Talk at FZI Karlsruhe about OpenSocial and Google App Engine. Titel: "Social Applications in the Cloud: OpenSocial and Google App Engine" Abstract: OpenSocial is an open specification defining a common API that works on many different social websites, including MySpace, Plaxo, Hi5, Ning, orkut, Salesforce.com and LinkedIn, among others. This allows developers to learn one API, then write a social application for any of those sites: Learn once, write anywhere. In addition, in order to make it easier for developers of social sites to implement the API and make their site an OpenSocial container, the Apache project Shindig provides reference implementations for OpenSocial containers in two languages (Java, PHP). Shindig defines a language specific Service Provider Interface (SPI) that a social site can implement to connect Shindig to People, Persistence and Activities backend services for the social site. Shindig will then expose these services as OpenSocial JavaScript and REST APIs. In this talk, we will explain what OpenSocial is, show examples of OpenSocial containers and applications, demonstrate how to create an OpenSocial application, and explain how to leverage Apache Shindig in order to implement an OpenSocial container. Simple OpenSocial applications can be built without any server side logic, leveraging the OpenSocial persistence API. For more complex applications requiring server side logic, many developers choose to use their own server. As their applications spread virally and become more successful, these developers end up spending most of their time making their applications scale instead of adding new features. Cloud computing services can provide a solution to these problems. We will explain how to build an OpenSocial application with server side business logic, on top of Google App Engine, a Cloud Computing service exposing Google's scalable infrastructure (GFS, BigTable) to developers. We will discuss how to use the Django web framework with the datastore API provided by Google App Engine to build scalable OpenSocial web applications with minimal fuss.