The second, known as piggyback, doesn't create any connections to the server. Instead, it waits until another DWR service call occurs and piggybacks pending events onto this request's response. 第二种称为piggyback,这种机制并不创建任何到服务器的连接,相反,将一直等待直至发生另一个DWR服务,piggybacks使事件等待该请求的响应。
"We can piggyback on decades of hard work in service of understanding heart disease," she says. 为了致力于对心脏病的了解,我们能够在几十年里挑起这个艰巨的重任!