[bind10-dev] Return codes for RESTful API

[zhanglikun]

　Hi all, I am working on http return codes of RESTful API, try to gather
more information by sending this email. 
　The RESTful API of cmdctl was designed like:URL:
/module_name/command_name, command paramters are sent with post-data. 
　Currently we don’t have a well-defined status rcodes list, if one command
sent from bindctl isn’t executed properly, some error message may be
printed by bindctl, which depends on whether the aim module provide
well-defined rcode and error message(anyway, we have defined the command
reply format, see
https://bind10.isc.org/wiki/ModuleConfigurationCommunication).

  There are two types of status rcode in my opinion:
1. Well categorized status rcodes.  
  Like http status rcodes.
  500 Internal Server Error
  400 Bad Request

2. Define unique rcode for different command.  
  Like the rcode in oracle: ORA-12504: TNS:listener was not given
SERVICE_NAME -- ASP.NET Connection
      
I think it's easy to locate the error if using the second way.

Any suggestion?

Thanks
Zhang Likun