Related link: http://thedailywtf.com/ShowPost.aspx?PostID=25790

I’ve had a lot of fun reading “The Daily WTF?”. It’s a daily affirmation that I’m not the only one who boggles at the code I have to maintain. It recently got a big infrastructure boost, leading to my own “WTF?”.

The announcement for the new site says

After reading that SQL Server was out of my price range, Raymond Chen and some of the other wonderful folks at Microsoft chipped in to buy SBS03 (which of course includes the SQL Server software required to power the site on a new server).

WTF? Raymond Chen and other Microsofties had to buy SBS03? I would have thought that they could have pulled one off the shelf and sent it for free. What’s up with that?

That wasn’t my first WTF? with this announcement though. They didn’t have the money to upgrade, so why not switch to something that gets rid of the problem? Not everyone has to use my favorite free operating system or database server because there are plenty out there. Even if you want to keep using Windows, you can use some of the free database servers.

Other than that, though, it’s a fun daily read, no matter what they have under the hood.

According to the OpenOffice.org website and material I’ve read in various articles there are approximately 40 million users of StarOffice and OpenOffice.org. That’s a pretty big user base, roughly the same number as the estimated number of Macintosh or Linux users in the world. Yet, for some reason, books written about OpenOffice.org do not sell. Macintosh and Linux books sell very well.

There are a number of titles out for OpenOffice.org. From the information I can gather, which you must understand is limited because there is no accurate way in the book industry to know the total sales through to a customer of any book, is that the best selling OpenOffice.org book has sold about 8,000 copies in the past 18 months. That is “decent” but nothing to write home about. The next closest book has only sold about 2,000 copies. That means it isn’t selling well enough to have a second edition.

O’Reilly decided to publish a book on OpenOffice.org specifically geared towards the component most people use, the word processor Writer. This book, OpenOffice.org Writer: The Free Alternative to Microsoft Office by Jean Hollis-Weber is a reprint of a self-published title formerly called Taming OpenOffice.org. It is geared specifically towards intermediate and advanced word processor users like students and other academics and technical and professional writers. Despite excellent reviews on Amazon this book has not done well.

But back to the discussion of OpenOffice.org and the 40 million people who supposedly use this software, but strangely enough don’t buy books on it. I’ve come up with a number of reasons for this, and I’m sure the readers of this weblog could come up with more.

1) Maybe there aren’t 40 million users of OOo and StarOffice. There might have been 40 million downloads or licenses distributed, but there are not that number of full time users. For instance, I installed OOo 1.1 on all the computers I used to administrate so the users would be able to open OOo files should they receive them, but not a single one of those 30 computer users run OOo full time. In fact, I doubt any of them run it at all. I’m sure there are lots of other “downloaded” copies of OOo that suffer the same fate.

2) I believe one group of people who adopt OOo are very experienced computer users. They are making a conscious decision to use OOo because it saves them money, avoids proprietary formats, because its geeky cool, or because they have identified abilities in the software that they like or need and can’t get from other Office suites. These people are usually savvy enough that they may feel they don’t need help to use a simple Office suite, so they just wing.

3) Another group of people are those who may have OOo foisted upon them by their IS department or “bosses”. Maybe these people work for a school, non-profit, or small business and they have been given OOo instead of MS Office in order to save the organization money. These people only need the most rudimentary of functions and OOo in its basic form is similar enough to Word and Excel that they have little trouble grasping it. And since these people never purchased MS Office books to learn with, they don’t bother with OOo books either.

4) People for whom English is a second language may not buy an English printing of OpenOffice.org Writer no matter how much they need it. And, of course, people who don’t speak or read English at all won’t buy the book. With the growing adoption of Free and Open Source software (FOSS) internationally and in poorer nations this is going to become increasingly common. A growing populace of OOo users in such places really need documentation, but traditional publishers like O’Reilly won’t find it profitable to publish an OOo book in Portuguese when they can’t even profitably publish it in English. These users needs may get taken care of by publishers native to that country or by community written documentation.

