How can I return a text file and an error log from a webpage separately

Question

I have a perl script which when run from the command line generates a text file of data with a specific format for use by another application. The script also prints informational warning messages on stderr. I'm writing a web front end for this. In an ideal world when the user clicks 'submit' on the associated form, a page would be displayed in the browser containing the informational messages, and simultaneously a pop-up would appear allowing the user to save the text file of data to disk. I would like this to work on browsers without javascript enabled, so I think exactly what I want is probably not possible.

Some sites I have seen deal with this kind of thing by displaying the page with the informational messages, and a link to the file to be downloaded. This would seem to mean having to store the files and sorting out some sort of security so that another user cannot download your file (not that this is a big deal for the application in question).

I'm wondering if there is a more elegant way of dealing with this? e.g Is it possible to use multipart messages to somehow achieve returning both pieces of information in one go? Is it possible to pop-up a second window with the informational messages without using javascript? Apologies if these seem like basic questions - my programming knowledge is in the domain of DNA sequence manipulation algorithms rather than web page generation..

Answer 1

If (and only if) the data is quick and easy to generate, do it once for error messages and a second time for download. The link or button of the error-message page would regenerate the results and prompt for download.

This is a bit of a hack since you need to consider what to do if the underlying data changes before the user hits the download link. Be careful to set the header correctly for file download vs normal webpage, eg,

if($submit) { 
    print header(-type=>'application/octet-stream',
         -Content_disposition=>'attachment; filename=foobar.dat');
    Gen_Results();
}

To be honest, I'd just use a little javascript anyway since it's a pretty safe assumption now a days. Otherwise, use a "noscript" tag for some alternative.