Simple Chatting Application, with a server written in C, and Client in C++ and C#

##Features

1. Heartbeat from server to Clients connected every 5-ish seconds
2. Broadcast a message to all connected clients
3. Send a message to a specific client
4. Create username
5. Login as a user
6. List all connected users
7. Endless unique usernames of up to ten characters
8. Up to 5 clients connected at once
9. Server ping

##Client Commands NEW USERNAME

Usage: NEWUSER (name)

Creates a new username in the chat server

BROADCAST MESSAGE

Usage: BROADCAST (msg)

Sends a message to all connected users

LIST USERS

Usage: LIST

Lists all corrently connected users

PING

Usage: PING

Get a PONG from the server

SEND MESSAGE

Usage: SEND $(user) (msg)

Send a message to the user specified, this is echo'd to the sender

BEAT

HEart beat sent from server to clients

ACK

Client acknowledge heartbeat

##Challenges

• Client recieve. The client must listen all the time for an incoming message from the server. To overcome this a thread is created which listens all the time, by using an Asynchronous NetworkStream.BeginRead() in a while loop.
• Server HeartBeat. The server sends a heart beat to the connected clients every 5 seconds - this is handled in it's own thread.
• Server Username storage. The server saves new usernames to a text file, and reads from this file on startup. This gives persistent usernames so a if the server is quit the usernames are remembered.

##To Improve

• Dynamic commands, maybe from a setup file etc
• Server
  • Connected client FD in a struct with their username too.
  • Thread ID's stored in a separate array - should be in the CURRENT_CONNECTIONS array or structs
  • The server doesn't act on the heartbeat ACK from the clients, either remove it or find a use for it
  • The server had no way of being quit once it's running, so although the code in place to free memory used and join the threads, it's never used
  • Refactor the source code into different files
  • Dynamic list of usernames which can grow/shink as clients connect
  • Saving usernames to a file for later re-use
  • Options Flags
• Client
  • If running for ages the garbage collector throws an error as it's unable to allocated some memory - not sure yet where it's being allocated. Doesn't seem to be present in QT Gui
  • GUI would be nice, failing that a more smart console interface
  • LOGOUT command
  • Some client side checking of the replies from the Server or the input commands Server side does the checking so this is pointless extra processing

##Server Design Although the server doesn't use 'state's, the following diagram helps to explain what it does

##GUI Images