This article is part of the article series "Musical Geek Friday."
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the day the rotuers died geek songThis week on Musical Geek Friday - a song about The Day the Routers Died!

This song is written and performed live at the 55th RIPE Meeting by Gary Feldman (scroll down for a video of him performing it live).

RIPE (Réseaux IP Européens) is a collaborative forum open to all parties interested in wide area IP networks in Europe and beyond. The objective of RIPE is to ensure the administrative and technical coordination necessary to enable the operation of a pan-European IP network.

A RIPE Meeting is a five-day event where Internet service providers, network operators and other interested parties from Europe and the surrounding regions gather. RIPE Meetings are open to everyone and provide an excellent opportunity for attendees to discuss Internet policy.

The song is about a problem that the current IPv4 address space is running out of IP addresses (read about the problem here). IPv4 address space can hold just 4'294'967'296 (232) addresses. The song suggests that we all move to IPv6 address space which can hold 2128 addresses. That many addresses will never run out.

Here it is! The Day the Routers Died geek song:

[audio:http://www.catonmat.net/download/gary_feldman-the_day_the_routers_died.mp3]

Download this song: the day the routers died.mp3 (musical geek friday #6)
Downloaded: 12601 times

Download lyrics: the day the routers lyrics (musical geek friday #6)
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Here is the lyrics of The Day the Routers Died song:

a long long time ago
i can still remember
when my laptop could connect elsewhere

and i tell you all there was a day
the network card i threw away
had a purpose - and it worked for you and me...

but 18 years completely wasted
with each address we've aggregated
the tables overflowing
the traffic just stopped flowing...

and now we're bearing all the scars
and all my traceroutes showing stars...
the packets would travel faster in cars...
the day... the routers died...

Chorus (ALL!!!!!)

so bye bye, folks at RIPE 55
be persuaded to upgrade it or your network will die
IPv6 just makes me let out a sigh
but I s'pose we'd better give it a try
I suppose we'd better give it a try

now did you write an RFC
that dictated how we all should be
did we listen like we should that day

now you back at RIPE fifty-four
where we heard the same things months before
and the people knew they'd have to change their ways...

and we - knew that all the ISPs
could be - future proof for centuries

but that was then not now
spent too much time playing WoW

ooh there was time we sat on IRC
making jokes on how this day would be
now there's no more use for TCP
the day the routers died...

Chorus (chime in now)

so bye bye, folks at RIPE 55
be persuaded to upgrade it or your network will die
IPv6 just makes me let out a sigh
but I s'pose we'd better give it a try
I suppose we'd better give it a try

I remember those old days I mourn
sitting in my room, downloading porn
yeah that's how it used to be...

when the packets flowed from A to B
via routers that could talk IP
There was data... that could be exchanged between you and me...

oh but - I could see you all ignore
the fact - we'd fill up IPv4

but we all lost the nerve
and we got what we deserved!

and while... we threw our network kit away
and wished we'd heard the things they say
put all our lives in disarray

the day... the routers died...

Chorus (those silent will be shot)

so bye bye, folks at RIPE 55
be persuaded to upgrade it or your network will die
IPv6 just makes me let out a sigh
but I s'pose we'd better give it a try
I suppose we'd better give it a try

saw a man with whom I used to peer
asked him to rescue my career
he just sighed and turned away...

I went down to the net cafe
that I used to visit everyday
but the man there said I might as well just leave...

and now we've all lost our purpose..
my cisco shares completely worthless...

no future meetings for me
at the Hotel Krasnapolsky

and the men that make us push and push
like Geoff Huston and Randy Bush
should've listened to what they told us...
The day... the routers... died

Chorus (time to lose your voice)

bye bye, folks at RIPE 55
be persuaded to upgrade it or your network will die
IPv6 just makes me let out a sigh
but I spose we'd better give it a try
I suppose we'd better give it a try

I also found a live video of Gary performing the song live at RIPE 55:

Ps. The Internet died once in 1997.

Download "The Day the Routers Died" Song

Download this song: the day the routers died.mp3 (musical geek friday #6)
Downloaded: 12601 times

Download lyrics: the day the routers lyrics (musical geek friday #6)
Downloaded: 3567

Click to listen:
[audio:http://www.catonmat.net/download/gary_feldman-the_day_the_routers_died.mp3]

Have fun and until next geeky Friday! :)

defcon logo post iconHere is something for all you hackers out there reading my blog: all the videos from the previous year's biggest and greatest hacker conference -- DefCon 15!

