扩展Schema语法定义的办法

Schema可以理解为所有要在目录中存放的节点对象的类型定义（可以说是类的定义）。要放入目录的所有节点都是这些类的实例。目录中所有节点的属性（如：name 之于 Person）也必须在Schema中定义，如：guid,password,email-address。类的定义在Schema中叫classSchema；属性的定义在Schema中叫attributeSchema。

    有下列方法可扩展Schema：

• 从已有Schma定义中继承类 – 子类继承所有父类的属性。需要通过继承来扩展Schma的情况：
  • When the existing class requires additional attributes, but otherwise is acceptable.
  • When the ability to transform existing objects of the class into a new class is not required. It is not possible to add a subclass to an existing object.
  • To use the existing Directory Manager snap-in to manage the extended attributes of the objects.
• 加入属性到已有的类定义上. When adding multiple attributes, perform this operation in a structured manner by defining an auxiliary class and adding that auxiliary class to the existing class.
• Modification of an existing class is required when an application requires the ability to extend existing objects of the class. For example, to add application-specific data to the User object, extend the class User normally, because you must handle existing Users and not just special Users created by your application.
• 创建新类定义. Create a new class; that is, a class derived from "Top" when no existing class fulfills the operational requirements