If you want to print the details of System Properties in JSP use the below code.
Here we get the System Properties and loop over the Enumeration object to print it on the screen.

Download File:

getSystemProperties

I was trying to install MySQL 5.0.24 on my friends new Laptop. We where stuck at this error “The application has failed to start because its side-by-side configuration is incorrect.Please see the application event log for more detail” when we ran the MySQLInstanceConfig.exe file. After a bit of googling we found the solution.

Step1: Download the Resource Hacker tool from here.

Step2: Unzip the folder and execute the file “ResHacker.exe”. This open a window, Go to File > Open and browse to the Path of your “MySQLInstanceConfig.exe” file inside “<Drive>:\MySQL\MySQL Server 5.1\MySQLInstanceConfig.exe”. This will load an assembly file, on your left navigational tree section click on folder 24 > 1 > 1003. This opens an XML configuration file.

Step3: Edit this file by changing the privilege “asAdministrator” to “requireAdministrator”.  Click button on the top of window which states “Compile Script”. Now go to File > Save as.  Save the File with name “MySQLInstanceConfig.exe” on the desktop.

Close the Resource Hacker tool, copy the “MySQLInstanceConfig.exe” file from desktop and overwrite it on the exisiting file in “<Drive>:\MySQL\MySQL Server 5.1\bin” folder.

Double click on the exe and the instance installation will begin.

References:

• http://www.weeklyworldwhatever.com/2008/02/21/cant-install-mysql-5051a-because-its-side-by-side-configuration-is-incorrect/#comment-50
• MySQL 5.1 Vista Bug

Downloads:

• Download MySQL from here.
• Check Windows Vista here.

Secure Socket layer (SSL) has been a standard protocol for providing security and data integrity for web based applications. This tutotrial will provide you with steps to SSL enable your Apache based Web Application using OpenSSL for windows based environment.

Step1: Donwload/Install Apache

• Download Apache HTTP Server from here. Get the apache_2.2.11-win32-x86-openssl-0.9.8i.msi installer and install the Apache Server.
• Open the conf/httpd.conf file and check if the line “LoadModule ssl_module modules/mod_ssl.so” is commented or not. If commented then uncomment the line and check if the file “mod_ssl.so” is available in the ‘modules’ folder, if not then you have downloaded the non ssl version of Apache please download the apache with openssl version and install it.
• Create a file named “ssl.conf” in the ‘conf’ folder which will hold all the ssl related configurations.Add the following line to “httpd.conf” file. <IfModule mod_ssl.c>
  Include conf/ssl.conf
  </IfModule>

Step2: Add SSL Certificate

• The second step is to add the SSL certifcate to the SSL configuration file, the certificate can be either self created or we can get them from Certifcate Authority, getting this from Trusted Certificate Authority is a better idea since this will not display warning to the users who connect to your application. Self signed SSL certificate can be used for demonstration purpose for small applications or in an intranet environment.
• Go to the ‘bin’ folder of the Apache and check if you have “openssl.exe” binary there, we will use this tool to create the self signed certificate.
• Download the “openssl.conf” file from here and place it in the ‘bin’ folder.(rename the opensslcnf.doc to openssl.cnf once downloaded)
• Go to the command prompt where the have “openssl.exe” file.
  Run the following command to create a new certificate request:
  prompt>openssl req -config openssl.cnf -new -out mycert.csr -keyout mycert.pem
  You’ll be prompted to fill answers to many questions. Remember your PEM pass phrase which you have entered. Now we need to create a nonpassword protected key for Apache 2 by running the following command:
  prompt>openssl rsa -in mycert.pem -out mycert.key
  This will create a key file as earlier but one without password protection.To create this file just enter your pass phrase given earlier.
  Lastly we need to create the X.509 public certificate.
  Run the following command:
  prompt>openssl x509 -in mycert.csr -out mycert.cert -req -signkey mycert.key -days 365
  This create the self signed certificate which expires after 365 days.

Step3: Configure the “ssl.conf” file.