5) Some people like to think that those who use FOSS programs are either pirates, cheap, or both. I don’t think this is universally true, but I do think that businesses, organizations, and governments who adopt open source solutions like OOo are interested in saving money. So, are these users too cheap, or just too poor to be able to purchase documentation. When you deploy OOo to a group of 1,000 users in your government for free exactly what documentation are you supposed to give them without spending $40 U.S. on a bible book? I would imagine most groups want something smaller and cheaper or are satisfied with the electronic documentation. This point also ties in with point 4 because many governments that are starting to use OOo are not English speaking nations.

6) I’ve noticed that a lot of technical books languish as middling sellers until they get some sort of exposure to a dedicated community, then they rocket to the forefront of book sales, particularly at online sites like Amazon. Exposure like this is sometimes a flash in a pan, and the book quickly moves back to obscurity afterwards, but other times the book continues to sell well once people became aware of its existence. Books reviewed favorably on Slashdot exemplify this trend. For instance, the recently released Knoppix Hacks was reviewed on Slashdot and in a matter of hours it was a top 100 seller on Amazon and briefly hit #1 in the Computer category. Whether it continues to sell well is still undecided, but its 15 seconds of Slashdot fame may be just the exposure it needed to become a top star instead of an also ran. Is it merely lack of exposure preventing a good OpenOffice.org book from starting down the path to best sellerdom? If so, exactly where does it need this exposure?

What all of this highlights for me is how little we sometimes know who our audience really is. I mean, just a couple of years ago who would have thought that a prime group of users of Mac OS X were really Unix nuts? When you walk around an open source conference like O’Reilly’s OSCon over 50% of the users have a Macintosh laptop, and probably less than 1% of them are running Linux on it. That’s one indicator that some Unix users were moving to OS X as a desktop OS, another was when O’Reilly took a chance and published Mac OS X for Unix Geeks and was rewarded with robust sales. And now that O’Reilly does know that many hackers with Unix backgrounds have adopted the OS X desktop, we were able to publish more titles useful to that group.

So, who is the group of users for OpenOffice.org? Because there aren’t yet any books that sell well to this group of 40 million it remains somewhat a mystery as to what these users want and need. A basic introductory title? A hacks book? A switching from MS Office book? And unfortunately, with sales of existing OOo books so poor most publishers aren’t willing and can’t afford to experiment in this field to find out exactly who this audience is or even if there is one.

If you’re an OOo user and are willing to buy books to learn OOo better, what type of information are you looking for?

Related link: http://news.bbc.co.uk/1/hi/technology/4022147.stm

Note: yes, I did file this one under “Web services”. Seems appropriate on too many levels.

In news of the Wild Wild Web, Mr. John Lockwood of Texas (where the heck else?) is planning to set up a hunt-by-Web site where people can remotely control a camera attached to a 22 rifle, and hope to bag big game with a few well placed TCP packets. I wonder how thorough the due diligence has been for this venture.

QoS: Hey, we’ve played FPSes on-line, and we know how annoying it is when Arm@gedn shows up with single digit ping and proceeds to annihilate the rest of the punters on the server. What happens when dude from, say, Crawford Texas logs on and has some fun snagging the choice specimens right out of the sights of his colleagues way out in San Diego 15 route hops away? BTW, will you be able to circle strafe antelope in the lockwood arcade? I don’t see how you have a chance any other way.

Market differentiation: Now that the Brady bill has lapsed without any move to replace it, will the Lockwood arcade soon have a Tek-9 fully automatic upgrade option? What about upgrading the Logitech familycam to a Predator[TM]-style laser sight with neurological implant control?

Security: Most of all, I want to know whether there is a failsafe in case Lockwood forgets to disconnect the router before wandering out to the range to restock? You never know whether there’s some humorless West Virginian logged on who happens to be disgruntled with his lousy lag.

What activity have you always dreamed of engaging over the Wild Wild Web? And no, don’t go there; the blue stuff has already been done to death.

I don’t use Windows, so I don’t get to use GMail Notifier. So I wrote my own. Now that GMail allows POP access, I can just check it that way. No big whoop.

