The purpose of this specification is to provide a common base for definition of commands.
Based on this specification it will be possible to use generic clients for execution and control of commands. That is why this specification has a strong emphasis on how to discover commands and the associated execution state machine.
In this context a command is seen as an "atomic" method that is triggered on the server by one invocation call. If the application requires a more complex set/sequence of methods, it is expected that a number of commands will be defined to control the sequence.
OPC Commands is a standalone specification in that Commands Servers and Clients can be implemented without using any other OPC-defined interfaces (like Data Access or Alarms &Events).
Note: OPC Commands Servers are also expected to implement the interfaces described in OPC Common Definitions and Interfaces 1.0. This document contains common rules, design criteria and the specification of interfaces which are common for most OPC Servers, including Commands.
This specification is intended for developers of OPC Commands Clients and Servers. It is assumed that the reader is familiar with Microsoft COM. It is also recommended that the reader review the reference documents described in Section 1.5.