Patent ID: 7624405

Claim:
A method for maintaining application availability during a change of a resource dynamic link library (DLL) in a clustered system, the clustered system including a plurality of nodes, each of the nodes being a computer having a cluster software and a dependency group application, the cluster software including a resource manager and a shim resource dynamic link library (DLL), the dependency group application having the resource DLL managed by the resource manager, the method comprising: linking the shim resource DLL to the managed resource DLL, the managed resource DLL exporting a function to control a resource in the clustered system; passing, by the shim resource DLL, to the managed resource DLL a call to an exported function unchanged during a normal mode; and during a change mode, the shim resource DLL: unlinking from the managed resource DLL to allow the managed resource DLL to be changed, and handling a call to an exported function without passing the call to the managed resource DLL.