Back to your hypothetical news page—you have a page, localweather.pl, that changes from person to person depending on their zip code. What is the best way to cache this?

You really do not want this document cached on the M-Business Sync Server. If you keep a cached version of localweather.pl that was created for a reader in Texas, and then repost that same page to somebody in Alaska, you could cause all sorts of weather-related havoc (not to mention fashion faux pas).

But remember, there is a second cache that exists on the user's mobile device. If your user in Texas synchronizes twelve times a day, you do not want to keep fetching new versions of the same weather report (especially if the weather report is updated only once a day.) Somehow, you have to find a way of telling the user's client cache to hold on to the Web page, while telling your M-Business Sync Server's shared cache to discard the page.