I'm trying to make a facebook app that needs to do something when a user updates their status. How would I make facebook notify my app when a user updates their status?
I know this is possible because the twitter app updates your twitter status when update your facebook status. I'm looking to do something like this.
Facebook has a set of open-graph meta tags that it looks at to decide which image to show.
The keys one for the Facebook image are:
<meta property="og:image" content="http://ia.media-imdb.com/rock.jpg"/>
<meta property="og:image:secure_url" content="https://secure.example.com/ogp.jpg" />
and it should be present inside the <head></head> tag at the top of your page.
If these tags are not present, it will look for their older method of specifying an image: <link rel="image_src" href="/myimage.jpg"/>. If neither are present, Facebook will look at the content of your page and choose images from your page that meet its share image criteria: Image must be at least 200px by 200px, have a maximum aspect ratio of 3:1, and in PNG, JPEG or GIF format.
Can I specify multiple images to allow the user to select an image?
Yes, you just need to add multiple image meta tags in the order you want them to appear in. The user will then be presented with an image selector dialog:
I specified the appropriate image meta tags. Why isn't Facebook accepting the changes?
Once a url has been shared, Facebook's crawler, which has a user agent of facebookexternalhit/1.1 (+https://www.facebook.com/externalhit_uatext.php), will access your page and cache the meta information. To force Facebook servers to clear the cache, use the Facebook Url Debugger / Linter Tool that they launched in June 2010 to refresh the cache and troubleshoot any meta tag issues on your page.
Also, the images on the page must be publicly accessible to the Facebook crawler. You should specify absolute url's like http://example.com/yourimage.jpg instead of just /yourimage.jpg.
Can I update these meta tags with client side code like Javascript or jQuery? No. Much like search engine crawlers, the Facebook scraper does not execute scripts so whatever meta tags are present when the page is downloaded are the meta tags that are used for image selection.
Adding these tags causes my page to no longer validate. How can I fix this?
You can add the necessary Facebook namespaces to your tag and your page should then pass validation:
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:og="http://ogp.me/ns#"
xmlns:fb="https://www.facebook.com/2008/fbml">
Simply fetch the data through this URL:
http://graph.facebook.com/userid_here/picture
Replace userid_here with id of the user you want to get the photo of. You can also use HTTPS as well.
You can use the PHP's file_get_contents function to read that URL and process the retrieved data.
Resource:
http://developers.facebook.com/docs/api
Note: In php.ini, you need to make sure that the OpenSSL extension is enabled to use thefile_get_contents function of PHP to read that URL.
Best Answer
You could try the status.get function (It's Beta ATM), and poll.
You could subscribe to the user's Status' RSS feed.