GZip is a commonly used compression algorithm for compressing/decompressing strings e.g. to transfer over a network. There is no native function in LabVIEW that supports GZip compression and as I'm working on RT, the .NET solution found here is not suitable.
The GZip file format itself contains a header, a DEFLATE compressed body and a footer containing a CRC32 checksum and length data.
The DEFLATE and CRC32 checksum calculation is done by the OpenG Zip Tools. For full RT support (e.g. Linux RT), you need to use a newer version of the library than (4.1.0-b2) which can be found here. Thanks rolfk!
20/01/2016: Changed compress VI to remove the last 4 bytes of the DEFLATE output - it didn't seem to be necessary and was causing errors parsing the compressed data in Java. Downgraded the error 42 out to a warning as it seems to be always generated in the Decompress VI - I didn't delve into the ZLIB INFLATE source to figure out why.