#!/usr/bin/perl
use Mail::POP3Client;

$pop = new Mail::POP3Client(
	USER     => $ENV{GMAIL_USER},
	PASSWORD => $ENV{GMAIL_PASS},
	HOST     => "smtp.gmail.com",
	PORT     => 995,
	USESSL   => 'true',
	);

my $count = $pop->Count;
my $plural = $count == 1 ? [ 'is', '' ] : [ 'are', 's' ];

print "$ENV{GMAIL_USER}: There $$plural[0] $count" .
  " message$$plural[1]n";

$pop->Close();

Related link: http://www.tuxmagazine.com/

If you are the type who responds to friends’ pleas to “help me get
this virus off my computer” by deleting Windows and installing Linux,
you may find a perfect holiday gift for the convert in a new
magazine called
TUX
from SSC, the publishers of the ground-breaking
Linux Journal.

Linux Journal (which I read every month the moment it comes) covers an
enormous range of topics in Linux technology as well as business, law,
politics, etc. In contrast, TUX is an end-user’s magazine for ordinary
desktop users. The editor in chief is the renowned Marcel
Gagné, who describes himself as the kind of friend I mentioned
in the first paragraph and who can attest to the viability of Linux as
an ordinary person’s desktop system.

TUX was proposed by Marcel after noting the success of his Cooking
with Linux column for Linux Journal (it’s the only column
consistently aimed at a desktop user, and has been voted the readers’
favorite column four years in a row) and of his book Moving to
Linux: Kiss the Blue Screen of Death Goodbye!, which has been one
of the best-selling books about Linux the past couple of years.

What are the topics for the new magazine? They’ll be somewhat like
Cooking with Linux, somewhat like Moving to Linux,
and somewhat like whatever the authors propose. Marcel is looking for
a friendly, jargon-free approach and style, non-threatening to average computer
users. The magazine should be useful for home, office, and
enterprise users, including knowledge workers.

Lots of companies talk a good game about desktop Linux, but it’s a
good sign for the phenomenon that SSC is willing to put their money
behind this new venture. Linux can’t yet be called a regular household
item, but it could break through at any time.

And the breakthrough will probably happen first outside of North
America–so TUX will be marketed internationally.

I’ve expressed some opinions about this trend in my

Report from the first Desktop Linux Conference
and in a subsequent article,

To push desktop Linux, radical shift may be required.
Time moves on, though, and the requirements for a tipping point can
change. Speaking of time moving on, I’ve got a month left to drop
some hints to friends and relatives about their holiday gift.

Is Linux on your workhouse desktop yet?

Related link: http://www.zend.com/php5/andi-book-excerpt.php

I’ve been prejudiced against Java ever since the early days on the web on my Mac, where any web page that included a Java applet would crash my browser. Years later, any web page with a Java applet makes my hard drive churn for 8 seconds, freezing the computer until it loads Java into memory I guess, just to run a stupid mouse-hovering menu on a website. So of course this experience made me think of Java as some ridiculous stupid bloated language.

(Plus Java was often mentioned with that word “enterprise” that always makes me run the other direction, because you know the suits are near.)

Being a guy that just makes websites, I always ignored (or scoffed-at) Java. But as I was learning the object-oriented style of programming, most of the examples were in Java.

PHP5 comes out, and I get to know it and love it. Then I realized as I’m reading Java examples in articles and books - they all make sense now! PHP5 is just similar enough to Java that if you know PHP5, you can at least understand Java.

Reading Robert Kaye’s language musings, I’m feeling that PHP5 also fits the praise he’s giving Python : the power of Java but much faster to type. I’m very very impressed with PHP5.

Related link: http://www.refactoring.com/

Finally reading the famous Refactoring by Martin Fowler, and man, I think this is one of the best books on programming I’ve ever read.

It might has well have been called “How to Write Clean Code”! It’s NOT just for bringing your program to the hospital when it’s desperately sick! Don’t just wait until you need to re-write a program to read this book! It’s for every-day every-function every-line you write. A toolbox of ways to keep your code clean, whether something you wrote two minutes ago or two years ago.

Since I didn’t learn programming in school, but from scattered articles and books, I’ve read mostly on the microscope-level : how individual commands work, how to query a database, how to make a class and object, the basics of encapsulation, etc.

