A Consumer block expect a well-formatted message

[eddbbt]

A conusmer block expects a specific object as message to parse and save, the scrutcure is not documented anywhere but in corresponding file. Official Docs shall be updated
Correct payload structure (extracted from file) to pass between pipe blocks is

 * `:key`: a unicode string that identifies the stream the message belongs to
 * `:metadata`: additional message metadata  (could be also and object)
 * `:type': message data type (e.g. integer, real, boolean, etc...)  (could be also and object)
 * `:subtype`: a string that represents the subtype, that is a mimetype for binaries.
 * `:timestamp`: timestamp in microseconds. (useful if explicit_timestamp is set in interface definition)
 * `:data`: the message payload.  (could be also and object)