#Overview An instant messaging service with a command line interface because who needs fancy GUI's. This project is built with Node.js, using the core Network module to communicate through TCP sockets over a Local Area Network.

#Server The TCP server acts as a middleman to the clients during communications. It is responsible for keeping track of all open sockets at any given point in time. When a client first connects, the TCP socket is stored, along with a username. This allows the server to emit messages across all open sockets as well as associate any given message with a username. When a client disconnects from the server this data is removed from memory.

#Client The client is fairly dumb in that it is only concerned with sending/receiving messages. Once a connection has been established with the server it too has a handle on the TCP socket. When a user wants to send data such as their username or message, it is written to the socket. Likewise when the client receives a message emitted from the server it is received and echo'ed out via stdout. You may have spotted an issue with using stdin/stdout for two-way communication. See below for details...

#Why? Why make an instant messenger for the command line? I'd be asking the same thing... This project was the result of being at campJS 2016 with no internet and very little resources (only Javascript/Node.js documentation). I quickly realised how much i relied on communication tools like Slack and Hipchat and thought why not have a crack at my own. Is it practical? No. Is it secure? Nope. But it has given me the chance to learn about:

• Node.js and its core modules
• New ES6 syntax

#Setup

• Clone the repo git clone [email protected]:tobyf93/command-line-messenger.git
• Install Node.js (>= v5.11.1)
• Install project dependencies npm i

#Usage ##localhost

• Start server node server.js --host localhost --port 3000
• Connect clients node client.js --host localhost --port 3000

##Local Area Network

• Get host's IP address ifconfig
• Start server node server.js --host HOST_IP --port 3000
• Connect clients node client.js --host HOST_IP --port 3000

#Using stdin/stdout For Two-way Communication ##Problem #1 Lets start up a server and connect to it via localhost:3000

node server.js --host localhost --port 3000
Started server: {"address":"127.0.0.1","family":"IPv4","port":3000}

node client.js --host localhost --port 3000
Connected To Server: {"address":"127.0.0.1","family":"IPv4","port":63237}
Name: Toby
[13:5:8] TOBY JOINED THE CHAT

So far so good! We have established a connection, provided our username and the server has acknowledged this by emitting a status update. Now lets start chatting!

[13:5:8] TOBY JOINED THE CHAT
this is my message                  // client input after hitting 'enter'
[13:8:5] TOBY | this is my message  // message emitted from server

See the duplicate messages? It seems as though when a user inputs a message via the command line the readline interface in Node.js writes it to the stdout stream before being able to read in the stdin stream. Ideally i would want to accept input without writing it to stdout but i don't think it's possible as the user needs to be able to see what they're typing...

##Problem #2 (Solved) Involves the server interfering with client input when messages are emitted. Assume the same server is still running and we will connect two clients: Toby and Frank

// Toby's client
[15:37:10] TOBY JOINED THE CHAT
[15:37:16] FRANK JOINED THE CHAT

Now lets begin typing a message on Toby's client while sending a message from Frank's.

// Toby's client BEFORE  Frank's message
[15:37:10] TOBY JOINED THE CHAT
[15:37:16] FRANK JOINED THE CHAT
hello my name is

// Toby's client AFTER Frank's message
[15:37:10] TOBY JOINED THE CHAT
[15:37:16] FRANK JOINED THE CHAT
hello my name is [15:40:52] FRANK | MESSAGE!
Toby

// Toby's client AFTER his message
[15:37:10] TOBY JOINED THE CHAT
[15:37:16] FRANK JOINED THE CHAT
hello my name is [15:40:52] FRANK | MESSAGE!
Toby
[15:42:37] TOBY | hello my name is Toby

Now i am not 100% across stdin/stdout streams but it seems as though Frank's Message gets written to stdout but doesn't effect the original Hello my name is Toby buffer.

###Solution Use the keypress package to allow process.stdin to emit keypress events. When a user is typing a message, the client stores received messages in a message queue. This queue is output after the user sends their message.

#Contributing

• Fork it https://github.com/tobyf93/command-line-messenger
• Create feature branch git checkout -b awesome-feature
• Commit changes git commit -am 'Some awesome change'
• Push branch git push origin awesome-feature
• Create a pull request

#Copyright & License All code in this repository is released under the terms of the MIT License.

Copyright (C) 2016 Toby Flemming