Authenticator and Component XML configuration

[Sergio]

Hello,

I'm quite a newbie with restlet. I'm creating an application with this 
resources:

/
/apps
/apps/{id}
/apps/{id}/objects

To attach the different URI to resources I have used the XML component 
configuration:

<?xml version="1.0"?>
<component xmlns="http://www.restlet.org/schemas/2.0/Component";
        name="AndroPi RESTful server" 
        description="Configures NAT and output interface for nodes into the 
inner network"
        owner="GRC UPV" 
        author="Sergio Martínez Tornell">
        <client protocol="CLAP" />
        <server protocol="HTTP" port="8080">
                <parameter name="tracing" value="true" />
        </server>

        <defaultHost>
                <attach uriPattern="/"
                targetClass="es.upv.grc.andropi.server.RootServerResource"/>
                <attach uriPattern="/apps"
                targetClass="es.upv.grc.andropi.server.AppsServerResource"/>
                <attach uriPattern="/apps/{appId}" 
                targetClass="es.upv.grc.andropi.server.AppServerResource"/>
                <attach uriPattern="/apps/{appId}/objects" 
        targetClass="es.upv.grc.andropi.server.ObjectsServerResource"/>
" 
        </defaultHost>
</component>

It works properly, but now I want to protect the /apps/{id} and 
/apps/{id}/objects from non-authorized users.

I have read the book "Restlet in action" and the tutorials available on the 
website, but I can't find how to do it.

How can I define a ChallengeAuthenticator to act as a filter to only come of my 
resources?

Can I define the ChallengeAuthenticator only for som methods of my resources? 
for example to protect PUT or POST but keep GET public.

Thank you very much.
Sergio

------------------------------------------------------
http://restlet.tigris.org/ds/viewMessage.do?dsForumId=4447&dsMessageId=3078257