Thursday, June 21, 2007

Snoop on Solaris and Ethereal

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I am a big fan of Ethereal tool and use it frequently for analysis of network traffic. The GUI is great and we can decode HTTP traffic from ...

Time complexity and Space complexity of algorithms

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I had just downloaded the SAP Memory Analyser and was impressed with its performance. More information on this tool can be found here . Goin...
Tuesday, June 05, 2007

Generating GUIDs on the client side web browser

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If your application requires that a GUID be created to identify the client, then we have 2 options: - If we are sure that the end users use ...
Friday, June 01, 2007

4 GB memory limitation for 32 bit machines

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What is the maximum heap size that U can allocate to a JVM or a .NET runtime? The answer is dependant on the operating system and hardware. ...
Sunday, May 20, 2007

servletContext.getRealPath() issue

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Our application was using getRealPath() method to obtain the base path of the web application on the server. I noticed that the method was n...
Tuesday, May 15, 2007

Silently print PDFs on the browser

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If your web application needs to print PDF's silently on the browser, then check out this blog . Of all options given, I found the iText...
Thursday, May 03, 2007

Modal Dialog submit issue

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In our application we were using a modal window pop-up. The user has to enter some fields and submit the form. The strange thing was that wh...

Generating PDFs on the fly

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If we need to generate PDFs on the fly in a JEE web application , then we have 2 open-source options: using Apache FOP or iText . The approa...
Tuesday, May 01, 2007

Setting Cache headers for Gifs, Css and JS files

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By default, browser and servers use the "if-modified-since" header to check if the file should be downloaded from the server or gi...

Setting nocache headers in Struts Applications

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In older versions of struts, it was a common practise to extend the ActionServlet and set the no-cache response headers there, so that they ...

Disabling keep-alive connections in Tomcat

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I was using TcpTrace utility to dump my HTTP requests/responses. But the problem was that my Server (Tomcat) was using keep-alive connection...

CSS caching in IE

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A strange problem regarding CSS caching had frustrated me for a whole 2 hours today. The problem was reported by one of the developers that...
Monday, April 30, 2007

Magic of JQuery

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We know that in IE, a form gets submitted whenever we press 'Enter' in a text-field. To disable it would require trapping the event ...
Friday, April 27, 2007

Mean, Median, Mode, Midrange and Standard Deviation

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A definition of terms to help my frail memory when I need it most :) The arithmetic mean is the sum of the numbers, divided by the quantity...
Wednesday, April 25, 2007

DST implementations in Operating Systems and Java

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I often wondered how operating systems knew about Day light saving offsets. Recently USA decided to change its DST settings and it immediate...

web.xml SAXParseException in Websphere v6.1

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I encountered a wierd problem while re-deploying a war file on Websphere v6.1. I started getting a SAXParseException in web.xml. The only ch...
Tuesday, April 24, 2007

Cool tools - Squirrel SQL Client, IzPack Java Installer

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Came across 2 tools that I liked :) Squireel SQL client: Use it to connect to any database using JDBC. http://squirrel-sql.sourceforge.net/ ...

Show friendly HTTP error messages in IE

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In web.xml, I added the tag to redirect to an error page when ever a 500 internal server error occurs. But in IE, the page was still not get...
Monday, April 23, 2007

UnsatisfiedLinkError while loading native libraries

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I encountered the following problem when calling native code from a Java application deployed on Websphere. Whenever I was redeploying the W...
Friday, April 20, 2007

Sequence numbers from a Oracle RAC cluster

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Today, I faced a peculiar problem. Our application was using a Sequence to autogenerate unique numbers required for a particular functionali...
Thursday, April 12, 2007

NTLM authentication using Commons HttpClient

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Recently I wanted to access a site outside the firewall thru Apache commons HttpClient. The proxy server was using NTLM authentication. Than...

Reset method of FormBeans in Struts

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We all know that FormBeans in Struts can have either a 'request' scope or a 'session' scope. In earlier versions of Struts, ...
Wednesday, April 11, 2007

JQuery Javascript library

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Came across this cool cool Javascript library that adds that extra jazz to Javascript programming. Some concepts I liked in this library: - ...
Friday, March 09, 2007

Private network addresses

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Can U look at an IP addresses and guess whether it belongs to a private network or is on the internet? The answer is yes. The Internet Assig...
Tuesday, February 27, 2007

Ruminating on dates, DST and days-between calculations

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In one of my programs, I needed to calculate the difference between 2 dates in days. Ironically I could not find any method for the same in ...
Thursday, February 22, 2007

Programming to interfaces

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We all know that as a good programming practice we should always program against interfaces and not actual subclasses. That's the reason...

Starting a java daemon on Solaris

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We were using Quartz as a scheduler to run our cron-like java programs on Solaris. Quartz gives us much more flexibility than the cron-tab, ...
Thursday, February 15, 2007

Daylight saving time

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Being brought up in India, we never have to worry about Daylight saving chores. But its very interesting and also important for any system d...
Monday, February 12, 2007

Spring JDBC quirks

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Spring JDBC's JdbcTemplate provides us with utility methods that return scalar values. For e.g. methods such as queryForObject, queryFor...

Printing Stack Trace in Java

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Quite often, developers use the statement exception.printStackTrace() to print the stack trace on to the console. It is important to remembe...