Microsoft ditches SML, returns to SDM?

I gave in to the temptation of a tabloid-style title for this post, but the resulting guilt forces me to quickly explain that it is speculation and not based on any information other than what is in the links below (none of which explicitly refers to SDM or SML). And of course I work for a Microsoft competitor, so keep your skeptic hat on, as always.

The smoke that makes me picture that SML/SDM fire comes from this post on the Service Center team blog. In it, the product marketing manager for System Center Service Manager announces that the product will not ship until 2010. Here are the reasons given.

“The relevant feedback here can be summarized as:

• Improve performance
• Enhance integration with the rest of the System Center product family and with the wider Microsoft product offering

To meet these requirements we have decided to replace specific components of the Service Manager infrastructure. We will also take this opportunity to align the product with the rest of the System Center family by taking advantage of proven technologies in use in those products”

Let’s rewind a little bit and bring some context. Microsoft developed the Service Definition Model (SDM) to try to capture a consistent model of IT resources. There are several versions of SDM out there, and one of them is currently used by Operations Manager. It is how you capture domain-specific knowledge in a Management Pack (Microsoft’s name for a plug-in that lets you bring a new target type to Operations Manager). In order to get more people to write management packs that Operations Manager can consume, Microsoft decided to standardize SDM. It approached companies like IBM and HP and the SDM specification became SML. Except that there was a lot in SDM that looked like XSD, so SML was refactored as an extension of XSD (pulling in additions from Schematron) rather than a more stand-alone, management-specific approach like SDM. As I’ve argued before (look for the “XSD in SML” paragraph), in retrospect this was the wrong choice. SML was submitted to W3C and is now well advanced towards completion as a standard. Microsoft was forging ahead with the transition from SDM to SML and when they announced their upcoming CMDB they made it clear that it would use SML as its native metamodel (“we’re taking SML and making it the schema for CMDB” said Kirill Tatarinov who then headed the Service Center group).

Back to the present time. This NetworkWorld article clarifies that it’s a redesign of the CMDB part of Service Center that is causing the delay: “beta testing revealed performance and scalability issues with the CMDB and Microsoft plans to rebuild its architecture using components already used in Operations Manager.” More specifically, Robert Reynolds, a “group product planner for System Center” explains that “the core model-based data store in Operations Manager has the basic pieces that we need”. That “model-based data store” is the one that uses SDM. As a side note, I would very much like to know what part of the “performance and scalability issues” come from using XSD (where a lot of complications come from features not relevant for systems management).

Thus the “enhance integration with the rest of the System Center product family” in the original blog post reads a lot like dumping SML as the metamodel for the CMDB in favor of SDM (or an updated version of SDM). QED. Kind of.

In addition to the problems Microsoft uncovered with the Service Center Beta, the upcoming changes around project Oslo might have further weakened the justification for using SML. In another FUD-spreading blog post, I hypothesized about what Oslo means for SML/CML. This recent development with the CMDB reinforces that view.

I understand that there is probably more to this decision at Microsoft than the SML/SDM question but this aspect is the one that may have an impact not just on Microsoft customers but on others who are considering using SML. In the larger scheme of things, the overarching technical question is whether one metamodel (be it SDM, SML, MOF or something else) can efficiently be used to represent models across the entire IT stack. I am growing increasingly convinced that it cannot.