Meta Entities

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. To do so, you must create your own entities from Meta Entities and their instances, which are called User instances.
You must create a Meta Entity and define it. Then, you must 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 defined with a Reference type and that are linked to other entities. User entities are managed in the same way as standard entities. You can assign them keywords and comments. Each User Entity contains a Description tab in which you enter the values of the fields that are specified in the Meta Entity.
Example: For a Department Meta Entity that contains two fields: Type of department and Number of employees, you can define the Account User Entity and specify Accounting department and 50 Employees.
Meta Entity Type
You can also create Meta Entity Type instances to extend standard entities by adding descriptions to them. When a Meta Entity Type instance is created, it is associated with the entity type that was specified 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). A description tab is added to the editor of the extended entity for each Meta Entity Type that is created for this entity type.
Example: To extend the description of the Program entity, you can create two Meta Entity Type instances that apply to the Program entity: Program 1 and Program 2. Two tabs are then added to the Program editor: Program 1 and Program 2. The description is saved in the entity itself, so you do not need to create a User Entity. The tab that extends the entity description is the same as the description tab of a User Entity.
Meta Entity Type "CR"
This Meta Entity applies to the Pacbase facet only.

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 the entities to add references between entities. Its description is available in the editors of all the 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 by an administrator only who can add fields but cannot delete the required 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 can be used in several Meta Entities, you can create Meta Data Aggregates. You create, define, and describe them as Meta Entities. Then, you can reuse them in Meta Entities or Meta Entity Types.

When you create a Meta Data Aggregate, a root is automatically inserted in the Composition tab of the Meta Data Aggregate editor. By default, it takes the name of the Meta Data Aggregate. It cannot be modified or deleted.

Example of a Meta Data Aggregate reuse in a Meta Entity:
  • A Meta Data Aggregate Address,
  • A Meta Entity Customer with two fields: Name and Address,
  • A Meta Entity Seller with two fields: Name and Address.

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