Short answer: you can't.

The problem is that HTTP and web browsers don't work that way. You (server) can't "send a file" to a browser, it is the browser that must request the file to you.

This said, I see at least two options to do something that works like you expect:

• Send a HTML page with the informations and generate server side the file. In the page, there will be a link to download the file.
• Same thing but a bit more automagic: instead of a link on the page you can have a short javascript doing the same thing. When the page is loaded in the browser, the script will start a second HTTP request to download the xls file.

In both approaches you have to consider two caveats: first that the file is created and saved server side, and should not be deleted until the browser downloads it, but consider also that the browser could never start the download. So you should implement some server side mechanism to delete all files older than X minutes/hours/days (depending on your context) or soon or later you'll have the server disk full.

The second point to remember is that the files generated in this way are exposed on the internet. If the files can contain sensitive data, you should at least generate them with random names, to reduce the chance of a guess on a sequential naming scheme.