直到现在，表达消息条件事实上还没有一个一致的方法，以便们可以应用于中间件层。

Until recently, there really has never been a single consistent way of expressing message conditions so that they can be applied on the middleware layer.

youdao

为了能够表达消息的语义，以及它们对系统状态的影响，我们引入了前置条件和后置条件。

To be able to express semantics of messages and their effects on system state we introduced pre- and postconditions.

youdao

正如前面提到的，插件扩展了即时消息传递客户机，它会根据初始化文件中的正则表达式，分析消息并寻找特定的关键词。

Remember that the instant messaging client was extended to analyze and scan the messages for particular key phrases, as specified through a regular expression in the initialization file.

youdao