protected function getCommonService() {
		if ($this->service === null) {
			if ($this->arguments === null) {
				$this->service = $this->initService();
			} else {
				$args = $this->normalizeArgs($this->arguments);
				$args = $this->processArgs($args);
				
				$this->service = $this->initService($args);
			}
		}
		
		return $this->service;
	}