• Create a folder ’ssl’ under ‘conf’ folder to keep your SSL key and certificate files. Add the two files created in the previous step “mycert.key” and “mycert.cert” file inside this folder.
• Open “ssl.conf” file and change the line DocumentRoot, ServerName and ServerAdmin as per your http.conf file. (Note: Its recommended to keep the SSL port as 443 since many firewalls block SSL on other ports).
• Now change the lines SSLCertificateFile and  SSLCertificateKey to path where the key and cert files in ’ssl’ folder are kept. SSLCertificateFile conf/ssl/mycert.cert
  #SSLCertificateFile conf/ssl/server-dsa.crt#   Server Private Key:
  #   If the key is not combined with the certificate, use this
  #   directive to point at the key file.  Keep in mind that if
  #   you’ve both a RSA and a DSA private key you can configure
  #   both in parallel (to also allow the use of DSA ciphers, etc.)
  SSLCertificateKeyFile conf/ssl/mycert.key
  #SSLCertificateKeyFile conf/ssl.key/server-dsa.key
• That’s all, just save the changes & restart the Apache Server.
• Open “https://localhost/” to test SSL.

(Note: We have assumed that Apache is running on port 80 and SSL on port 443 you can configure for any other port)

If you already have the Certificate’s provided to you from Certificate Authority just skip step two and put these certificates inside the ’ssl’ folder and add there respective path in the “ssl.conf” file.

You just got your Apache SSL enabled.

Problem:

WARNING: Parameters: Character decoding failed. Parameter skipped.
java.io.CharConversionException: isHexDigit

Cause:

• Generally we get this error when we try to add special characters like “%, @, $ .. etc” in the GET/POST request from Ajax Call.
• Since these characters are used to URL specific function like “&” id used to differentiate various URL parameters. This generates a “null” value for the parameter you will try to retrieve in Servlet.

Solution:

The simple way to get over this problem is to massage your Special Character String with “escape()” funtion in javascript.

Example:

Before:

var vUserEnteredData = document.formname.textbox.value ;  //  textbox = 100%

var parameters = “testId=A101&percentageNeeded=” + vUserEnteredData;

// Some Ajax Code …..

request.setRequestHeader( ‘Content-Type’, ‘application/x-www-form-urlencoded; charset=UTF-8′ );
request.setRequestHeader(“Content-length”, parameters.length);
request.setRequestHeader(“Connection”, “close”);
request.send(parameters);

// Note: Here the “%” will cause java.io.CharConversionException: while retriving the percentageNeeded parameter in Servlet.

After:

var vUserEnteredData = document.formname.textbox.value ;  //  textbox = 100%

var parameters = “testId=A101&percentageNeeded=” + escape(vUserEnteredData);

// Some Ajax Code …..

request.setRequestHeader( ‘Content-Type’, ‘application/x-www-form-urlencoded; charset=UTF-8′ );
request.setRequestHeader(“Content-length”, parameters.length);
request.setRequestHeader(“Connection”, “close”);
request.send(parameters);

Alternate Solution:

• We can use Ajax Frameworks rather than manually making the Ajax Request like PrototypeJS, DWR etc.

If you are required to create a backup of JavaScript Object use the clone() function rather than a for loop to individually copy the contents of one JavaScript Object into other Object. This will save a lot of time as well if in future the JavaScript Object is modified your are saved from the task of changing your for loop as well.

// Simple Java Script Object

function UserData (user_ID, user_Data_Preference, user_Theme_No){

this.user_ID = user_ID;

this.user_Data_Preference = user_Data_Preference;

this.user_Theme_No = user_Theme_No ;

}

Consider when the Web Page is loaded this object is populated dynamically and we display the user with respective theme and show data in his preferred form. (e.g. Km/Hr or miles/Hr).

Now you can create a duplicate copy of this JavaScript Object by using the clone() function.

Example:

var objUserDataOrg = new UserData(1, data_101, theme_aqua);

// To Create a duplicate copy

var objUserDataDuplicate = objUserDataOrg.clone();

This will be a new object hence changes in the Old Object will not be reflected in the new and vice-versa.

Pros: This is especially useful when you are required to deal with Array of JavaScript Object rather than a single Object.

Cons: All the attributes of the Object are copied into the new object in case you only want some them to be copied this may not work.

