Blummy wins Web 2.0 Bookmarking Award!

SEOmoz Web 2.0 Awards - WinnerI'm proud to announce that Blummy has been voted to first place of the bookmarking category by the Web 2.0 Awards by seomoz.org.

Blummy placed in front of Looksmart's Furl.net and it's similar sounding competitor spurl.net.

As all the other winners of each category, I have also been interviewed. I can highly recommend reading the other interviews, with

SEOmoz Web 2.0 Awards - Blummy Bookmarking Winner

Thanks for the award and congratulations for the excellent choice of nominees and winners.

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Looking into the Skype Protocol

As you all know, Skype is a very popular Voice-over-IP software. Skype also claims that all its communication is encrypted (which raised some discussion whether you should considered a criminal (digged also) if you „hide away" from eavesdropping).

Philippe Biondi and Fabrice Desclaux from EADS held a talk at Blackhat Europe conference where they show their latest discoveries.

The talk is rather technical and might be hard to understand. I picked some of the most interesting points:

  • Almost everything is obfuscated (looks almost random)
    This is a sign for good use of encryption.
  • Automatically reuse proxy credentials
    When Skype gets to know how to use your proxy, it will hand on the information to other Skypes.
  • Traffic even when the software is not used (pings, relaying).
    I heard quite a few times of some office PCs being promoted to Supernodes, generating enormous traffic.
  • No clear identification of the destination peer
    The destination IP is not disclosed to a firewall for example, network administrators can't block certain IPs.
  • Many protections, antidebugging tricks, and ciphered code
    This is an attempt to protect themselves from spies (i.e. hackers, government) but it might also hide away secret backdoors or them spying. This is often a problem of closed software.
    Using this techniques also hinders open source or simply 3rd party software from building compatible clients.

In Skype's FAQ they state that they use AES encryption. This seems to be proved and seems a good thing, but they embed the data into a proprietary protocol which may have its drawbacks and is incompatible to others. It's their right to do so, but this gives much power to those who know about the inner workings (this does not necessarily only include Skype).

They give as a conclusion:

  • Impossible to protect from attacks (which would be obfuscated)
    It basically means that we have to trust Skype that they keep up their secrets. There are very many users which makes the Skype audience an interesting target.
  • Total blackbox. Lack of transparency. No way to know if there is/will be a backdoor
  • Skype was made by clever people; Good use of cryptography
    They admit that it was built in a good way. But it's like the government that may be suspicious if you encrypt all your communication. Skype encrypts everything and itself. Should we be suspicious?

Further readings: Skype network structure, Skype's Guide for Network Administrators

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Veröffentlicht unter web

Delicious Interface Updates

Today del.icio.us did some really nice interface updates.

In the first place, they announced inline editing which is very slick. You just click on „edit" on the „your bookmarks" page and you can edit the item right away.

They also updated the URL page which looks very nice and tidy now.

These updates don't affect blummy, you can still use it to add your bookmarks from any page. If you haven't seen it, give it a try.

The announcement also says that private bookmarking (one of the big missing features) will be released next week.

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Veröffentlicht unter misc

A better understanding of JavaScript

I've been working with JavaScript for years. It was my replacement for a server side language when I couldn't afford to buy web space in the mid-90's. Still, as the language becomes popular again, I recognized that I did understand the basics but there was much more to the language.

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So I dug into the topic a little deeper. I can highly recommend reading the blogs of all the great JavaScript guys like Alex Russell (of Dojo), Aaron Boodman, Erik Arvidsson (both at Google), Douglas Crockford (at Yahoo). (Give me more in the comments ;)

So, JavaScript is easy to start with. You can take a procedural approach like in C. You declare a function, you call a function.

A Survey of the JavaScript Programming Language (by Douglas Crockford) does an amazing job at explaining the notable aspects of the language on a quite short page.

I want to point out the most interesting points for me:

Subscript and dot notation
You can access a member of an object by using two different notations:

var y = { p: 1 };
alert(y["p"]); // subscript notation
alert(y.p); // dot notation

The great difference is that with subscript notation you can also access member vars that contain reserved words (of which there quite a few in JavaScript). Dot notation is shorter and more convenient.

Different meanings of the this keyword
Consider this piece of code creating a small object.

click here
<script type="text/javascript">
var myobject = {
id: 'obj',
method: function() {
alert(this.id);
}
};
myobject.method();
var l = document.getElementById("link");
l.onclick = myobject.method;
</script>

When you call myobject.method();, this points to the current object and you receive an alert box with the text ‚obj'. But there are exceptions:

If you call this function from within a HTML page via an onclick event, this is refers to the calling object (i.e. the link). You will therefore receive and alert box containing ‚link' as message.

This can be useful in many cases, but if you want to access „your" object, you can't. Aaron Boodman proposed a function that was eventually named hitch:

function hitch(obj, meth) {
return function() { return obj[meth].apply(obj, arguments); }
}

You'd use it like this: l.onclick=hitch(myobject, 'method'); Now the this keyword points at the correct object.

You could also change the function to something like this and still use the previous notation:

method = function() {
if (this != myobject) { return myobject.method(arguments); }
alert(this.id);
}

Creating objects with new
I was always wondering how to create objects from a class as I am used to with other programming languages, which means that by instanciating the object is created according to the „building instructions" of a class.

Douglas shows this in more detail on his Private Members in JavaScript page.

I've quickly hacked together this example:

var x = function () {
var created = new Date();
this.when = function () { alert(created); }
}
var p, u = new x();
window.setTimeout("n()", 1000);
function n () {
p = new x();
p.when();
u.when();
alert(typeof p.created);
}

You receive 2 objects p and u that have different creation times. They also have a private variable created which is only accessible via the public function when (because specified via this).

So even as you create an object by using the new Object() or {} notation, you only receive a static object. If you want to instanciate it, you need to create it as function.

Closures
The example above already demonstrated closures. The fact that closures exist in JavaScript make it only possible to create private variables.

A closure is, to put it simply, a function within another function. The inner function has access to it's parents variables but not the other way round.

All together a function is just another data type that can be assigned to a variable. Therefore these two notations can be used interchangably:

function test() { alert(new Date()); }
var test = function() { alert(new Date()); }

The ominous prototype „object" is a way of using the this keyword from „outside".
Modifying the piece of code from before:

var x = function () {
var created = new Date();
}
x.prototype.when = function () { alert(created); }

But there's a pitfall. The created variable is private. Even though the function when now is a member of the object x it does not „see" the variable created. So in the original example the function when had privileged access (see Private Members in JavaScript).

Concluding
All in all I see that JavaScript is a powerful language. Many things that can be accomplished in an elegant (and sometimes quite unusual) way. (Curried JavaScript demonstrates even how to use it as a functional programming language)

I realize that there is a nice and clean solution for almost every problem you come across. This is where libraries come into play. The downside: you can quickly add tons of libraries, leading to large page sizes and memory consumption.

dojo for example is a really great library that provides you with numerous well thought-out functions, making your life a lot easier. But the size is 132 KB, just for the basic functions. More than a mega byte all in all. It circumvents needing to load everything by an in time loading mechanism (dojo.require).

In my opinion we'd need something like a local library storage. A Firefox extension would be a nice first step.
As far as I have looked into that topic, though, there are some difficulties. Foremost there is a problem with namespaces. Firefox clearly separates JS code by extensions from those coming from the web. A good thing, security-wise, but hindering in this case.

Maybe some Firefox guru can tell a way how to circumvent this, I think it might be worth a shot.

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