Parsing and visualising JSON

Over the last few days I've been working on a project that uses some fairly complex JSON objects. Because JSON (JavaScript Object Notation) is a lightweight data interchange format, it can be a great way to grab complex data structures via Ajax. It's been said that JSON is "the fat-free alternative to XML".

In theory JSON is easy to parse, but if your data structure starts to contain numerous nested objects and arrays, it can be come hard to keep track of and starts looking like a long jumble of punctuation.

I found Brenton Fletcher's JSON 2 HTML to be a quick and easy way to check your JSON syntax and visualize the data. You can either copy+paste a JSON string or sumbit a URL and the will page load the JSON string from the URL. It's definitely worth checking out if you're working with JSON.

Converting Media Formats

There are so many media format in common use these days that it's difficult to keep up with them, not just with when and why to use each format, but also being able to read them or convert between them.

Lately I found the need to convert a couple of different file formats that Windows isn't natively strong with. If you've ever tried to track down a codec for a slightly different format, then you'll know how annoying and confusing it can be, especially when you want to export to another format.

There is one tool I have found to be very useful in this area, and it's a great piece of freeware. The name of the application is "SUPER © Simplified Universal Player Encoder & Renderer".



Here's a warning though - the website is not very aesthetic or user firendly, but it's worth the effort to get the free fully functioned application with codecs included. Just scroll to the bottom of the first two pages looking for the download link, and then the actual download link should be on the third page. If I post the download page link here it'll just redirect you to the first page anyway...

Just to prove that it's useful, here a vdeo I made with a an old .m4a file that I could finally convert to a more useful wav/mp3 and threw together twith some screen captures from Winamp's Milkdrop plugin. I wrote this track years ago (when I was in my "synth" phase), the original files are long gone...

Hey, Where'd My Space Go?

Recently I was doing some routine stuff when I noticed the was a LOT less space on my main hard-drive than I expected. I was down to less than 500MB of space! I remember the days when I was smug about having a 30MB drive when the guy working on the next PC only had a 20MB drive. It's hard to believe in this age of relatively gigantic drives we can still fill them up without too much effort. I guess we can put it down to the ever increasing filesizes driven by higher pixel counts of digital cameras, the recent epidemic of software bloat, and the invention of peer-to-peer file sharing.

I needed to free up some space, so I dug out my favourite drive-space analysis tool. It's pretty lean and has a great interface, so I thought I would share it here.



This is Steffen Gerlach's freeware application for Windows called Scanner. Once the application has scanned your drive, you can drill down through each folder of the sunburst chart to easily identify what has been gobbling up your drive space. Admittedly the initial scanning can take a few minutes, but no more than it takes to grab a cup of coffee.

Installing Movable Type 4 on XAMPP

Yesterday, I finally got Movable Type 4 working on my development PC. I needed to install it for a project I am working on, and found it to be a lot more troublesome than expected. Movable Type is a weblog publishing system that was first released back in October 2001. It is written in Perl, and that's where the trouble started...

Downloading the latest version and setting up a virtual host for the test site was all as easy as I would usually expect. Then I pulled up the Quick Start Instructions to make sure I didn't make any assumptions. I carefully followed the process, making allowances for my install being on windows localhost, and met with failure after failure.

After much searching and reading, it became apparent that my old install of XAMPP required a Perl add-on patch. None of the download files I could find seemed to be the correct version, and since the current XAMPP installation package now includes Perl, I decided it was time to upgrade (see my previous post).

After the XAMPP upgrade, I started the Movable Type install again. More failures eventually pushed me to find a much more helpful installation guide from Brian Cantoni. Due to the multiple sites I have set up on my development PC, I used a different path in Step 3, and I chose to use SQLyog instead of phpMyAdmin for steps 4 - 6.

Step 7 is the crucial info missing from the Quick Start Instructions:

In the folder `c:\xampp\cgi-bin\mt4`, edit all the *.cgi files and change the first line to: `#!c:\xampp\perl\bin\perl.exe`

Unfortunately, Cantoni's guide doesn't mention how to handle the config file. Thankfully, you can find that information in Step 2 of this guide on etc. Another helpful hint in etc's guide is to use the MT system check script http://localhost/cgi-bin/mt/mt.cgi before trying to initialise your new install.

This is the point, I found that I still hadn't quite cracked it. I had some kind of Perl/mySQL install issue.

DBD::mysql
Your server does not have DBD::mysql installed, or DBD::mysql requires another module that is not installed. The DBD::mysql database driver is required to use MySQL Database. Please consult the installation instructions for help in installing DBD::mysql.

I resorted to installing ActiveState Perl to see how that compared. It wasn't the solution, but it did help me identify how to fix the DBD::mysql issue (I have subsequently uninstalled ActiveState). It seems that there was a dll file missing from C:\xampp\perl\site\lib\auto\DBD\mysql that XAMPP had already installed elsewhere on my machine. I copied the file C:\xampp\mysql\bin\libmysql.dll and pasted it into C:\xampp\perl\site\lib\auto\DBD\mysql and finally I had a working installation of Movable Type v4.31 on XAMPP v1.7.2.

