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Protocols enable things to connect and communicate, thus making the Internet of Things possible. The performance aspect of the Internet of Things protocols, vital to its widespread utilization, have received much attention. However, one aspect of IoT protocols, essential to its adoption in the real world, is a protocols' feature set. Comparative analysis based on competing features and properties are rarely if ever, discussed in the literature. In this paper, we define 19 attributes in 5 categories that are essential for IoT stakeholders to consider. These attributes are then used to contrast four IoT protocols, MQTT, HTTP, CoAP and XMPP. Furthermore, we discuss scenarios where an assessment based on comparative strengths and weaknesses would be beneficial. The provided comparison model can be easily extended to include protocols like MQTT-SN, AMQP and DDS.