In previous versions of WebSphere Enterprise Service Bus, only one input and outputterminal was allowed on the custom primitive; now this has been relaxed to allow multiple terminals.
在WebSphere Enterprise Service Bus之前的版本中，自定义原语上只允许一个输入和输出末端，而目前这个限制已经放松，允许多个末端。
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When you choose the once option, the aggregation is accomplished by wiring multiple flows from the outputterminal where each of these flows is initiated by the one firing of the message.
当您选择 once 选项时，通过连接来自输出末端的多个流来完成聚合，其中每个流都是由消息的一次触发发起的。