Read user's session variables from a query

Hi,

I need to use inside a query a variable stored in the user's session by an xaction with custom component. The Custom component's class pratically do this:

@Override
protected boolean executeAction() throws Throwable {
System.out.println("CrikhetComponent - executeAction");
String username = null;


if (isDefinedInput("username")) {
username = getInputStringValue("username");
}

//chiamata al WS
System.out.println("chiamata al ws, user:" + username);
setOutputValue("userUrl", "abc_" + username);
return true;
}

So my question is, what's the correct syntax for retrieve the userUrl value inside the query?