Parse an xml.dom Node object representing a preceding condition into
        this object.

def parse_xml_node(self, node):
        '''Parse an xml.dom Node object representing a preceding condition into
        this object.

        '''
        super(Preceding, self).parse_xml_node(node)
        p_nodes = node.getElementsByTagNameNS(RTS_NS, 'Preceding')
        if p_nodes.length != 1:
            raise InvalidParticipantNodeError
        p_node = p_nodes[0]
        if p_node.hasAttributeNS(RTS_NS, 'timeout'):
            self.timeout = int(p_node.getAttributeNS(RTS_NS, 'timeout'))
        else:
            self.timeout = 0
        if p_node.hasAttributeNS(RTS_NS, 'sendingTiming'):
            self.sending_timing = p_node.getAttributeNS(RTS_NS, 'sendingTiming')
        else:
            self.sending_timing = 'ASYNC'
        self._preceding_components = []
        for c in p_node.getElementsByTagNameNS(RTS_NS, 'PrecedingComponents'):
            self._preceding_components.append(TargetExecutionContext().parse_xml_node(c))
        return self