Friday, August 27, 2010


WebScarab is a tool created by OWASP that can be used to analyze the HTTP(S) traffic between your browser and the web server. In order to intercept traffic, you have to configure WebScarab as a proxy server in your browser. Whenever a request is send to the web server by your browser, WebScarab intercepts the request and holds it for reviewing or even modifying before actually sending the request to the web server. The complete request can be analyzed in all its detail, which includes HTTP headers.

It's a great tool for debugging complex problems or reviewing the security of your applications. Download WebScarab here.

Thursday, August 19, 2010


I have a colleague, who is always monitoring 2392 blogs, 503 RSS-feeds, and 3922 websites. So he doesn't miss out on the little things that make life or work just a little bit more efficient. His laptop and PC have over 293 little tools installed, which enables him to get his work done three clicks faster than the regular guy. He is Tool Man Tony.

Yesterday, he forwarded me an e-mail notification of one of his (many) RSS-feeds, which drew my attention. It was a blog post about a syntax highlighter tool, like the one found in your favorite IDE (Integrated Development Environment). But this one is different. This one is meant for highlighting code in web pages.

The tool is called SyntaxHighlighter. It's basically JavaScript files you can include in your blog or website to highlight code fragments, which make your code much more readable. Additionally, it can also number the lines of your code fragments automatically. All of this happens client-side. A screenshot of highlighted code:

SyntaxHighlighter supports most popular programming languages. The complete list of supported languages can be found here.

Installing and using SyntaxHighLighter is easy, and consists of the following basic steps:

  1. Download the installation files here.
  2. Extract the files and include them to your web page: shCore.js and shCore.css.
  3. Add brushes (syntax files) for the languages you want to highlight.
  4. Use <pre> or <script> tags to enclose your code fragment.
  5. Call the JavaScript method SyntaxHighlighter.all() to invoke SyntaxHighlighter.

As you can see, SyntaxHighlighter is loosely coupled to your web page, and is very easy to use.

Thanks Tool Man Tony for the tip!

Official SyntaxHighlighter site:

Tuesday, August 17, 2010

Getting Oracle SQL result set pages

When you want to display the result of a query that returns a large number of rows, it's common to divide the complete result in pages, and display them one page at a time. To offer the user a way of navigating through the pages, there are clickable page numbers or "next"/"previous" buttons at the bottom of the page. This technique is called result set paging.

To implement this efficiently, the paging should also be built into the query. Because it's not efficient when we use a query to return the complete result from the database, and discard rows we don't want to display afterwards.

Let's say that you want to page the following query:

SELECT col1, col2
FROM example_table
WHERE col2 = 'some_condition'

Before we can divide the result set, we need to number the rows of the result set. The pseudo column "rownum", provided by Oracle databases, numbers the rows of the result. The first row of the result is always 1.

Using this knowledge, we can retrieve the "page" we want using the WHERE clause with the corresponding start row and end row numbers. In the example below, we want to fetch rows from number 201 to 300.

FROM (SELECT r.*, ROWNUM AS row_number
FROM (SELECT col1, col2
FROM example_table
WHERE col2 = 'some_condition'
ORDER BY col1 DESC) r)
WHERE row_number >= 201 AND row_number <= 300;

The reason why we wrap the original query in another SELECT query, is that the database assigns ROWNUMs before the ordering, which makes our ordering ineffective for paging. To make sure the ROWNUMs are ordered, we retrieve the ROWNUM column in the outer SELECT query. The database will then assign the ROWNUM in the already correctly ordered result set.

This query can be optimized for newer Oracle databases by removing the top outer SELECT clause, while leaving the WHERE clause intact.

Friday, August 13, 2010

Mind mapping with FreeMind

Mind mapping is a learning method that uses tree-like graphs to help your brain to structurize information visually. The brain is better at remembering visuals than words.

As an experiment, I am using mind mapping to prepare for the Sun Certified Developer for Java Web Services(SCDJWS) certificate. I will publish this in the future. Unlike the traditional way of drawing mind maps using pen and paper, I'm using a tool recommended by a colleague. The tool is called FreeMind and can be downloaded here.

The first impression I got, was the compact way of storing a lot of information. Thanks to the possibility of folding away information nodes, to hide related information, and zooming in the information by unfolding directly connected nodes.

Although mind mapping is originally a learning method, I find it's also suited for storing information you regularly need in a structured way, because it makes the information much more "findable".

Monday, August 2, 2010