public function requestDataSending()
    {
        if (!$this->isEnded()) {
            foreach ($this->sources as $source) {
                $source->requestDataSending();
            }
        }
        return $this;
    }
public function requestDataSending()
    {
        if (!$this->isEnded()) {
            foreach ($this->sources as $source) {
                $source->requestDataSending();
            }
        }
        return $this;
    }
public function requestDataSending ( ) { if ( ! $ this -> isEnded ( ) ) { foreach ( $ this -> sources as $ source ) { $ source -> requestDataSending ( ) ; } } return $ this ; }
Request source nodes to send data.

@return Node This node object
Request source nodes to send data .