1. A method comprising: building in a host processor a set of descriptors that describe the operations to be performed by a Protocol Direct Memory Access Engine, the host processor building the set of descriptors in lieu of performing the operations described by the descriptors; providing the set of descriptors to the Protocol Direct Memory Access Engine; processing a protocol layer input data unit by means of the Protocol Direct Memory Access Engine by applying either compression or decompression to at least a portion of the protocol layer input data unit whereby the Protocol Direct Memory Access Engine executes the operations described in the set of descriptors to produce a protocol layer output data unit; and providing the protocol layer output data unit to a next layer of a network protocol stack.