Specification of DCP: 
                              =====================

                    The Distributed Configuration Protocol v0.1
                    ===========================================

Fabio, May, 28, 1998.

This is a preliminary version of the Distributed Configuration Protocol which
will be used to configure components and distributed component implementations
across a distributed system. DCP can be used in client/server,
peer-to-peer, and active networking situations.

It's being implemented initially on ACE and will provide reconfiguration of
TAO components. Later, it will be available to any 2K application or system
module.

Note that, in the protocol operations, the term SERVICE refers to a place
holder, or hook, to concrete implementations. It doesn't need to be a CORBA
service, it might be any place holder to which an implementation can be
hooked. Thus, it can refer to a TAO component, to an application internal
component, to a service running on top of TAO, etc.


1) Getting information about the remote node's persistent repository
--------------------------------------------------------------------

LIST_SERVICES 
returns: list of strings (separated by "\r\n") representing the
services in the local persistent repository

LIST_IMPLEMENTATIONS <service_name>
returns: list of strings representing the
implementations of a particular service in the local persistent repository


1.1)  Getting information about the services linked to the run-time
-------------------------------------------------------------------

LIST_LOADED_SERVICES
returns: list of strings representing the services linked to the server
process run-time.

GET_INFO <service_name>
returns: string containing a description of a particular service.

GET_USAGE <service_name>
returns: string representing the command-line initialization string for a
particular service.


2) Reconfiguring the services linked to the run-time
----------------------------------------------------

LOAD_SERVICE <service_name> <implementation_name> <init_parameters>
returns: ACK or NACK plus error message

HOOK_SERVICE <service_name> <app_name> <hook_name>

SUSPEND_SERVICE  <service_name> [<implementation_name>]
returns: ACK or NACK plus error message

RESUME_SERVICE   <service_name> [<implementation_name>]
returns: ACK or NACK plus error message

REMOVE_SERVICE <service_name> [<implementation_name>]
returns: ACK or NACK plus error message

REPLACE_SERVICE  <service_name> <implementation_name> [<old_implementation_name>]
returns: ACK or NACK plus error message

CONFIGURE_SERVICE <service_name> <implementation_name> <message_string>
<implementation_name> may also be "all" or "any". In the first case, the
message_string is sent to all running implementations of that service and in
the latter case it is sent to one of them.
returns: string

RESTART
returns: ACK or NACK plus error message


3) Updating the ORB persistent service repository
-------------------------------------------------

UPLOAD_IMPLEMENTATION <service_name> <implementation_name> <length> <binary-code>
returns: ACK or NACK plus error message

DELETE_IMPLEMENTATION <service_name> <implementation_name>
returns: ACK or NACK plus error message


4) Miscellaneous
----------------
QUIT
returns: ACK

HELP
returns: string containing human-readable help and protocol version information.

................................................................................


DCP class interface and implementation:
=======================================


The DCP.h and DCP.cpp files containing the implementation of this class in C++
is available at the 2K source tree.


class DCP {
 public:
  static const char * const LIST_SERVICES;
  static const char * const LIST_IMPLEMENTATIONS;
  static const char * const LIST_LOADED_SERVICES;
  static const char * const GET_USAGE;
  static const char * const GET_INFO;

  static const char * const LOAD_SERVICE;
  static const char * const SUSPEND_SERVICE;
  static const char * const RESUME_SERVICE;
  static const char * const REMOVE_SERVICE;
  static const char * const REPLACE_SERVICE;

  static const char * const CONFIGURE_SERVICE;

  static const char * const UPLOAD_IMPLEMENTATION;
  static const char * const DELETE_IMPLEMENTATION;

  static const char * const RESTART;
  static const char * const QUIT;
  static const char * const HELP;

  static const char * const ANY;
  static const char * const ALL;

 enum { major_version = 0, 
        minor_version = 1, 
        MAX_MESSAGE_SIZE = 1024};
};


class DCP_Reply {
 public:
  static const char * const ACK;
  static const char * const NACK;
  static const char * const UNKNOWN;
  static const char * const UNKNOWN_SERVICE;
  static const char * const EMPTY;
  static const char * const MALFORMED_REQUEST;
};