# Internet of Things Platforms for Academic Research and Development: A Critical Review
## 2 Internet of Things Platforms
### Closed Source Platforms  
Most major players in IT services developed their own IoT platform, in most cases as an extension or integration of their preexisting cloud services, leading to solutions that fall in general under the umbrella known as software-as-a-service (SaaS) or platform-as-a-service (PaaS). The PaaS approach is adopted by Ericsson for its IoT accelerator platform [13], that targets mostly business partners by proposing a platform that takes care of connectivity (leveraging the expertise of the company in mobile communications), security aspects, application programming interfaces (APIs) for business management support and user authentication/subscription/billing. The platform can integrate and manage all devices that support any of representational state transfer (REST), advanced message queuing protocol (AMQP), constrained application protocol (CoAP), and are compliant to LightWeightM2M (LWM2M) specifications. In terms of integration, the platform supports enterprise service buses for integration with enterprise IT back-end systems. Autodesk Fusion Connect [14] adopted a SaaS approach, providing a cloud-based internet of things (IoT) platform that enables bidirectional connection with field devices, regardless of whether they were designed for IP connectivity or not. It provided the capability to monitor, analyze, and manage these devices allowing a dynamic duty cycle scheduling, aiming at uptime maximization and optimal asset usage. The platform is, however, not listed anymore in the Autodesk product list, suggesting it has been discontinued. The IBM Watson IoT Platform [15] is another platform proposed by a major IT player. In this case as well, the platform adopts a PaaS approach, supporting devices that adopt REST, hyper text transfer protocol (HTTP) and message queuing telemetry transport (MQTT) protocols, among others, and providing powerful analytics, aggregation and visualization tools. The platform also makes available an editor for IoT apps, Node-RED, that allows the creation of IoT apps connecting hardware and cloud services. The Zoho IoT platform [16], formerly known as WebNMS [17], provides a cloud-based platform aiming at businesses in fields like energy management and remote asset tracking. Zoho promises device management and monitoring, data processing, support for legacy devices and cross enterprise operations. The Losant Enterprise IoT Platform [18] offers the possibility of building IoT solutions with minimum coding, offering public cloud access under a free pricing scheme, and private cloud and on-premises installations for enterprise customers. The platform targets ease of use and deployment of IoT applications, by means of application templates that can be customized to fit specific scenarios. The platform also supports edge-computing to prefilter data to be sent to the cloud for processing and visualization. The Ubidots Platform [19] is an IoT cloud platform supporting HTTP, MQTT, TCP and UDP protocols, and a wide range of IoT hardware platforms and cellular technologies by means of dedicated SDKs. The platform is available under a paid PaaS scheme, although a non-commercial, free tier with support of up to three devices is available. MindSphere [20] is also a PaaS proposal by Siemens, providing a set of APIs for interconnection of devices supporting HTTP and the JavaScript object notation (JSON) data exchange format; a wider range of protocols, including REST and MQTT, are supported through the MindConnect IoT Extension, allowing a wide range of devices to connect to the platform. Similarly to IoT Accelerator and the IBM Watson IoT Platform, the targets of MindSphere are mainly business customers, and the platform provides indeed support for integration with industrial back-ends such as supervisory control and data acquisition (SCADA) systems. General Electric also proposed its IoT platform, named Predix [21], that operates by combining two technologies for cloud and edge computing and communication, each with its own software stack.