| Platform SDK: Active Directory, ADSI, and Directory Services |
The schema container—CN=Schema,CN=Configuration,<DC=forestroot>—contains all the classSchema and attributeSchema objects that define the classes and attributes that can exist in an Active Directory® forest. The schema container also contains an object named Aggregate of class subSchema. This subSchema object is known as the abstract schema.
The abstract schema contains a subset of the information stored in the classSchema and attributeSchema objects. Its purpose is to provide a simple and efficient mechanism for retrieving the frequently used parts of the class and attribute definitions. For example, to retrieve the optional and mandatory attributes of an object class, you would have to bind to multiple objects to collect the mayContain, mustContain, systemMayContain, and systemMustContain values from the class and all its superclasses, as well as from any auxiliary classes of the class and its superclasses. The abstract schema conveniently collects all this information for you in a single object.
As with any Active Directory object, you can bind to the subSchema object and read its properties, parsing the string values to retrieve the desired information. However, ADSI provides a set of interfaces that make it much easier to read the abstract schema. For more information on these interfaces, see Reading the Abstract Schema.
The following table describes the key properties of a subSchema object.
| Property | Description |
|---|---|
| attributeTypes | A multi-valued property containing strings that represent each attribute in the schema. Each value contains the attributeID, lDAPDisplayName, syntax, upper and lower range, and an item that indicates whether the attribute can have multiple values. |
| extendedAttributeInfo | A multi-valued property containing strings that represent additional information for each attribute. Each value contains the attributeID, lDAPDisplayName, schemaIDGUID, and attributeSecurityGUID. |
| extendedClassInfo | A multi-valued property containing strings that represent additional information for each class. Each value contains the governsID, lDAPDisplayName, and schemaIDGUID of the class. |
| objectClasses | A multi-valued property containing strings that represent each class in the schema. Each value contains the governsID, lDAPDisplayName, mustContain, mayContain, and so on. |