But I’ve always wanted to see shining examples of great coding that puts these ingredients together! (”Now that you know the ingredients - here’s how to USE them wisely.”)

Refactoring does that better that anything I’ve read to date, with perfect-sized examples showing just enough to make each point and show it in a scaled-down version of a real-world situation.

By the way, if you read it online in O’Reilly’s Safari Bookshelf, it has the even-better benefit of all of the refactorings mentioned being hyperlinked directly to the info about that refactoring! (Hm… just realized that sentence doesn’t make sense until you’ve seen the book. But he’s constantly referencing other sections of the book, so in the paper version you’re constantly flipping around to keep a few chapters open at once. In the e-book version, it’s just a click away, with a back-arrow.)

Related link: http://blogs.macmerc.com/rick/archives/2004/11/16/ichat_info_thei.php

On the internet, no one knows you are a dog, unless you are using iChat. Rendezvous users on the same network may be able to snarf your personal information without you knowing it.

In the iChat Preferences under “Privacy”, check the box “Block Rendezvous users from seeing my email and AIM addresses”. This doesn’t matter much at home because my wife and cats already know who I am, but at conferences I usually find a long list of Rendezvous users.

Related link: http://lists.xml.org/archives/xml-dev/200411/msg00196.html

Updated: corrected misattribution from Shelley Powers to Dorothea Salo.

Many times I have argued with Mike Champion, in private and in public, Semantic Web technologies are hardly some crazed figment of academic imagination. I don’t mean the grand Semantic Web dream of intelligent agents weaving an autonomous Web with minimal human meddling. I’ve always said that Semanitc Web technologies are very useful in immediate, less ambitious context. They are indeed the next common-sense step from XML syntax. One of my core arguments has always been that the success of XML drives directly towards SemWeb whether or not the journey goes through significant bodies of explicit RDF data. I was surprised to learn that last week Mike Champion wrote:

FWIW, my recent epiphany that the Semantic Web [1] stuff is not as
wacky as I once thought came partly through the possibly heretical
thought that there is no need to convert much actual data, and perhaps
not much metadata, into RDF. The powerful Semantic Web idea for me is
the notion of an ontology — meta-metadata if you will — that relates
concepts and relationships in real-world metadata (service
definitions, XML schemas, data dictionaries, etc.) to one another in a
way that supports automated inference. DAML-OIL and OWL are RDF under
the covers, I guess, but that doesn’t strike me as any more
interesting than the fact that they are serialized as XML. The power
AND the challenge comes from the modeling exercise of defining a
network of resource-predicate-value assertions that can be navigated
to automate useful tasks.

I suspect that “epiphany” was just a vague re-remembering of the long-standing arguments of those of us, the XML people who have never had much of a problem with RDF (excepting the horrid XML syntax). Not just me, but also Eric van der Vlist, Bill de hÓra, Joshua Allen, and more recently Norm Walsh, Roger Costello and Bob DuCharme. Someone (I think Bill de hÓra) used this group as a counter-example to Dorothea Salo’s infamous rant against RDF absolutism.

Personally, I have never looked at RDF without an eye to making explicit RDF unnecessary given well-designed XML. It has been almost four years since we designed the XML <-> RDF mappings in 4Suite. It’s not perfect, but the idea is that data is stored in XML and automatically mapped into a back-end RDF store as basically a metadata index that XML people need not worry about after the initial schema design. I’ve had a lot of discussions with folks like Paul Prescod and van der Vlist over the years about designing some sort of RNG schema annotation for this purpose, and I’ve seen parallel efforts along such lines from others.

I’ve tended to argue that a mapping to RDF may be the easiest way to SemWeb, given all the very good work that has been put into RDF, but I’ve never let my imagination be limited by RDF in its best-known forms. In my Thinking XML column on IBM developerWorks I have a long-running (almost 30 article now) development of the ideas of XML semantic transparency, and the fact that all the trappings of the Semantic Web become low-hanging fruit once one achieves semantic transparency (more easily said than done), whether or not RDF is the means to this achievement. OASIS core components or XML Topic Maps could be as much a path to SemWeb as RDF, although in my experience, RDF is simpler and much more “hackable” than either of these (or any other alternative I’ve seen).

