Enterprise CIOs are increasingly concerned with the need to manage metadata – the information that describes the structure and content of their corporate data. Properly managed metadata enables rapid, even automatic, development of new application interfaces. Without it, interface development involves costly, handcrafted code, and enterprise agility through Service-Oriented Architectures is impossible. So the CIO must worry about the question of how to collect and manage metadata. For several years there was an accepted answer: to use a metadata registry as defined in ISO 11179. Latterly, this has been challenged by supporters of ontologies, with a claim that theirs is a superior approach. How accurate is this, and what strategy should a CIO follow?
Analysts are agreed on the growing importance of metadata management. Forrester’s Galen Schreck says that metadata has come to light as a critical element of automated information life-cycle management systems. According to Gartner’s Michael Blechar, the move to Java 2 Platform, Enterprise Edition and .NET service-oriented architectures means that organizations must understand model-based business processes and data architectures, and developers will need processes and tools that reuse and manage interrelated metadata across suites and environments. Blechar estimates that renewed interest in metadata management could result in the number of new repository purchases doubling from 2005 to 2010.
The established approach to metadata management is based on ISO 11179, a six-part International Standard for metadata registries. It describes what a metadata registry is, how to classify data, and how to store and manage descriptions of data. It assumes the established entity-relationship model that is associated with relational databases, the traditional data storage paradigm that is expected to continue to dominate for at least the next decade. Its basic data classification unit is the data element. Data elements can readily be identified in bottom-up fashion from enterprise database schemas and documentation. So, where there is a customer database with a “name” field, “customer name” is a data element. This is a straightforward way of capturing and managing metadata for existing and new applications within an enterprise.
Ontologies, by contrast, provide a top-down approach, in which concepts are identified and refined, and the relations between them are described. So the “customer” concept might be derived as a refinement of the “person” concept, and might inherit the “name” property from it (every person has a name, so every customer has a name). Ontologies are seen as providing a competing approach to that of ISO 11179 for metadata management. It is a new approach, but one that is rapidly gaining ground. By starting from the subject matter, rather than the implementation, it leads to metadata that is less product-specific and can more easily be understood across organizations.
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