Facebook visits pages that you post in messages and stays for many seconds

http://dontcode.tumblr.com/post/147428686798/tldr-facebook-visits-pages-that-you-post-in

by antoineMoPa • 10 years ago

24 19 10 years ago

dontcode.tumblr.com

killwhitey• 10 years ago

Previous discussion: https://news.ycombinator.com/item?id=11875419

powera3• 10 years ago

That seems different? Exposing (possibly private) URLs in messages via the API seems like a bug (though int64s aren't really guessable when you have DoS protection).

Just visiting the link shared is completely normal behavior.

lbrandy• 10 years ago

But why?

Go ahead and post a link in a message (I chose this one: http://imgur.com/gallery/wjANVCD). A little visual preview will appear. Where do you think this comes from?

And classify you as a good citizen for the NSA so that you don’t get killed in a drone attack

Or maybe that.

antoineMoPa2• 10 years ago

Why stay for so long though? Fetching an image is fast and using an automated browser is a bit overkill. Maybe they wait for 15 seconds in case the server is slow...

powera3• 10 years ago

Anti-virus. The post seems to be complaining that Facebook is using a browser, which probably means they're testing for malware.

GauntletWizard• 10 years ago

Or to detect JavaScript triggered malware or other nefarious behavior. Running a full headless browser for link scanning is actually quite doable for Facebook's scale.

morgante• 10 years ago

There are definitely some sites (particularly news sites) which can take 15 seconds to actually render the main content of the page.

corecoder• 10 years ago

JavaScript, webfonts, XHR... In my experience, if you don't wait most of the times you get a blank page.

kochthesecond• 10 years ago

Why not both?

Also, they probably need a browser and to wait for a full render to be guaranteed a finalized image for their preview thumbnail.

pshc• 10 years ago

Occam's Razor strikes again.

dack• 10 years ago

I don't think this is a big deal. You're posting a message _on their site_. It's reasonable for them to inspect the url.

taneq2• 10 years ago

Um yeah, the moment you type/paste a link in a post, it loads a preview and tries to pick a good representative picture of the page. As far as I can tell the image is even mirrored on Facebook's CDN for faster loading. It's not like they're subtle about it.

squiggy22• 10 years ago

Correct. This is the open graph bot. You can force fb to scrape your site at will and clear the current cached image preview.

https://developers.facebook.com/tools/lint

antoineMoPa2• 10 years ago

This is the part that happens before you send the message. The post is talking about the automated browser that visits the link after you post it and waits for 15 seconds with socket.io (thus javascript activated).

taneq2• 10 years ago

Oh. Something to do with trackbacks then, maybe?

omarforgotpwd• 10 years ago

Facebook probably sends an HTTP request to the link to get an image preview. I doubt that any human or computer is actually "looking" at the link for 15 seconds, more likely they just messed with the concept of time on the preview agent's Javascript interpreter so they can determine the layout of the "final page" with all animations and JS completed.

powera3• 10 years ago

This is not secret, surprising, or newsworthy, and the implication that it's for the NSA is pure conspiracy theory.

umhan35• 10 years ago

I guess it stays for many seconds because it waits JavaScript to finish executing to get an image preview. It's not uncommon that some sites needs many seconds (or even longer) to load.

awqrre• 10 years ago

also, if you want a URL to stay private, don't email it to anyone using a cloud email service (including yourself)...

Facebook visits pages that you post in messages and stays for many seconds

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