Directory Service Technology Introduction--ADSI (II)

The ADSI directory services that are currently implemented are listed below:
(1) Windows NT domain user management.
(2) LDAP (Exchange Server) directory service.
(3) Internet information Server
(4) NDS (Novell NetWare Directory Services)
At present, the existence of multiple directory services within an enterprise also poses some problems. For administrators, it must manage multiple directory services, which makes management more complex; for enterprise workers, to access information in different directory services, he must log into multiple directory services, and for developers to use directory services, He must choose which directory service to use or use multiple directory services. Although ADSI unifies the programmatic interface of directory services, the application of directory services must be planned in order to better use the directory services functionality within the enterprise. Because Windows 2000 fully employs ADSI as its application programming interface, applications built on Windows 2000 will make it easier to access the various directory services provided by the system, and the application can be better integrated with the operating system.
Second, ADSI structure
The ADSI programming interface includes two aspects that implement the provider of ADSI Directory services (provider) and customers who use ADSI. Each currently supported directory service must have a provider whose ADSI provider implements ADSI objects and namespace-related objects; ADSI clients, like ordinary COM clients, call the ADSI interface to access the various features provided by the directory service, including locating directories, Reads the properties of a directory object and, if allowed, modifies the object's properties.
ADSI provides the basic structure for directory access as shown in the following illustration:
Figure 1 ADSI directory service hierarchy diagram
ADSI provides two forms of programming interfaces, and for customers that support automation, it can invoke the properties and methods of the directory service provider through the ADSI Automation interface, and for customers with high performance requirements, it can access the directory service provider through a COM interface in vtable form. ADSI This dual interface structure can almost always meet the needs of client programs, about the principle and usage of dual interfaces please refer to the books on automation (automation), for the sake of simplicity, the ADSI interface is discussed only from the perspective of automation interfaces.
In the interface specification defined by ADSI, the directory object that corresponds to the directory service is also known as the Active Directory object (Active Directory objects). Another important object is the containment (Container) object, and the relationship of the package container object to the directory object is similar to the directory and file we use in the file system, a package container object can contain many other directory objects or package container objects, and the directory object represents a certain entity. For each ADSI provider, it starts with the root node of the basic namespace and forms a tree through the package container object and the directory object, as shown in Figure 2.