Meta Entities

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"

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