AVANTE: An architecture of CORBA components and XML Metadata for Web Based Instruction

Most current solutions for Web Based Instruction (WBI) use a centralized management model and a proprietary internal representation. The AVANTE Architecture is a WBI environment assembled using CORBA distributed components, implementing core services such as course management, user authentication, collaborative work, database access, presentation, and others. The AVANTE components conform to a 4-tiered model, with Client, Presentation, Management, and Low-Level Services component sublayers. Emergent XML standards for WBI describe all metadata definitions. Components at the Management layer manipulate JDBC-SQL data from the Low- Level Services Layer, and combine it with corresponding XML Schemas, instantiating course objects as new XML descriptions and component services. A filter-mapping service in the Presentation layer produces the dynamic HTML web pages needed for user interaction, processing these XML descriptions by applying one or more previously defined XSL stylesheets. A similar mechanism implements interface customization and remote service administration. The developed WBI system was deployed with open source software. Adding CORBA components easily achieves on-demand scalability. Future services include auditing, adaptive interfaces, grading, content development, and integration with existing systems.