然而，有时候可能需要根据外部事件或者从一个非ibm环境中使用自己的调度程序触发规则执行。
However, in some cases it may be necessary to trigger the execution of rules based on external events, or from a non-IBM environment using its own scheduler.
一个必须在精确时间内响应事件的应用程序无法确保不会在一个高优先级线程之前调度另一个低优先级线程。
An application that must respond to events in a well-defined time has no way to ensure that another low-priority thread won't get scheduled in front of a high-priority thread.
它使用一个调度程序来发起周期性的事件，比如爬网程序执行和全文索引维护。
It USES a scheduler to initiate periodic events, such as crawler executions and full-text index maintenance.
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