snaker-core/src/main/java/org/snaker/engine/core/SnakerEngineImpl.java
private Execution execute(Process process, String operator, Map<String, Object> args, 
			String parentId, String parentNodeName) {
		Order order = order().createOrder(process, operator, args, parentId, parentNodeName);
		if(log.isDebugEnabled()) {
			log.debug("创建流程实例对象:" + order);
		}
		Execution current = new Execution(this, process, order, args);
		current.setOperator(operator);
		return current;
	}
private Execution execute(Process process, String operator, Map<String, Object> args, 
			String parentId, String parentNodeName) {
		Order order = order().createOrder(process, operator, args, parentId, parentNodeName);
		if(log.isDebugEnabled()) {
			log.debug("创建流程实例对象:" + order);
		}
		Execution current = new Execution(this, process, order, args);
		current.setOperator(operator);
		return current;
	}
创建流程实例，并返回执行对象
@param process 流程定义
@param operator 操作人
@param args 参数列表
@param parentId 父流程实例id
@param parentNodeName 启动子流程的父流程节点名称
@return Execution