Abstract: Conferencing data is reliably delivered to computer systems participating in a hierarchically arranged multi-cast conferencing session. When a child computer system does not receive a multi-cast packet (e.g., an IP multi-cast packet), the child computer system sends a negative acknowledgment to a parent computer system. In response, the parent computer system re-transmits conferencing data that was contained in the multi-cast packet to the child computer system. Conferencing data can be re-transmitted to the child computer system via uni-cast (e.g., TCP). Accordingly, conferencing data that is not received or that is damaged via multi-cast can be repaired via uni-cast. Computer systems can join an existing multi-cast conference session without having to communicate with the root computer system. The root computer system adjusts a multi-cast send rate to compensate for changed network conditions.

Abstract: A method of incrementally refining queries and updating query result lists without requiring a user to provide an explicit indicator of query submission. In the method, one or more query related character patterns are defined. Entry of query defining characters by a user is monitored to detect entry of a defined query related character pattern. The user is provided with one or more suggested query refinement options and an updated query result list each time a defined query related character pattern is detected. The query related character patterns may be a character pattern that indicates a word has been input by the user.