“Life” is an example of cellular automata. All the activity takes place on a 2D grid of cells, where each cell is either “alive” or “dead”. Then from generation to generation whether a cell is born, lives or dies depends on some very simple rules:

• If a cell is alive and has 2 or 3 neighbours, it survives
• If a cell is alive and has less than 2 or more than 3 neighbours, it dies
• If a cell is empty, and has 3 neighbours, a new cell is born

From these simple rules, a huge array of patterns quickly coalesce out of even a random grouping of cells. Patterns like “traffic lights” which switch from 3 cells in a row horizontally, to 3 cells in a row vertically. Or “gliders” a shape that seems to “roll” in a way that means it moves one cell across, and one cell down ever 4 generations. Some people have even implemented simple adding computers using patterns on a “Life” grid, using gliders like electrical signals. Admittedly, probably not the fastest computer ever built…

So, I’ve now built a web page called “WebLife!” that gives you a random grid of cells and lets you single-step or automatically fast-forward through the generations that result. You can access it here:

http://www.asman-it.com.au/weblife/

And the page looks like this:

Screenshot for the WebLife! web page

Using the site is simple enough (if only because the functionality is pretty limited!). Refresh the page to get a “fresh” random grid, then use the Play icon to advance one generation at a time, or the Fast Forward icon to step through generations until the Stop icon is clicked.

I have a few features planned over the coming weeks, including:

• Ability to edit and “draw” your own patterns on the grid
• Ability to change the speed of “fast forward” playback
• Ability to set the grid to “wrap-around” so one side of the grid wraps around to the other side
• Ability to set your own rules, to explore the different patterns that result

As the WebLife page says, any feedback or suggestions are welcome. Happy exploring!

I did encounter an issue early on, though. My Kindle is the 6″ WiFi only model. When I first unpacked it, I connected it to my home wifi network, registered it, and downloaded a few books without any problems. By the end of the first night, though, it refused to connect to the network. Attempting to connect manually through “Settings” results in an error message:

“Your Kindle is unable to connect to the Wifi network. Would you like to enter the password again or manually set up this network?”

After trying a whole host of fixes, a factory reset seemed to clear things up. But the next time I went to use the Kindle, the problem re-occurred. Even upgrading to the latest Kindle firmware (3.02 beta) had no effect.

Finally clutching at straws, I looked at the other half of the wifi equation – my Wifi router. I have a Billion Wifi router (a BiPAC 7401VGPR3). It was running firmware 5.53.s5. Checking out the Billion web page, I found that a few releases had occurred since then, and the latest was 6.02c. I also noticed that the release notes for the 6.01 firmware mentioned “Updated wireless 11N driver to 2.2.0.3″.

Thirty minutes later and I had updated my router, and the Kindle was again connecting flawlessly. Moral of the story (as always) is to make sure that when bugs surface, you’re running the latest and greatest of the relevant pieces of software.

Hopefully this will come in handy for any similarly frustrated souls who are googling for a solution!

The installation documentation is incredibly extensive. Alas, I work in IT which means Murphy’s Law guarantees that the environment I’m given to work in will be unique, complex, and a million miles from a “Standard” setup. Consequently, I was dealing with reverse proxies, apache front-ends, https issues and more besides!

One issue that I did spend a while on was this one: http://jira.atlassian.com/browse/JRA-19051. Basically, JIRA has problems when installing on Tomcat 6 if you want to use a Context that is multi-level. So, something like “/servlets/JIRA” rather than “/JIRA”.

The fault is actually with Sitemesh that JIRA makes use of. Tomcat 6 uses a naming standard based on hashes as separators to specify a multi-level context. So, in the example above, the context XML and exploded WAR file is stored as “servlets#JIRA”. Unfortunately, this confuses Sitemesh who tries to drill into the expected Context directory structure and complains that directory “servlets” does not exist.

The issue linked to above is still unresolved and was raised in September 2009, so I suspect it’s probably a pretty low priority. I was able to work around it however by inserting the “<context>” stanza for JIRA in the main server.xml file rather than in a file of its own.

While this isn’t the preferred Tomcat way of doing things (any changes I make will require a Tomcat restart), doing the Context entry this way allows you to use the path attribute, where you specify the full Context path. Using a standalone Context file, you can’t use this attribute – it is inferred from the (special, hash-separated) file name.

I also used the docBase attribute to point to the exploded WAR file. I placed the exploded WAR file under the standard webapps directory, but nested to match the multi-level context path (so, something like …/webapps/servlets/jira, rather than the more Tomcat-6-normal /webapps/servlets#jira).

