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Smoothing Out Graphics Functioning Wrinkles in Linux and Unix
by James You
Nowadays, more and more Java applications contain embedded visual graphical elements-things like graphs, photos, charts, and text images. Because the typical Java interpreter's default configurations use native graphic libraries to carry out actual graphic rendering, these images won't be a problem on Windows and Macintosh systems.
However, on LINUX and UNIX, many Java applications need to access the Java AWT (Abstract Window Toolkit) library to perform these graphics functions. These apps will have problems rendering the images if the Linux or Unix server isn't running an X-Server In fact, may network admins don't ever install the largely unnecessary X-server because it'ss not a best practice. So, how do you achieve a rich-graphic environment without changing your existing Unix or Linux application's code?
A Closer Look at the Problem
Suppose your application requires dynamic visual image random text validation to be applied to its own self-registration process so as to prevent some kind of "computer" hacker
robots from attacking the system. You can do this using the CAPTCHA technology. A CAPTCHA (a backronym for "completely automated public Turing test to tell computers and humans apart", trademarked by Carnegie Mellon University) is a type of challenge-response test used in computing to determine whether or not the user is human. Check here for more details about CAPTCHA.
There are few Java open source libraries available for this purpose:
After comparing these options, I determines that the SimpleCaptcha library meets this project's requirements:
- It generates good-looking captchas.
- It requires minimal programming.
- It usually requires minimal configuration.
The following is the test application development environment:
- O/S: Sun Solaris 5.8 without X-Server
- Application Server: IBM WebSphere Application Server 5.1
- IDE: IBM WebSphere Application Developer 5.1
- Java JDK: Sun JDK1.4.2
According to SimpleCaptcha's documentation: "If you are running Linux/UNIX without an X-server you have a problem. Depending on your Java version you might be able to run your server with a -Djava.awt.headless=true vm switch." This means that you can't run this application in Unix or Linux platform without X-server installed without changing your code and specially configuring your application server.
This is the same rendering problem described earlier. After much research, I have found that this is the best way to integrate the SimpleCaptcha library into the Sun Solaris 5.8 Unix platform and IBM WebSphere Application 5.1 with JDK 1.4.2 environment, solving this common problem.
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