As agents see more use in dynamic, distributed information networks, information sharing facilitators, such as the SHADE matchmaker, and underlying knowledge-based agent communication protocols, such as the Knowledge Query and Manipulation Language, will see increased use. We have created several communities of agents collaborating via KQML and matchmaking within the domains of collaborative engineering and satellite image retrieval. Based on these experiences, matchmaking has proven to be very beneficial for multi-agent systems, but we have also identified a number of issues and extensions that are not only vital to KQML-based matchmaking, but to inter-agent protocols in general. These include representational approaches to advertising complex databases, approaches to error recovery and response timing, maintaining consistency among information providers, scalability, security, persistent requests in information brokering, and the dilemma between explicit vs. implicit brokering.

Structuring temporal relationships among multimedia information elements is one of the most important facilities for editing and creating multimedia documents. We have developed a multimedia system named MediaPreview which provides facilities for structuring and creating multimedia documents. In this paper, we present a document model which is adopted in MediaPreview. This model has been designed to realize spatial and temporal structuring for the documents. The main feature of this model is the concept of a "Multimedia Paragraph" (MMP) which is introduced to reduce the complexity of the temporal structuring, such as the asynchronous interactive operation among documents. The concept of "MMP" provides an explicit and basic unit which is used to create a document in a "top-down" manner. This paper also presents the system architecture and implementation of MediaPreview in a distributed environment including database system facilities. This system realizes "static" and "dynamic" integration schemes for multimedia information elements. Our system includes a parallel database engine which manipulates multimedia information elements as streams. This database engine is effectively used for creating multimedia documents.