1.
Building an alarm clock
with node.js
or
Hacking vs. Engineering
Felix Geisendörfer 29.09.2011 (v1)
Donnerstag, 29. September 2011

2.
Text
Welcome to the Siesta
right-after-lunch Session!
Donnerstag, 29. September 2011

3.
Building an alarm clock
with node.js
or
Hacking vs. Engineering
Felix Geisendörfer 29.09.2011 (v1)
Donnerstag, 29. September 2011

4.
@felixge
Twitter / GitHub / IRC
Donnerstag, 29. September 2011

5.
My Problem
• Getting up early in the morning
• That means before 12:00 (noon)
Donnerstag, 29. September 2011

6.
This talk
• How I solved this problem
• Hacking vs. Engineering the solution
Donnerstag, 29. September 2011

7.
Patient History
• 23 years
• Working from home
• Can work any hours
Donnerstag, 29. September 2011

8.
So why get up early?
• To get more stuff done ...
Donnerstag, 29. September 2011

9.
Previous attempts
Donnerstag, 29. September 2011

10.
Text
Behavioral Conditioning
Donnerstag, 29. September 2011

11.
Text
Flying alarm clock
Donnerstag, 29. September 2011

12.
Text
Circadian rhythm app (Sleep Cycle)
Donnerstag, 29. September 2011

13.
Text
Many alarms
Donnerstag, 29. September 2011

14.
Nothing was working
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15.
Text
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16.
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17.
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18.
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19.
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20.
VLC
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21.
pmset
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22.
The Script
https://gist.github.com/1a40a207cf6132f77efa
Donnerstag, 29. September 2011

23.
sudo ./alarm.js 7 30
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24.
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25.
Result
• Reliably waking up at any time
• Get to choose different music every night
Donnerstag, 29. September 2011

26.
Hacking vs. Engineering
Donnerstag, 29. September 2011

27.
(Software) Engineering
“Rigorous application of science”
Donnerstag, 29. September 2011

28.
Hacking
“Playful cleverness”
Donnerstag, 29. September 2011

29.
Hacking vs. Engineering
this project
Donnerstag, 29. September 2011

30.
Tests?
Engineering: Yes
Hacking: Maybe
Donnerstag, 29. September 2011

31.
Airtunes?
Engineering:
Implement protocol
Hacking:
Piggyback on iTunes or VLC
Donnerstag, 29. September 2011

32.
Code
var file = '/my/music/file.mp3';
var vlcPath = '/Applications/VLC.app/Contents/MacOS/VLC';
var vlc = spawn(vlcPath, [
'-R',
'--sout=#transcode {acodec = alac channels = 2, samplerate =
44100}: raop{host=10.0.1.13,volume=255}',
file
]);
vlc.stdout.setEncoding('utf8');
vlc.stderr.setEncoding('utf8');
vlc.stdout.on('data', process.stdout.write);
vlc.stderr.on('data', process.stderr.write);
vlc.on('exit', function(code, signal) {
console.log('vlc exit: %i %s', code, signal);
});
Donnerstag, 29. September 2011

33.
Wakeup from Sleep?
Engineering:
pmset schedule wakeorpoweron <datetime>
Hacking:
pmset schedule wakeorpoweron MTWRFSU
<time>
Donnerstag, 29. September 2011

34.
Code
var powerCmd = sprintf(
'pmset repeat wakeorpoweron MTWRFSU %02d:%02d:00',
powerHour,
powerMinute
);
exec(powerCmd, function(err) {
if (err) throw err;
process.setuid('felix');
});
Donnerstag, 29. September 2011

35.
Turn off speakers?
Engineering:
Install speakers in unreachable place.
Hacking: ?
Donnerstag, 29. September 2011

36.
Text
Duct Tape
Donnerstag, 29. September 2011

37.
Duct Tape of Concurrent I/O
Donnerstag, 29. September 2011

38.
Engineering Solution for Concurrency
Donnerstag, 29. September 2011

39.
Why am I talking about this?
Donnerstag, 29. September 2011

40.
JS has a very hacker-driven
culture
Donnerstag, 29. September 2011

41.
Text
Duct tape of the web
Donnerstag, 29. September 2011

42.
Text
Duct tape of the DOM
Donnerstag, 29. September 2011

43.
• Hacking is lots of fun, go do it!
• Hacking can be a good solution!
• But be aware that many problems call for
an engineering approach.
Donnerstag, 29. September 2011

44.
Where we need more
engineering:
• Libraries
• Domain logic
• Performance
Donnerstag, 29. September 2011

45.
TL;DL
• Hack when in doubt
• Engineer when clear
Donnerstag, 29. September 2011

46.
Hacking Engineering
Donnerstag, 29. September 2011

47.
Questions?
@felixge
Donnerstag, 29. September 2011