This section provides a sample virtual business service configuration comprising a multi-tier application. Figure: Sample virtual business service configuration shows a Finance application that is dependent on components that run on three different operating systems and on three different clusters.
Databases such as Oracle running on Solaris operating systems form the database tier.
Middleware applications such as WebSphere running on AIX operating systems form the middle tier.
Web applications such as Apache and IIS running on Windows and Linux virtual machines form the Web tier.
Each tier can have its own high availability mechanism. For example, you can use Cluster Server for the databases and middleware applications for the Web servers.
Each time you start the Finance business application, typically you need to bring the components online in the following order - Oracle database, WebSphere, Apache and IIS. In addition, you must bring the virtual machines online before you start the Web tier. To stop the Finance application, you must take the components offline in the reverse order. From the business perspective, the Finance service is unavailable if any of the tiers becomes unavailable.
When you configure the Finance application as a virtual business service, you can specify that the Oracle database must start first, followed by WebSphere and the Web servers. The reverse order automatically applies when you stop the virtual business service. When you start or stop the virtual business service, the components of the service are started or stopped in the defined order.