So I looked into putting an ad on my app to potentially recoup the submission fee, but I was unable to find any meaningful data regarding how long it would take, which left me on the fence as to whether or not it was worth the hassle.  Of course, this lack of public data is not that unexpected, as most companies doing this for profit would consider this a trade secret, but it was still disappointing.  So I justified to myself paying it as the cost of an experiment with a civil benefit:  Hopefully by publishing these numbers I can help either encourage or discourage future hobby developers as to whether or not it’s worth it to them to submit their own hobby apps.

Anyway, here are the numbers from ~24 hours after release: (AdMob is the advertiser)

• Downloads: 7687
• Ad Requests: 11,491
• Ad Impressions: 11,456
• Fill Rate: 99.70%
• Click Through Rate (CTR): 3.26%
• Estimated Revenue Per Thousand Impressions (eCPM): $1.11
• Total Revenue: $12.68

This completely shocked me, as it’s almost an order of magnitude higher than my most optimistic expectations.   (I was hoping for, and figured I would have considered it worth the submission fee, if I received on average ~$0.50/day in revenue)

I will post updates to this entry as I pass other timeline milestones.  (one week and one month, at least)  I’m very curious as to if this will be a sustained daily trend, will grow, or if this is a one-day newness peak that will drop off a cliff tomorrow.  :)

BTW, I strongly encourage other hobby developers to publish their numbers as well.  (or even share with me privately or anonymously)  I would love to compare against a larger data set.

Where’s My Car? helps you find your car in a crowded parking lot. When you leave your car, simply open the application. (It will automatically get your current GPS location) Leave the application open, and when you’re done doing whatever it is you have to do, click “Take Me To It!” An arrow will show up (as well as a distance measurement). Simply walk in the direction of the arrow, and you’ll be quickly guided back to your car! BTW, I originally wrote this app as a present for my wife. I’ve decided to place it on the App Store as a FREE app because I don’t see why the other apps that do the same thing charge $5 for such a simple feature. Let me know if you like it!

UPDATE: It has been approved/published!  To download, open the App Catalog.  Search for “car”.  Click the coins icon in the lower-right to show only FREE apps, and “Where’s My Car?” should be the first in the list!  :)

UPDATE 2: Click here to download:  Where’s My Car?

Screenshots after the break…

One of the interesting aspects of the academic side of computer science is the creation if new terms for old ideas. Take a well known concept, add a twist of lime, invent a new term, throw in a little obfuscation, and presto – an instant publishable paper (as long as you’re not submitting to a top-tier journal). It’s publishable because it’s very hard to classify between these junk papers and complicated but genuinely new concepts. (so hard in fact many journals don’t even try – even nonsensical papers can occasionally sneak through) And since people are judged on how many papers they produce, this problem has become an epidemic. The signal to noise ratio is currently mind-bogglingly low.

Dependency Injection I’m now certain is the corporate equivalent of this academic phenomenon. While people many not have as much incentive without the threat of not getting tenure due to too few papers published, the fame of being the guy who invented The Next Big Thing(tm) is non-trivial. And even if you don’t invent it yourself, being an early champaign of The Next Big Thing(tm) distinguishes yourself from your peers, helps you land new contracts, etc. In a myriad of career enhancing ways it’s still a viable incentive.

Not to say it’s a con-job mind you. Buzz-words are everywhere in this business. It’s exciting to be on the cutting edge, and it’s hard to separate out the true leading fronts from the fake ones. It’s real easy to get swept up in the excitement. (I’ve been guilty of it myself on more than one occasion) But that doesn’t change the basic question.

So… Dependency Injection: A new idea or Coke with Lime?

Let’s start with Martin’s own sample code.

class MovieLister...
    private MovieFinder finder;
    public MovieLister() {
        finder = new ColonDelimitedMovieFinder("movies1.txt");
    }
    public Movie[] moviesDirectedBy(String arg) {
        List allMovies = finder.findAll();
        for (Iterator it = allMovies.iterator(); it.hasNext();) {
            Movie movie = (Movie) it.next();
            if (!movie.getDirector().equals(arg)) it.remove();
        }
        return (Movie[]) allMovies.toArray(new Movie[allMovies.size()]);
    }

The method moviesDirectedBy uses an interface:

public interface MovieFinder {
    List findAll();
}

Look at the MovieListener constructor. Martin argues that it’s a bad implementation because it ties the MovieListener class to a specific implementation of a MovieFinder. And he’s absolutely right. It’s pointless to have a MovieFinder interface if your code can only ever use one instance of it.

