Google Technology User Group in Tel Aviv

GTUG TLV took place today in Google Tel-Aviv offices. I visited Haifa and New-York offices in the past but never been in Tel-Aviv one so it was nice to see it for the first time, of course.

It was somewhat surprising but the office is not that fancy, as other people may think of it. I mean, it’s totally fine and you get some nice colored walls painted in Google colors. I couldn’t see the whole office so who knows what was left but from what I saw it was just a normal office. The kitchen is Ok, two pool tables next to it and a medium-size conference room where the event actually took place. I was told once it’s a temporal location and Google Tel-Aviv would move into its own campus in Tel-Aviv university. So it may explain the lack of usual luxury you get to see in other offices.

But a bird’s-eye view on Tel-Aviv is truly fascinating:

Anyway, it wasn’t the office we came to see today, of course.

I stayed for three sessions:

• “Javascript Design Patterns” (video)
• “Android 101” (video)
• “Django AppEngine based platform building site” (video)

Unfortunately, I left earlier thinking I’m only missing the Python part (I’m less interested in) and forgot there’s “An introduction to Google Closure” (video) which I really wanted to hear. Shame on me!

1.

The following JavaScript patterns were nicely presented by Zohar Arad:

Singleton:

I don’t think there’s a need to elaborate on it 🙂 It’s just Something.getInstance(), as usual.

Module:

A re-usable and self-containable unit that can be instantiated and used for performing certain tasks.

var Module   = function( o ) { .. }; // A general function for converting object to module
var MyModule = new Module({ .. });   // Specifying module's definition
var m        = new MyModule();       // Instantiating the module, start using "m"

Engine

Callable unit that implements unique internal logic, exposing uniform API to consumers, similarly to Facade. It is used mostly in various browsers, implementing differently a certain functionality, like Web Sockets that was given as an example. So we implement IE engine, Firefox engine, Chrome engine, and Opera engine and override certain methods.

Event-Driven

Allows not to call some other unit directly but posts DOM events using commonly known names to which other party responds, since it has a listener registered. Used heavily in Flash to JavaScript communication, freeing from a need to know JavaScript method names and being forced to recompile Flash each time JS code is refactored. Putting a layer of isolation between them loosens the coupling a bit as there are no direct calls any more, one technology just fires events for another one. All major JS frameworks support customized event names like 'SomethingHappenedEvent' and here we assume event names won’t be changing as frequently as method names.

We had a comment from the audience about an importance of detaching event listeners on unload to clean up the references and prevent memory leaks that otherwise may be catastrophic, especially in Flash. And this kind of “unregistering” better be done automatically.

Templates

Adding lots of HTML to the page is better done by creating large String snippets rather than by manipulating DOM. When creating them, various templating techniques and syntaxes can be used. Naturally, when implementing it manually, ReGex-es are somewhat slower than a simpler String operations.

Btw, here’s the pattern to iterate through object properties, only those it actually owns:

for ( prop in o )
{
    if ( o.hasOwnProperty( prop ))
    {
        var j = o[ prop ];
        ...
    }
}

Being Groovyst in my heart I was dying to replace it with something like:

for ( j in o.findAll{ o.hasOwnProperty( it ) }.collect{ o[ it ] })
{
    ...
}

2.

Second presentation, “Android 101” by Dror Shalev from DroidSecurity was a killer! I always said you need two things to make a successful presentation: the material itself should be rock-solid and interesting, of course. But you also need a presenter who’s making a show out of it. When those two meet together .. well, that’s what people remember later for years, I believe. And that’s exactly what Dror demonstrated us today.

It was very interesting to hear how hackable Linux, Dalvik VM and Android are and how important it is to have a decent “antivirus-like” application on each Android phone. The problem is that neither of applications available in Android Market is checked by someone. It’s a free world for everybody. Bad things may (and do) happen if malicious software is installed. Now, DroidSecurity solution doesn’t scan files , it can’t, but it analyzes what’s happening and what’s running on the phone, communicating with company servers. To see it in the market, go to “Top Free/Paid”, choose “Communication” category and scroll down to “antivirus free” or “Antivirus Pro” (too bad it’s impossible to provide a direct link .. hmm, somebody?)

We were also told there’s an iAndroid community for Android developers in Israel.

3.

Third presentation, “Django AppEngine based platform building site” was about 9Folds, a CMS engine built by Alon Burg for quick Web sites creation using Django templates and AppEngine-deployed .. eeeh, engine. I’m not experienced with Django so I could less appreciate the beauty of it but Alon mentioned some nice AppEngine caching techniques. He’s also using a rather clever trick to upload template files to a “live” site: pushes them to a public GitHub repo where they’re downloaded from by an application code. What a brilliant idea, browser upload, be it Flash or not, doesn’t come close to "git push", of course.

Alon has also mentioned Varnish, a “high-performance HTTP accelerator”.

Take a look on 9Folds gallery or browse Narayan World to see how results look like.

So .. It was a very intense evening and I didn’t even see it all!
Many thanks to Omri for organizing and running this event!