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

                    The Distributed Configuration Protocol v0.2.1
                    =============================================

Date:   December 18, 1998.
Author: Fabio Kon (f-kon@cs.uiuc.edu)

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 a 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.

LIST_APPLICATIONS
returns: list of strings representing the applications registered with the
Dynamic_Service_Config.

LIST_HOOKS <application_name>
returns: list of strings representing the hooks in a particular application.

GET_COMP_INFO <application_name>
returns: a string describing a particular component (or application).

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>
returns: ACK or NACK plus error message

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

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

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

CONFIGURE_SERVICE <service_name> <message_string>
returns: ACK or NACK plus error message

RESTART
returns: ACK or NACK plus error message


3) Updating a remote node's 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.

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

Future Extensions
=================

- SECURITY

- MANAGE INTER-COMPONENT DEPENDECE
        - inter-service dependence
        - service <-> application dependence
................................................................................


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;		// implemented
  static const char * const LIST_IMPLEMENTATIONS;       // implemented
  static const char * const LIST_LOADED_SERVICES;       // implemented
  static const char * const GET_INFO;                   // implemented
  static const char * const LIST_APPLICATIONS;          // implemented
  static const char * const LIST_HOOKS;                 // implemented
  static const char * const GET_COMP_INFO;              // implemented

  static const char * const LOAD_SERVICE;               // implemented
  static const char * const HOOK_SERVICE;               // implemented
  static const char * const SUSPEND_SERVICE;            // implemented
  static const char * const RESUME_SERVICE;             // implemented
  static const char * const REMOVE_SERVICE;             // implemented
  static const char * const REPLACE_SERVICE;

  static const char * const CONFIGURE_SERVICE;

  static const char * const UPLOAD_IMPLEMENTATION;       // implemented
  static const char * const DELETE_IMPLEMENTATION;       // implemented

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

 enum { major_version = 0, 
        minor_version = 2, 
        MAX_MESSAGE_SIZE = 1024};
};


class DCP_Reply {
 public:
  static const char * const ACK;
  static const char * const NACK;
  static const char * const UNKNOWN_REQUEST;
  static const char * const UNKNOWN_ENTITY;
  static const char * const EMPTY;
  static const char * const MALFORMED_REQUEST;
};