As part of the remote object messaging, objects passed by-value are converted to and from byte representations. The Distributed feature marshaling is based on the Swapper tool, which is described in the Smalltalk User Guide.

SST has two general purpose message marshalers. The SstSwapperMarshaling is based on the Swapper. The SstLightweightMarshaling is optimized for the smaller messages typical in a distributed object application.