if you have items with different namespaces in a composite component to update one from other, using standard “:” to search in namespace will not work. You will get this exception :

Cannot find component with expression “form1” referenced from ….

You should use “@composite” in the update parameter. Example :

<cc:implementation >
    <h:form id="form1"> </h:form>
    <h:form id="form2">
         <p:commandButton update=":form1" />  <!-- ERROR -->
         <p:commandButton update="@composite:form1" />