Most business in today’s open market are demanding their websites & web application to have multilingual support. This is in order to attract non-English speaking audiences to increase their customer base and make people comfortable using the application in their native language. But for this, it would require an existing business application to be customized to support native locale. The process of producing an application that can be localized for a particular country without any changes to the program code is called Internationalization.

Following are the list of things one needs to take care while making an application to implement Internationalization. [click here to read complete article]

How many times have people said that your website is too slow and you found out that there is nothing you can do to improve its performance? The final option most of the times might have been either trying to change your hosting server (may be even blaming him for purposely slowing your website) or finding several ways to optimize your code.

Over last few months I have been facing this same problem. I browsed the web for answers, even went ahead and bought many books on Website Optimization. All of them more or less targeted the same issue of caching static contents using additional third party tools which improvises upon browser caching thus getting better performance and all that sort of stuff.

Analyzing the Website Performance

There were enough options to start that made me crazy as to which one to go ahead with, I wanted things to be under my control rather than adding complexities. For this I needed information as to what actually is traveling between my web server and web browser. I added loggers in my code to note the timestamps at server, even timed by database queries.

All I wanted to know was what actually was being downloaded by the client. In this situation one tool finally came to my rescue. That was .. Click Here to read the entire Post

The Class LinkedHashMap  is an extension of HashMap with specific feature of retaining the insertion order. Hence useful when order  of key-value pairs are to be retained. Also if one inserts the key again into the LinkedHashMap the original orders is retained. Such Collection is useful when you want to covert a record fetched from the database into a Java Object. The main advantage with this is that now we can shift the sorting logic of retrieved data into database rather than writing custom code here; that help in boosting performance.

Java Docs available @  http://java.sun.com/javase/6/docs/api/java/util/LinkedHashMap.html

Example Code:

import java.util.Iterator;
import java.util.LinkedHashMap;

class LinkedHashMapEx1  {
public static void main(String[] args)      {
LinkedHashMap map = new LinkedHashMap();

// Add some elements
map.put(“A”, “dataElement-1″);
map.put(“B”, “dataElement-2″);
map.put(“C”, “dataElement-3″);
map.put(“B”, “dataElement-4″);

// List the entries
for (Iterator it=map.keySet().iterator(); it.hasNext(); ) {
Object key = it.next();
Object value = map.get(key);
System.out.println( “Key = “+ key.toString() + ” Value = ” + value.toString() );

}
}
}

This new experimental feature of Google search called “Timeline View” seems cool to find information regarding a particular subject. Though the quality of search is not that great but the shear idea of attaching data mining reports with the keyword is worth appreciating for. We can spend few hours exploring the amount of information which can be obtained from this feature.

Seems here’s a tip which few businesses can replicate to mine their customer information and make predictions from past data, the bar displayed the information in the timestamped manner I would have loved if more drill down data operations on the search would be possible. Well there would be definite demand for this product in future if not for public domain but for small businesses. Definitely this can be a great tool if integrated with Google Desktop Search and some sort of report generation facility.

On the whole this one’s a good offering from google labs so good job googites. Keep them coming.

Some searches that worked and some that didn’t

The Pro’s :

• Java tours view:timeline

The Con’s:

• iPod tours view:timeline

Link : http://www.google.com/views?q=cars+view:timeline&esrch=RefinementBarTopViewTabs&sa=N&ct=timeline

This one I faced while developing a ajax utility in my application, which checks for user name availability. After developing the utility and testing for various combinations of front end validations i was convinced that it was ready to be introduced in the application, but as soon as beta testing started this strange error occurred and was not able to recognize the problems since it was running perfectly fine on my browser. Going through the logs I noticed that in IE the call to DAO was not happening if the data entered in the text field is same… here come the great IE caching problem. Now reading around some blogs http://webdescript.com/blog/intersection/archives/73-Internet-Explorer-Caching-AJAX-Calls.html and http://www.howtoadvice.com/StopCaching is found a good hack to the problem. Just a 5 minute patch and here the utilities running like its got to.

Solution:

Just append the time stamp to the url of the ajax call that solves the problem.

url = “http://www.yourwebsite.com?username=kingkong” + “&ms=” + new Date().getTime();