打开服务器后，我的PDF可以对服务器执行ping操作吗?
我有一个日常的cron工作，通过电子邮件将PDF发送给客户.我想测量一下打开了多少个PDF文件.有哪些可用的技术?
I have a daily cron job that email PDFs to customers. I want to get a measure of how many of those PDF files are opened. What techniques are available?
网页中的标准技术是包括一个img标记，该标记带有对记录ping的服务器端点的src引用.但似乎PDF不允许外部图像引用.
The standard technique in a web page is to include an img tag with a src reference to a server endpoint that records the ping. But it seems that PDF doesn't allow external image references.
有什么方法可以实现我想要的吗?
Is there some way to accomplish what I want?
更新:我们正在考虑让电子邮件带有指向PDF的链接，但是由于某些原因我们不希望这样做，所以我很想听听其他选项.
Update: we're considering having the email carry a link to the PDF, but there are reasons we don't want to, so I'm interested to hear other options.
要打电话回家"，您需要 Adobe LiveCycle Policy Server .
To "call home" you would need a Adobe LiveCycle Policy Server.
否则，如果有一种方法可以嵌入外部图像，则可以用于记录目的，但是我认为这是不可能的...
Otherwise, if there's a way to embed an external image, that might work for logging purposes, but I don't think that's possible...
编辑，可能会有一些方法，包括AcroJS .我自己还没有测试过它们，所以我不知道它们是否有用.
Edit, there might be a few methods, including AcroJS. Haven't tested them myself, so I've no idea if they're any good.
作为Linux用户，我应该指出，这两种非标准方法都不适用于非Acrobat Reader用户.
Edit 2: As a Linux user, I should point out that both of these non-standard approaches won't work for non Acrobat Reader users.