> I don't think this will scale. If the presence information is distributed > via RSS, then the nodes will have to poll each other very frequently to keep > it up to date. If you're the PA node, that means you have to poll every > city in the entire state of Pennsylvania every minute, or every couple of > minutes. The PA node would spend all its time polling and never have > bandwidth left to do anything else.
Well.... The in the presence system i proposed, the nodes would put all of their logged in users in a XML doc. Then the state aggregators would poll the city nodes (every 10 or 5 minutes would be ok imo). And then the top node would poll all the state nodes. I don't really see to much of a problem with this system. Heck - imagine what technorati is doing. say if we had on average 10 nodes per state + 75 state / super nodes. That would be 120 polls on average an hour for a state (super node), 900 polls an hour by the a central presence aggregator for a total of about 10K polls an hour for the entire network - doesn't seem to unreasonable to me. Besides, the news / calandar / media polling metrics will be much the same, if not larger when its all said and done. -Zack
