The CQ project at OGI, funded by DARPA, aims at developing a scalable toolkit and techniques for update monitoring and event-driven information delivery on the net. The main feature of the CQ project is a “personalized update monitoring” toolkit based on continual queries [3]. Comparing with the pure pull (such as DBMSs, various web search engines) and pure push (such as Pointcast, Marimba, Broadcast disks) technology, the CQ project can be seen as a hybrid approach that combines the pull and push technology by supporting personalized update monitoring through a combined client-pull and server-push paradigm.