Classes, properties, and instances 차이점

https://www.ibm.com/docs/en/cdfsp/7.6.0?topic=schemas-classes-properties-instances 

Classes, properties, and instances

Classes, properties, and instances

In Integration Composer, data schemas organize data into classes, which are groups of objects that share common properties. Properties are attributes or features that characterize classes. While classes are groups of objects, an instance is a specific object that actually belongs to a class.

Classes

A class is a group of data that has the same characteristics or properties. For example, you can define a class called 'Computer' because computers share many characteristics or properties.

Properties

The collection of properties assigned to a class defines the class. A class can have multiple properties. For example, objects classified as computers have the following properties: Hardware ID, Manufacturer, Model, and Serial Number.

The data schema defines the structure in which properties are stored and organizes the properties into classes. A data schema defines the formats for property data. A format might include a property name, type, and length. For example, the property Manufacturer might be named Manufacturer ID. Its type is integer. Its length is 10.

In Integration Composer, all properties have a name, type, and length.

• The name uniquely identifies the property in a class.
• The type of property indicates the format of the data. Integration Composer uses JDBC type names.
• The length of a property is determined by the limit defined for the database column that corresponds to that property. You can manually change the length, but the length cannot exceed the limit set for the corresponding database column.

Some properties have specialized functions and unique characteristics that you must consider when creating mappings in Integration Composer. Key properties and reference properties have specialized functions.

Instances

The class 'Computer' is characterized by the properties Hardware ID, Manufacturer, Model, and Serial Number. A specific instance of the class, the computer HQLz2310, is characterized by the properties 0399483 (Hardware ID), Dell (Manufacturer), Pentium 4 (Model), and 938348393 (Serial Number).

The instances of a class contain data about an object. Databases store this data in the structures defined for the properties of the class. All instances of the same class have the same set of properties, but each instance has different values for those properties.

• Class Hierarchy
  An Integration Composer data schema logically organizes classes into a hierarchy or tree. A bonding link between classes is called a relationship. Classes have two relationship categories, parent-child and reference.