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【CST8221–JAP 网络】CST8221–JAP,Assignment 2, Part 2,MMXX Page 1 of 9
Assignment 2 part 2: Othello Networking
Value: 8% of your overall grade.
Due date: December 13th (Sunday, midnight)
Purpose:
We’ve got the UI sorted out, so let’s finish the networking.
We’re going to build up a server that can handle any number of clients, and we’re going
to add networking capabilities to our client. When all is said and done, our Othello client
can connect to our central Othello server, making it much easier to get a good game on.
Minimum Requirements
You will need:
? A working networking modal from Assignment 2-1,
? The pink “output area” as a text area,
? A menu system of some sort,
? A text field, and
? A working “Submit” button.
If you’ve kept up with the assignments to date, you’re in a great position. Keep it up.
Changes:
There are always changes, aren’t there?
First and foremost, the client should not print a single thing to the console. Remove all
System.out.println lines. The client is a finished product.
Next, the “disconnect” option and the submit button in your client must start disabled.
You know you’ve done it right when they look sort of grayed out and unresponsive.
Finally, you will need to make a few changes to the modal.
? A new label, “Name:”
? A new textfield to take in name input, and
? “Status:” should now be blank
See the screenshot on the next page.
CST8221–JAP,Assignment 2, Part 2,MMXX Page 2 of 9
Figure 1: The new Network Connection dialog.
The modal will now act differently:
If the Address is blank, the Port input is invalid, or the Name has less than three
characters, make an error message appear on your status label.
Figure 2: Network Connection dialog error reporting.
The error messages are, “Address must not be blank”, “Valid port ranges are from 0 to
65535” and “Name must be at least three characters long.”
Pressing “connect” will not permit the dialog to close until all input is valid. The user
may press Cancel at any time.
(Note: Spelling matters. Plz no spelng mistakes in any messages.)
Be sure to correctly use the “connectPressed()” method already provided in your dialog
controller.
Client Implementation
If the user has pressed connect (and you can test with connectPressed() in the dialog),
the client should attempt to negotiate a connection. If the user has pressed cancel, no
message is printed to the output area.
If the connection has failed, you will want to display an appropriate message to the
output area.
CST8221–JAP,Assignment 2, Part 2,MMXX Page 3 of 9
Figure 3: Client reporting a failed connection.
If you do succeed in connecting, a “Connection successful” message is useful.
Immediately launch a new thread (details below) to manage the client connection.
Figure 4: Successful connection.
Note that “New Connection” is now disabled, “Disconnect” and “Submit” are now enabled.
We are now live and connected to the server.
CST8221–JAP,Assignment 2, Part 2,MMXX Page 4 of 9
Typing messages in the text field at the bottom, and then clicking “Submit”, will transmit
messages to the server. Selecting “Disconnect” from the menu should disconnect from
the server.
Class OthelloNetworkController
You will need a new class, OthelloNetworkController, which will be a thread. This thread
will monitor the socket, and when it detects input, promptly displays it on the output
zone.
Figure 5: Sent a command to the server and received a response.
Upon connection, the thread will pass the name you’ve provided to the server. You can
use “/name” for this—details to follow in the “Server” section of this document.
If the socket should close abruptly, or any other error should occur, it will close itself
down gracefully. “New Connection,” should be enabled, “Disconnect,” and “Submit”
should be disabled.
CST8221–JAP,Assignment 2, Part 2,MMXX Page 5 of 9
Figure 6: Disconnected.
The Server
The server will do much of the work in this assignment. It will have no UI and it operates
strictly from the command line. It will print status updates to the console as it goes
along.
The server will be in its own package, “server,” with a lowercase s.
The server should produce useful output as it goes along. Specifically:
? When a socket is first created, number it sequentially and print to console.
? When the thread is created and the user is first named, print that to console as
“(username) has connected.”
? If a user has disconnected from whatever means, a disconnection message is
required.
? Finally, if a user renames themselves, the old and new name should appear: “(old
name) has renamed themselves to (new name)”.
CST8221–JAP,Assignment 2, Part 2,MMXX Page 6 of 9
Figure 7: Server in operation with sample messages.
Class: OthelloServer
This will serve as your entry point. It will accept a command line argument for a port
and parse it. I should be able to run this server on any valid port. If the input is invalid, it
will default to port 62000
Figure 8: Server launch
The server should create a Server socket, monitor it on a loop, and create an
OthelloServerThread to manage that specific connection. It should also keep track of
that OthelloServerThread in a threadsafe manner.
