Hello,
The C data interface spec was updated following a suggestion by Wes and Uwe: https://github.com/apache/arrow/blob/3173f88dfa32ce3296a121b032f351e089888601/docs/source/format/CDataInterface.rst The metadata encoding was changed. It does not use JSON anymore but a very simple binary encoding. Quoting the spec: This string is not null-terminated but follows a specific format:: int32: number of key/value pairs (noted N below) int32: byte length of key 0 key 0 (not null-terminated) int32: byte length of value 0 value 0 (not null-terminated) ... int32: byte length of key N - 1 key N - 1 (not null-terminated) int32: byte length of value N - 1 value N - 1 (not null-terminated) For example, the metadata ``[('key1', 'value1')]`` is encoded as:: \x01\x00\x00\x00\x04\x00\x00\x00key1\x06\x00\x00\x00value1 The C++ draft implementation now supports metadata exporting and importing: https://github.com/apache/arrow/pull/5608 Regards Antoine.