This was enough to get me up and running. I suspect it might also be possible to do something using an Apache proxy, whereby Tomcat thinks it is running single level contexts (/jira) and Apache proxies the requests to those single levels (so it converts requests for /servlet/jira to simply /jira). Unfortunately this wasn’t possible in the environment I was running in, so I haven’t pursued it any further.

Hopefully this run-down is helpful to anyone else who hits this issue!

I’m in the process of getting my head around Scala, but when installing the Scala Eclipse plugin into my standard Eclipse Europa setup, I got the message that Scala Plugin couldn’t be installed because it required “org.eclipse.pde.runtime”.

I found a few references on Google, suggesting a full installation of Eclipse (i.e not a standard install), or reverting to Eclipse 3.2.

Instead I had success by:

1. Go to search for new plugins with “Help” -> “Software Updates” -> “Find and Install”
2. Choose “Search for new features to install”
3. Select the “The Eclipse Project Updates” repository”
4. Expand the “Eclipse SDK Eclipse 3.3.1.1″ category, and select the “Eclipse Plugin Development Environment”

This plugin includes the required “org.eclipse.pde.runtime” package, so once installed you should be able to get the Scala plugin up and running.

Now all I need to do is to relearn functional programming from my Uni days…

There was a time when I was a Linux guy through-and-through. I moved back to Windows on the desktop when I got a new machine (although my servers stayed Linux…of course!). So, its fair to say I’ve been out of the scene for a while and didn’t really know where the state of the Linux art was at.

But thinking about it, 95% of my time on the laptop is spent surfing the web, doing email, and writing the odd document – Linux can do all those with ease. So, with nothing to lose, I used the new Vista functionality to shrink my C: drive, and went about installing Ubuntu Linux on the newly created space.

Wow!

So straightforward! I downloaded the ISO image, burnt a CD, and booted off it. 30 seconds or so later, I was looking at a Gnome desktop with a fairly full complement of available applications, and an “Install Ubuntu” icon. Great way to do things – you can try out the OS, see if your machine has any incompatible hardware, and if not, proceed with actually installing it to your hard drive.

Seeing no obvious problems, I hit install, and 20 minutes or so later I had a laptop which let you choose Vista or Linux at bootup, and proceeded from there.

The experience has been fantastic. From the get-go, my Dell Inspiron 6400 laptop could see all the surrounding wireless networks, handle sound (even the custom volume up/down buttons work a treat!) and had all the software installed to surf the web, read email, and write documents and spreadsheets.

Thats not to say it was all smooth sailing – getting the laptop to actually talk to my WPA-protected wireless LAN took a bit of work – the built in graphical client didn’t want to connect, but once I put the appropriate details in /etc/network/interfaces it was all good. That’s pretty much been the only hiccup!

I’ve installed a few more things now – Google Earth is up and running (way to go Google, for supporting Linux!), the latest JDK is in, and my one indispensable piece of software – the Eclipse IDE – is up and running (pictured). This is one of the joys of doing Java development – the Operating System I choose to use is almost irrelevant – I don’t necessarily need to be running a system identical to my clients.

Since I’ve installed Ubuntu, there has yet to be a single reason to boot into Windows. Ubuntu even lets me read my Vista NTFS-formatted partition, so I can still get to all my music and documents. I suspect that what I may end up doing is setting up the laptop as a pure Linux system, with a VMWare image if I do come across something which absolutely requires Windows.

So, the technical details first – the installation was a snap. Just like the 2.0 series, a quick unzip and point your browser to a particular page, and minutes later the blog is up and running. From the admin perspective it feels like an incremental improvement – things seem a bit snazzier and smoother, but its hard to put your finger on any one “knock-your-socks-off” feature.

One item worthy of note is that the editor is much improved, so you can do your posts in the WYSIWYG editor reliably (I found the earlier incarnation a little flaky – so much so that I turned it off, and did my posts “manually”).

In terms of the new blog, this setup was all about bringing the latest incarnation Low Impact to life. A while back, I’d noticed that more and more of my posts had an environmental leaning which, while not clashing particularly, were starkly different from my tech-related posts. So, as an experiment, I setup a blog on Blogger called Low Impact.

I got a lot out of the experience – enough to know that:

• I liked the setup of having a specific blog for environmental topics, freeing up dasman’s World for more tech-related postings, and
• While Blogger is a great site, nothing beats having full control of your own website!

So, the domain was registered, a webserver setup, and WordPress 2.1 installed.

Low Impact’s purpose is to provide postings specifically about reducing our impact on the environment. If that’s a topic that interests you, you might want to check it out!

Hmmmm. Let me think….. *scratches head* There must be something….

