NAS Information Architecture Committee (NIAC)
(January 24, 2002)
Dynamic Metadata Support in Air Traffic Environments
Auldenfire Sweden AB (Stockholm, Sweden) presented an architectural framework approach for metadata designed for Dynamic Metadata Support in Air Traffic Environments before the National Airspace System Architecture Committee on January 24th, 2002. The presentation was provided by Chris de Vaney, Chief Architect for Auldenfire Sweden AB, with responsibility for the Enterprise Systems Architecture Laboratory (ESAL).
Chris de Vaney played a major role in remodeling the Eurocontrol Environment (ENV) Database from a networked to an object-oriented model with constraint logic. He is currently a member of the OMG Analysis & Design task force, working on the Model-Driven Architecture definition, finalization of the Real-Time UML specification, and the next version of the Meta-Object Facility (MOF) for UML. Previous involvement with the OMG included membership and active participation on the OMG's Common Warehouse Metadata Interchange specification team.
Mr. de Vaney began by describing the ESAL project, which basically provides all the services - central repository and directory, messaging, security, workflow, transformations, etc. - and tools needed to let users experiment with different application frameworks and configurations. ESAL has four enterprise architecture frameworks under development now:
The classic notion of metadata, which is "data about data" and pretty much restricted to entity-attribute modeling (e.g. a relational model can produce a static data dictionary), is not sufficient for developing enterprise frameworks like those described above. Different user communities are struggling with this and consequently have produced a number of specialized views and standards for metadata, such as Dublin Core metadata for social sciences, FIXML for financial services, UDDI and SOAP for e-business, etc. Mr. de Vaney contends that a better definition for metadata is that it describes the knowledge, structure, processes and organization of the systems and their content. An enterprise architecture, including an architecture for air traffic management, requires that metadata be established at five levels:
As opposed to static informative data dictionaries, this is dynamic metadata. Its artifacts are used not only as models for systems development or for generating code or databases, but also to control information for system configurations (e.g. what to do if a network node is dropped) and runtime support (e.g. directory schemas). Slide #9 is a high-level use case model showing the roles involved in defining each of the above levels, and slides #15-21 show how the ATM Framework is implemented in the ESAL framework, including examples of ontological, conceptual, logical, and physical metadata from this framework. Mr. de Vaney went on to describe and demonstrate examples of how this metadata is being managed and used at the ESAL facility in Stockholm, Sweden (Farsta).
Auldenfire Sweden's ESAL team under the leadership of Chris de Vaney, Chief Architect, has developed detailed metadata describing the generic Air Traffic Environment (over 95 object classes like flight, aircraft, etc. and 1000 attributes, modeled in UML) and from them created views of real-world environments such as the metadata objects describing the Dallas-Fort Worth airport's runways, radars, communications systems, routes, and approach/departure procedures. Other tools such as simulators then use these objects. The ESAL team has implemented platform-independent models developed by Chris de Vaney of core air traffic environment systems and used these to generate platform-specific code - an application of the OMG's model-driven architecture (MDA) approach; see the MDA website at http://www.omg.org/mda.
Auldenfire Sweden's ESAL team is also building a message library in XML based on the ATC business objects and developing a virtual private network between Sweden and New Zealand so that they can link ATC simulation environments. This capability should go into production in March. Mr. de Vaney concluded that the complexity, security, and performance requirements of ATC make it the most challenging of the frameworks developed at ESAL. Future activities include collaboration with the OMG Air Transport Committee (http://transport.omg.org/).
You can view the slide show presentation here.
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