CompressionAndRMI

I am writing this page in case there are others who try to implement compression over rmi and find that it is more difficult than expected. There are several other pages that describe how to create and use an rmisocket factory. The tricky part is to develop the compressing input and output streams that can be used by a socket with rmi. The main difficulties are

1. the client hangs when trying to communicate with the server. This is what happens if you simply try to use a GZIPInputStream and a [GZIPOutputStream. The flush operation on the GZIPOutputStream is not sufficient to have the desired effect on the client. RMI expects that when it flushes the output stream on the server that all the data flushed will appear on the client. Instead in this case the client is still waiting for the rest of the data. I believe that the issue is that the GZIPOutputStream is in the middle of a compress operation and is not ready to flush everything down the wire.
2. A common solution to the above is to modify the GZIPOutputStream so that on a flush() operation it invokes finish(). This is indeed useful for flushing out all the data. Unfortunately what I found is that when rmi later writes to this same stream again after the flush, an exception is thrown because one is not supposed to finish a GZIPOutputStream and then continue writing.

So what I needed was a way to tell the compressing stream that I had a unit that could be compressed in its entirety without interfering with future writes. My solution was to make a compressing output stream out of a ZipOutputStream out of a

There are several other pages that tell you how to set up a compressing socket but I had problems making these implementations work.

Now some of the other pages describe how to then construct a rmi socket factory that will compress and decompress data going over the wire. The critical step in this work is the construction of a compressing input and output stream that will compress the data over the wire.