chat-server

README

Chat Server is basic IRC like server written in Go with drivers for Telnet, WebSocket, and HTTP REST.

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Telnet and WebSocket Servers

Users can connect to chat server with a simple TCP client like telnet or WebSockets. After connecting to the server users can join or create channels and publicly chat with everyone in the channel. Users can use the /msg command to send private messages to each other. Chat Commands are supported for both Telnet and WebSocket clients.

Supported Chat Commands

/help                       Shows the list of all available commands.
/list                       Lists user nicknames in the current channel.
/ignore @nickname	        Ignore a user so that he or she can't send you private messages.
/join #channel              Join a channel.
/msg @nickname message	    Send a private message to a user.
/quit	                    Quit chat server.

HTTP Rest Server

Administrators can use the HTTP RESTful endpoints to broadcast a public announcement to everyone connected to the server. There's also an end point to query the messages stored in log files. To see the swagger documentation for RESTful API's please browse /docs on the HTTP port (4001 by default).

How to Run Locally

• Download and install dependencies by running go get github.com/emicklei/go-restful and go get github.com/gorilla/websocket
• Download and install by running go get github.com/spring1843/chat-server/src/ and then CD into the directory
• Run all tests make test
• Modify or review default settings by editing config.json
• To start serving run make serve or go run main.go -c config.json or chat-server -c config.json
• To check-in new code run make checkin to automatically format, lint, vet, race check, run all tests and review each change

How to Connect

To connect with telnet when the server is running locally try telnet localhost 4000 To connect with a WebSocket open a browser with WebSocket support (such as Google Chrome) and browse to http://localhost:4004/client These ports are defined in config.json

Logs

Besides start up messages, everything else is logged in a log file. Almost all interactions including the followings are added to the log file specified at run time along with a timestamp:

• Public Messages
• Private Messages
• Chat commands executed
• New and closing connections
• Errors

Docker

To build

docker build -t chatserver .

To run

docker run -d -p 4000:4000 -p 4001:4001 -p 4004:4004 -t chatserver

Note that if you are running docker in a VM or boot2docker, the host needs to forward these ports.

Design

A config structure is initially parsed from the .json file specified by the -c flag and passed around to every package.

The chat package is in charge of creating the chat experience. Important entities in this package are Server, User, Channel, ChatConnection, and ChatCommand.

Chat server can serve anything that implements the ChatConnection interface providing basic io.Writer and io.Reader methods and a few network specific concepts like RemoteAddr and Close. Examples of such drivers in use are Telnet and WebSockets.

The Server also exposes certain internal entities and functionality to be used by external entities that do not necessarily have a persistent connection for example the main file is able to attach a logger to the server, and the REST driver can query the server.

One instance of Chat server is created at the beginning of execution and passed around to different drivers when they are started. When a new connection is made the Server welcomes the new user and tries to identify the user. Upon successful identification the user and the open connection associated with him are attached to the Server until the connection is closed.

After identification users can use ChatCommands are commands that a user can execute on the server. Each command has a syntax and certain parameters. The chat package is able to identify, parse their parameters from the input and execute them.

Users can /join a channel. Users can join only one Channel at any given time and participate in the conversations. They can also send private messages to each other with /msg command.

Channels, Users and ChatCommands are represented with #,@,/ prefixes respectively.

Credits

• go-restful for configuring, standardizing, documenting and running HTTP REST Endpoints
• Swagger for auto generating HTTP REST API's and providng an easy to use front end client http://localhost:4001/docs
• Gorilla WebSocket for handling WebSocket connections and example client http://localhost:4004/client

Further Improvements

• Strive for 100% test coverage
• Deploy to Heroku
• Handle client tcp disconnect may be ping and pong?
• Use flags package for parsing command line options