Abstract

This paper presents congestion control mechanisms for reliable and scalable message-oriented middleware following the publish/subscribe communication model. 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, to allow brokers in recovery to eventually catch up, and other brokers to keep up. We present a detailed experimental evaluation of our implementation of these mechanisms in the Gryphon system by injecting network failures and link congestion. Document type: Part of book or chapter of book

Abstract

This paper will stress the importance of Ship Handling Simulation (SHS)-based Maritime Autonomous Surface Ship (MASS) prototype development and aligns it with the IMO Guidelines on Software Quality Assurance and Humancentered Design for e-Navigation. This is demonstrated by means of an implemented semi-autonomous ship concept. This concept envisions a periodically unmanned bridge with an advanced autonomous navigation system taking over in the absence of the officer of the watch. Thus, it is equipped with autonomous monitoring, collision avoidance as well as harsh weather applications embedded within an ECDIS environment, that require sufficient integration and testing. Based on a requirement analyses, the need for SHS-based testing is derived and a technical framework (SMARTframe) enabling connection of MASS prototypes with SHS on the basis of a message-oriented middleware is introduced. Finally, an indication is given how this set-up ensures proper MASS testing and developing for technical as well as Human-centered Design development.