var ChannelDefinition = function ( channelName ) {
	this.channel = channelName || DEFAULT_CHANNEL;
};

ChannelDefinition.prototype.subscribe = function () {
	return postal.subscribe(arguments.length === 1 ?
	       new SubscriptionDefinition( this.channel, arguments[0].topic, arguments[0].callback ) :
	       new SubscriptionDefinition( this.channel, arguments[0], arguments[1] ));
};

ChannelDefinition.prototype.publish = function () {
	var envelope = arguments.length === 1 ?
		(Object.prototype.toString.call(arguments[0]) === '[object String]' ?
			{ topic: arguments[0] } :
			arguments[0]) :
		{ topic : arguments[0], data : arguments[1] };
	envelope.channel = this.channel;
	return postal.publish( envelope );
};