Brokers and Services: Constructs for the Design and Implementation ofProcess-Oriented Environments

Cooperative process-oriented environments (CPEs) are federations of human agents and multiple (heterogeneous) software tools which cooperate to accomplish complex and long-lasting tasks. Appropriate abstractions must be available in order to properly design and implement CPEs, including tasks such as the control of and cooperation among their participating entities. In this paper, we introduce the concept of brokers, which are components reacting to environmental stimuli and are used to model participating entities in CPEs: human participants, existing software tools, or parts of the environment infrastructure. Services model the functionality offered by brokers. Although these brokers are actually abstractions on top of active object-oriented database management systems, they are also influenced by concepts developed in other research areas, such as (concurrent) programming languages, artificial intelligence, and software architectures. We therefore also position the broker model with respect to similar concepts from these domains.