1 Introduction

The generic object management system ACPLT/OV enables an easy use of object management functionality in process control components. This functionality can be devided into the following groups:

1.1 Management of objects and their relationships

Objects and their relationships are stored in a persistent database. At run time, objects and their relationsships (which are described by links) may be created or deleted and attributes or objects may be read or modified. Rather than just storing data, objects own operations encapsulating their functionality. Objects may even be active objects, which means that they are actively process data. The complete contents of a database can always be exported to the generic human-readable ACPLT/OV instance desription language which may be modified and be reimported to an existing or new database.

1.2 Implementation of objects and their relationships

Objects are classified by (object) classes, relationships are classified by associations. The implementation of classes is carried out in ANSI C which provides a high portability - ACPLT/OV not only runs on a workstation but also on a microcontroller! While ANSI C lacks a support for object oriented programming, the ACPLT/OV C code generator automatically creates virtual function tables and the ACPLT/OV library helps out with many functions and macros supporting the object oriented programming style. The input for the C code generator is the ACPLT/OV modelling language (see below). Implementations of classes and associations are grouped to libraries, which may be DLLs or shared libraries and can be loaded into the system at run time.

1.3 Information about information: meta information

The class and association definitions provided by the ACPLT/OV modelling language do not only support the implementation; rather they are converted into meta objects, which are instances of the ACPLT/OV meta model. If a library is loaded, these meta objects are instantiated in the database. The benefits are: - Reflection: Objects may explore the meta information about themselves or other objects (of which class they are, which variables they own or the like). - Introspection: Clients may explore the database, which is -- due to the meta information -- self descriptive. This means, that you do NOT have to configure anything to access any information (see the following topic).

1.4 Information access at run time

The information stored in the attributes of the managed objects as well as structural information about the objects and their relationships can be accessed over the network through an integrated ACPLT/KS server.

1.5 Engineering functionality at run time

ACPLT/OV does not only show "a picture of the world inside" but also allows to modify the (engineered) structure of the object system through the CreateObject, DeleteObject, Link and Unlink services provided by the integrated ACPLT/KS server.