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Full Paper AbstractsCongestion Control in a Reliable Scalable Message-Oriented MiddlewarePeter Pietzuch and Sumeer Bhola (U. of Cambridge and IBM T.J. Watson) This paper presents congestion control mechanisms for reliable and scalable message-oriented middleware. We focus on the publish-subscribe communication model, implemented using an overlay network of brokers. Brokers can perform hop-by-hop filtering of messages on the path from a publisher to a subscriber, and can cache messages at intermediate hops for satisfying retransmission requests. We identify the key requirements of congestion control in this environment, how it differs from congestion control for the Internet, and propose a combination of two congestion control mechanisms, (1) driven by a publisher hosting broker (PDCC), (2) driven by a subscriber hosting broker (SDCC). SDCC decouples the notion of a receive window and a NACK window, and is used by subscriber hosting brokers in recovery mode. PDCC implements a scalable and low latency feedback loop between a publisher hosting broker and all subscriber hosting brokers, which is used to adjust the rate of publishing new messages. PDCC normalizes the rate at different subscriber hosting brokers, regardless of which subset of messages they receive, and handles recovering brokers in a way that they are guaranteed to eventually complete their recovery phase. We present a detailed experimental evaluation of our implementation of these mechanisms in the Gryphon system by injecting network failures and link congestion. |
Latest update: 13 June 2003 - Questions and Comments about the Site: fmc@inf.ufg.br |