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The Abstract Schema

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The schema container contains all of the classSchema and attributeSchema objects that define the classes and attributes that can exist in a 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 data stored in the classSchema and attributeSchema objects. Its purpose is to provide a simple and efficient mechanism for retrieving the frequently used elements of the class and attribute definitions. For example, to retrieve the optional and mandatory attributes of an object class, 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 data in a single object.

As with any object in Active Directory Domain Services, you can bind to the subSchema object and read its attributes, parsing the string values to retrieve the desired data. However, ADSI provides a set of interfaces that make it much easier to read the abstract schema. For more information, see Reading the Abstract Schema.

The following table lists key attributes of a subSchema object.

Attribute Description
attributeTypes A multi-valued attribute that contains strings that represent each attribute in the schema. Each value contains the attributeID, lDAPDisplayName, attributeSyntax, rangeLower, rangeUpper, and an item that indicates whether the attribute can have multiple values.
extendedAttributeInfo A multi-valued attribute that contains strings that represent additional data for each attribute. Each value contains the attributeID, lDAPDisplayName, schemaIDGUID, and attributeSecurityGUID.
extendedClassInfo A multi-valued attribute that contains strings that represent additional data for each class. Each value contains the governsID, lDAPDisplayName, and schemaIDGUID of the class.
objectClasses A multi-valued attribute that contains strings that represent each class in the schema. Each value contains the governsID, lDAPDisplayName, mustContain, mayContain, and so on.