Appsterdam Guru Session: Google App Engine for beginners

One of the things I was not expecting when I moved to Amsterdam was its active and vibrant tech community. Appsterdam, a non-profit organization focused around aggregating people with a passion for technology, is probably one of the central forces in this movement.

In my year in Amsterdam I had been to a few meetups organized by people from Appsterdam and always came back home having learned something new. This is why when my colleague Matt (who himself is quite an active Appsterdam member) talked me into presenting a guru session on Google App Engine, I saw that as an opportunity to return the favor.

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Presenting Professional Invaders

A few weeks ago I attended The Next Web Conference in Amsterdam and join a bunch of fellow programmers for another edition of the Kings of Code Hack Battle, the same kind of event as the one where Bring Your Own Music was born.

Following the usual schedule, after a brief presentation from the API partners (Spotify, SendGrid, Braintree, Deezer, Pearson, Nokia, Rebtel,, Smart TV Alliance and LinkedIn), all the attendees started evaluating ideas about what to build.

Hacking @ The Next Web #TNW

A post shared by Alessandro Bahgat (@abahgat) on

I teamed up with Alexander, a friend of mine I already had the chance to work with back in the days when I when I was consulting.

Having LinkedIn among the sponsors seemed to encourage us to build serious applications for serious professionals, but after discarding a few alternatives that would have been better projects for a Startup Weekend than a hackathon, we decided to take the opposite direction: building the silliest possible thing with the APIs we had access to.

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User authentication with webapp2 on Google App Engine

Google App Engine for Python ships with the capability to manage user accounts without the need of any additional library. This functionality is, however, insufficiently documented. This post will be structured as a step-by-step tutorial addressing user registration, login, password reset and a few other details.

The webapp2 framework on Google App Engine for Python 2.7 is definitely a step forward from the original webapp.
Despite the increase in flexibility and functionality, however, there are a few items that are still more laborious than in other frameworks. The most notable aspect is user account management.

Unsurprisingly, since it is meant to run on Google’s App Engine, using Google Accounts with webapp2 takes one line of code. OpenID authentication, while still defined experimental, is almost trivial to implement as well. There are some open source projects like SimpleAuth that attempt to offer a standard and unified API to handle signing in with Google, OAuth and OpenID accounts.

While it generally makes sense to offer support for authentication through popular services – it decreases friction for new users to try a service – in some cases users may prefer having a special login to access your application.

As experience teaches us, managing passwords securely is not a trivial task, and users legitimately expect application developers to take all the necessary measures to protect their passwords.

Since this is a use case that has to be considered countless time, there is significant value in using library functions to handle user accounts.

Here is how to do that using the functionalities embedded in the webapp2_extras package that is distributed with all standard installations of App Engine for Python 2.7.

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Story of a hack: Bring Your Own Music!

This post is a summary of the weekend we spent at the Kings of Code 2012 Hack Battle in Amsterdam. What started as an occasion to get to know smart people doing cool things in Amsterdam (something I look for since I moved here) turned out to be one of the funniest experiences I had in a while.

After a brief presentation of the services offered by the hackathon partners (Apigee, Esri, Spotify and Sendgrid) Diderik, Mattia, Mike and I teamed up to build the hack featured here. We started with the most obvious concept we could come up with: putting songs on a map and having people visualize them. We tried to elaborate the concept to include as many of the partners’ APIs as we could, but then we decided for something simpler, something we could build over the weekend.

Bring Your Own Music card reader
Bring Your Own Music!

It took us a couple of iterations to get to the final idea we developed: Bring Your Own Music, a toy application that allows users to control music playback through NFC-enabled objects by using an Arduino-powered NFC reader driving a Spotify app.

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Do languages shape IDEs or IDEs shape languages?

Duke, the Java Mascot, in the waving pose. Duk...I spend most of my days at work on powerful IDEs like Eclipse or Netbeans, tools so advanced in functionalities that their feature lists span over several pages. Their power, however, has its own drawbacks: their memory consumption is measured in the gigabytes, and running them on underpowered computers is the most frustrating of experiences. Issues that any Java developer on Earth will have to face, sooner or later.

Having grown frustrated by Eclipse being too slow on my 4 years old work laptop (I will not comment on this), I decided to drop the IDE for a while, switching to an extremely powerful editor that offered me the one thing that matters the most to me: blazing fast navigation between different source files.

Of course I knew I would miss some of Eclipse’s advanced features but I wanted to give it a try, especially since Andraz’s post left me with a bit of curiosity: how much the tools we use affect our abilities? And why IDEs are so used by desktop developers while they are not so popular with web frontend developers who generally use scripting languages?

