This illustration shows the Oracle8i Cache environment in more detail:

• The client tier shows three PCs being used as Web browsers. In addition, it shows a PC that is running Cache Manager, the graphical user interface for Oracle Database Cache.
• The middle tier shows one node containing a Web server, an application, the cache router, and a cache. Requests flow from the client tier to the middle tier. In the middle tier, the cache router determines whether the data is in the cache. If so, it routes the request to the cache. If not, it routes the request to the origin database.
• The database tier shows one node as the database server, which contains the origin database.

The illustration also shows communication between Cache Manager and both the middle-tier cache and the origin database.