Assume you are working on a "Soap Opera Daily" channel that consists of 25 individual pages, each of which are updated every day at midnight. It is a very popular channel, and you have also got a subscriber base of half a million people. Your customers, wanting to get the latest Soap Opera news every day, are updating their channels daily like clockwork.

Here is what happens if you do not have your channel set up for caching:

Step 1: Every day, half a million people ask the AvantGo sync server for updates to your channel.

Step 2: The AvantGo sync server hits your home page, grabbing 25 individual pages half a million times a day, meaning your server is dishing out 12.5 million pages a day just to the AvantGo sync server.

Step 3: The AvantGo sync server compresses these files and uploads them to the users' Palm OS device, Pocket PC device, or other mobile device.

This is a pretty slow process. Your server is probably struggling under the weight of dishing out 12.5 million pages a day just for your AvantGo channel. Worse, your readers are waiting a long time for their channels to sync because the AvantGo sync server first has to get the pages from your overworked server, compress them for better viewing on the AvantGo Client, and then upload them to their mobile device.

This is what happens if you do set up your page for caching:

Step 1: You specify that all the pages on your channel are good for, say, 24 hours.

Step 2: Each day, the first time a user asks to update the channel, the AvantGo sync server hits your home page, grabbing 25 individual pages. It compresses them, and uploads them to the user's AvantGo Client.

Step 3: The AvantGo sync server holds on to those pages (already compressed) for future use.

Step 4: The remaining 499,999 times a user asks to update the channel, the AvantGo sync server simply sends off the pre-compressed, pre-loaded channel pages to users' Palm OS or Pocket PC machine.

Note: This is an oversimplification. We cache different versions of the compressed page depending on the client device type (Palm OS vs. Pocket PC), and there are actually several AvantGo sync servers, each with its own cache. So it is not actually a savings of 500,000 to 1. It is more like a savings of 500,000 to 60. Which is still pretty good.

Your server is happy because its only working to push out 25 pages a day instead of 12.5 million. Your readers are happy because they can get pages directly from the AvantGo sync server instead of having to wait for our server to retrieve them from the Internet and then compress them. And we are happy because if our customers can sync faster, they will keep using AvantGo.