Class Hierarchy

Parent-child relationships

Most relationships in a tree are parent-child relationships. A parent-child relationship is a very strong relationship between two classes. Think of it as a "has a" or "containment" relationship.

In a parent-child relationship:

• Every child class has a parent class. Every instance of a child class has an instance of a parent class.
• A parent can be a child in another relationship.
• A parent class instance can exist without a child class instance.
• Every child class has only one parent class, but a parent class can have more than one child class.
• In terms of databases, a parent class has a one-to-many relationship with a child class.

Reference relationships

A reference relationship is weaker than a parent-child relationship. Think of it as a "refers to" relationship.

In a reference relationship:

• A reference relationship exists between two classes when one class has complementary information about another class.
• A class in a reference relationship can exist without the other class.
• In terms of databases, a parent class has a many-to-one relationship to a reference class.
• A class can appear only once in a parent-child relationship but many times in a reference relationship.

Tree View

The tree view lists classes and, if you are browsing the data source by data, instances for the selected data source in a hierarchical structure that shows class relationships. Integration Composer displays class names in bold; instances are in plain text. When you select a class or instance in the tree, Integration Composer highlights it with a blue background and displays data about the class or instance in the table view. Click the + icon to expand a class or instance. Click the - icon to collapse a class or instance.