I’ve hear a lot of castigation of Semantic Web technologies over the years. Of the many complaints I’ve heard, Mike Champion’s have always been the hardest to credit. He would argue from the point of ostensible “practicality”, along lines that would never have admitted the success of XML 1.0, and which were always contradicted by the growth and energy of the RDF community. This made it hard to understand where his “practice” was coming from, or what universe of developers it intersected (certainly not much of the very diverse universe of developers I’ve been lucky enough to work in).

One funny thing about the timing of Mike Champion’s posting is that it was two years ago that I first saw the idea of Semantic Web from XML in a more mainstream context. It was a presentation by William Ruh of Software AG, where Champion worked at the time. Ruh pointed out (and I was happy to hear a Veep type say what XML veterans had been saying in narrower XML circles) that the many industry efforts to standardize XML semantics were a path to the Semantic Web. I found other interesting people at Software AG (including Klaus Fittges, CTO) who saw practicality in and were looking to profit from SemWeb technologies.

In the end I keep coming back to my mantra. RDF is not an XML syntax. RDF is not a DBMS system. RDF is not an AI or inferencing system. RDF is just a specification of directed, labeled graphs (circa Somp Sci 201) with URIs as edge labels and URIs or literals as node labels. That’s all. I would claim that almost all abuse of RDF has stemmed from failure to understand this point. Maybe it’s too subtle a point? Seems clear enough to me, but I maybe I’m missing some complicating perspective. In any case it is nice to see others begin to come around to it (a lot of people have been taking off Semantic blinders lately, I’ve noticed). Welcome to the club, Mike.

Related link: http://blogs.sun.com/roller/page/MartinHardee/20040916#worst_practice_click_here

Writing for books is far different than writing for the web, at least when it comes to hyperlinks. Until the day someone invents a mouse for dead trees (or ink on paper stops being a great way to find information), books have to print hyperlinks without descriptive titles.

Web pages are far, far different though too many of them ignore that difference. Weblogs are particularly bad. (That sentence could have multiple meanings.)

The greatest sin of bad hyperlinking is not linking a link at all. The rule here is very simple. If you’re writing in a web page and want to give a link to another page, make it an actual, clickable link.

The next sin is omitting the link title. See the link to Martin Hardee’s weblog up above here? That’s a terrible example of a link; there’s almost no context at all. The only good news is that Martin’s provided an anchor which gives some indication of the link destination. Most links aren’t that useful. Links have titles for a reason; use them.

The third sin is even more prevalent — it’s giving links bad titles. “Click here” is one. “This” is another. Rephrasing an example from an article I’m editing right now (I don’t want to ridicule an author, but I do want to improve technical writing for the web), you might see:

You can see more details in <a href=”some_file.cfg”>my</a> system configuration.

I changed the link title to something like my some_file.cfg file. Now the link title describes its destination; there’s no surprise to the user.

One of the dozens of things Ward Cunningham did right in the Portland Pattern Repository wiki code is to JoinCapitalizedWords
to link to other wiki pages. Without any special syntax to make ironic or alternate link titles, users don’t have to go to any trouble to make coherent links! They happen naturally, in the flow of the text.

It’s true that writing an article that describes how to download and install, say, the latest version of MisterHouse, needs more complicated hyperlinks, but it doesn’t take much extra work on the writer’s part to make life much, much easier for multiple readers.

There are occasions where the style of writing allows for ironic linking (or bad linking, as I did above for didactic purposes). However, in technical writing, links are a tool for clarity. Used properly, they can provide powerful background or backchannel information. Used improperly, they will distract from the writing.

The final sin is overlinking, but if people start providing decent link titles, I’m happy to delete an extra hyperlink or two now and then.

Yep, it’s my pet peeve of the day. What do you say?

Related link: http://www.oreilly.com/catalog/knoppixhks/

This summer I had the pleasure of being the editor for the new O’Reilly book Knoppix Hacks. Though I had futzed with Knoppix before, and even created a customized version of it for an O’Reilly event, I was not a regular user of the live CD.

