Is Quest Foglight a CMDB? If not, what should you implement first?

Recently another customer inquired if Foglight can help with their CMDB (Configuration Management Database) initiative. Foglight is an APM (Application Performance Monitoring) solution, which is certainly not a CMDB in the traditional sense. Also, it is important to note that a CMDB is not a prerequisite for APM. However, there often is significant overlap in objectives between a CMDB initiative and an APM initiative as well as a benefit to them "sharing" data.
So what is the difference and relationship, both in theory, and more importantly, in real-world practice between a CMDB solution and an APM solution? Also, which of these management technologies do successful IT organizations tackle first?
While CMDB concepts and technologies have been around for a very long time, the ITIL definitions related to CMDB have changed significantly in recent years. Basically, in theory a CMDB system is a place-of-record for all of a company’s IT components, including configuration, relationship, status and other information for each component tracked (referred to as “configuration items” or “CIs”). As you can imagine, fully automated discovery and real-time refresh of this information in any sizeable IT organization is a challenging task in real-world practice. In fact, given the dynamic nature of IT environments today, the data captured in a CMDB is likely to be out of date before the latest refresh is complete. The type of information managed by a CMDB system is closely associated with Asset Management, but is also typically associated with Service Management, which is where the overlap with modern APM technologies really begins.
APM solutions typically monitor the user experience, transactions, and infrastructure associated with the most critical applications and services in an IT organization. Monitoring the interaction of these items in real-time creates knowledge about the topology of the IT components that comprise the monitored applications and services, which sounds a little like part of a CMDB. In theory, a CMDB system containing all information about all of a company’s IT components and their association to applications and business services can be integrated into an APM solution to centralize the definition of the application and service topologies and the underlying IT components to be monitored in context. In practice however, rather than waiting for a massive CMDB project to successfully complete, most customers typically achieve a much faster ROI by configuring their most critical application and service definitions directly into an APM solution first. Additionally, some APM solutions like Foglight continue to add more auto–discovery and dependency mapping capabilities to simplify this setup.
Note that APM solutions typically do not offer asset or comprehensive configuration management capabilities offered by many CMDB solutions, so a blended strategy may be necessary. And the good news is that most CMDB vendors recognize the fundamental requirement for federation, so that over time, a range of “trusted” technologies, such as an existing APM solution, can federate the CI information that they collect up into a federated CMDB system via an API or other technique (note that CMDB-F is an emerging standard for this sort of interface).
Successful, wide-scale adoption of enterprise CMDB systems is still somewhat nascent, so in the meantime most IT organizations, such as a very large global bank Foglight customer, first adopt targeted, fast ROI APM implementations to reduce MTTR for production incidents, and then after an enterprise, federated CMDB is fully implemented, they plan to integrate these tools to simplify ongoing administration of both systems. A similar approach may make sense for your organization.