Bulletin Board: A scalable and robust eventually consistent shared memory over a peer-to-peer overlay

We present the design and early experience with a completely new implementation of the Bulletin Board, a topicbased distributed shared memory service employed by commercial-grade application middleware, to achieve robustness and administrative simplicity with adequate latency and costs at the required throughput and scale. To facilitate scalability, only weak consistency is provided. For robustness and ease of use, the implementation is designed in a fully peer-to-peer fashion leveraging the weakly consistent group communication services provided by a semi-structured overlay network. We discuss issues in providing good (while not perfect) stability and reliability at tolerable cost. We address scalability issues, such as supporting large numbers of processes, large subscription spaces, and complex interest patterns. We also consider comprehensive API instrumentation.