3 Protocol Details
The methods in this RPC interface MUST return ZERO (0x00000000) or a nonerror HRESULT (as specified in [MS-ERREF] section 2.1) to indicate success or a nonzero error code as specified in section 2.2.4, to indicate failure. Unless otherwise specified in section 3.2.4, the client-side of the File Server Remote VSS Protocol MUST NOT interpret returned error codes and MUST simply return error codes to the invoking application.
The following diagram describes the typical client and server environments and the interactions between various components.
Figure 1: FSRVP client and server environments and components
The application server hosts VSS writers that are components of the applications accessing their data from a remote file share. The backup/restore tools interact with the shadow copy utility on the application server to perform backup of the application's data on the remote file server. When the storage location supplied by the backup tool is a UNC path, the shadow copy utility directs the backup requests to the FSRVP client. The FSRVP client exchanges messages with the FSRVP server on the file server to query, create, or delete the shadow copies. The FSRVP server acts as a backup tool on the file server and interacts with the local shadow copy utility to respond to client's requests. The server's processing behavior is outlined in section 3.1 and the client's processing behavior is outlined in section 3.2.<1>