Caching and Updating Web Parts in SharePoint Portal Server 2001 (290618)

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Digital Dashboards and Web Parts

The portal of your SharePoint Portal Server is integrated with the Digital Dashboard. The Digital Dashboard is a collection of modules that are called Web Parts. These Web Parts are organized on a Web page. Web Parts are reusable components that deliver Web-based content to a Digital Dashboard by wrapping Extensible Markup Language (XML), Hypertext Markup Language (HTML), and scripts with a standard property schema. This standard property schema controls how the Web Parts are rendered in a Digital Dashboard.

Because the SharePoint Portal Server portal is integrated with a digital dashboard, you can take advantage of all of the programs and services that are packaged as Web Parts. You can add new features to your portal by choosing new Web Parts from a catalog. You can also build your own Web Parts, and then plug them into your SharePoint Portal Server portal.

For additional information about creating Web Parts, view the SharePoint Portal Server Software Development Kit (SDK) from the following Microsoft Web site:

Caching Web Part Items

You can also cache Web Parts by editing the Advanced Settings for the Web Part, and then setting the appropriate property values under Should the content of this Web Part be cached?. If you cache these items, you may dramatically improve performance when you refresh. However, the Web Part may potentially ignore new data from a content link until the cache time-out occurs. Because of this, a Flush application level cache option is available in the Management Dashboard on your portal.

The application cache of the portal is flushed the next time that a portal page is rendered after one of the following actions:

• When you add, rename, delete, or change any item in an all classic folder under the Portal Content folder.
• When you add, rename, or delete any Category folder.

Some actions that do not cause a cache flush include:

• When you add, rename, delete, or change any item in a smart folder under Portal Content.
• When documents are added or removed in a category.

Because of this, a notification mechanism is available to the portal to maintain some appearance of cache coherence. This may account for 95 percent of the items from which you still have to manually flush the portal cache. Such items include:

• Folder Enumerator-based start page parts, such as News, Announcements, Quick Links, and any other parts that the user added (as long as the parts obtain their content from under the Portal Content).
• The top-level categories part on the start page.
• The top-level categories and second-level categories when you click directly on the Categories Dashboard.
• Subcategories in a category when you use the Categories Dashboard to display a specific category.

If you use the Web Part on the Management Dashboard to flush the cache, you flush everything in the cross-user cache. However, the only entries in the per-user cache that the Web Part on the Management Dashboard can flush are the current user's. This is because the Web Part does not have access to caches that belong to other users. Per-user cached items remain cached until they time out. You can restart Internet Information Services (IIS) to flush the cross-user cache and all of the per-user caches.