However, after seeing some of the hacks that the author Kyle Rankin put together I became much more interested. Knoppix is an incredibly versatile tool, in that it is a convenient medium for carrying a bunch of other tools that let you do some insanely useful and sometimes just fun things. Of course, that is the whole purpose of a hacks book.

The chapter I particularly enjoyed was Chapter 7: Rescue Windows. A collection of 9 hacks that showed me that even Windows users need a little bit of Linux in their life. On the strength of this chapter alone I think Knoppix Hacks (which includes a Knoppix CD) makes a great gift for the Windows geek in your life.

One useful hack tells the reader how to scan their Windows machine for viruses offline (well, from Linux running from CD actually), without fear of infecting the machine further, infecting other machines on the network, or sending keystrokes (and passwords) to someone else. If you’ve ever been frustrated by the need to connect an infected machine to the network to download virus definitions and had that machines infect others while you were doing this, you know why this hack is important.

A related hack tells you how to download patches from Microsoft’s website and put them on the Windows partition so you can apply them from within Windows when you aren’t connected on the network. This is useful because a freshly installed Windows XP machine on an unprotected network, like that which exists in most users homes, can be infected in just a few minutes. If you downloaded these patches while running the unprotected machine you could possibly get infected before the first service pack had downloaded.

Another hack allows you to restore corrupted system files. Using this hack I was able to instruct someone on how to replace a deleted explorer.exe on a Windows Me installation which was preventing Windows from booting.

One of the most useful hacks covers the ability to boot Knoppix and access a Windows hard drive to backup or retrieve important data. This is useful when you can’t boot into Windows because a virus, malware, or user mistake has rendered Windows inaccessible. Windows users sometimes find themselves having to resort to the OEMs restore CDs, and by using Knoppix they can safely backup their data before they blow everything away.

With the Resize Windows Partitions hack there is no need to purchase a third party tool like Partition Magic if you need to reconfigure your hard drive partitions. Likewise, the Clone Hard Drives hack in Chapter 5 makes it easy for users to backup an entire hard drive, or migrate to a new larger one without the use of third party software that needs to be paid for.

Many of the other hacks in the book also apply to Windows and Linux users alike. And since the book starts off with several easy hacks on using the Linux desktop, it is even a mini-tutorial on capabilities of Linux as a desktop system. Which means it is a good tool for Linux evangelism to your open source deprived friends.

With Knoppix, Linux is no longer just for Linux users.

At last, I finally have the sanity (or insanity) to delve back into working with my Lego Mindstorms set with Java. This time, I want to use Java and Lego Mindstorms for telerobotics.

I moved to a new home this past summer, and I have settled nicely in the new place. I also graduated back in May with my Master Degree in Computer Science. Thus, life has slowed down, and I have more free time to spare. So what am I going to do now with my free time and the upcoming “dead-time” in Massachusetts, the start of a predictably long and cold-harsh winter, besides watching college hockey?

I am not eager to shell-out money for a new hobby. I like to be resourceful, and use what I have. I also know that there will not be many opportunities for me to utilize much of what I learned and accomplished in my studies in Computer Science.

Then I thought about my Lego Mindstorms set. I was one of the lucky few that received one of the very first sets for Christmas nearly six years ago. I haven’t touched it since my Senior Design Project at Tufts, where my project was an improved bowling computer scoring system with pin tracking. I prototyped the pin tracking component using the Lego Mindstorms RCX brick with a light sensor, programmed using Java.

Ah yes, I programmed the Lego Mindstorms RCX brick using Java. More specifically, I used leJOS, the firmware replacement (a 32 K Java Virtual Machine) for the Lego RCX brick that enables me to program Lego Mindstorms robots in Java. Software such as RCX Code (which comes with the Lego Mindstorms set) and ROBOLAB were great for fun and education, but they never provided me a whole lot of flexibility, considering my programming experience. Furthermore, I could never have the ability receive or send commands to the RCX brick directly from my PC. When the leJOS project was released, it was a blessing for me, and it gave my Lego Mindstorms some new life. My pin tracking prototype was simple: one light sensor beneath a pin. I would press the RUN button on the RCX brick to read a value for the light (low value for dark, bowling pin standing; high value for bright, bowling pin down), and then send the information to my scoring system interface. You see the issue here is that I have to press a button on the RCX brick to trigger an action, instead of triggering a command on the scoring system to the RCX brick to read the light value. But for some reason, I could never get the latter capability to work –telerobotics, commanding a robot from remote distances (the most famous examples are used in medical operations, and by NASA to explore Mars).

