Text.Trim().Length != 0){chan = new TcpChannel();ChannelServices.RegisterChannel(chan,false);// Create an instance of the remote objectobjChatWin = new frmChatWin();objChatWin.remoteObj = (SampleObject)Activator.GetObject(typeof(RemoteBase.SampleObject), txtServerAdd.Text);if (!objChatWin.remoteObj.JoinToChatRoom(txtName.Text)){MessageBox.Show(txtName.Text+ " already joined, please try with different name");ChannelServices.UnregisterChannel(chan);chan = null;objChatWin.Dispose();return;}objChatWin.key = objChatWin.remoteObj.CurrentKeyNo();objChatWin.yourName= txtName.Text;this.Hide();objChatWin.Show();}}
Here
from user client application takes a name and check to server is the
name available or not. If name is available then user gets the
‘CurrentKeyNo’ of server, it is the number of last chat message (how the
key generated, describe in later) and open the ChatRoom window.
If user name is already taken by other user, then application asks to user for different name.
In server side to join a user in chat server “JoinToChatRoom()” method invokes, lets see what happens within the method –
public bool JoinToChatRoom(string name)
{if (alOnlineUser.IndexOf(name) > -1)return false;else{alOnlineUser.Add(name);SendMsgToSvr(name + " has joined into chat room.");return true;}}
Here is user can successfully logged in to server then his name is added in a user collection, ‘alOnlineUser’ is it an ArrayList type object.
Send message to server:
Send message to server:
When
user type some message and press on ‘Send’ button or just press ‘Enter’
button then client application try to send message to server. To do it
client call the below method –
private void SendMessage(){if (remoteObj != null && txtChatHere.Text.Trim().Length>0){remoteObj.SendMsgToSvr(yourName + " says: " + txtChatHere.Text);txtChatHere.Text = "";}}
Here client application in invokes the “SendMsgToSvr()” method of server. Let’s see the method what doing-
public void SendMsgToSvr(string chatMsgFromUsr){hTChatMsg.Add(++key, chatMsgFromUsr);}
Wow!
This is very small code. Actually this is adding the users’ message to
another collection. I have used for this collection of HashTable type,
you may use any other collection type to store string data.
See
here has one counter ‘key’ which is incrementing by one. This is the
counter which is maintaining the chat message number. It will help us to
get chat message from server.
Receive Message from Server:
Ok friend, next look at how data are getting from server –
In
chat room a timer always fires, which try to get message from server
and current available user in server. Here below codes plays in Client
side –
private void timer1_Tick(object sender, EventArgs e){if (remoteObj != null){string tempStr = remoteObj.GetMsgFromSvr(key);if (tempStr.Trim().Length > 0){key++;txtAllChat.Text = txtAllChat.Text + "\n" + tempStr;}ArrayList onlineUser = remoteObj.GetOnlineUser();lstOnlineUser.DataSource = onlineUser;skipCounter = 0;if (onlineUser.Count < 2){txtChatHere.Text = "Please wait untill atleast two user join in Chat Room.";txtChatHere.Enabled = false;}else if(txtChatHere.Text == "Please wait untill atleast two user join in Chat Room." && txtChatHere.Enabled == false){txtChatHere.Text = "";txtChatHere.Enabled = true;}}}
Here client invokes “GetMsgFromSvr()” method to get message, with parameter key. The codes of the method are –
public string GetMsgFromSvr(int lastKey){if (key > lastKey)return hTChatMsg[lastKey + 1].ToString();elsereturn "";}
The
server just takes the key as last-key of user’s message and uses it in
Chat message collection to fetch the next chat message, after that the
message return to the client.
To online user client application invokes “GetOnlineUser()” method, lets see what happen in server side within the method.
public ArrayList GetOnlineUser(){return alOnlineUser;}
So this method returns the user collection object which was created in “JoinToChatRoom()” method.
Leave the Chat Room:
When
user closes the chat room, then client application request to server to
remove his/her name from server’s online user list. In client side the
below method invokes –
private void Form1_FormClosed(object sender, FormClosedEventArgs e){if (remoteObj != null){remoteObj.LeaveChatRoom(yourName);txtChatHere.Text = "";}Application.Exit();}In server side the “LeaveChatRoom()”method invokes, the code of that method is –public void LeaveChatRoom(string name){alOnlineUser.Remove(name);SendMsgToSvr(name + " has left the chat room.");}
Now server has deleted your name from online user list.
