waelchatila.com - java tag

Turn your roomba into a walking google bot

Tue, 02 Mar 2010 07:26:00 GMT

When my latest son was born I got a little worried since he didn't look at all like me. I decided I needed a discrete device to spy on my wife while I was at work. I started hacking my roomba and made a GåågleBot (pronounced /google-bot/). GåågleBot is a "home crawler" consisting of a vacuum roomba with an on board webserver and camera. While the vacuum goes about its business, it extracts text from the images it takes. The text is later put in a database on the roomba and searchable through a web interface. This was a good pretext for my wife. I, of course, also added the ability to remote control the roomba using AJAX...for spying purposes...hehe.

I created a dedicated site for the little fellow for fun with showcase app. http://www.GaagleBot.com

This is the next version of My AJAX Lego Robot. I'm working on yet another version of my AJAX Remote Controlled thingies...stay tuned.

Running Jetty as Non Root

Wed, 21 Jan 2009 07:16:00 GMT

I'm kicking the tires of Jetty and am in the process of setting it up on a production machine and found that the latest Jetty realeas (6.1.14) has a really easy way to start jetty out running as root and later switch to a uid of your choice which enables you to open up server sockets on the privileged ports 80 & 443. See the README file under {jetty.root}/extras/setuid. The process is just a one-liner...well, there are some more perks as you'll see at the end.

The README seems little bit out of date as my

mvn install

did all of the compiling and copying steps. However, when I try to launch jetty with the new jetty-setuid.xml config file I get the following error.

2009-01-20 23:10:33.887::WARN: Config error at <Set name="uid">jetty</Set> 2009-01-20 23:10:33.888::WARN: EXCEPTION java.lang.reflect.InvocationTargetException at java.lang.reflect.Constructor.newInstance(libgcj.so.81) at org.mortbay.xml.XmlConfiguration.set(XmlConfiguration.java:405) at org.mortbay.xml.XmlConfiguration.configure(XmlConfiguration.java:248) at org.mortbay.xml.XmlConfiguration.configure(XmlConfiguration.java:214) at org.mortbay.xml.XmlConfiguration.main(XmlConfiguration.java:974) at java.lang.reflect.Method.invoke(libgcj.so.81) at org.mortbay.start.Main.invokeMain(Main.java:194) at org.mortbay.start.Main.start(Main.java:523) at org.mortbay.start.Main.main(Main.java:119) Caused by: java.lang.NumberFormatException: invalid character at position 1 in jetty at java.lang.Integer.parseInt(libgcj.so.81) at java.lang.Integer.<init>(libgcj.so.81) at java.lang.reflect.Constructor.newInstance(libgcj.so.81) ...8 more

My jetty-setuid.xml file looks like:

<Configure id="Server" class="org.mortbay.setuid.SetUIDServer"> <Set name="startServerAsPrivileged">false</Set> <Set name="umask">2</Set> <Set name="uid">jetty</Set> <Set name="gid">jetty</Set> </Configure>

For some reason its expecting an integer instead of "jetty"...well well

> su jetty > id uid=1002(jetty) gid=1003(jetty) groups=1003(jetty)

My jetty-setuid.xml now looks like:

<Configure id="Server" class="org.mortbay.setuid.SetUIDServer"> <Set name="startServerAsPrivileged">false</Set> <Set name="umask">2</Set> <Set name="uid">1002</Set> <Set name="gid">1003</Set> </Configure>

...works like a charm.

GreenMail v1.3 Released

Wed, 19 Dec 2007 23:39:00 GMT

This release contains minor changes to GreenMail core, most notable the introduction of slf4j for logging.

New in this release is a JBoss service for GreenMail. The service runs GreenMail as a lightweight mail server sandbox, nicely suited for developers.

Check out the project page http://www.icegreen.com/greenmail for the latest documentation!

Note about the released files (goto download page):

greenmail-1.3-bundle.jar : mvn upload bundle
greenmail-1.3.jar : contains all greenmail core classes
greenmail-1.3-src.zip : contains sources, javadoc, required libs, docs
greenmail-1.3.zip : like above, but no sources
greenmail-jboss-service-1.3.sar : deployable JBoss service archive

Changes:

Added logging via slf4j, replacing System.out.println
Minor improvements:
- c.i.g.AbstractServer exposes ServerSetup
- c.i.g.util.GreenMailUtil exposes sendTextEmail(...)
New JBoss service wrapper (see the project page)

Credits:
Marcel May added the JBoss service and contributed the logging changes. Thanks!

Upcoming changes:
For 1.4 we plan to replace the current Foedus smtp and pop implementation with http://subetha.tigris.org

RXTX on Gumstix

Fri, 24 Aug 2007 17:10:00 GMT

Since it could be tricky to get the RXTX sources compiling properly for the gumstix platforms I thought I'd spare anyone the pain by providing my binaries.

librxtxSerial_PXA255.so (Connex / Basix)
librxtxSerial_PXA270.so (Verdex)

However, since you're here, I would advise against using java on the gum. Sure, the programs themselves are a breeze to develop, but getting jam and classpath to compile and run properly can very well take a considerable amount of time. Just think of the reason why you are reading this. Chances are you probably have troubles getting the RXTX sources to compile or run smoothly. Just do yourself a favor, write it in small fast c/c++ or something.

Groovy vs BeanShell

Thu, 10 May 2007 05:38:00 GMT

Below is a quick and dirty test to compare the speed performance between bean shell and groovy. Bean shell is an order of magnitude faster. If you don't need groovy closure and other nice groovy features...just use bean shell. It's only one small jar away.

public static void main(String[] args) throws EvalError { StringBuilder script = new StringBuilder(); for (int i=0;i<900;i++) { script.append("res"); script.append(i); script.append("="); script.append(i+"+"+i+"*"+i); script.append(";\n"); } GroovyShell groovyShell = new GroovyShell(); Interpreter bsh = new Interpreter(); long t = System.currentTimeMillis(); groovyShell.evaluate(script.toString()); System.out.println(System.currentTimeMillis() - t); t = System.currentTimeMillis(); for (int i=0;i<1000;i++) { int j = i+i*i; } System.out.println(System.currentTimeMillis() - t); t = System.currentTimeMillis(); bsh.eval(script.toString()); System.out.println(System.currentTimeMillis() - t); }