| Resource Interface
The resource DLL interfaces are formally specified and published as part of the Cluster software development kit (SDK). This interface allows application developers to make resources of their applications. For example, a database server application could provide a database resource to enable the Cluster Service to fail over an individual data-base from the server on one system to the server on the other. Without a database resource, the Cluster Service can only fail over the entire server application (and all its databases). Since a resource can be active on only one system in the cluster, this would limit the cluster to a single running instance of the database server. Providing a database resource makes the database the basic fail over unit instead of the server program itself. Once the server application is no longer the resource, multiple servers can be simultaneously running on different systems in the cluster, each with its own set of databases. This is the first step towards achieving cluster-wide scalability. Providing a resource DLL is a requirement for any cluster-aware application.
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