I have seen this posted numerous times in other places without a true answer. I am trying to implement compression over RMI calls. I am able to get the code from Sun's RMICustomSocketFactory working without problems- other than it is NOT designed to be used in production and doesn't really compress the data. I have attempted to use the java.util.zip.GZIP*Streams and the pure-Java zlib libraries from Jcraft (http://www.jcraft.com/jzlib) with very little success. When using the Jcraft libraries, I receive a "MarshalException: Transport not supported." Any suggestions/help appreciated.