The composition of a Meta Entity or Méta Data must be done
in the Composition tab, which 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 window, you define the composition
of the Meta Data Aggregates which are used then in Meta Entities,
or to give the composition of a Meta Entity Type which is used to
extend a Standard Entity.
About this task
A Meta Entity (Type) or Meta Data Aggregate have sometimes
several levels of descriptions, that is, a description can call a
child description, which can also 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 and it is not possible to change its cardinality. In a root
description of type 'DataAggregateDescription', you can have '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, or right-click and select Open.
Then you can access the Composition tab from
the Overview tab or by clicking directly the Composition tab
in the Entity editor.
- For a Meta Entity or Meta Entity Type, if the description
pane is empty, 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
for the description and a label in the definition pane 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, neither
deleted.
- Click again Add and select Add
Data Aggregate Description to create the first Data Aggregate
description, in which the Data Element Descriptions, Pac Data Elements
and Meta Data Aggregates are included then.
- Then, click Add and select Add
Data Element Description if you want to have Data Element
Descriptions at this level of the tree structure. For a Data Element
description, you must enter its type, its definition, its allowed
values, and its intervals in the definition pane which shows up.
- To insert a Data Element call in the description tree,
click Add and select Add Pac Data
Element. A selection wizard opens up, you can click a
Data Element instance or create a new one. When the Data Element displays
in the composition tree. You do not have to enter any definition for
this Data Element as it has been described and previously defined
in the Data Element editor. You can also add Meta Data Aggregates
by following the same procedure as for the Pac Data Elements.
- To create another level of description in the tree, click
the Data Aggregate description root, then click Add,
and select Add Data Aggregate Description.
Give the description a name and a label in the definition pane. 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 may occur 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.