This illustration shows three separate topologies, highlighting the roadmap to arriving at high availability as covered in the Oracle Fusion Middleware documentation.

The first topology, labeled "1", shows an DBHOST with a database, and an APPHOST with a WebLogic Domain, which contains an Administration Server, and a cluster containing a Machine with two Managed Servers.

The second topology, labeled "2", shows the same topology as "1" but also include an Oracle HTTP Server in the WebLogic Domain.

The third topology, labeled "3", represents the high availability topology. The DBHOST contains a RAC database now, instead of a single database instance. There are also two APPHOST boxes (APPHOST1 and APPHOST2); APPHOST1 contains the Administration Server, a singe machine, and a single Managed Server, while APPHOST2 contains a second machine and second Managed Server. A cluster is shown encompassing both Managed Servers across both APPHOST1 and APPHOST2.

Above the APPHOST boxes, there are two additional boxes called WEBHOST1 and WEBHOST2, both of which contain an instance of Oracle HTTP Server. Finally, a box labeled "WebLogic Domain" is shown to include both Oracle HTPP Server instances and both Managed Servers.