让我们查看一个利用清单2中所示的数据访问代码的简单应用程序。
Let's look at a simple application that leverages the data-access code shown in Listing 2.
EJB截取程序是我接下来要论述的几个基于截取的插装示例的第一个，借鉴了清单1中查看的跟踪方法。
EJB interceptors are the first of several examples of interception-based instrumentation that I'll discuss next, drawing on the same tracing methods I reviewed in Listing 1.
如果主机是已知的，但是用户抱怨这个主机本身或它上面运行的应用程序没有响应，那么使用ping并查看数据包丢失率是否为0%(见清单6)。
If a host is known but you find that users are complaining that the host itself or an application running on it isn't responding, use ping and look for 0% packet loss (see Listing 6).
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