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.

New multimedia applications have emerged on top of information infrastructures, such as on-demand services, digital libraries and museums, online shopping and document management, which require new databases. That is, next-generation database systems must enable users to efficiently and flexibly develop and execute such advanced multimedia applications. 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 take an approach based on an object-oriented database, which is more suitable for the description of media structures and operations than a traditional relational database. We extend the object-oriented approach by providing temporal and spatial operators, and control of distributing computing and QOS (quality of service). In this paper, we describe a multimedia data model and its efficient implementation.