As reported earlier I had been given an Arduino Uno. I subsequently received my Ethernet Shield to hook the board up to the network. I’m clearly heading towards the Internet of things… Although I am still not 100% certain about what I’m going to do with the board (or how many additional ones I am going to have to buy) one things is pretty clear: It will have to be controllable and/or configurable over a web interface.

I found the Webserver example that ships with the Arduino IDE to be rather dull and unflexible. It wasn’t long before I stumbled upon Webduino, a very flexible generic Web Server library originally written by Ben Combee. The Webduino project homepage on Google Project Hosting points to this GitHub page. I downloaded the version adapted to Arduino 1.0 and started hacking away. Let me say this now: Webduino does meet my expectations.

However after a short while I ran into problems. None of them were to blame on the library, but rather on myself, but that’s actually not the point of this post… When I ran Wireshark to look at the data going over the network I noticed that for every page loaded Firefox also tries to download favicon.ico from the web server. Since Webduino sends a 400 error back on any requests for resources that have not been defined Firefox just keeps retrying forever.

At around the same time I discovered that, to avoid excess traffic from robots, there is a default robots.txt built into Webduino. So I decided to add a default favicon.ico, based on the icon used in the “Web_Image” example that ships with Webduino. Now when the first page is requested, Firefox loads the icon file, which actually eats more resources than one 400 error, but it pays off down the road when Firefox caches the icon and does not request it again, saving the Arduino from having to generate many 400 errors…

Webduino "Hello World!" page with favicon.ico

Webduino "Hello World!" page with favicon.ico; this is the default favicon.ico in my version of Webduino

And since I see projects hosted on GitHub as an open invitation to fork I ended up with my own Webduino project on GitHub. Feel free to look at the code, to fork, clone, whatever (MIT license), and to let me know what you think! (Oh, and I gave the readme some TLC and also added a keywords.txt file for syntax highlighting.)

Update: I started to write a “beautiful” API documentation

I found an Arduino Uno under the X-mas tree:

Arduino Uno

I’m still waiting for my Ethernet Shield to ship. In the meantime I wanted to get started with some of the “simple” stuff like controlling single LEDs, triggering events using pushbuttons etc. It came in handy I still had my 1980′s “Kosmos electronic X3000″ workshop kit around, which I used to experiment with when I was a teenage nerd:

Kosmos electronic X3000 workshop

I guess I’m still a nerd: My heart jumped a bit when I found out they seem to still sell these things.

Here’s what they look like in combination:

Arduino Uno with Kosmos "breadboard"

You and I know that talking about new ideas prematurely is the best way to kill them. Anyhow you should expect some Arduino related posts over the next year or so…

Some of my clients are using their WordPress installs with pages only, i.e. without any posts, and with comments turned off completely. This is often referred to as “WordPress as a CMS”. To free the screen from clutter I like to remove the comments link from the new/revised WordPress 3.3 Admin Bar. I also usually change the “+ New” link to default to creating a new page instead of creating a new post.

To accomplish this you can drop the following lines into your theme’s functions.php file:

function my_admin_bar_menu( $wp_admin_bar )
  $wp_admin_bar->remove_node( 'comments' );
  $newpage = $wp_admin_bar->get_node( 'new-page' );
  $wp_admin_bar->add_node( array( 'id' => 'new-content', 'href' => $newpage->href, ) );
add_action( 'admin_bar_menu', 'my_admin_bar_menu', 100 );

To find out more about the Admin Bar API you should check out this post by Andrew Nacin on the official WordPress Development Blog.

Since the upgrade to version 3.2.2 Nagios does not update the host alias macro when the configuration is reloaded. Macros are the variables used in commands, such as notification commands, i.e. the information you receive via E-mail when there is a problem with your hosts or services.

As long as you don’t change your host alias information you will never notice. I did change it and I found myself scratching my head for some time, especially since the same information does get updated in the web interface.

I found a greater number of forum discussions relating to this, but none seemed to offer a practical solution for larger scale environments.

After some pondering I came up with these lines:

service nagios stop
cp /usr/local/nagios/var/retention.dat /usr/local/nagios/var/retention.bak
grep -v ^alias /usr/local/nagios/var/retention.bak > /usr/local/nagios/var/retention.dat
service nagios start

They do the trick in my installations.

Update: Here’s a brief summary of the error and what the script does to work around it.

