## 2 Internet of Things for Healthcare
### IoT Open-Source Platforms and Operating Systems  
Currently, there are numerous open-source platforms and operating systems that aim to provide support for different systems, data confidentially, safety, fusion, and dissemination. This section presents the most relevant IoT platforms and operating systems (Figure 3), which are recognized by their significance for the improvement of the state of the art and creative highlights, which can likewise be utilized to create secure and scalable healthcare systems. (1)**SiteWhere:** An open-source IoT platform. It offers a system that accelerates the storage, handling, and incorporation of device data. SiteWhere provides an IoT server platform, device management, and third-party integration frameworks. This IoT platform aims to provide IoT functionalities for monitoring, automation, and analytics for healthcare systems [42]. Figure 3: IoT platforms and operating systems. * **DeviceHive:** An open-source IoT data platform that aims to connect devices to the cloud and device data stream. It also provides creation and customization of IoT/M2M (machine-to-machine) applications with a secure, scalable, and cloud-ready functionalities [43]. * **Platformio:** An integrated development environment for IoT. It supports cross-platform build functionality without external dependencies to the operating system software, having compatibility with 200+ embedded boards, 15+ development platforms, and 10+ frameworks. It also provides a built-in serial port monitor and configurable build flags/options and automatic firmware uploading for IoT system development [44]. * **RIOT**: A free, open-source operating system for the majority of the relevant open standards supporting the IoT. It provides code compatibility for 8,16,32-bit platforms, energy-efficiency, real-time capability due to an ultra-low interrupt latency, multi-threading with ultra-low threading overhead but also 6 LoWPAN, IPv6, an IPv6 routing protocol for low-power and Lossy networks (RPL), UDP, CoAP, and concise binary object representation (CBOR) protocols [45]. * **ARM mbed**: An IoT platform that delivers the operating system, cloud facilities, tools, and designer ecosystem in order to develop scalable systems based on IoT. It implements safety functionalities, such as transport layer security (TLS) as well CoAP and RESTful API to design M2M networks [46]. * **Ubuntu Core** (Snappy): A development version of Ubuntu for IoT systems that offers safety and extensibility of an Ubuntu operating system. It also delivers management systems for safe, reliable, transactional updates controlled by Canonical's AppArmor security system [47]. * **IoTivity**: An open-source software framework that provides device-to-device communications to the IoT systems. The IoTivity project is sponsored by the Open Connectivity Foundation (OCF), a specification and certification program to address IoT open issues [48]. * **Distributed Services Architecture** (DSA): An open-source IoT platform that aims to join the heterogeneous hardware and software in IoT and provide a scalable, resilient decentralized solution. DSA is composed of DSBroker, DSLink, and nodeAPI. DSBroker acts as a router for incoming and outgoing streams. NodeAPI provides node compatibility and bi-directional control and monitoring ability between connected things. DSLink is connected to the DSBroker that acts as the source of the data streams [49]. * **Calvin-Base:** An open-source platform built with a centralized architecture that supports REST API and it is particularly scalable implementing a variety of plugins for interoperability [50]. * **Cylon.js:** A JavaScript framework for the IoT that uses Node.js. This framework provides code compatibility between different hardware for IoT. Supports multiple platforms, such as Arduino, Intel Galileo, Intel Edison, and Raspberry [51]. * **Brillo:** An Android-based operating system, with core services that provide a developer kit and developer console to build IoT applications.