"ERROR:  While executing gem … (IOError) Access is denied"

It cost me ours to figure out what was the problem.  Netbeans was trying to write to local ruby gems directory which is likely to on the system disk and is protected by Windows. The solution is simple:

Just run Netbeans “As Administrator”. I suppose you know how to do this since many program would have similar problem. In the case you are not sure, please right click you Netbeans startup icon and choose “Run as administrator” on the dialog.

Short story:

just type this:

getconf LONG_BIT

Longer story:

You can also type

uname –m

if it is x86_64, then it is 64bit.

cat /proc/cpuinfo doesn’t work in this case, because what it shows is about CPU. 32bit linux can run on 64bit CPU.

They should make this more obvious.

Basically you have to do two tricks: a) modifying the google tracking js b)creating a custom filter to make the results more readable.

Let’s suppose you own two sites, www.orangecabin.com and www.google.com

Step 1 : Create profile

You have to decide which domain is the primary domain,  and create a normal profile for it as usual. Since www.orangecabin.com is more important (I hope so), you use it. It really doesn’t matter which one you use.

Step 2 : Customize tracking js

Now google show you the tracking javascript you are supposed to add to your site. Copy the js, save it to a file and edit it to something like this:

<script type="text/javascript">
var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www.");
document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
</script>
<script type="text/javascript">
try {
var pageTracker = _gat._getTracker("UA-4966487-9");
 
// tracking multiple domains
pageTracker._setDomainName("none");
pageTracker._setAllowLinker(true);
pageTracker._setAllowHash(false);
 
 
pageTracker._trackPageview();
} catch(err) {}</script>

These lines are added:

// tracking multiple domains
pageTracker._setDomainName("none");
pageTracker._setAllowLinker(true);
pageTracker._setAllowHash(false);

You will use this js instead of the original one.

Step 3 : Create a custom filter

The customized js is enough for google to collect information for all domains, but it won’t handle domain names correctly, www.google.com/index.html and www.orange.com/index.html will be reported as the same page. So you have to add a custom filter. If you don’t know what it is, don’t worry just follow me.

Return to the profile list,  find the newly created profile and click edit

Find “Add Filter” on the new page

Click “Add Filter”, Create it using these parameters:

Filter Name: MultipleDomains

Filter Type: Custom filter > Advanced

Field A: Hostname

Extract A: (.*)

Field B: Request URI

Extract B: (.*)

Output To: Request URI

Constructor: /$A1$B1

as shown on this image:

Click save changes.

The next time you create another multiple-domain profile, you can reuse this filter instead of creating one.

step 4 add your customized js to your sites

That is it. Once you have enough data, you can get some report like this:

Ruby has “all-in-one” installer for Windows, but it is outdated. As of May 2009, Ruby 1.9.1 is released, the installer is still 1.8.6. If you want the latest version, you need the zip package. But the zip package is missing zlib.dll, libeay32.dll, ssleay32.dll and readline.dll . Here is how to install it on windows.

Download the file

First you download the 1.9 package from http://www.ruby-lang.org/en/downloads/
Choose “Ruby 1.9 xxx binary” instead of “Ruby xxx Installer”.

Install it

Just Unpack the zip to c:\ruby.
Then add c:\ruby\bin to windows PATH.
Open a windows command console and type
gem update --system
Oops, it is broken! The binary is missing some dll files.

