Yahoo launched the first piece of the puzzle last week, a site called where end users can manage their activities, interests and social connections in one place. Next week will mark the launch of the developer component. It's built on top of Yahoo's existing network infrastructure and consists broadly of three layers.

The first is the Yahoo Social Platform, a repository where Yahoo stores the personal data about its users, along with their "social graph," or information about who their friends are. Above that is the Application Platform, which provides the development framework. And above that is the Yahoo Query Language, which developers will use to pull personal user data from Yahoo's servers and write their programs. YQL is very similar to the widely used SQL database language, according to Yahoo.

The platform also makes use of public APIs such as , for aggregating user data from other social networking sites, and , a protocol for consuming and publishing personal data. The tools and documentation will be available for free download next week from the Yahoo Developer Network, said Jay Rossiter, head of Yahoo's Open Strategy project. He wouldn't say exactly which day.

Yahoo officials gave examples of the types of applications it wants developers to build. If a person receives an e-mail telling them it's a friend's birthday, an application could allow them to view their friend's Amazon.com from within Yahoo Mail. Another program might automatically upload photos received via Yahoo Mail to an online photo account, be that Flickr or a non-Yahoo service such as Shutterfly.

Part of the challenge will be getting Yahoo's users to buy into the idea. At some time in the future, when they log into a Yahoo service they'll see the Yahoo Activator, which will present a list of all their contacts pulled from Yahoo Mail, Yahoo Messenger and other services. They'll use this to build their connections list and decide who can see what information.