I found these videos via this post on Roy/SAC's blog. He bought a full set of DVDs for several hundred dollars and uploaded them to Google Video! I sincerely appreciate his effort!

Total of more than 200 videos!

For your convenience, here is the full DefCon 15 session listing:
Download Full DefCon 15 Session Listing (.pdf).

You're welcome to comment here on lectures you found intriguing and liked the most!

Have fun!

This article is part of the article series "Musical Geek Friday."
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The Eternal Flame, God Wrote in Lisp SongThis week on Musical Geek Friday - God Wrote in Lisp (also known as The Eternal Flame) song!

This song is written by Bob Kanefsky and is performed by Julia Ecklar. It's a parody of another song of hers - "God Lives on Terra".

The song is about a question which programming language God could have used to create us?

God had a tight 6 day deadline to create the world, so he had to make a smart decision which language to use. Some folks say that it could have been C++ or C, but these languages are out as God would not have been able to even count grains of sand with 32-bit integers! Others say it could have been Fortran, Java, COBOL or even APL. But we all know the truth...

God wrote the world in Lisp!

Here it is! The God Wrote in Lisp song:

[audio:http://www.catonmat.net/download/the_eternal_flame-god_wrote_in_lisp.mp3]

Download this song: god wrote in lisp.mp3 (musical geek friday #5)
Downloaded: 37429 times

Download lyrics: god wrote in lisp lyrics (musical geek friday #5)
Downloaded: 2161

If you liked this song, it's included in a music CD "Roundworm" which contains parodies about Star Trek, dead cats, Lisp programming (this song), and everything in between!

Here is the lyrics of The Eternal Flame (God Wrote in Lisp) song:

I was taught assembler in my second year of school.
It's kinda like construction work — with a toothpick for a tool.
So when I made my senior year, I threw my code away,
And learned the way to program that I still prefer today.

Now, some folks on the Internet put their faith in C++.
They swear that it's so powerful, it's what God used for us.
And maybe it lets mortals dredge their objects from the C.
But I think that explains why only God can make a tree.

For God wrote in Lisp code
When he filled the leaves with green.
The fractal flowers and recursive roots:
The most lovely hack I've seen.
And when I ponder snowflakes, never finding two the same,
I know God likes a language with its own four-letter name.

Now, I've used a SUN under Unix, so I've seen what C can hold.
I've surfed for Perls, found what Fortran's for,
Got that Java stuff down cold.
Though the chance that I'd write COBOL code
is a SNOBOL's chance in Hell.
And I basically hate hieroglyphs, so I won't use APL.

Now, God must know all these languages, and a few I haven't named.
But the Lord made sure, when each sparrow falls,
that its flesh will be reclaimed.
And the Lord could not count grains of sand with a 32-bit word.
Who knows where we would go to if Lisp weren't what he preferred?

And God wrote in Lisp code
Every creature great and small.
Don't search the disk drive for man.c,
When the listing's on the wall.
And when I watch the lightning
Burn unbelievers to a crisp,
I know God had six days to work,
So he wrote it all in Lisp.

Yes, God had a deadline.
So he wrote it all in Lisp.

Download "God Wrote in Lisp" Song

Download this song: god wrote in lisp.mp3 (musical geek friday #5)
Downloaded: 37429 times

Download lyrics: god wrote in lisp lyrics (musical geek friday #5)
Downloaded: 2161

Click to listen:
[audio:http://www.catonmat.net/download/the_eternal_flame-god_wrote_in_lisp.mp3]

Have fun and until next geeky Friday! :)

python design patterns video lecturesIn my previous post about learning Python programming through video lectures I stopped at three lectures on Design Patterns. This time I continue from there.

If you don't know what a Design Pattern is, think of it as a simple solution to a specific problem that occurs very frequently in software design.

For example, suppose you use a bunch of unrelated pieces of code. It is a nice idea to bring the unrelated pieces of code together in a unified interface. This design pattern is called Facade. There are a bunch of patterns like this one!

The three lectures are given by Alex Martelli who works as "Über Tech Lead" for Google.

Python Design Patterns, Part I

Alex briefly covers the history and main principles of Design Patterns and quickly moves to discussing Structural and Behavioral DPs in Python.

