Microsoft Introduces ADSI

Welcome Guest. | Log In| Register | Membership Benefits

June 10, 1999 (8:14 AM EDT)

Microsoft has released a key component for building applications that use directory data.

The most current release of its Active Directory Services Interface, called ADSI 2.5, is a feature-complete version of the development software for Microsoft's Active Directory, a key component of Windows 2000.

Most observers agree that ADSI 2.5 will simplify development of applications that call on Active Directory, particularly for developers not familiar with programming to directories.

The version of Active Directory included with the current Windows 2000 beta release is the first complete version of the widely touted directory. Although Microsoft has released previous iterations of ADSI, version 2.5 consists of COM objects and class libraries that are specific to Active Directory, said Microsoft's Active Directory lead product manager Peter Houston. Earlier ADSI releases were more generic to the LDAP standard.

For example, ADSI 2.0 looked for information in the target LDAP directory, but with Active Directory support, ADSI 2.5 can look for specific proprietary features, such as instructions for changing a password.

Microsoft and most observers agreed that ADSI 2.5 will be important to developers who want to use directory data without learning new programming models. Specifically, ADSI 2.5 will let application developers use familiar programming tools without learning the intricacies of Active Directory, Houston added.

"The fact that they are COM classes means that you can use things like Visual Basic or Active Server Pages to access directory information," Houston said.

Moreover, the new release supports OLE DB, meaning that SQL programmers can write applications that call on Active Directory.

"It provides a common way to access data regardless of whether it is in an SQL database, a file system, or now in a directory," Houston said. "The thing I find most powerful about that is you no longer have to think about LDAP or directory programming. A programmer can look at a directory as a source of data that is effectively the same as, say, a relational database."

ADSI also can make it easier for developers looking to program applications that call on information that resides in directories based on the LDAP version-3 standard.

"As a developer, you don't have to write directly to LDAP, which is a fairly convoluted and low-level interface," said Dwight Davis, an analyst at Summit Strategies Inc.

Key to providing interoperability between Active Directory and LDAP directories is a service-provider interface offered by Microsoft. Novell offers a different ADSI service-provider interface for connecting NetWare clients to Active Directory. Integration of these interfaces remains to be done.

In the future, Novell will offer a service-provider interface with NDS, said Adam Smith, Novell's NDS product marketing manager. Smith would not give a time frame.

"ADSI is something we will use quite extensively to interoperate with Active Directory," he said. "Any applications written to ADSI can take advantage of NDS as well as Active Directory."

ADSI 2.5 is currently intended for writing applications that will let Windows NT workstation, Windows 9x, and, ultimately, Windows 2000 clients connect to data residing in Active Directory.

Developers have the option of referring to objects in the directories with a globally unique identifier, rather than with a formal LDAP name. That simplifies keeping track of objects linked to the application and the directory, according to Houston.

Other ADSI 2.5 features include support for Kerberos authentication, sorts that can be performed against Active Directory before data from queries are returned to the client, and clients that can bind automatically to Active Directory and select the server replica most likely to offer the highest quality of service.