Hopefully you've heard about the upcoming hackathon that Facebook and Microsoft are hosting at the Facebook headquarters in San Francisco on Jan. 17. Head over to the registration page for details and to RSVP for the event.

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The goal of the hackathon is to help developers integrate Facebook Login, announced in November of last year, into their Windows and Windows Phone apps.

Facebook Login is an essential part of the fabric of social integration in mobile apps. Developers have been asking for a seamless and officially supported way of integrating the Facebook experience into their Windows and Windows Phone apps. This has been on our radar for a while and started gaining momentum as we entered 2013.

In spring of last year, we approached Facebook with the idea of integrating the Facebook Login into Windows and Windows Phone, with the goal of providing an even greater social experience. Facebook was excited about this, and we started working together on this project. 

From a technology point of view, the problem was challenging due some of the architectural differences between Windows and Windows Phone. For Windows Store applications, the Windows team used the WebAuthenticationBroker to integrate a streamlined authentication process into the OS.

The great thing about WebAuthenticationBroker is that it gives users a consistent way of logging in using any authentication provider. It also enables the secure use of Single Sign On with any Windows Store application via the OAuth open standard. With support from Facebook, getting Facebook Login integrated into this flow was a straightforward effort.

But this technology wasn’t available for Windows Phone 8, so Microsoft and Facebook engineers invented an approach to carry out the authentication using Application Redirects (that is, applications invoke the Facebook app via an app redirect to authenticate the user). After successful authentication, the Facebook app would invoke the original app and return an access token for the user.

To enable this approach, Windows Phone engineers made changes to the Store, introduced elements in the app manifest, and created a callback mechanism — all while keeping a sharp eye on the security model. 

To get the ball rolling on the work, Microsoft’s Windows Phone engineers visited Facebook headquarters last summer and participated in a hackfest with Facebook engineers. Out of that interaction, a barebones proof of concept was produced. As it was further refined over the next few months into Facebook Login, we reached some other important milestones, such as getting the Facebook application into the Windows Store and enhancing the Facebook app on Windows Phone.

In late summer, Facebook engineers visited Microsoft and we all sat down with plenty of coffee and completed the work at a number of hacking sessions that often ran late into the night. With the motto of quick iterations and incremental polish, we crossed the finish line and released the Facebook Login.

Now it is your turn. Come join us for the hackathon at Facebook headquarters. You will get in-person access to both Microsoft and Facebook engineers, learn how to build socially integrated applications for Windows and Windows Phone, and have a chance to win cool prizes . We hope to see you there.