ACCESSIBILITY

Current image captchas tests are not very accessible, and this is a major concern for us.
There is currently no consensus around this issue, but some solutions are rising.
See :

• Matt Presents: Escape from CAPTCHA
• Inaccessibility of Visually-Oriented Anti-Robot Tests

We are working on a the logic puzzle solution, and on the Sound captchas...

X11

Question :
Argh! :

com.octo.captcha.CaptchaException: java.lang.InternalError: Can"t connect to X11 window server using ":0.0" as the value of the DISPLAY variable.

Answer :
You have correcly find out what is wrong : by default, you need a XServer to use jcaptcha. the java Toolkit use it to build images.
The captcha team (in fact mathieu) had a thought about this and designed a ToolkitFactory helper class.
It provides a way to avoid the installation of a xserver. This trick is documented
in the javadoc.
Extract:

/**
 * Description: This Factory is used in order to switch from the
 * java.awt.Toolkit component to other implementation like <a href="http://www.eteks.com/pja/en/">PJA Toolkit</a>. By default this factory
 * return the java.awt.Toolkit object.
 But if the the parameter
 * <code>toolkit.implementation</code> is fixed as a parameter of the virtual machine with
 * the value of the class name of another implementation of Toolkit, this
 * factory return an implementation of this class. For exemple if you set to
 * your virtual machine <code>-Dtoolkit.implementation=com.eteks.awt.PJAToolkit</code>, the
 * factory returns an implementation of com.eteks.awt.PJAToolkit
*/

See also this link :

• http://schmidt.devlib.org/java/image-faq/no-x-server.html

Performance

Image generation is a very heavy process : it cost a lot of CPU and RAM.
A particular attention has been given to performance in the devellopement and test process of JCaptcha.
In order to achieve transparency on this subject, the framework is heavily load tested, and tests results are provided in the source distribution.
The tests are currently run on my own PC wich is a standard home computer.
We encourage you to run and publish the load tests on your own production platform...
Load tests concerns :

• JCaptcha engines integration load tests: to compare the CPU/RAM cost of a particular captcha test generation
• JCaptcha services mocked load tests: to compare the CPU/RAM cost of a particular life cycle management strategy
• JCaptcha services integration load tests: to compare the CPU/RAM cost of a particular life cycle management strategy with a particular
  see :
• Engine junit report
• Service junit report

Management and JMX

The jcaptcha service provide some jmx facilities.
A manageable service provides :

• Runtime engine switch
• Usage and success statistics
• Cache and Buffer management
  The current implementation of the ManageableCaptchaService interface is JMX enabled.
  All modules includes a JMX registration parameter that automatically register the Jcaptcha Service
  to a JMX server.
  See modules documentation and java docs for details.