domingo, 25 de diciembre de 2016

https web server with ubuntu, letsencript and nodejs

sudo apt-get install letsencrypt
letsencrypt certonly --standalone -d

Note: this will generate the following files in folder /etc/letsencrypt/live/ cert.pem chain.pem fullchain.pem privkey.pem

Now you are ready to implement and execute your nodejs https server. Run the following program and then open and it should be working without any browser warning, ready for production.

const https = require('https');
const fs = require('fs');

// cert.pem  chain.pem  fullchain.pem  privkey.pem

const options = {
  key: fs.readFileSync('/etc/letsencrypt/live/'),
  cert: fs.readFileSync('/etc/letsencrypt/live/')

https.createServer(options, (req, res) => {
  res.end('hello world\n');

miércoles, 22 de junio de 2016

writing selenium in javascript node with webdriverio - instructions for impatients

The following is what you need to do in order to write a javascript program that will command your browser through selenium using node library.

 First is about installing and running the selenium server. Second is a little webdriverio example. 

Installing the selenium server

The following instructions are give in a shell script that was tested on mac:
#install java

# download selenium server: 

curl -O

#download googlechrome selenium drivers: 

curl -O

#Execute selenium server: 

java -jar selenium-server-standalone-2.53.0.jar

The Program

From here the instructions are the same as in - just execute ```npm install webdriverio``` in your node project and execute the following file. In this simple program that will navigate to google and when is ready print the document title in the console:
var webdriverio = require('webdriverio');
var options = {
    desiredCapabilities: {
        browserName: 'chrome'
    .getTitle().then(function(title) {
        console.log('Title was: ' + title);

Appendix: Technologies used

  • - the infrastructure that talks to browsers (java) 
  • - the selenium javascript api 
  • - selenium driver to manage chrome browser.
  • java and node

jueves, 19 de mayo de 2016

Minify JavaScript code with esprima and escodegen

var esprima = require('esprima'), 
escodegen = require('escodegen');

function doUglify(s)
  var ast = esprima.parse(s);
  s = escodegen.generate(ast, {format: escodegen.FORMAT_MINIFY}) || s;
 return s;

lunes, 18 de enero de 2016

first steps with postgresql for inpatients

The following is a bash script that show easy steps for getting started with postgresql and verified in a arch linux distribution. There are also some comments for explaining, ideal for inpatients:
mkdir myproject
cd myproject

initdb -D $DATA_FOLDER

sudo chmod -R a+wr /run/postgresql/ 

postgres -D $DATA_FOLDER >logfile 2>&1 &

createdb mydb

sábado, 7 de noviembre de 2015

jasmine for node: execute test files and set jasmine timeout globally

When developing jasmine tests in node, I want to declare which files to run. I don't want / like the way of indicating this in a jasmine.json file and it wasn't working as expected.
Also I had some difficulties guesssing how to set the timeout interval globally. Mainly my difficuly was not to now that jasmine was creating a global 'jasmine' object when requiring it.
The following code shows both things:
 path = require('path')
, glob = require('glob').sync
, Jasmine = require('jasmine')

var jasmineRunner = new Jasmine();
jasmine.DEFAULT_TIMEOUT_INTERVAL = 99999999;

jasmineRunner.specFiles = glob(path.join(__dirname, '*Spec.js'));

martes, 6 de octubre de 2015

Queue based on Q promises

So just that,I'm working with promises in JavaScript and at certain point I needed a queue for executing asynchronous tasks. My promises are implemented by q library and my particular requirements are as follows. I implemented this web service client without knowing that no concurrent operations are allowed. In some cases, if you request two operations at the same moment the server will return an error. In my case, an obvious quick solution was to en-queue the method that makes the requests in my client. Something like make it synchronous (similar as java methods can be declared as 'synchronous' when multi threads access it).

I research a little and there are plenty alternatives, most appreciated was the queue utility of async, a library that also use. Nevertheless instead learning how to use it, and because I know this problem can be solved w promises wanted to try something else

I very liked the solution proposed here because is simple so I adapted to use Q promises instead jQuery's. This is the result (working example in node, but should work also in the browser)

var Q = require('q')

var Queue = function () 
    var lastPromise = null;

    this.add = function (obj, method, args, context) 
        var methodDeferred = Q.defer(); 
        var queueDeferred = this.setup();
        if(context === undefined) { context = obj; }

        // execute next queue method
        queueDeferred.done(function () 
            // call actual method and wrap output in deferred
            setTimeout(function () 
                obj[method].apply(context, args);
            }, 100);
        lastPromise = methodDeferred.promise;

    this.setup = function () 
        var queueDeferred = Q.defer(); 

        // when the previous method returns, resolve this one
            lastPromise = Q.defer(); 
            lastPromise = lastPromise.promise;
        lastPromise.done(function () 

        return queueDeferred.promise;

var queue = new Queue();
queue.add(console, 'log', ['one']);
queue.add(console, 'log', ['two']);
queue.add(console, 'log', ['three']);
setTimeout(function ()
    queue.add(console, 'log', ['four']);
}, 2000);

martes, 24 de marzo de 2015

console.timing() - measure multiple calls of a code block

The following is an utility, similar to console.time / console.timeEnd to measure how long a code block takes to execute but it will take in account sevaral times and report the total calling time and average. Very useful wile profiling code blocks execution time.

console.timing = function(key)
 this.timings = this.timings || {}; 
 this.timings[key] = this.timings[key] || []; 

console.timingEnd = function(key)
 var t0 = this.timings[key][this.timings[key].length-1]; 
 this.timings[key][this.timings[key].length-1] = - t0;

console.timingReport = function(key)
 var times = this.timings[key]; 
 var sum = 0;
 for (var i = 0; i < times.length; i++) 
  sum += times[i]; 
 var average = sum / times.length;
 console.log(key + ': times: ' + times.length + ', sum: ' + sum + ', average: ' + average);  

console.timingReset = function(key)
 this.timings[key] = [];