Project 2: GWack (GW Slack Simulator) #

Watch the videos for this project on this YouTube Playlist

In this project, you will be write a client and server that implements a chat room, similar to Slack (or GWack!). Your client software should be GUI based, and your server software will be command line based.

Setup #

You should create at least the two files below – note that they have different due dates, and two different grading rubric requirements below:

• GWackClientGUI.java: the client code and GUI for interacting with a server.
• GWackChannel.java: the server code to host a channel/chatroom

Github setup #

Use git, as discussed in Lab 0, to create a repo called gitusername-project2, add these two files to it, and commit and push the changes to github. The timestamp of your invitation of the grader as a collaborator must be from the lab first session for this project.

Testing/Grading #

There are no test scripts. You will be graded based on functionality and OOP design.

Compiling and Running your Code #

While you may submit other code, we should be able to compile and run your programs using the following commands. This is how the grader can test the different components of the project independently.

For the client GUI, it is run as such.

javac GWackClientGUI.java
java GwackCliengGUI

And for the server:

javac GWackChannel.java
java GwackChannel port

Where port is replaced by the port for the server to bind to.

While there is no starter code, and you may design as you see fit, you MAY NOT USE any packages other than what ships with Java. We will not install any third party packages to compile/run your code.

GWack Slack Protocol #

GWack, the GW Slack simulation, is a chat room where multiple clients can message each other. Any message posted to the chatroom will be sent to the server and then relayed to all connected clients. As part of this project, you will be implement both a client GUI that connect to a server and the server that hosts the chat room, or GWack channel.

Public channels for testing #

To facilitate testing, we are hosting a channel you can connect to and interact with:

see Ed for details

You can use this server to design and test your GUI, before you actually implement the server yourself later.

IMPORTANT: These channels are shared for the entire class. We will monitor the connections and what is posted to these channels. Any behavior considered hateful (broadly defined) may result in disciplinary and academic actions.

Client/Server Protocol #

So that everyone’s GWack client to can interact with each other and the public channels, we must define a standard protocol.

Initial Handshake #

When a client first connects, it sends the following information to the server.

SECRET
3c3c4ac618656ae32b7f3431e75f7b26b1a14a87
NAME
username

Note that there are newlines \n here. It is important for parsing you send each as a complete line. So your server can read a line, then expect the next line, and so on.

Note that username should be replace with whatever this client chooses as a username. Like if they were named george it would be george instead of username

If successful, the server responds with the member list (see below), otherwise, the server will simply close the connection. The server must check that the SECRET sent by the user matches that expected value on the server side.

Member List Updates #

One feature of the GWack channel is that you can view all the members of the channel. This is done by the server regularly distributing a list of members in the channel. These messages are always of the following form:

START_CLIENT_LIST
username1
username2
...
END_CLIENT_LIST

Note that username1 … will be the names chosen by the users.

... is indicate that all the clients should be listed here, and is not part of the protocol.

Sending/Receiving Messages #

All other communications are considered as channel messages. A client simply sends one line a message at a time to the server. For example, supposer username send the following message to the server

GWack is so much better than slack

When the server receives that message, it then distributes it to all the clients, including the client that just sent the message inset in []

[username] GWack is so much better than slack

When a client receives a message from the server, it will display that it in the display panel.

GWack Client #

You will implemented a threaded, GUI GWack client. Here’s a visual of my implementation of the GWack Client. Yours can have different design and features, as long as the major features are there.

It’s a visual of a connected client mid-message:

Required methods and classes #

Your GWack Client GUI must have the following code, in addition to the GUI widgets:

• a class named GWackClientGUI which extends JFrame and containds the necessary GUI widgets
• GWackClientGUI must have an instance of aGWackClientNetworking class as a field (to manage the networking components)
• GWackClientGUI must have the methods newMessage(String message), updateClients(String clients), and sendMessage() to implement the required functionality for those logical components
• GWackClientGUI must define, as private classes, a ConnectActionListener and DisconnectActionListener to help implement the required functionality for connecting and disconnecting. When the user clicks Connect, this listener will then change the button’s text to be Disconnect, and it should remove the ConnectActionListener and add the DisconnectActionListener. You can do that with the following methods:
  GWackClientGUI.this.connectButton.removeActionListener(this); and GWackClientGUI.this.connectButton.addActionListener(new DisconnectActionListener());. The behavior will be symmetric inside the DisconnectActionListener’s actionPerformed method.

Your GWackClientNetworking class must have the following code:

• fields to store the information needed for a single connection
• writeMessage(String message), isConnected(), and disconnect() methods to implement the required functionality
• a private class called ReadingThread that extends Thread and is used to start a new thread in the GWackClientNetworking constructor to serve this specific connection (so it must have a run() method)

Connecting and Disconnecting #

You should have a mechanism for clients to set a name, a host/ip address and a port to connect to. There should also be a button for connecting and disconnecting. There also needs to be visuals for when the user is connected vs. not connected.

For example, here are the menu options for connected clients

and disconnected clients

You should also consider making the text-areas non-editable once connected as well.

ERROR reporting #

You should have some mechanism for reporting errors with connections. I choose to use message dialogs, like the following. You can use something else, but you have to have something.

Some errors to consider:

• Cannot connect to server
• Invalid host
• Invalid port
• Server disconnected

Message Sending and Display #

You have should have two text display areas.

The first is to display all the messages that have been received. This text area should not be editable.

The second display should be used to draft messages, this should be editable. There should be some sort of button to initiate a send.

Additionally, you should have a key listener so that messages send when the user hits ENTER:

msgTextArea.addKeyListener(new KeyListener(){

            @Override
            public void keyTyped(KeyEvent e) {
                if(e.getKeyChar() == '\n'){
                    sendMessage();
                }                
            }
            @Override
            public void keyPressed(KeyEvent e) {}
            @Override
            public void keyReleased(KeyEvent e) {}

        }); 

Important: the user can either send a message by hitting “ENTER” or clicking the button.

Members in the channel #

There should be a display for the current members in the channel. This should update as the members come and go, but it should not be editable by the user.

Grading and submission for the GWack Client/GUI #

See the bottom of this page.

GWack Server #

Your GWack server (GWackChannel) should host a single chatroom or channel at a specified port, provided as a command line argument. The remaining requirements of the server are as follows:

• The server should be able to handle multiple connected clients
• All incoming messages should be distributed to all connected clients
• Clients should be able to connect and disconnect gracefully
• The current client list should be distributed and updated when clients leave
• The protocol for client interaction (as described above) should be observed

Required methods and classes #

Your GWack channel must have the following functionality:

• a class named GWackChannel that represents the server and contains the main method
• a private class GWackConnectedClient inside of GWackChannel that is used to manage individual connections to the server. This class must extend the Thread class, and have the following methods: sendMessage(String message), isValid(), getClientName(), and run()
• serve(), addClient(GWackConnectedClient client), enqueuMessage(String message), dequeueAll(), and getClientList() methods to implement the required functionality

Grading rubric and submission #

Use git, as discussed in lab zero, to submit your work in a repo called gitusername-project2. You will be graded on the following:

GWackClientGUI grading #

GWackServer grading #