Classes and class hierarchy

Pega Platform™ facilitates rule reuse between case types and applications. Developers often reuse rules — from single data elements to entire processes — in applications. Rule reuse improves application quality and reduces development time. Within an application, Pega Platform groups rules into classes according to their capacity for reuse. Each grouping is a class. Each application consists of three class types.

• The Work class contains the rules that describe how to process a case or cases, such as processes, data elements, and user interfaces.
• The Integration class contains the rules that describe how the application interacts with other systems, such as the integration assets that connect the application to a customer database or a third-party web server.
• The Data class contains the rules that describe the data types used in the application, such as a customer data type or order items data type.

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A class can also contain other classes. A class that contains another class is a parent class, while a class that is contained by another class is a child class. A child class can reuse or inherit any of the rules defined for its parent class.

The Work class contains a child class for each case type in your application. Each case type child class contains all of the rules unique to a case type, such as an auto insurance claim. The Data class contains a child class for each data type.

In the following image, click the + icons to learn more about the parent and child classes.

The classes that comprise an application are organized into a multi-level class hierarchy to organize application assets. Classes are organized from most-specific to least-specific in the class hierarchy. The class hierarchy determines how developers can reuse rules within the application. The application can leverage any rule that is available to an application through the class hierarchy. The application cannot leverage rules directly that an application cannot access through the class hierarchy. 

When attempting to identify the rule to use at run time, Pega Platform starts with the most-specific class and expands the search to increasingly general classes.

The name of each class identifies the position of the class within the class hierarchy. Consider the TGB-IT-Work class. A hyphen separates each level of the class hierarchy (-). So, TGB-IT-Work is a child of the class TGB-IT, which is a child of the class TGB.

In the following image, click the + icons to learn more about the groups of classes in the class hierarchy.