HTTP Compression is on by default
As mentioned in HTTP Compression and Chunking, MarkLogic 11 now supports HTTP compression for all HTTP endpoints when clients include the Accept-Encoding: gzip HTTP header. Custom HTTP endpoints written for versions prior to MarkLogic 11 had the ability to look for the Accept-Encoding: gzip HTTP header and perform compression of the results themselves using built-in functions. When running these custom endpoints in MarkLogic 11, you must remove the logic in the custom code that does compression code or the results will be compressed twice and not be usable by clients.