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49 dardization efforts. This was done in part to avoid overlaps (specifically, NHTSA's crash records schema) already going with existing work, and in part to identify workable stew- on in this business area. ardship models for TransXML. The experience of NCHRP Project 20-64 and, in particular, the decisions made in Beyond Data Exchange; Towards Interoperability that effort to adopt certain technical components of other schemas--or in one case a complete schema--as part of NCHRP Project 20-64 emphasized data exchange among TransXML, underscore the importance of developing a deeper applications--defining a common format for data to allow one and continuing relationship with these other efforts. application to export a data set that can then be imported into The TransXML Project should therefore emphasize coor- a variety of other applications. Current information systems dination with other larger-scale, relatively well-established technology is increasingly directed towards service-oriented XML Schema standardization efforts in the transportation architectures (SOA), in which a variety of information systems arena (ITS, commercial vehicles, crash records, etc.) so as to operate in parallel, providing services to each other in an "on avoid proliferation of incompatible standards. While this call" environment. This approach (often referred to as "web sounds straightforward, it represents a substantial practical services" in the context of systems that interoperate over the challenge. Other standards efforts have different goals and World Wide Web) often leverages XML as a communications objectives and serve different audiences, and often rely on medium that allows information systems to operate in tandem, very different technical foundations. For the TransXML Proj- packaging services provided by a number of different systems ect to influence existing schema standardization efforts, it into applications that meet specific end-user requirements. The will need to build up credibility through meaningful partici- TransXML Project should make an effort to promote these pation. In doing so, the project should be able to leverage its potential benefits of XML in addition to the potential data adoption of GML as a unifying framework. Participation in exchange benefits. Examples of potential web services in trans- these other efforts requires familiarity with the work per- portation might include searches for facilities (rest areas, tran- formed to date and the needs and other characteristics of sit stations) by location, queries of traffic conditions on a route, participants in the relevant standardization community. validation of standard data sets (e.g., NBI, HPMS), or price This, in turn, will require time and financial resources. lookups for standard pay items. In each of these examples, the web service represents a modular function that consumes and produces a standardized XML data set, and can be called from Balance Schema Development, Advocacy, a variety of web-based applications. and Industry Coordination The TransXML Project will need to strike a careful balance TransXML Project Mission Statement between different levels of activity: providing a technical foundation and infrastructure (both administrative and col- The NCHRP 20-64 project team recommends the follow- laborative) to support schema development activity; address- ing Mission Statement for the TransXML Project: ing specific data exchanges through schema development; The TransXML Project promotes data exchange and inter- and working with other transportation standards bodies to operability of software applications and information systems used help establish an overarching architecture for transportation by transportation agencies in areas where such interoperability is data. The first of these is essential to yield a coherent and most needed and will generate the greatest benefits. The Project coordinated set of work products and to simplify and stream- intends to increase the utility of these systems and enable them line schema development efforts; the second is essential to to work together more effectively, overcoming existing data communication obstacles, empowering the industry to operate provide a continuous demonstration of successful efforts and more efficiently and, ultimately, improving transportation in the value being derived from the project effort; the third is in United States. many respects the "heart of the matter" with respect to the ultimate objectives of the effort. 6.5 Function and Roles of a While coordination of existing XML schema development TransXML Stewardship efforts (and, where possible, providing support for these efforts Organization via TransXML standards and infrastructure) is extremely important, it should not dominate the project. The construc- The TransXML stewardship organization should provide tion and materials business area clearly needs a stewardship the following functions: body to facilitate development of schemas. The safety busi- ness area also needs a stewardship body to coordinate a wide Continually develop and refine a vision of where inter- variety of schema, despite the fact that there are important operability is most needed and where it can generate the and relatively well-established schema development efforts greatest benefits. The steward must not only devise a clear