When you are receiving content via HTTP, you are always going to get the whole header in a particular format. To set a cookie, you are required to send it as part of this header but before the content type is passed to the browser. i.e.: 

Set-Cookie: blahblahblah
Content-type: text/html

<html>
.....

[download]


Where blahblahblah is the properly formatted cookie information. When banner adverts print their info, they do something along the lines of (but possibly not exactly - hey its only an example :P) 

Set-Cookie: blahblahblah
Content-type: image/gif
....
<data>

[download]


Although the cookie section is not part of the HTTP spec (according to my O'Reilly book) - everyone uses it (as we all well know :P).

So if you want to do something after the page has been displayed, you're best bet is to have a perl script that delivers a blank image with the cookie as part of its transaction to the browser. i.e: 

  <img src="http://www.mysite.blob/cgi-bin/imager.pl?IMAGE=one">

[download]


As far as I know - this is the only way you can have cookies from one site set by another (by the second site including that image).

Hope that helps - if not - reply and I'll see what I can do :)

In reply to Re: Cookie flexibility and limitations by simon.proctor
in thread Cookie flexibility and limitations by legLess

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.