PureBasic Forum

Yo all,

Having returned from holiday I'm curious about something Facebook have started doing, and would like to implement a similar service on my own website. It's an HTML/server question and, though I've asked it on a more suitable forum, I think somebody here may know the answer.

If you're a registered user of Facebook, you can comment on something on another website using your FB identity. Your FB identity seems to be automatically recognised; the FB commenting stuff appears without you doing anything. If you post a comment, it gets added to that site AND to your Facebook wall.

I don't understand how they do this. How do they know it's you looking at this other website? Is it done by your IP address or the new client-side storage thing?

I ask because I'd like to do something similar for my own site - ie allowing registered users of my site to comment on things on other websites.

Thanks for reading,
Seymour.

If you are using the PC that you used to register with FB, then may be they saved a cookie on your system for this purpose?

I'm guessing that (as IdeasVacuum said) it is a cookie entry in your browsers cookie file that identifies you, but since cookies are supposed to be readable only from the domain that created it, I guess the form that allows you to create the post actually executes from the FB site and is embedded in your website's pages.

All Facebook boxes on other sites are in fact embedded via iframe.

Ah! An iFrame... of course!