Professional Microsoft® SharePoint® Designer 2007

14.3. Web Part Storage

As you know, a SharePoint page is served partially from the content database and (potentially) partially from the file system. Customized pages are served entirely from the database. In the case of dynamic Web Parts (those in Web Part Zones), all instance information is always served from the database, regardless of whether the page itself is customized. Although this information is kept in the content database, it can be thought of as a distinct repository, which is known as Web Part storage.

Web Part storage primarily contains the current values of each dynamic Web Part's properties. This is also known as the state of the Web Part. The retrieval of state information from Web Part storage was called a discovery service, but the updating of this information is called the state management service.

14.3.1. The Properties Collection

As noted earlier in this chapter, database access — especially updating — is an expensive operation. To make access as efficient as possible, the Properties collection of a Web Part is not retrieved from Web Part storage until a property is requested by the client.

When a property is requested, the WPSC checks to see if the properties have already been loaded from storage. If not, the entire Properties collection for that Web Part is retrieved and cached locally. All access to the properties thereafter, whether reading or writing, is made against the cache.

14.3.1.1. Into the Ether: Saving Changes, Or Not

So, what if you make ...