Virtual Campfire - Collaborative Multimedia Semantization with Mobile Social Software Dominik Renzel 1 , Ralf Klamma 1 , Yiwei Cao 1 , Dejan Kovachev 1 1 Chair for Computer Science 5, Information Systems & Databases RWTH Aachen University, Ahornstr. 55, 52056 Aachen, {renzel, klamma, cao, kovachev}@dbis.rwth-aachen.de Abstract. Apart from automated techniques, collaborative multimedia semantic annotation by people, in particular communities of domain experts, are and will be powerful contributors to multimedia semantization. Recently, we extended our LAS server towards an XMPP server, thereby enabling the real time intertwining of communication and the collaborative utilization of remote services, in particular MPEG-7 multimedia semantic annotation and retrieval services. Within the context of the UMIC Virtual Campfire scenario, this contribution presents a set of mobile multimedia semantic annotation services and tools and their usage in a collaborative multimedia annotation scenario for cultural heritage documentation. In particular NMVX, an MPEG-7 multimedia semantic annotation tool in conjunction with a standard XMPP IM client are demonstrated, both powered by the same LAS XMPP server. Keywords: Multimedia semantic annotation, MPEG-7, mobile social software, SOA, XMPP, community information systems 1 Introduction to Virtual Campfire In recent years, great progresses have been made in technologies of mobile network technologies, mobile applications and services, mobile user interfaces, and mobile devices. Like the Linux developer communities in the early years, developers have paid attention to applications and services running on mobile devices such as Java ME devices, iPhones, Google Android devices, etc. User generated services and applications on mobile devices are going ahead together with user generated content on the Web 2.0. Challenges in developing mobile services and applications are multifold. There is a great variety of mobile standards, operating systems on different devices. Often unfortunately, one application can work on one cell phone well, while it does not work on the other. Meanwhile, Social Software allows users to be content prosumers (consumer and producer in parallel) anywhere at any time. Web 2.0 and Social Software result in a great amount of multimedia content which should be used by mobile communities. How well the mobile services and applications work is also hard to measure.