Google launched a new application programming interface (API)on Friday that is designed to help developers make use of social networking relationship data.

The Google Social Graph API provides developers with an easy way to control social relationships in their applications and on their Web sites. Developers can code applications which can link up people on the Web. That means that the new APIs will prevent social network users the hassle of redeveloping their entire network of friends when they join new networks.

Google will then take the final data and make it available to third parties, who can build this into their applications and Google will include this in their Google Open Social applications.

You can make it easy for users to bring their existing social connections into a new Web site and as a result, users will spend less time rebuilding their social networks and more time giving your app the love it deserves, explained Google engineer Brad Fitzpatrick in a blog post.

A developer can use the Social Graph API to create a button for a Web site that allosw a registered user to easily add friends. This makes social data more portable and as result, makes social networks like Facebook and Myspace less relevant.

Fitzpatrick explained that Google will crawl the Web to find publicly declared relationships between people's accounts, just like Google crawls the Web for links between pages. But instead of returning links to HTML documents, the API returns JSON data structures representing the social relationships we discovered from all the XFN and FOAF.

When a user signs up for your app, you can use the API to remind them who they've said they're friends with on other sites and ask them if they want to be friends on your new site, he added.