Write a chat application that allows multiple clients to participate in a simultaneous text chat. General guidelines for the project are

• Chats all take place in a single chat room. All clients who log on to the same server will be involved in the same chat.
• When a client connects to the chat server they will send a name to use as their handle for the chat.
• After putting up a dialog asking the user what handle they would like to use, the client application will put up its main frame. The bulk of the frame will be taken up by a text area that shows the transcript of the conversation. There will be a text field at the bottom that the user will use to enter a new comment. Next to the text field there will be a send button. When the user clicks send the contents of the text field will get sent to the server and stored in a transcript there.
• When a client first connects they will get sent the entire transcript that has accumulated up to the point when they joined.

The first thing you will need to do is to construct a transcript class to represent the conversation. You should store the transcript as a list of strings. Each time a comment comes in from a client that comment will get added as a new string at the end of the transcript list.

As is usual for servers, you will be creating a task object running in a thread to manage the interaction with each client. Each time a comment arrives the thread will call an appropriate method in the transcript class to have that comment added to the transcript.

On the client side you should set up a proxy class with the following interface:

public class ChatGateway
{
	public void startChat(String handle) {}
	public void sendComment(String comment) {}
	public int getCommentCount() {}
	public String getComment(int n) {}
}

To handle fetching comments from the server, you should set up a thread in the client that wakes up, say, twice every second and checks for new comments:

while(true) {
  if(gateway.getCommentCount() > count)
		// Fetch new comments and put them in the text area
	
	try {
	  Thread.sleep(500);
	} catch(InterruptedException ex) {
	  // Fail silently
	}
}

The thread code contains an infinite loop. On each trip through the loop, the code will go to the gateway and check to see what the comment count is now. If the gateway tells you that more comments are available than you have downloaded, go back to the gateway to get the new comments and append them to the text area that shows the transcript. After doing this, the thread code goes to sleep for 500 milliseconds. After it wakes up from that sleep is goes back through the loop again.