I thought more about the problem. If I could successfully resolve the dilemma, then it would open up a world of technical and professional development opportunities for me. I never really had the opportunity to work with microprocessors or hardware projects during my studies in college. The RCX brick is essentially a microprocessor. This endeavor would also be an opportunity to utilize many facets of Computer Science and the physical sciences including Human-Computer Interactions/User Interfaces, Artificial Intelligence, Algorithms, and Physics.

First things first, I bought new batteries for the RCX (requires 6 AA batteries) and for the IR tower (requires one 9-volt battery). I have not touched both devices for over a year. I downloaded and installed the latest version of leJOS onto my computer (Win32 version), and I downloaded a fresh new version of the leJOS firmware onto the RCX (via serial communication port). One of the major differences for me now is my experience with the Eclipse IDE, which makes creating, managing, and debugging Java applications significantly easier. The last time I worked with leJOS, I did not have a satisfactory Java integrated development environment to suit my needs and resources.

In particular, I am interested in creating a Java client application using AWT and Swing that will allow me to control the RCX. For now, I am not interested in creating an interface on the web that will allow me to control the RCX because it will involve time setting up a web server and among other things. For a simple test, I wanted to create an interface that will allow me to run and stop a motor connected to the RCX. Thus, the interface will consist of two components: a client program with one button to run and stop the motor, and a program on the RCX to listen for inputs from the client program on the PC.

I created a new Java application project in Eclipse and imported the leJOS class files into my project (external JAR files in the .../lejos/lib directory). I tried using some leJOS plugins for Eclipse and found them to be cumbersome (e.g. valid statements that references the RCXBean class not recognized). I create a client program with one button to start and stop a motor on the RCX, and a program for the RCX to listen to the actions from the client program. In the client program, I used the RCXBean class to communicate with the RCX, which was trivial to do.

I connected a motor with a wheel to the C motor port on the RCX. I turned on the RCX, compiled and downloaded the RCX program to it, and ran the program by pressing the RUN button. The motor is idle and the RCX is waiting for an input. I compiled and ran the client program via Eclipse. A window with one button labeled Start Motor appeared. When I pressed the button, the motor ran with the wheel spinning, and the label of the button on my client program changed to Stop Motor. A few seconds later, I pressed the newly labeled button, and the motor stopped! I repeated the process several more times, and my interface worked without any problems.

I skipped through some technical details above. Thanks to my time, and after looking into the leJOS framework much further, I can now create Java client programs, and even web applications, to communicate with my RCX brick. This past weekend, I also created an interface that allows a user to press a touch sensor connected to the RCX, and the signal is sent to a PC client program. The source code for the motor interaction example above (see MotorControl1RCX.java, MotorControl1Client.java) and for the touch sensor interface (see SensorControl1RCX.java, SensorControl1Client.java) are available on my personal website. I am excited about this development, and it opens many possibilities. Certainly, I can create even more complex user interfaces to communicate with the RCX. For example, a control system for fictitious cable car or transportation system. Or how about a fictitious energy management control system (solar panels)? Or a small-scale surveillance system that measures environmental information (e.g. temperature) and returns data to a client program on the PC? The educational benefits from using Lego Mindstorms with leJOS and Eclipse are tremendous. For cost-conscious curricula, the software involved is open-source and can be downloaded for free. This can be a great advanced learning experience for those who have mastered the traditional drag-and-drop Lego Mindstorms applications. There are possibilities for educators to build small-scale fictitious systems to illustrate real-world scenarios. I am sure I will have more news and developments soon.

UPDATE (November 25, 2007): Due to the continuing interest on this project, I created a project on Google Code at http://rcx-telerobotics.googlecode.com/. Source code examples are available there.