 its data sources. Although it doesn't need to have a place to store the data it is managing, a virtual database does need a place to store its model, mappings and other information.
Why not use enterprise application integration (EAI)? Because that can carry unnecessary overhead. As its name implies, EAI connects applications. Each application has its own database; an integration server takes the data that's output by one application and modifies it so that it can be read and used by another application. By contrast, a virtual database connects an application directly to the sources of data. Doing so eliminates the need for unique adaptersbecause the data can be accessed by standard database protocolsand also saves processing time and energy by avoiding the application that sits in front of a database.
What are the drawbacks? The biggest problem is the same one that faces every integration effort: building a universal data model. A single schema that satisfies all or even half of a company's data needs is awfully hard to come by, especially with the general uncleanliness of existing data.
Who's using it? Most companies are just beginning to consider EII and virtual databases seriously. It's a pretty difficult idea to sell inside a company that already has spent a lot on EAI, though. The organizations that are furthest along are the ones that have to meet strict regulations, such as the Health Insurance Portability and Accountability Act, or, like the Department of Defense, need to perform complex data analysis without creating a warehouse of data.
As Statistics Editor of Baseline magazine, Regina creates interactive tools, worksheets and project guides for technology managers. Before joining Ziff Davis, she worked as a technical program manager for a database company, where her projects included data management applications in XML, Java, Visual Basic and ASP. Her other experience includes running the new media department at Christie's Inc. and writing and editing for Internet World and PC Magazine. Regina received a B.A. from Yale.