def getConfiguration(requestor, service, nodeIdentifier):
    """
        Called when a node configuration retrieval request has been received.

        @param requestor: The entity the request originated from.
        @type requestor: L{JID<twisted.words.protocols.jabber.jid.JID>}
        @param service: The entity the request was addressed to.
        @type service: L{JID<twisted.words.protocols.jabber.jid.JID>}
        @param nodeIdentifier: The identifier of the node to retrieve the
                               configuration from.
        @type nodeIdentifier: C{unicode}
        @return: A deferred that fires with a C{dict} representing the node
            configuration. Keys are C{str}s that represent the field name.
            Values can be of types C{unicode}, C{int} or C{bool}.
        @rtype: L{Deferred<twisted.internet.defer.Deferred>}
        """
