The Meta Entities and Meta Entity Types can be used to
create customized concepts that the metamodel does not manage in a
standard manner. Meta Entity Types extend all the model entities that
are managed by Rational Programming Patterns.
When a Meta Entity instance is defined and described, it is managed
as any other instance. User Entities are instances of a Meta Entity.
- META ENTITY AND USER ENTITY
- You can customize the information of 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 mirrors
the composition of the corresponding Meta Entity. In the Meta Entity,
you must define User relations for the fields that are included in
a User Entity. These fields are defined with a Reference type in the
Meta Entity it is related to. User entities are managed in the same
way as standard entities. You can assign them keywords and comments.
For each User Entity, you can enter values in the description tab
for each component that is entered in the associated Meta Entity.
Example: For a Meta Entity "Service" with
two Data Elements: "Type of service" and "Number of employees",
you can define the User Entity "Info" and specify "Computing
Service" and "50 Employees".
- META ENTITY TYPE
- You can also create Meta Entity Type instances to extend 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
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 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 that are
created for this entity type.
Example: If
you want to extend the description of a Program entity and if you
create two Meta Entity Type instances ("Program 1" and "Program
2") that apply to the Program entity, two tabs are added to the
Program editor ("Program 1" and "Program 2"). The descriptions
are saved in the entity itself, so you do not need to create a User
Entity. The tab corresponding to the extension of the entity description
is the same as the description tab of a User Entity.
- META ENTITY TYPE "CR"
- If you migrate a Pacbase database,
a Database_Name.INTER project is automatically
created at the root of all the projects when the ta2 file
is imported. The project can then be shared by all the other projects.
It contains an instance of the Meta Entity Type "CR", which is
the standard structure that is used by all entities to add references
between entities. Its description is available in the editors of all
entities with the CR Lines tab. With this tab,
you can add new references that are not defined in the design of entities.
The contents of CR Lines in the "INTER" project
can be modified only by an administrator who can add fields but cannot
delete required existing fields. However, it is forbidden to modify
the Composition tab in the Meta Entity Type
CR.
- META DATA AGGREGATE
- To create a hierarchy of data that 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. 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 or 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"