Conclusion

What About LDAP?

In most instances, XML programmers will prefer DSML to LDAP. However, LDAP will remain important, for three reasons:

First of all, for the time being at least, LDAP still provides the “last leg” of directory access. The DSML service talks LDAP to the directory service and DSML to the XML application. That is, essentially, a DSML service is an LDAP-to-XML translator. The DSML spec is written with this in mind. The LDAP-centricity of the DSML spec reflects the assumption that LDAP will continue to be a feature of DSML implementations.

Second, this architecture means that a direct LDAP interface can provide better performance than DSML, because it eliminates the step of translating into XML.

Finally, LDAP may even provide better performance than a native DSML directory interface (if such existed), because DSML is a markup language, designed to be understandable by humans, and therefore of necessity somewhat verbose, while LDAP is a protocol, designed to be parsed only by computers, and therefore it can be less verbose.

Beyond DSML

As Web services become more business-oriented, more formal layers of management will be required on top of directory structures. For instance, businesses will want audit trails of directory changes. They will want to know where information came from. To manage functions such as directory versioning and licensing of intellectual property, they may need various kinds of metadata, such as keywords and information about authors, versions and copyright.

Though not yet widely implemented, the most likely candidate for building these kinds of functions is RDF (Resource Description Framework). RDF is a W3C standard designed to help manage large collections of HTML and XML documents. An RDF schema defines a metadata layout shared by all documents in a collection.

DSML: a Common Language

DSML gives directories a language for publishing information, and it gives XML programmers a language for including directory functions in their programs.

It will never be the only way of talking to directories. It may not be the most efficient way; both LDAP and vendor-specific approaches may beat it on that front. It may not rack up the most directory transactions per day; Windows-optimized interfaces, driven by Microsoft, may win that honor. But DSML will provide a common language for working with directories, combining the qualities of vendor- independence and accessibility to a wide range of programmers and programs.

Resource List:

OASIS
Robin Cover's DSML page at OASIS.
DSML.org
"About DSML"at DSML.org
Sun's DSML/JNDI effort

Other Directory Vendors
Introduction to Directory Services Markup Language (DSML)