MetaProperty

Basics

In UBIK^®, a MetaProperty describes a single feature of a certain MetaClass. A MetaProperty will never hold own values, but it serves as a definition for a resulting BaseProperty on a derived ContentClass.

For enhanced reuse, MetaProperties can be organized in a Pool and linked to many MetaClasses, using the Systemrelation MetaProperty

Data Types

A MetaProperty needs to have a data type that determines which kind of data should be stored in it. The following data types are supported by UBIK^®:

Boolean

A boolean value that can be either True or false

ByteStream

A serialized stream of bytes, non human readable.

Source Code

A compressed text value, typically used to store texts with lots of white spaces and formatting information, such as source code.

Date/Time

Date and time in a combined value, where the actual format is depending on the cultural/regional settings of the machine.

Floating point

Double-precision floating-point format, optionally with unit of measurement that can be configured with the setting Unit item.

File reference

A path to a physical file in DOS/Windows- or UNC notation.

Geographic Coordinate

Absolute geographic position combined of Longitude, Latitude and Altitude in WGS84 format.

Guid

A pointer to another object, represented with the GUID of the target object.

Integer

An integer number.

Text

A string value.

XML

Markup text in XML format.

Configuration

A MetaProperty can be configured with various additional options which are described in the following.

Default value

The default value of a MetaProperty defines which value will be delivered by a property if it doesn't have an own value set.

Initial value

The initial value of a MetaProperty defines which value will be set to the property initially when a new instance of it is created. Once the value is changed, the initial value is lost for this instance.

Editing a MetaProperty

Once a MetaProperty is used on a single MetaClass editing of properties is restricted to properties that may not effect data validity. The System uses a Rule to validate the edited properties and creates a RuleViolation whenever a "locked" property is edited. Following properties may not be changed/edited for a "used" MetaProperty:

• Name
• PropertyType

Released To LiveMode

A MetaProperty is marked as released to live mode when:

• It is used on at least one MetaClass which is already released.
• It is referenced by at least one PoolMetaProperty which is used on at least one MetaClass which is already released.

Editing a released MetaProperty is restricted to properties that have no effect on the released table structure. The System uses a Rule to validate the edited properties and creates a RuleViolation whenever a "locked" property is edited. Following properties may not be changed/edited for a released MetaProperty:

• Name
• PropertyType
• StringLen
• Multilanguage
• Indexcount
• Serialize
• NeedsValidation
• IndexType

See also

• MetaClass
• Requirements
• Create a new MetaProperty