public function loadDefinition($workflowId, $source)
	{
		$wfClassname = $this->getClassname($workflowId);
		$defProvider = null;
		try {
			$defProvider = Yii::createObject(['class' => $wfClassname]);
		} catch ( \ReflectionException $e) {
			throw new WorkflowException('failed to load workflow definition : '.$e->getMessage());
		}
		if( ! $defProvider instanceof IWorkflowDefinitionProvider ) {
			throw new WorkflowException('Invalid workflow provider : class '.$wfClassname
				.' doesn\'t implement \raoul2000\workflow\source\file\IWorkflowDefinitionProvider');
		}

		return $this->parse($workflowId, $defProvider->getDefinition(), $source);
	}