That's also a hard question to answer, for much the same reason. The way a program running on the server communicates with the client is by sending a chunk of data back to the client. The client decides what to do with that data.

There are ways to return HTML, XML, CSS, JavaScript, Java, and even Flash to the client, but you're at the mercy of the client as to what it will and will not accept. In a tightly controlled environment, you can use client-side Perl Script, but it sounds like server-side Perl, by itself, is not the right solution for you.