PHP Parse Error: syntax error, unexpected $end

Yesterday I decided to upgrade my XAMPP install from (ye olde) v1.5.5 to (the current) v1.7.2. This was mainly precipitated by my inability to install Movable Type - apparently due to missing PERL libs. I like XAMPP. In my experience it's the easiest way to install the Apache/PHP/MySQL stack on a Win32 machine and I've been using it for years. So, since there was no simple upgrade path from v1.5.5 to v1.7.2, I set about backing up all of my development mySQL databases, and httpd.conf and extra\httpd-vhosts.conf files, etc...

I like to keep my root folder clean, so on the last install I'd opted for "c:\program files\xampp", but since I'd read that "program files" could cause major PERL problems, this time I installed in "c:\xampp". Installation went pretty smoothly, and I was able to drop in my old extra\httpd-vhosts.conf file with no problems. Then I re-imported the mySQL databases I needed and checked all my development sites were OK.

I did have an unexpected problem when I tested one of my sites - I was presented with the following error:

Parse error: syntax error, unexpected $end in {filename} on line {linenumber}

If you Google that error, you'll see a lot of pages stating that "it is caused by a missing curly bracket" or a bad class definition, which was definitely not the case for me. The cause in this instance was that this particular site's code was using Short Open Tags.

XAMPP's php.ini file states that Short Open Tags is a php.ini directive that:

"...determines whether or not PHP will recognize code between <? and ?> tags as PHP source which should be processed as such. It's been recommended for several years that you not use the short tag "short cut" and instead to use the full <?php and ?> tag combination. With the wide spread use of XML and use of these tags by other languages, the server can become easily confused and end up parsing the wrong code in the wrong context. But because this short cut has been a feature for such a long time, it's currently still supported for backwards compatibility, but we recommend you don't use them."

Due to the number of pages using these codes, I opted to update php.ini to allow Short Open Tags, but I fully endorse the above recommendation to use <?php in any new or updated code.

Finding the cause and implementing the solution was a simple matter, however I thought I should post a note about it here as the curly bracket comments could confuse some users, and hopefully this will help somebody. The default PHP setting for this directive is "On", (although XAMPP have disabled it in their install), so Short Open Tags will be supported unless your php.ini contains the following line - I'll let you decide if that's good or bad.

short_open_tag = Off

How to use Playstation Controllers on PC

Last week I posted how useful I'd found the wired SingStar mic's USB adaptor to be outside of the SingStar game. Writing that post got me thinking about the old PS2* controllers and how useful these could be. Like many PS3 owners, I wasn't keen to shell out £35 on a second wireless controller and purchased a PS2/PS3 USB adaptor. This works pretty well on Little Big Planet or any other games not reliant on SIX-AXIS motion.

Because I had purchased this adaptor for the PS3, it had not occured to me before now to try plugging this USB adaptor into my PC. I tried this today and was pleased to see it automatically install as "HID-compliant game controller" on both XP and Vista. The next thing I did was fire up TrackMania Nations Forever on the hunch that it would be fun to play with a game controller. The controller was instantly recognised although all actions seemed to be assigned to the buttons on the left side of the controller. I prefer steering on the left and acceleration on the right, so I went into the Inputs configuration.

This is the point where things started to get a little confusing. I had no idea which button was Button 0 or 1 or 4, etc. So after a little but of experimentation I put together this handy reference image.

I even tried this with an old PS1 controller and it also performed well (apart from the controller's buttons being a little sticky). The only difficulty I found (apart from mapping the buttons) was finding games that support game controller input, TrackMania is the only game I have installed that does. It is nice to play it with a controller though.

* Connecting a PS3 controller is a completely different process which is nicely addressed by davies lim and HowToGeek, although you map still find the the button map above to be useful.

Short rant about quotes

It seems to me that a high percentage of PHP programmers are making a simple mistake in their code that increases the execution time of their scripts. I certainly seem to be frequently fixing the problem in other people's code, whether I am maintaining a website, or using an open source class or plugin, etc.

To some, the following two statements might appear to be functionally identical, but in the second statement PHP has to parse the double-quoted content and check for any variables to evaluate before outputting it.

<?php

echo 'Hello World, so long and thanks for all the ghoti!';
echo "Hello World, so long and thanks for all the ghoti!";

?>


If you're thinking, "So what? It's just one line..." then you are not thinking like a programmer. "Expect the unexpected" is one of the first rules of defensive programming. Imagine using this statement in a function or method that is executed many times in one script, or if it's called a few hundred times from within a loop, and maybe on a page which suddenly gets ten times the traffic you expected. All those extra CPU cycles quickly start to add up.

Now, think about all the times that static text is used inside your scripts outside of echo statements, because they will be parsed in exactly the same way. It's easy to imagine how this can start making a difference to the resources your site uses.

In a nutshell, if you're not evaluating anything in the string, use single quotes.

NB: ghoti = fish.