Let us fix it

zlib

Download zlib windows binary from
http://gnuwin32.sourceforge.net/packages/zlib.htm

unzip the package, then find a file named “zlib1.dll”.
Copy “zlib1.dll” to your ruby\bin directory AND rename it to zlib.dll
What the heck?! Why renaming it? Because ruby source code reference the dll as zlib.dll. It is common to use alias like this on Linux. Ruby source was coded on Linux.

openssl

Download openssl windows binary from
http://gnuwin32.sourceforge.net/packages/openssl.htm
Unzip it.
Find “libeay32.dll”, copy to ruby\bin. Don’t rename it.
Find “libssl32.dll”, copy to ruby\bin and rename it to ssleay32.dll

readline

Download readline windows binary from
http://gnuwin32.sourceforge.net/packages/readline.htm
Unzip it.
Find “readline5.dll”, copy to ruby\bin and rename it to readline.dll

Done

That is all. Now type
gem update --system
then
gem install rails

It doesn’t have to be that complex. I will demonstrate how to create a simple plugin in 20 lines, the plugin can add some HTML to page footer and/or post.  This is an “Hello World”, so I won’t explain the plugin framework in detail but I will cover essential concepts.
This tutorial is for (newbie) plugin developers, it won’t explain how to use WP and how to code PHP.

Creating a plugin

Create a directory “simple-add-to-footer” under wp-content/plugins, then create a file “simple-add-to-footer.php”. Add this code to the newly created page.

<?php
/*
Plugin Name: Simple Add To Footer
Plugin URI: http://localhost/wordpress/
Description: Add HTML snippets to posts and/or page footer.
It is a plugin tutorial using latest plugin API of WP2.7+
Version: 0.1
Author: me
Author URI: http://blog.orangecabin.com/
Disclaimer: Use at your own risk. No warranty expressed or implied is provided.
*/
?>

This is called “Standard Plugin Information”, you can read more about it on http://codex.wordpress.org/Writing_a_Plugin. That is all it needs to be a valid plugin. Now this “plugin” can be activated like other plugins.

Adding something interesting

OK it does nothing till now. Please add this after the plugin info.

add_action('wp_footer', 'simple_add_to_footer_wp_footer');
function simple_add_to_footer_wp_footer(){
	echo '<div>Hello world! '. get_option('blogname') .'</div>';
}

If you activated the plugin now, you can see it print something in the page footer.

What is “action”

Here goes some theory : “action” is one type of the extension points of WordPress, that means you extend an action to do something to WordPress.
add_action is “the interface” between wordpress and your plugin. The 1st parameter “wp-footer” is a simple action which is called to produce page footer. The 2nd parameter is name of you function. And you do what you need in that function.
simple_add_to_footer_wp_footer calls get_option(’blogname’). It is a WordPress defined API to get blog options, like blog name.

Filter – another type of extension point

Now add this to the file

add_filter('the_content', 'simple_add_to_footer_the_content');
function simple_add_to_footer_the_content($content = ''){
	return $content .'<div>I am '. get_the_title(). '</div>' ;
}

Reload your blog page, now you can see it adds some info to the post.
Filter is another type of extension point. Instead of echo something directly, you get a parameter ($content) from WordPress and you can manipulate it, like upper case or something.

Conclusion

That is all. Here is what we have now:

<?php
/*
Plugin Name: Simple Add To Footer
Plugin URI: http://localhost/wordpress/
Description: Add HTML snippets to posts and/or page footer.
It is a plugin tutorial using latest plugin API of WP2.7+
Version: 0.1
Author: me
Author URI: http://blog.orangecabin.com/
Disclaimer: Use at your own risk. No warranty expressed or implied is provided.
*/
add_action('wp_footer', 'simple_add_to_footer_wp_footer');
function simple_add_to_footer_wp_footer(){
	echo '<div>Hello world! '. get_option('blogname') .' </div>';
}
 
add_filter('the_content', 'simple_add_to_footer_the_content');
function simple_add_to_footer_the_content($content = ''){
	return $content .'<div> I am '. get_the_title(). '</div>' ;
}
?>

You can download source code here: simple-add-to-footer_0.1
OK I know it is not really useful. But this plugin can be easily extend to do interesting stuff, like inserting arbitrary HTML code to page footer. To do that, you need a page for the plugin user to type the HTML they want to insert. The next post will explain how to do that easily using latest WordPress plugin API.