Resource dynamic-link libraries (DLLs)

Resource DLLs contain instructions that manage cluster resources of one or more types. The most important role of the resource DLL is to detect application failures.

When the Cluster service issues a request to a resource, that request is passed to the Resource Monitor. The Resource Monitor, in turn, calls an entry point function in the resource DLL responsible for the resource.

XOX and XOX define several resource types and provide resource DLLs to manage them. However, a server cluster is not limited to the resource types provided with the operating system. Developers can create their own resource DLLs to replace or augment the resource DLLs provided with the operating system. Custom resource DLLs have detailed knowledge of the resources they manage and are used by resource monitors to determine the resource state (dead/alive).