Carsten Pils Ioanna Roussaki Tom Pfeifer Nicolas Liampotis Nikos Kalatzis Federation and Sharing in the Context Marketplace. 121-138 2007 conf/loca/2007 LoCA http://dx.doi.org/10.1007/978-3-540-75160-1_8 db/conf/loca/loca2007.html#PilsRPLK07