April 19, 1999
Still Evolving, LDAP Standard Opens Up Collaborative ComputingBy Steven L. Telleen
Q:How are intranets going to affect messaging, workflow, and collaborative computing? \
A: In one sense, the whole Web phenomenon is just the standards version of messaging/workflow/collaborative computing. However, there's more to it than standards.
Traditional collaborative computing applications were designed around a shared database model, where applications relied on a common database for coordination and update. Collaborative workflow applications were built to rely on this common database structure for integration, which created a closed, proprietary system. If you used a project management application, you had to use the mail application for the same product, because both relied on the same database to keep track of directory services.
The Web was designed around a very different model: standard content with server and client object wrappers (the HTTP Web server and the HTML browser). Instead of coordinating by sharing a common database, the applications communicate using a messaging approach. Generally this model is conceived as a publish-and-subscribe model that is event-driven. If an object has information that other objects might want, it publishes its availability. When another object wants that information, or the updates, it subscribes to that service. When it no longer wants the information, it unsubscribes. In this way very little needs to be managed centrally.
Even the directory services, which are the key to finding information in this model, do not have to be centralized. The LDAP standard was designed to support communication between distributed directory services. What this means is that functionality does not all have to be built around a single database or application standard, as was the case with the Lotus Notes, Microsoft Exchange, and Novell GroupWise implementations of the past. Using standard components, an LDAP directory server, a mail server, a workflow manager, and a resource scheduler could all come from different vendors and still work together. All would use the LDAP directory services to find current resources and permissions and then communicate with each other via messaging. For this reason, any one of the packages could be swapped out without affecting the others, and more important, new services could be added as they are needed.
While much of this is in place, and products are emerging, the LDAP standard still has a few deficiencies that are important to collaborative computing. Companies should implement LDAP solutions, though, while using proprietary solutions to help with synchronization, multimaster replication, and access control--the three functions not yet available in the LDAP standard.