SUMMARY
The increasing number of IoT (Internet of Things) devices is accelerating the research on new solutions of communication protocols and cloud services. The selection of an effective communication protocol as well as a cloud service is a challenging task for any IoT project since it depends on particular requirements of the IoT system. In this paper, at first, we evaluate four main communication protocols, which are commonly used in IoT systems: MQTT (Message Queuing Telemetry Transport), CoAP (Constrained Application Protocol), AMQP (Advanced Message Queuing Protocol) and HTTP (Hypertext Transfer Protocol). Afterwards, we perform an in-depth analysis of two cloud services for storing and transmitting data: CloudMQTT and Firebase Realtime Database (FRD). Finally, we perform a simple IoT system using FRD to demonstrate the efficiency of the cloud service. Based on the detailed evaluation, the user can choose an appropriate communication protocol and a cloud service for IoT systems according to their requirements.