When Nagios parses the configuration and finds a new host it loads the alias field into memory. When Nagios reloads the configuration, the alias information that is already in memory does not get updated. When Nagios stops (or before reloading the configuration) the alias information in memory is dumped to the retention.dat file. When Nagios isn’t running and you start the service, it doesn’t load the alias information from the configuration files but from retention.dat, unless that information is not present in the file. So my solution does the following:

  1. Stop Nagios
  2. Make a backup copy of the retention.dat file (Note: I’m copying the file instead of renaming it to make sure that it will still have the same owner/group and permissions when I write to the original file in the next step)
  3. Strip all lines starting with “alias” from the backup file and overwrite the original retention.dat file with this data
  4. Start Nagios

You may have to tweak the file location for the retention.dat and backup files. You may also need to change the commands that stop and start the Nagios deamon.

The next version 1.1 of my Open Graph Pro WordPress Plugin will feature an API (a public method and two filter hooks) that can be utilized by theme and plugin developers who would like to add “Like” buttons to their blogs. The API also allows you to add Custom Object Types.

If you want to test-run the API go to the Open Graph Pro download page and grab the Development Version. The API is not going to change anymore. The code is also pretty much final. I’m merely working on some final UI touches and i18n/L10n of the plugin.

Code snippets for adding “Like” buttons or using Custom Object Types are part of the API documentation.

I just released version 0.4.2 of my Comment E-Mail Verification WordPress plugin. Most important change: verification codes are no longer being generated (and thus no longer cluttering up the database) for trackbacks and pingbacks. Thanks to Joost de Valk who contributed a few lines of code that ultimately took this important aspect off my todo-list.

As always: Download it directly from the plugin directory!

So I’ve been playing around with Google+ for a little. And then +Lars Becker actually made me “Send feedback” to Google… seems that they have a little problem with their privacy settings:

If you hide who’s in your circles from your profile page, but then post something to a circle, people can click on the word “Limited” above your post and see a list of people who you’ve shared this post with, i.e. a list of the people who are in your circle(s).

If you’re on Google+ please click the “Send feedback” in the bottom right corner and let Google know so they can fix this ASAP!

If you want to add me to your circles, here’s my profile: +Martin Lormes (get used to the “+”!)

BTW: +Lars Becker also made the point that given enough posts to varying audiences one could even find out who’s in what circle (except for the names of circles, but the groups will be self-explaining I guess).

Peter Westwood and some other WordPress core developers have written a great plugin for WordPress plugin and theme developers: the Debug Bar. It plugs into the Admin Bar that was introduced with WordPress 3.1 and outputs various details about the current page, but to (super) admins only.

Thanks to the consequent usage of WordPress Plugin API functions there is a fairly easy and straightforward way of outputting your own debug information into the Debug Bar.

Your own Debug Bar Panel

You should create a separate file for your Debug Bar tab, let’s call it my-debug-bar-panel.php, and place it in the same directory as your plugin file or your theme’s functions.php file. In this file you create a child class of Debug_Bar_Panel, e.g. my_Debug_Bar_Panel, with at least one method render() in which you can output everything that should be on your tab.

class my_Debug_Bar_Panel extends Debug_Bar_Panel
  function render()
    echo '<div id="my-debug-par-panel">';
    echo '<h3>Some header</h3>';
    echo '<p>Some debug output</p>';
    echo '</div>';

Now back to your main plugin file or functions.php: You need a function that hooks into debug_bar_panels. I put a double check in my example to make sure the base class Debug_Bar_Panel exists (since you never know whether they drop this in a future release which would cause fatal runtime errors). Then you create a new instance of my_Debug_Bar_Panel with the title, which you would like to see on your tab, passed to the constructor:

function my_debug_bar_panels($a)
  if (class_exists('Debug_Bar_Panel'))
    require_once dirname(__FILE__).'/my-debug-bar-panel.php';
    $a[]=new my_Debug_Bar_Panel('My tab title');
  return $a;
add_filter('debug_bar_panels', 'my_debug_bar_panels');

Believe it or not, you’re done!

Here’s why I don’t normally apply updates on the first day: Backdoors in three popular WordPress Plugins

June 22, 2011 | No comments

I have just released my newest WordPress plugin to the public:

Open Graph Pro automagically adds Open Graph Protocol metadata to your WordPress powered blog/website. Through the Open Graph Protocol you can control how your posts and pages appear on Facebook when someone shares a link or likes your stuff.

The plugin does not add any “Like” buttons to your site just yet, but that’s on my to-do-list.

It does however give for a great deal of customization already by allowing you to change the object type of your entire site as well as the object type of individual pages, e.g. when you have a single page for each album or song of your band, or for each product of your company, etc. If you go to the settings page in the admin section of your site you can enter your Facebook user ID and give your site/blog the full potential of a Facebook page.

And just in case you’re wondering: I’m not using this plugin on this site at the moment, because liking or sharing stuff on Facebook only looks good with images, or it actually looks really crappy without them, and as you may have noticed I have very little eye-candy on my site at the moment. Now that the majority of all the coding is done I will focus next on the visual aspects of this blog, and then install the plugin when things have become more graphical around here…

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