To declare a richlet, you have to add the richlet element to zk.xml. You could specify any number of richlet elements. Each of them must have two child elements, richlet-name and richlet-class, and might have any number of the init-param child elements.

The class name specified in the richlet-class element must implement the org.zkoss.zk.ui.Richlet interface. The name and value specified in the init-param element can be retrieved when the init method of org.zkoss.zk.ui.Richlet#init(org.zkoss.zk.ui.RichletConfig) is called.

<richlet>
    <richlet-name>Test</richlet-name>
    <richlet-class>org.zkoss.zkdemo.TestRichlet</richlet-class>
    <init-param>
        <param-name>any</param-name>
        <param-value>any</param-value>
    </init-param>
</richlet>

Once declaring a richlet, you can map it to any number of URL by the use of the richlet-mapping element as described in the next section.