XML spec for directory access nears completion

By the end of the year, the group working on an XML-based standard for directory access expects to deliver a specification that would define how applications running on the Web or mobile devices can access a directory without needing a special client, as required with the Lightweight Directory Access Protocol.

The specification, a set of protocols called Directory Services Markup Language (DSML) 2.0, promises to create a standard way for a client application to read, query, update and search a directory. The hope is that DSML 2.0 will provide IT executives with general-purpose clients that can access any directory that supports the specification.

DSML 2.0 also promises to simplify application creation because developers can write exclusively in Extensible Markup Language (XML) without having to know LDAP.

"You eliminate the special-purpose client code, everything is brought into XML," says Dan Blum, an analyst with The Burton Group Corp. "XML shifts the complexity from the client to the directory server where the XML is processed. XML is the native language of the Web so it makes sense that the directory should speak that language also."

DSML 2.0 is being developed by the DSML working group within the Organization for the Advancement of Structured Information Standards (OASIS). Version 1.0 was completed in 1999 and defined a standard way to describe the contents of a directory.

In July, the group accepted a proposal from Microsoft to create DSML 2.0 as an XML version of LDAP. Microsoft developed the proposal using the IETF RFC 2251 for LDAP, which describes standard ways to get information in and out of directories.

The DSML group modified the proposal slightly; it decided DSML 2.0 would not address user identification and authorization or chaining, the act of stringing directories together. But the specification will support referrals, which lets one directory refer queries to another directory.

The advantage of wrapping XML around LDAP is vendors and companies don't have to reinvent what they have today. Every directory vendor supports LDAP today and DSML 2.0 will add a more efficient way to deliver queries to their directories, possibly with the Simple Object Access Protocols as a transport mechanism.

"What it means is a dramatically broader reach of directory services to a new level of client applications," says Peter Houston, director of business strategies for the Windows division at Microsoft. "Imagine a cell phone or PDA using XML to access a directory. In the past you would have needed an LDAP implementation on that client."

The implications are huge for XML-based e-commerce applications and the emerging notion of Web services, chunks of reusable application code.

The group hopes to finalize the specification during a meeting Sept. 20-21 at the Microsoft campus in Redmond, Wash. If it can submit the specification by Sept. 30, DSML 2.0 can be put to a standardization vote by the full membership of OASIS in December. The full membership meets once every three months.

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