The composition of a Meta Entity or Meta Data must be specified
in the Composition tab. This tab is common
to the Meta Entity, Meta Entity Type, and Meta Data Aggregate editors.
For the Meta Entities, the information entered in this tab helps you
to define the structure of the User Entities which are created from
the current Meta Entity. In this tab, you define the composition of
the Meta Data Aggregates which are used in Meta Entities. You also
specify the composition of a Meta Entity Type which is used to extend
a standard entity.
About this task
A Meta Entity (Type) or a Meta Data Aggregate sometimes has
several description levels: a description can call a child description,
which can in turn call a child description, and so on. But all Meta
Entity descriptions must have a root element of type DataAggregateDescription
or Pac Data Element. The root element is unique. You cannot change
its cardinality. In a root description of type DataAggregateDescription,
there can be Data Aggregate Descriptions with Data Element Descriptions,
Pac Data Elements, and Meta Data Aggregates.
Procedure
- Open the Composition tab of an entity.
To do so, select a Meta Entity (Type)/Meta Data Aggregate in the Design
Explorer view and double-click. You can also right-click
and select Open. You access the Composition tab
from the Overview tab or by clicking directly
the Composition tab in the entity editor.
- If the description pane is empty in a Meta Entity or Meta
Entity Type, it means that no description has been added. If so, click Add and
select Add Data Aggregate Description to create
a description root. Enter a name and a label in the Data
Aggregate Description section which automatically opens
up. For a Meta Data Aggregate, the root is created automatically.
It takes the name of the Meta Data and cannot be modified or deleted.
- Click Add again and select Add
Data Aggregate Description to create the first Data Aggregate
description. This description can contain Data Element Descriptions,
Pac Data Elements, and Meta Data Aggregates.
- Then, click Add and select Add
Data Element Description to insert Data Element Descriptions
at this level of the tree structure. You must enter a type, a definition,
the allowed values, and the intervals in the Data Element
Description section which automatically opens up.
- To insert a Data Element call in the description tree,
click Add and select Add Pac Data
Element. In the selection wizard that opens up, click
a Data Element present in your workspace or create a Data Element.
The new Data Element must be defined in the Data Element editor. You
can also add Meta Data Aggregates by following the procedure used
for the Pac Data Elements.
- To create another description level in the tree, click
the Data Aggregate description root and click Add.
Select Add Data Aggregate Description. Give
the description a name and a label. The number of descriptions in
a Meta Entity/Meta Data Aggregate is unbounded.
What to do next
CAUTION:
Do not modify a Meta Entity when it
contains User Entities. It might cause errors.
Do not forget
to complete the fields in the definition panes which open up when
you insert or select a composition line in the tree.
When the
composition of Meta Entity Type is modified and saved, the description
of the entity that is associated with the Meta Entity Type is updated
automatically. For example, if you modify the composition of a Meta
Entity Type named "Program 3" extending a Program entity, the "Program
3" tab is updated in the Program entity.