GWS uses zlib to compress data

GWS support data compression by using the zlib library.

The zlib component is a utility library widely used for data compression.

GWS SOAP and RESTful web services support data compression by using the zlib library.

The GWS modules requiring compression will search for the zlib library installed on the operating system. If zlib is not found on the system, GWS will fallback to the zlib provided in FGLDIR/lib/wse.

The zlib implementation is provided as a libz.so file on Linux®, ZLIB.DLL on Windows®, and libz.dylib on macOS™.

The corresponding zlib library is provided in the FGLGWS package as fallback, if not present on the OS.

There should always be a zlib available. If zlib is neither available on the system, nor in FGLDIR/lib/wse, GWS features will work until compression is required. As soon as compression is required, GWS will produce the runtime error -15549, with sqlca.sqlerrm containing "Cannot initialize compression".

Use FGLWSDEBUG=1 output to check if zlib is found:

If zlib is found on the system:

WS-DEBUG (Info)
Default zlib loaded
WS-DEBUG END

If zlib is found in FGLDIR:

WS-DEBUG (Info)
Loaded zlib from 'full-path-to-zlib' 
WS-DEBUG END

If zlib is not available but required for compression:

WS-DEBUG (Error)
No zlib loaded
WS-DEBUG END