With the massive increase in the number of IoT devices being deployed in smart cities, it becomes paramount for middlewares to be able to handle very high loads and support demanding use-cases. In order to do so, middlewares must scale horizontally while providing a commensurate increase in availability and throughput. Currently, most open-source IoT middlewares do not provide out-of-the-box support for scaling horizontally. In this paper, we present "Vermillion'', a scalable, secure and open-source IoT middleware for smart cities which provides in-built support for scaling-out. We make three contributions in this paper. Firstly, the middleware platform itself along with a formal process for data exchange between data producers and consumers. Secondly, we propose the use of hash-based federation to distribute and manage load across various message broker nodes while eliminating inter-node synchronisation overheads. Thirdly, we discuss a case study where Vermillion was deployed in a city and briefly discuss about deployment considerations using the obtained results.

中文翻译：

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Vermillion：适用于智慧城市的高性能可扩展物联网中间件

随着智能城市中部署的物联网设备数量的大量增加，中间件能够处理非常高的负载并支持要求苛刻的用例变得至关重要。为此，中间件必须水平扩展，同时提供相应的可用性和吞吐量增加。目前，大多数开源物联网中间件不提供开箱即用的水平扩展支持。在本文中，我们提出了“Vermillion”，一种用于智能城市的可扩展、安全和开源的物联网中间件，它为横向扩展提供内置支持。我们在本文中做出了三个贡献。首先，中间件平台本身与数据生产者和消费者之间的数据交换的正式流程。其次，我们建议使用基于哈希的联合来分布和管理各种消息代理节点之间的负载，同时消除节点间同步开销。第三，我们讨论了 Vermillion 部署在一个城市的案例研究，并使用获得的结果简要讨论了部署注意事项。