Inside Microsoft® Exchange Server 2007 Web Services

Push Notifications

One problem with pull subscriptions is determining when and how often to poll the server using GetEvents. If you poll too frequently, you may receive many StatusEvent responses basically stating that there is nothing to return. This is wasted effort on the part of the client, and it causes the server to do unnecessary work. In fact, if you recall the earlier example of Ken at the restaurant, Ken’s frequent and fruitless trips to the hostess station before his table was ready is a great example of polling too frequently. If you poll too in frequently then there is a delay between an event occurring on the server and the client being aware of that event.

Let’s revisit Ken Malcolmson and Tina Makovec at the world famous Contoso ...