MetaProperties for Generic Programs and Generic Beans

Introduction

Different ControlDeviceClass and ClassVersions have different properties. The MetaProperty class is an attempt to describe the important properties of each class in a uniform way. This information can be used by generic programs to decide what to do with a device of a class that is not known directly by the program.

Initially, the metaproperties will cover the GM classes. Soon, the FESA classes should be added, and finally, it would be very useful to implement metaproperties for SL classes, provided we can group the families in a reasonable number of more or less homogeneous classes.

Data input with Oracle Forms

The attributes for metaproperties are filled in by the application section with webform application CONSOLE. The data are stored in Oracle table ABC.METAPROPERTIES The metaproperty records for a controldevice class are identified by a choice of standard metaproperty names which indicate the nature and purpose of the property.
They are of following form: The MetaProperty attributes can be class data or instance data.

MetaProperty Class Attribute Literals

The data is the same for all instances of the class, irrespective of the class version. The data are entered in the form as literal strings or numbers.

MetaProperty Instance Attribute References

The value of the metaproperty attribute depends on the ControlDevice instance or on the class version. The data are entered as references to the place where the instance data can be found:

Note that the list of attributes is not yet completely settled, but we must at least keep the useful information in the previous directory service for the GM devices. These GM metadata have been converted to the new format. The old GM metadata can now evolve independently as long as they are needed for DBRT and the old directory service.

Data acquisition with the Java Directory Service

Metaproperty information can be obtained though Directory Service classes. See the API Javadoc for detailed information.

ControlDeviceClass

Here we can get the MetaProperty object arrays for doing tasks such as: KNOB, KNOB2, DISPLAY, ALARMS ...

MetaProperty

Here we can get some general data plus the identifiers of the device properties we have to set or acquire.

DeviceProperty

For obtaining the detailed attributes for a property of a device instance.