An ad hoc middleware workshop was held at the International Center for Advanced Internet Research in December 1998. The Workshop was organized and sponsored by Cisco, Northwestern University's International Center for Advanced Internet Research (iCAIR), IBM, and the National Science Foundation (NSF). The goal of the workshop was to identify existing middleware services that could be leveraged for new capabilities as well as identifying additional middleware services requiring research and development. The workshop participants discussed the definition of middleware in general, examined the applications perspective, detailed underlying network transport capabilities relevant to middleware services, and then covered various specific examples of middleware components. These included APIs, authentication, authorization, and accounting (AAA) issues, policy framework, directories, resource management, networked information discovery and retrieval services, quality of service,