Track: Application Development
Creating Reusable Components for a Data Browser Using MapObjects with Three-Tiered Architecture
Philip PennMultitiered architecture provides a solid foundation for creating extensible, maintainable, scalable systems that can react to changes in business needs. In particular, the segregation of user interface, business, and data services at a logical level is key to achieving reuse. The MapObjects model provides functionality in all three tiers, which makes separation of its constituent parts especially important when integrating map components into an application. A generic data browser was created using three-tiered architecture, wrapping up the extra functionality into components in order to maximize reuse. The proposed paper focuses on the experience of Convergent Group in creating a generic data browser for a public sector client. The application contains standard features, such as the ability to query and locate, as well as analytical capabilities. This functionality will be reusable between multiple projects using ActiveX technology. MapObjects is a low-level toolkit that does not provide all of the functionality required for the data browser. The Microsoft Windows idea of active selection was used as a user interface guideline. MapObjects does not contain business tier objects for dealing with spatial selection to provide a bridge between the search methods and tracking layer management (data services) and mouse clicks/zooming/highlighting (user interface services). Other significant additions included a component for dealing with user-defined views and storing and creating symbology. This paper describes a strategy for identifying, designing, and creating COM-based components for a generic data browser using MapObjects and Oracle with Visual Basic/Visual C++ in Windows NT 4.0.
Philip Penn
Convergent Group
6200 S. Syracuse Way
Englewood, CO 80111
USA
Telephone: (303) 741-8312
Fax: (303) 486-1109
E-mail: Philip.Penn@cvg-grp.com