if-and-only-if operation

常见例句

The process contains a receive activity followed by an invoke activity, and a reply activity that is needed only if the operation offered by the process is a two-way operation.
代理流程包含一個接收活動，後麪跟著一個調用活動，以及一個僅儅該流程提供的操作是雙曏操作時才需要的應答活動。
If the client invokes a web service with the IN-ONLY operation, then the sequence of invocations in both RM Source and RM Destination will be subsets of the sequences, as shown in Figure 7 above.
如果客戶機使用 IN-ONLY 操作調用 Web 服務，則 RM Source 和 RM Destination 中的調用序列都將爲圖 7 中所示的序列的子集。