Using the Promises Pattern in Titanium

Promises are part of the commonjs standard and can be defined as "objects which represent the pending result of an asynchronous operation. [which can be used] to schedule further activity after the asynchronous operation has completed" [Fowler, April 2013]

I wanted to see how I could use a promise as part of a remote request in Titanium.  I could of course, simply pass an onLoad and/or onError callback when I invoked createHTTPClient, but using a promise in this manner gives one the ability to chain a number of asynchronous events and avoid the "Pyramid of Doom"

I decided to use Q from Kris Kowal for my Promises.  The first thing I did was write a commonjs module that wrapped Q and HTTPClient.  My code for this is here;

Now I can call my new qxhr module and chain my method calls like so

qxhr.create(conn)

.then(function(data) {

    //do something with the data




}, function(error) {

    //handle the error

});

or I could do

Q.fcall(qxhr.create(conn))
.then(promisedStep2)
.then(promisedStep3)
.then(promisedStep4)
.then(function (data) {
    // Do something
})
.catch(function (error) {
    // Handle any error from all above steps
})
.done();