In order to enable the mat extension, please do the following steps

Step 1. Please insert the following to into 
web@xml@path.

<servlet>
<servlet-name>mat</servlet-name>
<description>mat</description>
<servlet-class>org.greenstone.mat.servlet.MatServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>mat</servlet-name>
<url-pattern>/analyse</url-pattern>
</servlet-mapping>

Step 2. Restart the Greenstone server.