Task: Dynamic Color Filtering of Images
One annoyance with using GIF or JPEG images is that their colors are static.
Once you've produced the images, in order to change the colors, you have
to pull out a graphics editor and use the tools to change the colors, statically.
What we need instead is the ability to generate graphics with colors that
can be altered programmatically and the ability to manipulate the color
changes from the XML and XSL. Then, for example, if we want to change
the colors used in the tabs, it would be a matter of declaring the color
in the XML/XSL and the programmtic color filtering will take care of the
The solution will need to be implemented in Java. What is required
is a Java Servlet that accepts a particular HTTP request, processes the
request, and returns a stream with MIME type image/gif or image/jpeg
to the requesting browser. The servlet would need to use some sort
of server-side caching strategy to keep the request-response cycle performant.
Your tasks are:
To define the request-response semantics for specifying how the colors
should be filtered for a particular image.
To write a Java servlet that performs the color filtering.
To define XML semantics for requesting color filtering.
To write XSL for rendering the XML into the right HTTP request for the
color filtered image.