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mclarens.js
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/*
* Mclarens Bar: Redis based Instant Messaging
* Nikhil Marathe - 22/04/2010
 
* A simple example of an IM client implemented using
* Redis PUB/SUB commands so that all the communication
* is offloaded to Redis, and the node.js code only
* handles command interpretation,presentation and subscribing.
*
* Requires redis-node-client and a recent version of Redis
* http://code.google.com/p/redis
* http://github.com/fictorial/redis-node-client
*
* Start the server then telnet to port 8000
* Register with NICK <nick>, use WHO to see others
* Use TALKTO <nick> to initiate a chat. Send a message
* using MSG <nick> <msg>. Note its important to do a
* TALKTO so that both sides are listening. Use STOP <nick>
* to stop talking to someone, and QUIT to exit.
*
* This code is in the public domain.
*/
var redis = require('./redis-node-client/lib/redis-client');
 
var sys = require('sys');
var net = require('net');
 
var server = net.createServer(function(stream) {
var sub; // redis connection
var pub;
var registered = false;
var nick = "";
 
function channel(a,b) {
return [a,b].sort().join(':');
}
 
function shareTable(other) {
sys.debug(nick + ": Subscribing to "+channel(nick,other));
sub.subscribeTo(channel(nick,other), function(channel, message) {
var str = message.toString();
var sender = str.slice(0, str.indexOf(':'));
if( sender != nick )
stream.write("[" + sender + "] " + str.substr(str.indexOf(':')+1) + "\n");
});
}
 
function leaveTable(other) {
sub.unsubscribeFrom(channel(nick,other), function(err) {
stream.write("Stopped talking to " + other+ "\n");
});
}
 
stream.addListener("connect", function() {
sub = redis.createClient();
pub = redis.createClient();
});
 
stream.addListener("data", function(data) {
if( !registered ) {
var msg = data.toString().match(/^NICK (\w*)/);
if(msg) {
stream.write("SERVER: Hi " + msg[1] + "\n");
pub.sadd('mclarens:inside', msg[1], function(err) {
if(err) {
stream.end();
}
registered = true;
nick = msg[1];
// server messages
sub.subscribeTo( nick + ":info", function(nick, message) {
var m = message.toString().split(' ');
var cmd = m[0];
var who = m[1];
if( cmd == "start" ) {
stream.write( who + " is now talking to you\n");
shareTable(who);
}
else if( cmd == "stop" ) {
stream.write( who + " stopped talking to you\n");
leaveTable(who);
}
});
});
}
else {
stream.write("Please register with NICK <nickname>\n");
}
return;
}
 
var fragments = data.toString().replace('\r\n', '').split(' ');
switch(fragments[0]) {
case 'TALKTO':
pub.publish(fragments[1]+":info", "start " + nick, function(a,b) {
});
shareTable(fragments[1]);
break;
case 'MSG':
pub.publish(channel(nick, fragments[1]),
nick + ':' +fragments.slice(2).join(' '),
function(err, reply) {
if(err) {
stream.write("ERROR!");
}
});
break;
case 'WHO':
pub.smembers('mclarens:inside', function(err, users) {
stream.write("Online:\n" + users.join('\n') + "\n");
});
break;
case 'STOP':
leaveTable(fragments[1]);
pub.publish(fragments[1]+":info", "stop " + nick, function() {});
break;
case 'QUIT':
stream.end();
break;
}
});
 
stream.addListener("end", function() {
pub.publish(nick, nick + " is offline");
pub.srem('mclarens:inside', nick, function(err) {
if(err) {
sys.debug("Could not remove client");
}
});
});
});
 
server.listen(8000, "localhost");

This is like a NodeRed-lite. Nice.

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