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Posts Tagged ‘web development’

JSTL, instanceof, and hasProperty

December 4th, 2009 vivin 2 comments

I’ve been doing a little bit of JSTL over the past week, especially custom tags. I’ve written custom tags in Grails before, and there you use actual Groovy code. I guess this was how custom tags used to be written (in Java), but now you can can build your own custom tags using the standard tag library. The standard tag library is still pretty useful when it comes to building custom tags. Since it’s not straight Java, it forces you think really hard about your logic. You don’t want to put any business or application logic in your tag, and you want to restrict everything to view or presentation logic. A side effect of it not being Java is that if you want to do anything extremely complicated, you’re probably better off writing the tag in Java (making sure that you don’t let any business logic creep in).

While writing my own custom tag, I noticed that although instanceof is a reserved word in the JSTL EL (expression language), it is not supported as an operator. The reason I wanted to use the instanceof operator is that I have an attribute that could either be a List or a Map and depending on the type, I wanted to do different things.

Another thing I was trying to do, was to inspect the incoming object to see if it had a certain property (reflection). JSTL uses reflection so that you can access the properties of an object via dot notation, if they follow the JavaBean naming-convention. However, there was no way for me to see if an object had a certain property. To solve both these problems, I wrote my own JSTL functions.
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Displaying images side-by-side in Wordpress

November 5th, 2009 vivin 6 comments

I’ve been using Wordpress for about two months now and I really like it. It takes away a lot of the pain from blogging. Recently I was writing a blog post and I was trying to get two images displayed side-by-side. This proved to be more difficult than I thought. There’s no immediately obvious way in Wordpress to display images side-by-side. I tried to use tables, but that didn’t work out. I also tried to use the gallery, but that displays all the images, and I just wanted to display two. I was able to get it working finally.
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Performance testing using The Grinder

July 27th, 2009 vivin 5 comments

About a month ago at work, I was trying out a bunch of different performance-testing tools to figure out which one to use to performance-test our software. I ended up discovering a tool called The Grinder which uses Jython to build performance-testing scripts that you can then use to test your application. I even built a little framework in Jython to make the test scripts more modular and reusable. Over the next few days I’ll be publishing three articles (this one included) that talk about Grinder.

Introduction

In this article I’ll go over installing and setting up Grinder. I am not going to go into too many details since my aim is to provide information that will enable you to have Grinder up and running quickly. If you want more information, you can look at the rather thorough Grinder User Guide. At the end of this guide, you’ll know how to install and set up grinder, record a test, modify (and/or parameterize) it, start running it through the console, and record data from the test. Note: The instructions in this guide relate to a Linux environment. You can run Grinder in Windows; the set-up is not much different. The only differences will be in installation locations and shell scripts. If you want more information about setting up Grinder in a Windows environment, please take a look here.
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jQuery tip: Changing the TYPE attribute of an INPUT element

May 26th, 2009 vivin 7 comments

I was trying to change the type attribute (using jQuery) of an input element from submit to button when I got this error:

type property can’t be changed

Apparently, you can’t change the type attribute of an input element once it’s part of the DOM. I figured out a way to do it by cloning the old element and then changing its attribute. Since the element isn’t part of the DOM, you can change its attribute. After that, you can add it to the DOM and remove the old element:

var oldButton = jQuery("#Submit");
    var newButton = oldButton.clone();

    newButton.attr("type", "button");
    newButton.attr("id", "newSubmit");
    newButton.insertBefore(oldButton);
    oldButton.remove();
    newButton.attr("id", "Submit");

Wallpaper

February 27th, 2003 vivin No comments

I added another wallpaper of Shakira. I have no life. It is official. I hope I get that job I applied for… It’s Web Development with PHP and MySQL… along with working on UNIX machines and network stuff. Fun stuff…