But this is not a new concept. This is the very basis of object-oriented programming. He may as well have called Dependency Injection “Non-Retarded Programming”. A non-retard implementation would probably contain this:

    public MovieLister(MovieFinder finder) {
        this.finder = finder;
    }

Which, low and behold, is exactly what he recommends. His example is nothing but a straw-man argument.

So my question to you is this: When did having a constructor that takes an argument become a new idea worthy of a new term? I wrote Java programs in 1996 that did this. C++ did it long before that. I mean good god, this idea is as old as object-oriented programming itself.

Now if you’re using the Spring framework, you might write some controlling XML not unlike the following:

<bean id="ColonDelimitedMovieFinder" class="org.kered.ColonDelimitedMovieFinder">
    <constructor-arg index="0" ref="movies1.txt"/>
</bean>
<bean id="MovieLister" class="org.kered.MovieLister">
    <constructor-arg index="0" ref="ColonDelimitedMovieFinder"/>
</bean>

And then the Spring controller would parse this XML, generate your objects, and offer some lookup service to some other code that uses MovieListener. But I ask you this: Why do you need a framework for that? How is this XML any less complicated than actual Java code that does the same thing? For example:

public class MyController {
  private static MovieFinder finder = new ColonDelimitedMovieFinder("movies1.txt");
  private static MovieListener listener = new MovieListener(finder);
  public static getMovieListener() { return listener; }
}

Presto – no framework needed! Plus, you’ve not given up compile-time validity checking of your code. (I love the “rename class” feature of Eclipse – too bad it breaks hard when all your inter-class ties are defined in XML configuration files. Back to using grep on every rename…)

Now, one might argue that the XML configuration gives you run-time flexibility in your architecture. That it allows non-programmers to configure your application in any way they please. But this is a fallacy. These XML configuration files *are* quasi-programming languages (interpreted ones at that). All you’re saving is the compile. You still have to be a programmer to modify them. It is no simpler than modifying the Java source code directly (or the bash/bat script that launches it). You’re simplifying nothing – only shifting the location of the complexity.

Ok Derek, yes, I can’t have my users editing the spring application context files themselves. But I still need to deploy multiple configurations of my architecture that vary significantly. How do I do that when it’s statically compiled?

Simple. Create multiple “controller” classes. (in a 1-to-1 parallel to whatever XML you would have to write anyway) Switch between them with runtime parameters, or a one-line configuration option. Again, Programming 101. And as a bonus, you get to fix the possible number of deployable configurations to a number that’s economically testable, and you prevent the setup of nonsensical configurations.

But Derek, in your example, “movies1.txt” is hard-coded into your program.

Yes, but “movies1.txt” is hard-coded into *both* examples. No application is going to instruct the user to modify that blob of XML either. Both systems would need an additional config file or gui somewhere to expose that option to the user.

To recap: I’m not saying dependency injection is crap. In fact I’ve apparently been programming it for over a decade. I’m just saying it’s a vacant term that offers nothing new to the field of computer science. And I’m saying that Spring’s XML configuration for dependency injection offers you virtually nothing in terms of ease of configuration (except for it being run-time interpreted, which you can get in a variety of simpler ways), and destroys one of Java’s greatest assets: strong compile time validity testing. (And if you don’t care about that, why are you using Java? Go learn Python!)

Update: Check out http://code.google.com/p/unsprung/.

while(c=System.in.read()>-1){
  System.out.print(backspaceChar);
}

Doesn’t do what you’d expect. (hide console input) It appears that System.in is being silently buffered.

So a little googling: http://java.sun.com/developer/technicalArticles/Security/pwordmask/

Sun’s recommendation is a busy-wait loop in a separate thread that constantly rewrites the previous character?!? I mean, seriously, WTF?!?

Edit: It looks like Sun implemented a new API for non-echoing prompts in v1.6: http://java.sun.com/javase/6/docs/api/java/io/Console.html

But this is still crappy. Introducing a new API to partially work around the broken functionality of an old API is how you get bloated monstrosities to begin with.

Plus they played with the stats too much. “There used to be X thousand meat processing plants, but now 13 produce 80% of the meat in this country.” This doesn’t tell me anything. That last 20%, is that 2,000 smaller plants? Or 3 other really huge ones? What percentage did the top 13 used to produce? Apples-to-oranges statistical comparisons make me distrust the source.

