A fingerprinting function is a hash function that can be computed incrementally. RDC divides a file's data into chunks by computing the local maxima of a fingerprinting function that is computed at every byte position in the file. Remote Differential Compression Algorithm Overview RDC can also be used on faster networks if the amount of data to be transferred is relatively large and the changes to the data are typically small. RDC is suitable for applications that move data across a wide area network (WAN) where the data transmission costs outweigh the CPU cost of signature computation. The RDC application bears the responsibility for choosing the appropriate transport and performing any client or server authentication that is required to support the transport's security model. Therefore, the RDC application is responsible for performing file I/O on behalf of the RDC library.īecause it is transport independent, RDC can be used with RPC, HTTP, or other desired transport mechanisms. RDC does not assume that the file data to be synchronized resides in physical files. Because differences between files are computed on the fly, RDC is ideally suited for synchronizing files that are different or have been updated independently. RDC makes no assumptions about file similarity or versioning. BDC requires the server to have copies of all versions of the file, and differences between each pair of versions are precomputed so that they can be distributed efficiently from a server to multiple clients.
RDC is different from patching-oriented differencing mechanisms, such as Binary Delta Compression (BDC), that are designed to operate only on known versions of a single file. Remote Differential Compression (RDC) allows data to be synchronized with a remote source using compression techniques to minimize the amount of data sent across the network.
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