In fact, you'll be sent to the "Update Preferences" page where you can select the categories you wish to add. You can also uncheck the ones related to the content you don't want on your device, as shown in Figure B.

FIGURE B

Here is the Reuters Channel "Update Preferences" screen.

After making the changes you need to tap on "Update Preferences" and synchronize.

How does this work? Since the Channels are built using HTML tags, you can take advantage of cookies in order to personalize and send specific content to each user. The differences between cookies on a regular Web site and cookies in AvantGo Channels is that in the channel, the cookie is stored in the AvantGo server and linked to an AvantGo username and an ID on your database.

Creating a channel with preferences
To create a channel with preferences, you'll also need to use forms, which are always associated with actions. The reader ( the user) fills and submits the form, and after being processed by the server, the results are shown to the reader in a new page. Even though handhelds are usually not connected to the Internet on a full-time basis, this is also how it works with AvantGo. The difference is that after submitting a form from a channel, the person accessing the content will be sending all the data to the "Forms Manager." The information will be kept there until the handheld is synchronized again. After the HotSync, the information is processed on the server, and an HTML page is sent back to the PDA.

You can keep a database on your server with a list containing user IDs and their preferences. When a user accesses the channel page through AvantGo, your system will check the cookie for that user and obtain his or her ID. You can then use the ID to look up preferences on the database and generate a custom page using dynamic pages (i.e., ASP, PHP, etc.).

If your user wishes to change his preferences, he can use the forms on the channel to check or uncheck the items. And if it's the first time your user is accessing the channel, a cookie will be addressed, and he'll receive an ID in your database. This user will then receive a default page, which he can personalize in the future.

If you wish to implement your channel with personalization fields using cookies and forms, you'll find a very detailed explanation on the AvantGo Web site (at http://avantgo.com/doc/developer/channels/creating/personal/personal.html).

What are the benefits?
What are the benefits for creating and using channels that can be personalized? There are lots of advantages. First, you can allow the channels to be personalized by users, saving development time and resources. It's also possible to create a sign-in page, which is very important in a lot of cases: to offer personalized content, for e-commerce purposes, or any other kind of interaction between the end user and the Web site.

As for your channel users, it's important to know that there are different kinds of users. Maybe one is more concerned about the information itself and the images are not so important, especially to save memory. Or maybe it's important to have the same kind of information available in the handheld as there is on a customized page on the Web.