It must also announce to the console when a new user has connected,
CST8221–JAP,Assignment 2, Part 2,MMXX Page 7 of 9
Some suggested methods:
broadcast(String): Broadcasts the given message to all existing threads.
remove(OthelloServerThread): removes this thread from the list. Useful when a given
thread has disconnected one way or another.
who(): returns a list of the names of all currently connected clients.
This list is not exhaustive. You will need to make a method that broadcasts to all
connections save the one that issued that event. (ie: for /name functionality)
Class: OthelloServerThread
This class is responsible for monitoring the actual socket. If the user enters certain
commands (they all start with the slash—“/”) then a special command will occur.
Otherwise, it is a text message to be broadcast to all users who are connected.
There are four commands that must be implemented:
? “/help” will display a help message. See Figure 5, above.
? “/bye” will make the server disconnect the client
? “/who” will return a list of all connected users to the client, and
? “/name (newname)” will permit you to change your name.
Figure 8: Who is on my server? I am! Twice!
CST8221–JAP,Assignment 2, Part 2,MMXX Page 8 of 9
Figure 9: Name changing is getting out of hand.
Some specifics on “/name”: The user that initiates a new name change should get a
server message: ”Name changed to (new name)”. Every other connected client should
see, “(old name) has renamed to (new name)”.
Likewise, both “/help” and “/who” should only report to the user that sent the command,
not to all clients.
Helpful hint: setName() and getName() are reserved methods in a thread. You’ll have to
call them something else. While you could override them, I don’t suggest it for this
assignment.
Final advice:
Plan your code. While the server code isn’t as intricate as OthelloModel was, there are a
few complexities involved, and having a plan will help.
Your client and your server should not be throwing exceptions. Several network
operations will require you trap specific exceptions; this will let you handle abrupt
disconnections gracefully. Have your Client report useful error messages to the user
wherever possible.
Test your code. Connect with multiple clients. Close the server abruptly with CTRL+C, or
just shut close a client without disconnecting. If either the client or server throws an
exception when you do this, read the stack trace, find where the exception occurred, and
add a catch statement to handle it gracefully.
I will be running my version of the server from time to time, generally during my lab
hours (refer to my schedule in Course Information). You can test your client against it if
your router and firewall permit it. (IP: 69.196.152.225, port 21438) Because of how my
CST8221–JAP,Assignment 2, Part 2,MMXX Page 9 of 9
server works, telnet will not connect to the server properly and your connection will be
dropped.
Connecting to my server is not strictly necessary. Connecting to your own is, of course.
Roughly 60% of the marks in this assignment marks are in the server.
Useful material for this assignment will be covered in lectures. Do attend. You’ll find it
useful.
Finally, there can be no extensions on this assignment, it is literally as pushed-back as I
can make it. A half-working assignment that’s late is worth some marks, but I can not
accept a late submission at all. Get on it early.
BONUS MARKS
There are a chance to earn a few bonus marks. These will only be available if your
server and client work well—if I can connect to a server, transfer messages, execute
server commands successfully and have no exceptions thrown under normal
circumstances, then you’ll qualify.
As these are bonuses, they will be held to a higher standard of marking. In all cases,
provide a readme.txt file detailing what bonuses you are attempting, and a bit of
implementation detail. You don’t need an essay, but I should have a clear idea what
you’re doing. A paragraph or two will generally do. You may need to update the /help
command as well.
Bonus 1: Emote messages (easy)
If a user types “/emote (message)”, it should appear without the colon. For example, if I
do “/emote is marking assignments”, everybody connected will see, “Daniel is marking
assignments” in their clients, as opposed to “Daniel: is marking clients”.
Bonus 2: Unique Names on Server. (medium)
There’s nothing stopping three people from having the same name. You should enforce
unique names. Specifically how this is enforced is up to you. An already-connected user
gets priority. (ie: you can’t be Daniel on my server if I’m already Daniel).
Bonus 3: private messaging (hard)
If a user types “/pvt (user) (message)”, the user named (and only that user) should
receive a private message (message). If the user can’t be found, the user will get a
useful error message. You may need to restrict user names and name changes in some
manner. Detail those specifics in your document as well. It doesn’t need to be an essay
or anything.
Have fun with this assignment. There’s still a lot of implementation and expansion that
can be done. Make this truly your own piece of code, and remember:
“There is no tennis without a serve, and no client without a server.” –Anonymous Swing
Programmer.

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