Converting a String to org.jdom.Document

import org.jdom.*;

String xml="<name> buddhika < /name >";

SAXBuilder builder=new SAXBuilder();

Document doc = builder.build(new StringReader(xml));

Useful Linux Commands and Tools

To list the kernel routing table
$ netstat -nr

To get the information about USB buses in the system and devices connected to them
$ lsusb

To get a listing of open ports with associated processes
$ sudo lsof -i
or
$ sudo netstat -lptu

Using netcat to setup a server
$ nc -l -p [port]

Using netcat as a proxy
$ nc -l -p [listening-port] | nc [host:port] | nc -l -p [output-port]

Any request sent via the listening port will be directed to the host defined in the second stage of the pipe and the results can be gathered from the output port.

Building ODE- Errors and Tips

It seems building ODE is not the easiest thing to do. I found this the hard way when I really messed up all sorts of things when trying to build ODE in my office machine. (Funny thing is that it went to the extent of reinstalling the OS). The process is quite strange if you are new to the Ruby world like me, because ODE uses a Ruby build system called buildr. Before installing buildr following packages has to be installed if Ruby is not installed in your system.

Ruby - packages related to the language
RubyGems - the Ruby package manager

buildr internally uses the Ruby build program Rake which is a simple ruby build program with capabilities similar to make.

So the second time I was prepared. I metaculously went through the instructions in the ODE and buildr sites. Since the information is scattered a bit across sites, here is the exact the steps I went through for a succesful ODE build. Note that ODE branch and ODE trunk uses different versions of buildr. So both versions of buildr has to be installed first.

Important: I am using an Ubuntu box. So these steps are for an Ubuntu system.

Installing buildr


Step 1 - Installing Ruby

$ sudo apt-get install ruby-full ruby1.8-dev libopenssl-ruby build-essential

Step 2 - Installing RubyGems

$ wget http://rubyforge.org/frs/download.php/38646/rubygems-1.2.0.tgz
$ tar xzf rubygems-1.2.0.tgz
$ cd rubygems-1.2.0
$ sudo ruby setup.rb
$ sudo ln -s /usr/bin/gem1.8 /usr/bin/gem

Step 3 - Installing buildr

$ sudo env JAVA_HOME=$JAVA_HOME gem install buildr -v 1.2.10
//this version is used to build ODE branch

$ sudo env JAVA_HOME=$JAVA_HOME gem install buildr -v 1.3.2
//this version is used to build ODE trunk

Step 4 - Source checkout

Now installing buildr has been done ODE can be built from its source. To checkout ODE.

Branch

$> svn checkout http://svn.apache.org/repos/asf/ode/branches/APACHE_ODE_1.X ode-1.X

Trunk

$> svn checkout http://svn.apache.org/repos/asf/ode/trunk ode-trunk

Step 5 - Build ODE

Go to the checkout directory. In this case ode-1.x in case of branch and ode-trunk in case of trunk.

Building branch

$> buildr _1.2.10_ clean install TEST=no

Building trunk

$> buildr _1.3.2_ clean install TEST=no

Generating Eclipse project files

$> buildr eclipse

Generating IDEA project files

$> buildr idea

Note: It also work even if you don't mention the buildr version in trunk build. But in the branch build version number has to be used. Otherwise you may see an error similar to this.

rake aborted!
can't activate buildr (~> 1.2.4, runtime), already activated buildr-1.3.2
~/ode-1.x/Rakefile:17

Using Eclipse BatchCompiler

Using the BatchCompiler to compile a Java source at runtime is well documented in the Eclipse help system. The problem that I came across was providing the classpath for the compilation to happen. Actually the jars needed, I had included in the runtime classpath of my plugin and were inside the plugin project. First challenge was to get the classpath entries so that I can append them to compile String to be fed in to the compiler. Surprisingly it wasn't easy enough as I had thought. After some experimentations on plugin API I finally got following code to work.

Dictionary manifest=Activator.getDefault().getBundle().getHeaders();
Enumeration cpKeyEnum=manifest.keys();
String classpath;

while(cpKeyEnum.hasMoreElements()){
Object cpKey=cpKeyEnum.nextElement();
if(cpKey.toString().equals("Bundle-ClassPath")){
classPath=manifest.get(cpKey).toString();
break;
}
}

Activator is the plugin activator class. Here the classpath is obtained as a comma seperated list of relative paths included in the "Bundle-ClassPath" header of MANIFEST.MF.

After solving that soon I realised the BatchCompiler itself cannot access the jars from the relative paths I got from the earlier exercise. So I had to extract these jars to a temporary location and feed the absolute path of this location to the BatchCompiler.

Changing runtime classPath of an Eclipse plugin programmatically??

While I was developing some functionality for a Eclipse plugin I came across the need to change the classpath at runtime so that some runtime generated class files can be accessed by the code. I found a hack after some Googling. (http://forums.sun.com/thread.jspa?threadID=300557). It worked fine when run as a standalone Java program. But when tried to port my code to the plugin it failed miserbly.
Only other thing that I could think of was using a seperate classloader to load these classes which actually worked. Seems that's the way to go to be on the safe side.

Revolution or scam?

I happened to hit upon an incredulous site when I was lazily surfing the web. This site happens to be promoting a book which says the science that Newton and Einstien nurtured is fundamenatally flawed. First chapter is freely available at the site. This guy goes on to say that even the mathematical derivation of some of Einstien's equations are wrong. Not being much of a physicist I am not in a position to challenge them. But what can be said is that the first chapter is full of drama. He discredits most fundamental aspects of science concepts such as work etc. May be just like most Internet hypes this may well be a scam to make some quick buck. Anyway since radical thinking is the corner stone of science this may be an interesting reading to an open minded to ponder about.

Way to reach the site for anyone interested.
www.thefinaltheory.com.

Lessons to be learnt

So finally it happened. What many Americans thought impossible to occur within their lifespan. The first black president at the helm of American power machinery. What's more important is to reflect what took him there with having a big barrier that so many thought would crush him, the color of skin.

Apart from political reasons (economic downturn, tax policy etc. etc.) I think there were other factors at play which decided it for Obama.

The best place to start lies within the end itself. That acceptance speech he did. The indisputable fact of his oratorship was portrayed time and time again in that speech. For me it's not been about his policy (being neutral), but the style and variations in his speech that struck to me as remarkable, which I thought were far better than Mr. MaCain. The final touches were as impressive as ever. The grandma who lived to see the how the generations has changed, boy he is a conjurer of creating imagery and penetrative words. Did I see some lady in tears when he spoke that? No doubt he was effective.

One of the remarkable things that even in the acceptance speech I saw was amount of youth excitement and participation. The secret was partly in the way that he reached out the masses. He was talking to the modern America using modern ways. How about at his funding campaign? The decison of not being restricted to federal funding and reaching masses with an effective online funding mechanism was highly successful and proved to be a winning decision at the end of the day in both monetary wise and political wise. Today I was brought to notice about his Twitter account. Guess how many were following his posts. More than 100,000. I was surprised. How many limitless possiblities these new avenues in technology has brought us allowing us to communicate better and effectively. No doubt Obama had clearly understood the changing times has strategically adapted to them in his campaign. His effective online presence no doubt would have reached scores of young floating votes. At the end MaCain had to admit that he was addressing the 'old' America using old ways which was one of the reasons for the downfall of him.

One thing is clear. Change or no change Obama has pulled off a great campaign all together and he derserves what he's got.