Previous columns in this space suggested the use of formal methods and modeling tools, particularly when your projects involve many objects and complex database schemas. The objective of modeling is to complete a rigorous design with quality checks before you build a physical system. When you use a modeling tool, you create an abstract representation of the real world that defines relationships, structure, rules, and other information. Last month I discussed three types of modeling that will be important technologies in the new millennium. This trinity of modeling techniques includes object modeling, content modeling, and data modeling, using the Unified Modeling Language (UML), the extensible Markup Language (XML), and Object-Role Modeling (ORM), respectively. To build some Web applications, you might use two or three modeling techniques. For example, there are e-commerce working groups using UML and XML to create new electronic data interchange (EDI) standards. Developers creating multitier applications might use UML for middle-tier components and ORM to produce database schemas. UML and ORM share concepts such as an object-centric methodology and conceptual modeling, but ORM is a tool for designing databases, not application classes.
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