The Meta Entity helps you to create your own customized
concepts that the metamodel does not handle in a standard manner.
When a Meta Entity instance is defined and described, it is handled
as any other Pac instance. User Entities are instances of a given
Meta Entity.
- META ENTITY/USER ENTITY
- You can customize the information saved in a database to adapt
it to the specificity of your business by creating new entities: Meta
Entities and User instances, which are the instances of Meta Entities.
- You must create a Meta Entity first and then describe the structure
of its User Entities in the Composition tab
of the Meta Entity editor. The description of a User Entity entirely
depends on the composition of the corresponding Meta Entity defined
by the user. User relations must be defined in the Meta Entity, for
the fields included in a User Entity and defined with a Reference
type in the Meta Entity it is related to. User entities are managed
in the same way as standard entities. So you can assign them keywords
and comments. For each User Entity, you can enter values in the description
tab for each component entered in the associated Meta Entity.
Example: For a Meta Entity 'Service'
containing two Data Elements: 'Type of service' and 'Number
of employees', you can define the User Entity 'Info'
which can be completed as follows: 'Computing Service',
and '50 Employees
- META ENTITY TYPE
- You can also create Meta Entity Type instances, to extend Pac
standard entities and thus add descriptions to an entity Type. When
a Meta Entity Type instance is created, it is associated with the
type of Pac entity that you defined in the Meta Entity Type creation
wizard. As a consequence, a new tab is added to the editor of the
extended Pac entity. By default, it takes the label of the Meta Entity
Type, or its name if no label is specified. There are as many description
tabs added to the extended entity editor as Meta Entity Type instances
created for this entity type.
Example: If
you want to extend the description of a Program entity and if you
create 2 Meta Entity Type instances ('Program 1' and 'Program
2') which apply to the Pac Program entity, you find then in the
Program editor, two additional tabs ('Program 1' et 'Program
2') . The descriptions are saved in the entity itself, so you
don't have to create any User Entity. The tab corresponding to
the extension of the entity description is the same as the description
tab of a User Entity.
- META DATA AGGREGATE
- To create a hierarchy of data which is to be used in several Meta
Entities you can create Meta Data Aggregates. These are entities that
you create, define, and compose as you do for Meta Entities. When
it has been defined and described, you can reuse a Meta Data Aggregate
in your Meta Entities or in your Meta Entity Type. However, a Meta
Data Aggregate contains a specificity, as when you create a Meta Data,
a root is automatically inserted in the 'Composition' tab
of the Meta Data editor. This root is given the name of the Meta Data
Aggregate by default, and it cannot be modified, nor deleted.
Example of Meta Data Aggregate reuse in a Meta Entity: - A Meta Data Aggregate 'Address',
- A Meta Entity 'Customer' with two fields 'Name'
and 'Address',
- And a Meta Entity 'Seller' with two fields 'Name'
and 'Address'.