It became pretty quiet around directory services during the last years. When I remember the discussions back some 10, 15 or 20 years around NDS versus LAN Manager (and the underlying domain approach) or Active Directory when it came to market, and even the discussions which came up in the early days of OpenLDAP, it is pretty quiet nowadays. Are all the problems solved? Are the right directories in place? Are the best solutions chosen when something changes?

When talking with end user organizations it becomes obvious that we are far away from that state. There are implementations of different directories, and most of them work well for their specific use case. But once it comes to optimization, the situation changes. What to put in the Active Directory, what not? How to optimize the way applications are dealing with directories? How to best build a corporate directory or a meta directory (the directory as data store, not the meta directory service as technology for synchronization!)? How to interface directories for specific use cases and how to best retrieve information?

There are many aspects to discuss and to understand to end up with an optimized “directory infrastructure”. First of all, it is important to understand which directories you have and how they are used – usually there are far more directories out there than you’d expect. And I’m not only talking about the Active Directory, eDirectory and all the LDAP servers, but as well about “de facto” directories in the form of tables in databases and so on. I’m talking about anything which acts as a directory. That includes the application directories, which might be hundreds of small directories. And they sometimes contain sensitive information like privacy-relevant data. Besides this, they frequently have somewhat redundant data. Based on this analysis, you can drill down and identify which attributes have to flow between which directories in which use cases.

The latter is more about really optimizing your provisioning. The analysis is, on the other hand, as well a good foundation for optimizing your directory infrastructure. Where can you avoid redundancy?

Based on such an overview, you can think about some other aspects:

• Which central directories do you need for which use cases?
• How to optimize application access on directories?
• Where do you need specific technology for these directories beyond standard LDAP?

There is always a need for some more or less central directories. The Active Directory or eDirectory are examples, used for the primary authentication of internal users and for many infrastructure services – but they can’t do anything. There are Corporate Directories for centralized access to corporate information. There are more technical meta directories as the “source of truth” about distributed information.

We have to think about optimizing the application directories. One or few centralized directories together with Virtual Directory Services which are offered for example by Radiant Logic, Oracle, and Symlabs are an interesting option do build such a centralized yet flexible infrastructure, with the Virtual Directory Service as interface layer.

And we have to look at specific use cases where we need specialized technology. There are some innovative vendors out there. UnboundID for high scalable environments, where others like Oracle, Novell, Siemens, and so on are active as well. eNitiatives with their ViewDS services for strong querying capabilities and the ability to easily build interfaces in a “yellow page” style to these directories.

My experience is, that there is still a lot of need to think about directory services – and there is a lot room for improvement in most IT environments. What is your view on that topic?

LDAP (Lightweight Directory Access Protocol) is well established. It is the foundation for today’s Directory Services, which support LDAP as a protocol and which usually build their data structure on the associated LDAP schema. There are many interfaces for developers to use LDAP, from the LDAP C API to high-level interfaces for many programming environments.

Even while LDAP is well established, it is somewhat limited. There are several restrictions – two important ones are:

• The structure of LDAP is (more or less) hierarchical. There is one basic structure for containers – and linking leaf objects (think about the association of users and groups) is somewhat limited. That structure is a heritage of X.500, from which LDAP is derived – with LDAP originally being the lightweight version of the DAP (Directory Access Protocol) protocol. X.500 was constructed by telcos for telcos, e.g. with respect to their specific needs of structuring information. However anyone who ever has thought about structuring Novell’s eDirectory or Microsoft’s Active Directory knows that there is frequently more than one hierarchy, for example the location and the organizational structure. The strict hierarchy of LDAP is an inhibitor for several use cases.
• LDAP is still focused on the specific, single directory. It doesn’t address the need of storing parts of the information in fundamentally different stores. But the same piece of information might be found locally on a notebook, in a network directory like Active Directory, in a corporate directory and so on. How to deal with that? How to use the same information across multiple systems, exchange it, associate usage policies, and so on? That is out-of-scope for LDAP.

I could extend the list – but it is not about the limitations of LDAP. LDAP has done a great job for years but there is obviously the need to do the next big step. An interesting foundation for that next big step comes from Kim Cameron, Chief Identity Architect at Microsoft. He has developed a schema which he calls system.identity. There hasn’t been much noise around before. There is a stream from last years Microsoft PDC, there is little information at the MSDN plus a blog post, there is the Keynote from this year’s European Identity Conference. But it is worth to have a look at that. The approach of system.identity is to define a flexible schema for identity-related information which can cover everything – from local devices to enterprise- and internet-style directories, from internal users to customers and device identities, including all the policies. It is, from my perspective, a very good start for the evolution (compatibility to LDAP is covered) well beyond LDAP and today’s directories.

I’ve put the concept under a stress test in a customer workshop these days. The customer is thinking about a corporate directory. Most people there are not directory guys, but enterprise IT architects. And they definitely liked the path system.identity is showing. It covers their needs much better than the LDAP schema. That proved to me that system.identity is not only for the geeks like me but obviously for the real world. Thus: Have a look at it and start thinking beyond LDAP. The concept of system.identity, despite being early stage, is a very good place to start.

Last week I’ve been talking with Andrew Ferguson and Steven Legg of eB2Bcom. Probably you’ve never heard of them, at least as long as you are neither from the APAC region nor working in the government and defense business where they have most of their customers outside the APAC region. eB2Bcom is, first of all, a system integrator and distributor of IAM and GRC products.

But eB2Bcom is as well the company which develops the View500 directory service. You haven’t heard of this product? At least it is worth to have a look at. Basically, it is a directory service which goes beyond typical directory service offerings, which mainly focus on being the best LDAP server. They have for example integrated XML support, for SAML, XACML, or ebXML. Thus, they go well beyond the DSML support some directory services are offering – with DSML being in fact sort of a web service incarnation of LDAP. The difference is that the semantics of XML documents are supported. Other features include the matching of synonyms or typing correction for improved search and indexing.

eB2Bcom ist adding additional features. The support for SAML and XACML is particularly interesting. In adding these capabilities to the directory service, that system can for example act as an integrated identity provider for federation. Instead of having a federation system and a directory server, it is one system with obviously less communication overhead. The same is true with XACML support and the directory acting as PEP (Policy Enforcement Point). One system instead of two or three in typical implementations.

Interestingly, what Microsoft is doing around Active Directory with ADFS (Active Directory Federation Services) or the server components of “Geneva” isn’t that different. It is sort of “pimp my directory server” by directly adding additional features instead of delivering separate products. The closer to the directory these features are implemented, the more efficient they are. On the other hand, we might end with well integrated solutions which lack important features. Thus this approach isn’t a no-brainer, for sure. But I think it is really worth to consider if there aren’t features which are best integrated with directory services because the directory service is, anyhow, asked all the time. Thus, instead of having the directory service providing just a part of the answer and another system adding to that answer (with repeated requests to the directory server, complex caching,…) it might be a good idea to do all these things in one place.

That won’t solve everything – but it is an interesting option. By the way it might as well be a good choice to add some virtual directory service capabilities to a directory server like Sun has done this with their Sun Directory Server instead of fully relying on an external virtual directory service. Might also provide a better performance especially in the situations in which most of the requested data is in that directory.

Another interesting point is that XML-enabled directory service will become an interesting option for a centralized policy management. They can store these policies and provide them or answer requests about these policies. Another emerging field where that approach might become popular over the next few years.

I will have a look at the evolution in the directory services market. And, from a vendor perspective, it is worth considering these options because it would move directory services back from a commodity to a market segment where companies can earn a lot of money because they have strong unique selling proposition due to the services they’ve added to their directory service.