After successfully building a couple of applications in RoR with SQLite3 and PostgreSQL, I'm now trying to use Oracle as the database for Ruby on Rails application. When I tried db:migrate I ran into an error that said select_rows implementation is not available in oracle_adapter.rb.

$RUBY_HOME\lib\ruby\gems\1.8\gems\
activerecord-oracle-adapter-1.0.0\lib\
active_record\connection_adapters

Live Search has been very popular recently in the web 2.0 world. I was recently working with a desktop application, in which I wanted to provide a similar feature. You have JTable displaying the data you fetched from somewhere (database etc.) and you provide a simple text field using which the table can be filtered. It works just like your Firefox History side bar search. You can call the method using the KeyListener so that it looks very "alive" :-)

Here's the LiveSearchTableModel implementation you can use to create live filtering of JTable rows.

After successfully running JRex, I moved on to embed JRex in RCP application. RCP applications are developed using Eclipse Rich Client Platform. Including JRex in RCP is little tircky, since JRex is based on Swing/AWT. But Eclipse RCP provides SWT and AWT bridge, using which any AWT component can be embedded in SWT component.

Today I started working on JRex, and embeddable Gecko(Mozilla) browser for Java. I spent almost 3 hours to get JRexworking on my machine. I followed all the steps in the releases page.

And when I try to run the program here's the error I got

Python has two kinds of attributes for objects: Class and Data. Class attribute is similar or equivalent to static variables in Java. That means they belong to the class rather than an instance of the class. The data attributes are like instance variables, that are bound to an instance rather than the class.

The class and data attributes are declared normally in Python. But the way they are accessed inside the class is different. Here's the sample code to find how class and data attributes work:

I've just finished Classes in Python chapter. Here's the python class to say helloworld!

So yesterday, I started reading the book Dive Into Python, and finished reading first 4 chapters. The language seems to be very interesting, somewhat similar to perl. I worked on a perl project during '04.

• Python is an Object Oriented language in which everything is an Object.
• Python functions are declared using def def some_function(param1, param2=value): ... The second parameter is an optional parameter, which takes the default value "value" if we don't specify when we are calling that function.
• Every python script or program can be called as standalone program or can be import as modules into other scripts. So the following block of a script is executed only when the module is called as a standalone program. if __name__ == "__main__": ... So this if block serves a main method for the script.
• Python's statements end with a new line character, phew! no more semicolon typing
• In Python block's are identified using the indentation. So bye bye braces!
• Python has "in-built" support for Lists, Dictionaries and Tuples. Lists are like ArrayList in Java, Dictionaries correspond to Hashtable in Java and Tuples are immutable lists in which the order is preserved.
• Python provides various powerful introspection methods like getattr(Object, Method) which will retrieve the reference to the method of the object.
• Python provides support for lambda functions - kind of inline methods, which can be assigned to any variable and reused anytime. This is very convenient when we want to evaluate a single expression and return some value.

I was busy working on some Windoze application, Since it needed COM Port access, couldn't work on FreeBSD. Yesterday, I started portupgrade after cvsupping to the latest ports snapshot. And in the middle the laptop went off and the pkgdb got corrupted.Then I tried using pkgdb -uf command. But the pkgdb was not rebuilding. I thought the system got messed up, I need to install all the pkgs, ports again.

I changed to the /var/db/pkg directory. And then a mv pkgdb.db pkgdb.db.old. Did the pkgdb -fu again. Voila! it rebuilt the pkgdb. So today morning I started the portsupdate -a. I'm sure it will take some good time for upgrading all the 561 packages Once the ports are upgraded, I'll switch to FreeBSD 7.0 series next week!

import java.io.FileReader;
import bsh.ParseException;
import bsh.Parser;

/**
 * * BshCompiler Class is used to compile the scripts and verify for the syntax
 * errors, before interpreting. * The class constructor takes the Script file
 * name/path * as the argument, and checks for the syntax. Once the process is
 * complete, use * isSuccess to get the result, and also the getResponse * and
 * getErrors to get the respnses. Note that this class is not synchronized, it
 * has to be handled externally. * *
 *
 * @author Vijay Kiran Duvvuri *
 * @version 0.1
 */
public class BshCompiler {
 private StringBuffer response;

 private StringBuffer errors;

 private boolean success;

 private FileReader fileReader = null;

 private Parser parser;

 private String script;

 /**
  * * scriptFile - path of the scriptFile *
  *
  * @param scriptFile
  */
 public BshCompiler(String scriptFile) {
  this.script = scriptFile;
  compileScript();
 }

 private boolean compileScript() {
  response = new StringBuffer();
  errors = new StringBuffer();
  success = false;
  try {
   fileReader = new FileReader(script);
   parser = new Parser(fileReader);
   parser.setRetainComments(true);
   while (!parser.Line()/* eof */) {
    response.append(parser.popNode() + "\n");
   }
   success = true;
  } catch (Error error) {
   errors.append(error + "\n");
  } catch (ParseException parseException) {
   errors.append("PARSE EXCEPTION: " + parseException.toString()
     + "\n");
   errors.append("ERROR MESSAGE: " + parseException.getMessage()
     + "\n");
  } catch (Exception e) {
   System.out.println("Other Exception");
   errors.append(e + "\n");
  } finally {
   try {
    if (fileReader != null) {
     fileReader.close();
    }
   } catch (Exception e) {
    e.printStackTrace();
   } catch (Error error) {
   }
  }
  return success;
 }

 public StringBuffer getResponse() {
  return response;
 }

 public StringBuffer getErrors() {
  return errors;
 }

 public boolean isSuccess() {
  return success;
 }
}

Introduction

XUL Applications

As described already XUL applications need XUL Runtime, which can be any mozilla browser instance. But for starting XUL Application as a seperate standalone application, we can use XULRunner. Similar to the JRE, xULRunner provides the runtime environment for the XUL application. For development purposes, we can use the XUL App Directory Structure. The deployment/installable package structure will slightly differ from this setup. The deployment will be explained in a later section.

Development Package Structure

helloworld/
  application.ini
  chrome/
    chrome.manifest
    content/
        helloworld/
           ---  XUL and JavaScript files. ----
    locale/
       en-US/
         helloworld/
           --- DTD files for en-US locale ---
     skin/
       helloworld/
         -- CSS for styles etc. ---
  defaults/
    preferences/
      helloworld-prefs.js

The main folders of a chrome package are content, locale and skin.

Content - Windows and scripts

Locale - Locale specific files

Skin - Style sheets, images and other theme specific files

• First download the XULRunner from here
• Extract the XULRunner to the hard disk (C:\xulrunner).
• Download the helloworld.zip attached with this article. You can even create your own application structure as explained below. But starting with the skeleton pakcage will give you more flexibility.
• Extract the helloworld.zip to the hard disk (C:\helloworld).
• Run the application using the command c:\xulrunner\xulrunner.exe c:\helloworld\application.ini