Interesting ideas from the lecture:

  • [03:24] The name "Design Patterns" was first used by Christopher Alexander, an architect, who abstracted the idea of building buildings as building them using well known patterns which can be applied to the same problem over and over again without ever doing it the same way twice.
  • [05:30] Design Patterns are mostly applied to Object Oriented programming because it's the most widely spread programming paradigm nowadays.
  • [08:36] Design Patterns are not invented, they are discovered.
  • [10:00] Alex says that the original book Design Patterns by the Gang of Four should be read only when you are a master of DPs.
  • [13:10] Three classical categories of DPs are - Creational (deal with object instantiaton), Structural (deal with composition of objects) and Behavioral (deal with interaction of objects).
  • [14:05] "Program to an interface, not to an implementation."
  • [17:00] Use inheritance only when absolutely necessary, otherwise use "hold or wrap" principle.
  • [18:30] Never have more than one dot - Law of Demeter.
  • [18:50] Inheritance cannot restrict, use wrapping to restrict.
  • [21:41] In most of the cases when you need a single instance of something in Python, use a module instead of a class.
  • [22:23] Otherwise, just make 1 instance (without enforcing one).
  • [22:59] Singleton is also called "Highlander".
  • [24:50] There is basically no way to support subclassing well in Singleton.
  • [25:45] Monostate is also called "Borg".
  • [27:00] Python's data overriding helps in Monostate Design Pattern.
  • [29:00] Each Python's type/class is essentially a factory.
  • [32:06] Python does a "two-phase object construction".
  • [35:30] Adapter Design Pattern (it tweaks the interface to your needs).
  • [41:22] Facade Design Pattern (it provides a simple subset of a complex functionality).
  • [47:25] Bridge Design Pattern (it abstracts interface from the implementation).
  • [49:30] Decorator Design Pattern (it transparently modifies some functionality.).
  • [50:24] Proxy Design Pattern (sounds the same as decorator just for access control).
  • [51:21] Q and A!

Python Design Patterns, Part II

In this lecture Alex discusses behavioral patterns. Unlike the first part, he goes in depth of some of the patterns and explains how they can be implemented in Python.

Interesting ideas from the lecture:

  • [02:25] Template Method is a great pattern with a lousy name, a better name is "self-delegation".
  • [03:43] Example of Template Method Design Pattern (text pagination).
  • [08:50] Template Method Rationale.
  • [09:45] The "Hollywood Principle" - "don't call us, we'll call you"
  • [12:05] In Python you can also override data.
  • [13:10] Example of Template Method in Queue.Queue.
  • [14:05] If you are a good Python programmer, use Queue in threaded applications.
  • [17:45] Customizing Queue.
  • [19:30] Example of Template Method in cmd.Cmd.cmdloop.
  • [21:22] Example of Template Method in asyncore.dispatcher.
  • [22:30] Variant of Template Method - Mixin (not presented in Gang of Four book). It's a class to be multiply-inherited from and supplies organizing methods only.
  • [25:50] Template Method in DictMixin class.
  • [26:45] Example of DictMixin usage.
  • [29:00] Hooks can be factored out in another class. Two examples of this from Python's stdlib are HTML's formatter vs. writer, SAX's parser vs. handler
  • [32:40] Hook method introspection example of cmd.Cmd.docmd.
  • [33:30] There are three kinds of Template Methods - plain, factored into separate classes, and introspective.
  • [34:35] Example of all three kinds of Template Methods used in unittest.TestCase.
  • [36:17] State and Strategy Design Patterns. Very similar classes in what they do. They both factor out object's behavior.
  • [40:40] Ring buffer example done via State Design Pattern.
  • [43:35] Q and A!

Python Design Patterns, A Recap

This video lecture was presented at Google Developers day. It is a short version of the previous two video lectures. It starts with an example of Facade Design Pattern, moves on to history and all the types of design patterns.

I did not write out the interesting moments from this lecture as it was a subset of previous two lectures.

If you liked these lectures, check out this geek song about another commonly used design pattern - Model-View-Controller Song :)

Even though these were Python design patterns, to understand some of them I used Perl Design Patterns website!

Were there any interesting points in the lectures that caught your attention?

This article is part of the article series "Musical Geek Friday."
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model view controller mvc musical geek friday songThis week on Musical Geek Friday - the Model View Controller (MVC) song!

This song was written and performed by James Dempsey, an engineer at Apple. James says that he searched iTunes for a model-view-controller song but there was none, so he wrote his own song about this topic.