A commonly accepted explanation is that it is easier to write IDEs for static languages, when lots of information is known at compile time. It is easier to extract information from the code and use it to build powerful and useful features.

However, after a few weeks of experimentation, I ended up with a slightly different point of view on the whole matter: the popularity of IDEs for Java encouraged coding conventions would not be so widely accepted if the majority of coders used a plain text editor to edit their source files. Those conventions grew so popular that that today Java appears to be designed to be used with an IDE. Let me give a few examples.

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How achievements can improve software quality

Visual Studio Achievements logoLast Friday, a blog post on Channel 9 announced Achievements for Visual Studio, an extension for the Microsoft IDE that tracks the actions of programmers as they write code and unlocks badges based on their behaviour.

Now that the concept of gamification has become (even too much) mainstream, it is not surprising that this is not the first time an idea like this is proposed. Jason Rudolph has published an excellent blog post about programming achievements. Websites like coderwall already inspect source code repositories on GitHub and others in order to build achievement-based profiles for coders. There even is an earlier project, called Strokes, that added achievements and challenges to Visual Studio.

Introducing mainstream achievement support right within the IDEs, however, can have a stronger effect on the way we write software, as those tools can inspect code right while we are writing it. The strong link between action and reward lead to a stronger feeling of accomplishment when we earn those achievements, and programmers are likely to be receptive towards game mechanics (most of us have a background as gamers). But there is more than that.
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Tip: serve local files over HTTP with one console command

This weekend I was playing with Facebook’s JavaScript SDK and I needed a quick way to serve over HTTP the files I was working on, so that I could access them in a browser window at http://localhost.

I didn’t want to go through the hassle of setting up Apache on my Mac, though, and I was looking for some quick alternative to installing a local web server. After some Googling, I found a wonderful one liner that did the job, provided that you have Python installed.

Open a Terminal window and go to the directory containing the files you want to serve and run:

python -m SimpleHTTPServer

or, if you are using Python 3,

python -m http.server

you will then be able to access your files on http://localhost:8000/. (You can specify a different port number by passing the number as last argument, just remember that you need root permissions to open sockets on ports lower than 1024.)

Authors ≠ committers: why most Open Source projects should switch to distributed revision control

I had been thinking about the idea behind this post for a while now, but reading this post about getting newbies involved in open source just convinced me to write it down.

Being a concept developed in the Open Source world, it is no wonder that distributed revision control systems give their best in that context. There are many pros and cons, that other people described in detail better than I can do. Of all the features they offer, however, the one I prefer is the least technical one, and it is related to the way they encourage new developers to contribute to open source projects. In that perspective, git and mercurial are a lot more effective than svn, for example.

It all comes as a side effect of authors and committers being two different roles. This can encourage new contributors, who are approaching a new project for the first time, and individuals who may not have the time and energy to dedicate long periods of their time to a project, but may be able to contribute with just a few patches.

A commit from GitHub
How GitHub displays both the author and the committer of a single change. Oh, and yes, there is something wrong with the dates. 😉

Think about that. Recognition is one of the most important drivers for Open Source contributors but, unfortunately, centralized revision control (subversion, CVS and the like) doesn’t help in giving credit to newcomers or occasional contributors.

That’s because, generally, sending a single patch (or even a few of them) is not enough to be granted commit access to a project repository (and rightly so) and the commit itself must be done by a project member with enough privileges.

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Failure is an option

As Software Engineers, we often tend to be overly optimistic about software. In particular, it often happens that we underestimate the probability of systems and components failures and the impact this kind of events can have on our applications.

We usually tend to dismiss failure events as random, unlikely and sporadic. And, often, we are proven wrong.

Systems do fail indeed. Moreover, when something goes wrong, either it’s barely noticeable, or it leads to extreme consequences. Take the example of the recent AWS outage: everything was caused by a mistake during a routine network change.

Right now, some days after the event, post-mortem analyses and survival stories count in the dozens. There is one recurring lesson that can be learned from what happened.

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What I learnt from coding offline

During the last weeks, I’ve been writing a lot of code while commuting.

Since I was working on an application that uses Facebook’s and Amazon’s APIs and I was working offline, I often found myself unable to test the code I was writing against live data.

I must confess I struggled at the beginning.

I had no chance to try out my small application while I was working on it and, generally, I had to code during 1-hour trips, waiting until I got to work/home to see whether everything was performing as expected.

The outcome? I was surprisingly productive. And I’m sure it was not just because of the absence of common distraction sources (IMs, Email, Twitter and the like).

So, what made the difference? Here are some of the insights I got from the experience.

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