Not to say it was all bad. The patenting of GMOs and the strong-arm tactics of their producers are definitively abusive, which I have ranted about before.

But overall, it seemed more anti-corporate, anti-science and hippy-ish than anything resembling a reasonable collection of recommendations on how to better our food production system.

Here is the request:

<?xml version="1.0"?>
<SOAP-ENV:Envelope
 xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
  <SOAP-ENV:Body>
    <calculateFibonacci
      xmlns="http://namespaces.cafeconleche.org/xmljava/ch3/"
      type="xsi:positiveInteger">10</calculateFibonacci>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

Here is the response:

<?xml version="1.0"?>
<SOAP-ENV:Envelope
 xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" />
  <SOAP-ENV:Body>
    <Fibonacci_Numbers
      xmlns="http://namespaces.cafeconleche.org/xmljava/ch3/">
      <fibonacci index="1">1</fibonacci>
      <fibonacci index="2">1</fibonacci>
      <fibonacci index="3">2</fibonacci>
      <fibonacci index="4">3</fibonacci>
      <fibonacci index="5">5</fibonacci>
      <fibonacci index="6">8</fibonacci>
      <fibonacci index="7">13</fibonacci>
      <fibonacci index="8">21</fibonacci>
      <fibonacci index="9">34</fibonacci>
      <fibonacci index="10">55</fibonacci>
    </Fibonacci_Numbers>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

Dear $DEITY, why do we need to define a new data type to hold a list of integers? And what in the world is that “index” attribute doing there? IT’S A FUCKING LIST. This is like a real-life example of the old XML binary encoding joke:

<data>
  <binary>
    <bit index="0">0</bit>
    <bit index="1">0</bit>
    <bit index="2">1</bit>
    ...
    <bit index="n">1</bit>
  </binary>
</data>

It’s just sad…

For the sake of it, let’s compare to a JSON-RPC version: (not the epitome of efficiency mind you, but an order of magnitude better)

--> { "method": "calculateFibonacci", "params": [10,], "id": 1}
<-- { "result": [1,1,2,3,5,8,13,21,34,55], "error": null, "id": 1}

Which would you rather use?

So a little googling led me to “deadman anchors”, which are basically anything buried in the ground. A basic design is some angle iron and steel cable. So a trip to Lowes and a few minutes assembly, and I have the following:

1 4ft piece of aluminium angle iron, cut into 4 6″ sections. 4 3ft sections of 1/16″ steel braded cable. 4 eye loops, and 4 pairs of cable crimps. <$15 total.

We’re beaching camping again this weekend at Mustang Island. Will update with how well they worked.

Security: Dynamic WEP (802.1x)
Authentication: Protected EAP (PEAP)
PEAP Version: Automatic
Inner Authentication: MSCHAPv2

Plus your UTD username/password.

To upgrade, hit Alt-F2 and type in “update-manager -d”.

So, to marry the two, I wrote for myself some wrapper code. It’s pretty much only good for one thing: multiplying large matrices together really fast. But it’s really good at it. (and it’s really easy to use) For example:

import numpy
from pycublas import CUBLASMatrix
A = CUBLASMatrix( numpy.mat([[1,2,3],[4,5,6]],numpy.float32) )
B = CUBLASMatrix( numpy.mat([[2,3],[4,5],[6,7]],numpy.float32) )
C = A*B
print C.np_mat()


All CUBLAS alloc and free calls are mapped to the CUBLASMatrix object’s life in Python, so you don’t have to worry about memory management. (other than filling up the card, or course)

Here are some performance numbers: (includes memory transfer times)
(4160×4160)*(4160×4160) = 43.0X faster than numpy
(4096×4096)*(4096×4096) = 34.0X
(3900×3900)*(3900×3900) = 47.3X
(2048×2048)*(2048×2048) = 28.2X
(1024×1024)*(1024×1024) = 58.8X
(512×512)*(512×512) = 24.1X
(256×256)*(256×256) = 6.3X
(128×128)*(128×128) = 1.1X
CPU: Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz stepping 06
GPU: nVidia Corporation GeForce 8800 GT (rev a2)

Note: This version only supports float32.
Note: CUBLAS limits matrix dims to (65536×65536).

Source code available here: pycublas.py (rename download to pycublas.py to use)