node-magento-api

gistfile1.txt

var xmlrpc = require('xmlrpc'),
    sys = require('sys');


var config = {
                host: 'www.mymagentohost.com',
                port: 80,
                path: '/api/xmlrpc/',
                login: 'apilogin',
                pass: 'myapikey'

             };

var magento = {

	client: xmlrpc.createClient(config),

	init: function(cb) {
		this._discover(cb);
		return this;
	},

	login: function(next) {
		var self = this;
		self.client.methodCall('login', [ config.login, config.pass ], function(err,sessionId) {
			if (err)
				console.log("Login Error: " + err);
			else {
				console.log('session-id:' + sessionId);
				self.client.sessionId = sessionId;
				next();
			}
		});
	},

	end: function(cb) {
                var client = this.client;
		client.methodCall('endSession', [ client.sessionId ], cb);
	},

        _xcall: function(api,apiargs) {
                var self = this;
                var client = self.client;
                var args = Array.prototype.slice.call(apiargs);
                var callback = args.pop();

                var next = function() {
                        client.methodCall('call', [ client.sessionId, api, args ], function(err,res) {
                                if (err) {
                                        // try logging in again
                                        if (err.faultCode == 5 && client.sessionId) {
                                                client.sessionId = undefined;
                                                return self._xcall(api,apiargs);
                                        }
                                }
                                callback(err,res);
                        });
                }

                if (client.sessionId == undefined)
                        self.login(next);
                else
                        next();

        },


	_call: function(apiargs) {
		var args = Array.prototype.slice.call(apiargs);
		var callback = args.pop();
		var api = args.shift();
		var client = this.client;

		client.methodCall('call', [ client.sessionId, api, args ], callback);
	},

	_discover: function(cb) {
		var self = this;
		var client = self.client;
		var next = function() {
			client.methodCall('resources', [ client.sessionId ], function(err,resources) {
				if (!err) {
					for (var j =0; j < resources.length; j++) {
						var resource = resources[j];
						var methods = resource.methods;
						self[resource.name] = {};
						for (var i = 0; i < methods.length; i++) {
							var method = methods[i];
							self.define(method.path);
						}
					}
					cb(null);
				} else {
					sys.log("an error occured " + err);
					cb(err);
				}
			});
		}

		if (client.sessionId == undefined)
			self.login(next);
		else
			next();
	},

	call: function() {

		console.log("call called with arguments " + arguments);

		var self = this;
		var client = self.client;
		var apiargs = arguments;

		var next = function() {
			self._call(apiargs);
		}
		if (client.sessionId == undefined)
			self.login(next);
		else
			next();
	},

	define: function(apiname) {
		var obj = this;
		apis = apiname.split('.');
		if (obj[apis[0]] == undefined)
			obj[apis[0]] = {};
		obj[apis[0]][apis[1]] = function() {
			console.log('calling xcall for ' + apiname + '(' + arguments[0] + '...);');
			obj._xcall.call(obj, apiname, arguments );
		}
	}
}



module.exports = magento;

if (require.main == module) {
magento.init(function(err) {
	magento.sales_order.info('order_id', function(err,order) { sys.log(sys.inspect(order)); });
});
}

you should just call it as

magento.catalog_category.level(null,null,3,function(error,result) {
if (error) { throw error; }
response.json(result);
});

The first argument is website_id, second is storeView, and third is parentCategory.

There were a few issues in the gist that I found and fixed later - would update the above soon.

Edit: I've solved my problem.
Note: If you get an error like this: "Login Error: Error: Unknown XML-RPC tag 'TITLE'", is the reason, that your server has hypertext access. To resolve this, configure a extra domain without hypertext access for the domain "your.domain.com/api/xmlrpc". For example you can use authorization header in Nginx to do that.

I've began to create a web-application based on your node magento api: https://github.com/JumpLink/magento-nodejs-sync-app