Managed Meta Data Environment: A Complete Walkthrough (part 1 of 8)
By David Marco
This article is adapted from the book “Universal Meta Data Models” by David Marco & Michael Jennings, John Wiley & Sons.
Almost every corporation and government agency has already built, is in the process of building, or is looking to build a Managed Meta Data Environment (MME). Many organizations, however, are making fundamental mistakes. An enterprise may build many meta data repositories, or “islands of meta data” that are not linked together, and as a result do not provide as much value (see “Where’s my meta data architecture?” below).
Let’s take a quick meta data management quiz. What is the most common form of meta data architecture? It is likely that most of you will answer, “centralized”; but the real answer is “bad architecture”. Most meta data repository architectures are built the same way data warehouse architectures were built: badly. The data warehouse architecture issue resulted in many Global 2000 companies rebuilding their data warehousing applications, sometimes from the ground up. Many of the meta data repositories being built or already in use need to be completely rebuilt.
The goal of this eight part series of columns is to ensure that your MME’s architecture is constructed on a rock solid foundation that provides your organization with a significant advantage over the poorly architected MMEs. During this series I will present the complete MME architecture, walk through, in detail each of the six major components and the sustainment of the MME.
The managed meta data environment represents the architectural components, people and processes that are required to properly and systematically gather, retain and disseminate meta data throughout the enterprise. The MME encapsulates the concepts of meta data repositories, catalogs, data dictionaries and any other term that people have thrown out to refer to the systematic management of meta data. Some people mistakenly describe an MME as a data warehouse for meta data. In actuality, a MME is an operational system and as such is architected in a vastly different manner than a data warehouse.
Companies that are looking to truly and efficiently manage meta data from an enterprise perspective need to have a fully functional MME. It is important to note that a company should not try to store all of their meta data in a MME, just as the company would not try to store all of their data in a data warehouse. Without the MME’s components, it is very difficult to be effective managing meta data in a large organization. The six components of the MME, shown in Figure 1, are:
Meta data sourcing layer
Meta data integration layer
Meta data repository
Meta data management layer
Meta data marts
Meta data delivery layer
Figure 1: Managed Meta Data Environment
MME can be used in either the centralized, decentralized or distributed architecture approaches: Centralized architecture offers a single, uniform, and consistent meta model that mandates the schema for defining and organizing the various meta data stored in a global meta data repository. This allows for a consolidated approach to administering and sharing meta data across the enterprise. Decentralized architecture creates a uniform and consistent meta model that mandates the schema for defining and organizing a global subset meta data to be stored in a global meta data repository and in the designated shared meta data elements that appear in local meta data repositories. All meta data that is shared and re-used among the various local repositories must first go through the global repository, but sharing and access to the local meta data are independent of the global repository. Distributed architecture includes several disjointed and autonomous meta data repositories that have their own meta models to dictate their internal meta data content and organization with each repository solely responsible for the sharing and administration of its meta data. The global meta data repository will not hold meta data that appears in the local repositories, instead it will have pointers to the meta data in the local repositories and meta data on how to access it.1 At EWSolutions we have built MMEs that use each of these three architectural approaches and some implementations use combinations of these techniques in one MME.
Next month I will begin my detailed walkthrough of each of the six MME components, starting with the Meta Data Sourcing Layer.
1 See Chapter 7 of “Building and Managing the Meta Data Repository” (David Marco, Wiley 2000) for a more detailed walkthrough of these approaches.