It could be the result of the resource adapter receiving some external stimulus from a back-end system. Or it could just be some internal event, possibly even timer driven.

• 它可以是资源适配器接收到后端系统的一些外部刺激之后的结果,也可以仅仅是一些内部事件,甚至可能是由计时器驱动的事件。