In recent years, there has been an explosive growth in the popularity of
online social networks such as Facebook. In a new twist, third party developers
are now able to create their own web applications which plug into Facebook and
work with Facebook's "social" data, enabling the entire Facebook user base of
more than 400 million active users to use such applications. These client
applications can contain subtle errors that can be hard to debug if they misuse
the Facebook API. In this paper we present an experience report on applying
Microsoft's new code contract system for the .NET framework to the Facebook
API.We wrote contracts for several classes in the Facebook API wrapper which
allows Microsoft .NET developers to implement Facebook applications. We
evaluated the usefulness of these contracts during implementation of a new
Facebook application. Our experience indicates that having code contracts
provides a better and quicker software development experience.Comment: In Proceedings TAV-WEB 2010, arXiv:1009.330