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36 materials to the website, and monitoring and responding to XML schemas developed for TransXML. UML modeling is stakeholder comments. standard practice--several standards bodies (OpenGIS, TC211, An administrator for the entire website managed general TC204), have adopted UML as their modeling language of project content (not specific to a business area) and user priv- choice. While XML Schemas are humanly readable, it is ileges. The website was set up with public areas containing extremely difficult to grasp the data relationships being rep- general project information and a working group section for resented in an XML schema (.xsd) document. UML models each of the four business areas. Stakeholders interested in present this information graphically and symbolically, facili- joining working groups were able to register on the site. The tating the review process. Just as it is always easier to modify site administrator then granted them access to the relevant software (or any constructed item) in the design stage than working groups, allowing them to read and download mate- after it is under construction, it is much easier to modify UML rials, and participate in discussions. Registration was required models than completed XML schema. In addition to facilitat- to prevent spamming, but it may have presented an obstacle ing the design review process, UML diagrams also serve as use- to achieving greater stakeholder participation--particularly ful documentation for the XML schema and are invaluable for since there was a time delay between registration and grant- supporting maintenance of the schema over time. ing of access. Figure 5 shows a sample UML class diagram. This diagram The initial website went live on March 26, 2004. As of the end conveys the following information: of June 2004, over 100 individuals had signed up on the website to be on the project's mailing list and/or participate as schema A road project is composed of 0 or more road project pay developers or reviewers. At the close of the project, 376 peo- items. ple had registered on the website. A road project has three attributes: a project number, a While several general comments were made at the start of project name, and a project engineer. The project number the project, and a few individuals did perform a detailed tech- has a special ID data type; the project name and project nical review of UML models and submitted comments, the engineer attributes are character strings. overall level of participation in the TransXML project was A road project pay item has two attributes: quantity and esti- considerably lower than anticipated. mate. Both quantity and estimate are numerical data types. The collaborative website was developed using open source. A road project pay item must correspond to an entry on a NET software. The entire site, including the supporting data- standard contract pay item list. base with all site content is being provided to NCHRP as part A standard contract pay item is described by four attributes: of the deliverables for this project. an item number (ID), an item name (character or string), an optional description (character string), and units of measure (which is a special measurement units data type). 5.4 UML Modeling Measurement units must be selected from a code list, Unified Modeling Language (UML) class diagrams (ISO which has four fixed choices: linear feet, cubic yards, tons, Standard 19501) were used as the primary design tool for the or each as well as an option for a user-specified other value. > > RD_Project RD_ContractPayItem + projectNumber: ID + itemNumber: ID + projectName: CharacterString + itemName: CharacterString + projectEngineer: CharacterString + description[0..1]: CharacterString + units: TG_MeasureUnits 1 +standard item +project item > 0..* 0..* TG_MeasureUnits > + linearFeet RD_ProjectPayItem + cubicYards + quantity: Number + tons + estimate: Number + each Figure 5. Sample UML class diagram.