Context Broker Architecture (CoBrA) is an agent based architecture for supporting context-aware systems in smart spaces (e.g., intelligent meeting rooms, smart homes, and smart vehicles). Central to this architecture is an intelligent agent called context broker that maintains a shared model of context on the behalf of a community of agents, services, and devices in the space and provides privacy protections for the users in the space by enforcing the policy rules that they define.

Key differences between CoBrA and other similar architectures are the following:

• CoBrA uses the Web Ontology Language OWL, a W3C Semantic Web standard, to define ontologies of context (people, agents, devices, events, time, space, etc.). In other systems, context is often implemented as programming language objects (e.g., Java classes), lacking the expressive power to support context reasoning and high-level knowledge sharing.
• CoBrA provides a resource-rich context broker to maintain a shared model of context for all computing entities in an associated space. In other systems, individual entities are usually required to manage their own contextual knowledge.
• CoBrA allows the users to define privacy policy to control the sharing and the use of their situational information (e.g., where they are, who they are with, what they are doing). In other systems, the computing entities are usually free to share any acquired situational information of a user.

Figure 1 shows an overview architecture diagram of CoBrA. For more information, please see the documents listed in the paper section.