The song is about a particular Design Pattern in software engineering. A Design Pattern is a simple solution to a specific problem that occurs very frequently in software design. The MVC Design Pattern was first discovered and described by Smalltalk people (see the original paper). This key idea of this pattern is that it decouples data to be displayed (model) from the code displaying the data (view) and code receiving user input (controller).

Here it the Model View Controller song:

[audio:http://www.catonmat.net/download/model_view_controller_song.mp3]

Download this song: model-view-controller song.mp3 (musical geek friday #4)
Downloaded: 40690 times

Download lyrics: model-view-controller lyrics (musical geek friday #4)
Downloaded: 2986

Talking about the MVC design pattern in this song, Ralph Johnson on squeak's mailing list comments:

The problem is that the song is NOT about Smalltalk MVC. In this song, the controller is a layer between the view and the model, which usually means it is a mediator. The song also says that the controller is copying values from one field to another, which also indicates that it is a mediator. However, in true MVC, the controller is a strategy for handling events. The events come directly to it, rather than to the view. The controller changes the model, but it is not notified by the model. When the user presses a key or moves the mouse, the controller receives the event. It checks with the view to map mouse locations into model coordinates, then interacts directly with the model. If it changes the model then the model notifies all dependents (observers), which notifes the view, which redisplays.

The song desribes Ivar Jacobson's Model/Interface/Control, in which the Control is responsible for an entire use case. It is not MVC. Jacobson's model is like the MVC model, but his Interface is a combination of View and Controller and his Control is not at all like a real Controller.

Here is the lyrics of MVC song:

Model View, Model View, Model View Controller
MVC's the paradigm for factoring your code,
into functional segments so your brain does not explode.
To achieve reusability you gotta keep those boundaries clean,
Model on the one side, View on the other, the Controller's in between.

Model View - It's got three layers like Oreos do.
Model View creamy Controller

Model objects represent your applications raison d'tre.
Custom classes that contain data logic and et cetra.
You create custom classes in your app's problem domain,
then you can choose to reuse them with all the views,
but the model objects stay the same.

You can model a throttle in a manifold,
Model level two year old.
Model a bottle of fine Chardonnay.
Model all the twaddle stuff people say.
Model the coddle in a boiling eggs.
Model the waddle in Hexley's legs.

One, two, three, four.
Model View - You can model all the models that pose for GQ.
Model View Controller

View objects tend to be controls that view and edit,
Cocoa's got a lot of those, well written to its credit.
Take an NSTextView, hand it any old Unicode string,
the user interacts with it, it can hold most anything.
But the view don't knows about the Model:
That string could be a phone number or the words of Aristotle.
Keep the coupling loose and so achieve a massive level of reuse.

Model View - All rendered very nicely in Aqua blue
Model View Controller

You're probably wondering now.
You're probably wondering how,
the data flows between Model and View.
The Controller has to mediate,
between each layer's changing state,
to synchronize the data of the two.
It pulls and pushes every changed value.
Yeah.

Model View - mad props to the smalltalk crew!
for Model View Controller

Model View - it's pronouced Oh Oh not Uh Uh
Model View Controller

There's a bit more on this story,
a few more miles upon this road,
well nobody seems to get much glory
writing controller code.
Well the model is mission critical
and gorgeous is the view,
But I'm not being lazy, but sometimes it's just crazy
how much code i write is just glue.
And it wouldn't be so tragic,
but the code ain't doing magic:
it's just moving values through.
And I wish I had a dime
for every single time
I set a TextField's stringValue.

Model View - how we're gonna deep-six all that glue
Model View Controller

Controller's know the Model and View very
uahh - intimately
They often are hardcoding
which is very verboten for reusability.
But now you can connect any value you select
to any view property.
And I think you'll start binding,
then you'll be finding less code in your source tree.
Yeah I know I was astounded,
that's not even a rhyme.

But I think it bares repeating
all the code you won't be needing,
when you hook it up in IB.

Model View - it even handles multiple selections too
Model View Controller

Model View - hope I get my G5 before you
Model View Controller

Yeah, yeah, yeah. Yeah.

I also found a video of James singing it live on WWDC 2003. Here is the video:

Download "Model View Controller" Song

Download this song: model-view-controller song.mp3 (musical geek friday #4)
Downloaded: 40690 times

Download lyrics: model-view-controller lyrics (musical geek friday #4)
Downloaded: 2986

Click to listen:
[audio:http://www.catonmat.net/download/model_view_controller_song.mp3]

Have fun and until next geeky Friday! :)

PS. One of my next posts will be on Design Patterns in Python, so check back! :)