The IADsClass Interface

This is by far the most complex interface in ADSI, and it contains the following properties:

Property	Type	Description
`PrimaryInterface`	`BSTR`	UUID of optional provider-specific interface that can be used for direct access to this class's properties.
`CLSID`	`BSTR`	Class identifier of optional provider-specific associated COM object
`OID`	`BSTR`	Provider-specific Object Identifier defining the class
`Abstract`	`VARIANT_BOOL`	Abstract class flag; if set, this class cannot be instantiated, although other classes can be derived from it
`Auxiliary`	`VARIANT_BOOL`	Auxiliary class flag; if set, this class cannot be instantiated, although other classes can use it as a source of additional properties (see `AuxDerivedFrom` below)
`MandatoryProperties`	`VARIANT`	Array of names of mandatory properties
`OptionalProperties`	`VARIANT`	Array of names of optional properties
`NamingProperties`	`VARIANT`	Array of names of properties that go to make up the Relative Distinguished Name (RDN) for this class of object; the RDN is a set of properties that uniquely identifies the object
`DerivedFrom`	`VARIANT`	Array of pathnames of classes that this class is derived from
`AuxDerivedFrom`	`VARIANT`	Array of pathnames of auxiliary classes that this class is derived from
`PossibleSuperiors`	`VARIANT`	Array of pathnames of classes that can contain instances of this class
`Containment`	`VARIANT`	Array of pathnames of classes that can be contained within this class
`Container`	`VARIANT_BOOL`	Flag indicating whether or not objects of this class are containers
`HelpFileName`	`BSTR`	Name of help file (may not be implemented)
`HelpFileContext`	`long`	Help context identifier (may not be implemented)

It also has a single method, which may optionally be implemented:

Method	Parameters	Description
`Qualifiers()`	`[out, retval] IADsCollection ppQualifiers`**	Returns collection of objects describing additional qualifiers

We needn't concern ourselves too much with some of the more obscure features of this interface for the time being. Instead, let's just pick out a couple for special attention:

PrimaryInterface

OID

Firstly, take a look at that

PrimaryInterface

property. For a lot of object classes, there is a further interface available to allow easy access to the properties contained therein. For example, all objects of class User
implement a further ADSI interface called IADsUser
, which has about three pages of properties like FullName
and FirstName
and so on. If you want to use these, I recommend that you take a look at the Microsoft documentation for the interface in question.

The next interesting property is

OID

, the Object Identifier. We won't be seeing any value in this slot for the WinNT:
namespace, but it will acquire greater significance later on, when we look at LDAP. This is a universally unique identifier for the class. Unfortunately, it's not a UUID as we have come to know and love them, but rather a sequence of numbers allocated by a central standards authority. I'll come back to this a little later on.

By far the most important properties in the interface are, of course, the … er … properties themselves, mandatory and optional. We're in severe danger of terminology overlap here, and there is a shift in the more recently developed interfaces towards the use of the term attribute rather than property. However, provided we keep our wits about us, we shouldn't get too confused. These two lists of properties (or attributes) effectively define every object that is a member of this class. Going back to our

User

class example, we have things like FullName
, Description
, LastLogin
and so on.