• I’ve continued to spend far too much time cursing at J2ME. When it comes to UIs, you either have full, low-level control where you draw every single pixel yourself, or you have almost no control where you populate a Form with Items and wonder what on earth it will look like on the various platforms. If only there was a happy medium… And yet, despite my complaints I can’t walk away – the lure of knowing your program can run on potentially so many devices is too much!

• I gave NetBeans another shot for my J2ME development with version 5.5, and decided all is forgiven. It feels way “snappier” than version 5, and I haven’t had it hang on me while using the Visual Designer part of the Mobility Pack (which is the killer feature for me). Good work guys!

• I’ve upgraded WordPress around 50 times to cope with all the dot releases that have been coming out. I’m actually getting a bit excited about the big 2.1 version due out soon – I have a sister working overseas who has been a blogger in the past and toys with getting back into it – perhaps a snazzy new piece of software will be the impetus she needs!

• I finally decided to sit down and tick off something thats been on my To Do list for about 6 months now, and upgrade the search page at www.asman-it.com.au to use the new “inline” Google search results. And, like all things you put off for ages, it took around 10 minutes (although admittedly my page won’t win any prizes for aesthetic or robust web design!).

So, we’re back up to date. Perhaps my next post will be a little more on-time!

So, taking advantage of a long weekend here, I decided to upgrade SpamAssassin.

Wow.

This morning, I opened my Inbox to find 0 spam messages. And a quick look at my “Spam” folder showed that 65 spam messages had been caught – the majority of which had been caught at the server. The new setup has only been running for 10 hours, but that certainly looks promising!

Upgrading to the latest engine no doubt helped, but there have been two specific “extras” that I think are making a big difference.

• I’ve added the Net::DNS perl module to my system – I gather SpamAssassin uses this for RBL lookups and the like. When I first installed SpamAssassin, I didn’t bother with this – it lists a pile of optional modules you’re missing, but is happy to build without them. Net::DNS is one of these “optional modules”. I’d recommend you consider it mandatory!
• I’ve enabled Bayesian filtering. This is the feature that allows SpamAssassin to “learn” which messages are spam. It is a bit of a fiddle – permissions in particular are the big gotcha – but I’m hoping that this will also help keep my spam defences “ahead of the curve”.

So, as all serious programmers know, you need fuel when your churning out top-quality code. Salty, calorie-laden fuel! Some swear by pizza. Others are into chips. BBQ Shapes are my programming snack of choice. I love it when you get one that has a lot of the “topping” – that salty red powder that gives ‘em their flavour!

But you can have too much of a good thing. Tonight, I reached into the box and pulled out a handful of Shapes to find, well….this:

(I promise, the biscuit is not a setup, thats how it came out of the box, and that spice “stuff” is packed on there like cement!)

Wow. Next step is to put it up on EBay, right? Surely there’s people who’d pay good money for that sort of “flavour explosion”!

Part of the blame (or thanks?) has to go to the centameter – a device telling you your current household power consumption, which I’ve blogged about before. The old adage “out of sight, out of mind” was never truer than for electricity consumption. I turn on the electric wall heater (I know, I know, don’t get me started), and the centameter tells me my power consumption has shot up from a modest 0.3 kW to a planet-destroying 5.9 kW. Eeeek!

But I’ve found the power tyrant lifestyle requires surprisingly few concessions. When I had the urge to make this blog entry, I fired up the laptop. Even when plugged in, it only uses 50 to 80 watts or so. In the past I would have fired up my high-powered “beast” PC – gigs of RAM, masses of harddrive, and around 200 watts of awesome processing power….none of which is needed when typing in a few paragraphs of text into a blog!

Never one for self-sacrifice, I still use my planet destroying electric heater (I live in Canberra after all – anyone who knows Canberra will understand the heating requirements!). But the heater no longer gets turned on by reflex just because I’ve walked in the door after work. I come home, I get changed into reasonably warm clothes, look at the temperature guage and actually think about whether I’m cold. And whether, perhaps, a pair of daggy slippers wouldn’t do the job just as well!

There are other examples too – like not filling my 8 cup kettle to the brim to boil water for one cup of tea. Or, after my centameter smugly pointed out my climate-change-inducing 3.8kW power draw when the hot water heater goes on, making sure my washing machine was doing cold washes. All easy stuff, and requires next to no lifestyle-sacrificing either!

There’s no rocket science, obviously. And (having undeservedly acquired the “hippie” nickname at work much earlier ), I was already aware of all these little power-saving tips. But its amazing what incentive you have to improve when there’s a little white digital meter metaphorically tsk-tsking at you from the kitchen bench.