Category: interactive media art

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node.js: including files

The old way…

By Udo G at Stack Overflow

from: http://stackoverflow.com/questions/5797852/in-node-js-how-do-i-include-functions-from-my-other-files

If, despite all the other answers, you still want to traditionally include a file in a node.js source file, you can use this:

<code>var fs = require('fs'); // file is included here: eval(fs.readFileSync('tools.js')+'');</code>
  • The empty string concatenation +'' is necessary to get the file content as a string and not an object (you can also use .toString() if you prefer).
  • The eval() can’t be used inside a function and must be called inside the global scope otherwise no functions or variables will be accessible (i.e. you can’t create a include() utility function or something like that).

Please note that in most cases this is bad practice and you should instead write a module. However, there are rare situations, where pollution of your local context/namespace is what you really want.

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answered Apr 27 ’11 at 20:13
Udo G
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Cool, this is useful for quick’n’dirty putting JS libs designed for client-side into a node.js app without the need of maintaining a Node-styled fork. – Kos Dec 11 ’11 at 13:24
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The “+”” is just a shortcut to force string casting. The more readable solution would be “String(fs.readFileSync(‘tools.js’))” or if the read.FileSync returns an object then “fs.readFileSync(‘tools.js’).toString()” should also work since toString is attached to the base Object prototype (i.e Object.prototype.toString). – Evan Plaice Jan 20 at 23:22
-1 Blindly importing JS into the global namespace can open the code to unintended naming conflicts. If the code in the tools.js file were written in object literal format you could assign them to a local variable which works like a pseudo-namespace. Also, I don’t really think the eval is required (masylum’s code makes it seem like the code is already eval’d during the require). I think you’re import/eval-ing the code with require, casting that code back to string and eval-ing it again just to pidgeonhole it into the global namespace. Looks like you’re doing it wrong. – Evan Plaice Jan 20 at 23:31
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I just answered the original question, which is about including code, not writing modules. The former can have advantages in certain situations. Also, your assumption about require is wrong: The code is certainly eval’d, but it remains in it’s own namespace and has no way to “pollute” the namespace of the calling context, hence you need to eval() it yourself. In most cases using the method described in my anwer is bad practice but it’s not me that should decide if it is for TIMEX. – Udo G Jan 21 at 17:03
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@EvanPlaice: do you have a better suggestion which actually answers the question? If you need to include a file which is not a module, do you have a better approach than this? Otherwise, downvoting it seems absurd. – jalf Apr 21 at 11:04
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node.js reverse proxy in Ubuntu Apache2

(update) having problems with this when using socket.io from external clients. So it may be worth looking at the alternatives described in the Shelley Powers book on NODE.js

 original post

Here is now to set up a reverse proxy so that a node.js server is visible from the outside world. In our case we redirected any traffic with the subdirectory /nodejs/ to port 8124

for example, this web address http://zerokidz.com/nodejs/

Add the following to the /etc/apache2/sites-enabled/default file: (inside the section already set aside for the virtual host zerokidz)

ProxyPass /nodejs/ http://127.0.0.1:8124/
ProxyPassReverse /nodejs/ http://127.0.0.1:8124/
<Proxy *>
 Order deny,allow
 Allow from all
</Proxy>

So it will look something like this:

<VirtualHost *:80>
  ServerName www.zerokidz.com
  ServerAlias zerokidz.com *.zerokidz.com
  DocumentRoot /home/tkzic/public_html/zerokidz

# Nodejs reverse proxy rule
# sends all traffic for zerokidz.com/nodejs
# to the nodejs server on port 8124

ProxyPass /nodejs/ http://127.0.0.1:8124/
  ProxyPassReverse /nodejs/ http://127.0.0.1:8124/
  <Proxy *>
    Order deny,allow
    Allow from all
  </Proxy>

</VirtualHost>

Then restart apache, of course

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Slow data

notes

Examples of slow data streams.

  • bicycle wheel sensor that triggers once per rotation
  • The data stream from an OBD-II scanner which can only be polled every 300ms or slower
  • a traffic sensor on a quiet street

There aren’t enough data points to use typically smoothing methods like moving average or logarithmic smoothing. Here are 2 ideas for increasing data points using repetition:

  • feed the data into the right inlet of an [f] object to set its value. The left inlet receives the output of a [metro] set at the desired stream rate. Then the output of the [f] object can be smoothed using conventional methods.
  • convert data to a signal using [sig~] then smooth using [slider~] or [rampsmooth~] then convert back to float using the right outlet of [number~]

 

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Max OBD sensor project

Preliminary files are in:

/Automax

rpm3- reads rpm/speed from obd bluetooth

This patch demonstrates two methods of polling. For RPM and vehicle speed, the request codes and polling are linked and controlled by a single metro object which splits the polling time between the two codes.

The engine load is a simpler setup – with separate metros to do writing and reading.

If the polling speed is set too fast, the OBD port will crash and you have to reset everything.       So on the 2001 Acura you can’t poll faster than 300 ms. – but on the 2006 Jetta you can poll at 100 ms. – which is much more realistic for doing engine simulation stuff…

waveguide engine2e-1 – gets rpm and sends to engine speed

 

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Max bicycle speed / engine example patch

notes:

I’m trying to organize the examples for measuring wheel speed. These patches need to be consolidated – and have the extraneous stuff stripped out. For example, just need a wii-mote detector without all the envelope stuff.

max teaching examples/tz examples

bicycle2.maxpat – need to clean up

wheelspeed.maxpat

waveguide engine3c bike.maxpat

notes: wheelspeed2.maxpat has some experiments with smoothing by converting to signal in order to get more data points.