Monday, May 25, 2009

More Wicket filter options

Wicket has this very clever idea to serve requests from a servlet Filter instead of a Servlet. The brilliance of it is that you can serve pages on the root of your context, but still allow the servlet container to process requests that Wicket has nothing to do with.

By default this works correct automatically. Incoming requests that are not recognized by Wicket are just passed through.

However, there is an optimization that is not very well documented. When you already know that certain paths are never going to be handled by Wicket (for example because you configured a servlet for them), you can tell the Wicket filter to ignore those paths in the same file as where you define the servlets: in the web.xml.

Example web.xml configuration:

<filter> <filter-name>wicket.filter</filter-name> <filter-class>org.apache.wicket.protocol.http.WicketFilter</filter-class> <init-param> <param-name>ignorePaths</param-name> <param-value>images/,rest/</param-value> </init-param> </filter>
This will let the Wicket filter immediately pass through to the servlet container for all URLs that start with http://host/app-context/images/ and http://host/app-context/rest/.

Note: make sure the paths are comma separated without additional whitespace.