Nowadays, structured data such as sales and business forms are stored in data warehouses for decision makers to use. Further, unstructured data such as emails, HTML texts, images, videos, and office documents are increasingly accumulated in personal computer storage due to spread of mailing, WWW, and word processing. Such unstructured data, or what we call multimedia documents, are larger in volume than structured data and precious as corporate assets as well. So we need a document warehouse as a software framework where multimedia documents are analyzed and managed for corporate-wide information sharing and reuse like a data warehouse for structured data. We describe a prototype document warehouse system, which supports management of simple and compound documents, keyword-based and content-based retrieval, rule-based classification, SOM-based clustering, and XML data query and view rules.

New multimedia applications, such as digital libraries and document warehousing, require next-generation database systems enabling users to efficiently and flexibly develop and execute such networked applications. To this end, we focus on development of a database system which enables flexible and efficient acquisition, storage, access and retrieval, and distribution and presentation of large amounts of heterogeneous media data. We propose a multimedia database system for networked multimedia applications, based on an OODB model extended with agents. We describe an early prototype multimedia database system to verify the proposed approach, which supports multimedia scripts, keyword-based and content-based view retrieval with QoS control, self-organizing map-based clustering and WWW integration.