Upgrading Windows SharePoint Services
This section provides information about how to extend the process of upgrading sites that have been heavily customized in Microsoft Windows SharePoint Services from version 2 to version 3. The most common customizations made in version 2 involve Web Parts, site definitions, or customizations made in Microsoft Office FrontPage.
Windows SharePoint Services provides an object model for defining upgrade actions, and a schema for defining upgrade definition files. The object model provides a means to execute custom upgrade code from the unique upgrade processes required by the external server application. Custom applications can wrap Windows SharePoint Services upgrade methods and drive the upgrade process. The upgrade definition schema makes it possible to create files that map existing files and resources in the previous version to features in the new version.
Windows SharePoint Services does not support extending database schemas, and its upgrade code assumes that they have not been modified. Installations that violate this assumption may experience data loss after Windows SharePoint Services upgrade code runs. Parties affected are responsible for reading in their unsupported data prior to the SharePoint upgrade code, and re-inserting it after upgrade.