Andrei Popovici Andreas Frei Gustavo Alonso A Proactive Middleware Platform for Mobile Computing. 455-473 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2672&spage=455 2003 conf/middleware/2003 Middleware db/conf/middleware/middleware2003.html#PopoviciFA03