The vision of an Internet of Things is turning into a reality with tiny embedded devices that are directly connected to the Internet over IP. The Internet Engineering Task Force (IETF) has been standardizing several protocols to incorporate resource-constrained devices that are very limited in energy, memory, computational power, and bandwidth
These include 6LoWPAN to adapt IPv6 to low-power, lossy networks (LLNs), RPL to route over the fluctuating links, and compression to optimize higher protocol layers.
The emerging Constrained Application Protocol (CoAP) has created a stack to have a fully standardized protocol suite which will make the IP-based IoT interesting for industrial application.
Also industry standards bodies such as ETSI M2M and the IPSO Alliance have adopted the light-weight RESTful protocol to achieve global interoperability for networked embedded systems.
When the idea of an universal Internet of Things was first conceived in the late 1990s everydayobjects were at first interconnected through their virtual representations using barcodes and later RFID.
Later, application level gateways where used to bridge between different communication solutions for embedded systems. Then came compact implementations of the Internet protocl suite for resource-constrained devices allowing things to be accessed directly over IP.
The standardization work of the IETF only reached up to thetransport layer, though. So projects continued to implement custom application protocols over UDP, with the result that 6LoWPAN devices were not interoperable.
Having two RESTful protocols to cover the full spectrum of device types, the IPSO Alliance has started the next step for device interoperability in commercial products. The so called “IPSO Profile” defines a standard resource structurefor embedded Web servers.
In this paper, we present a survey on the current state of the art of lightweight REST implementations and we find that although CoAP is a very new protocol, over 20different implementations in various programming languages are known for devices ranging from resource-constrained devices such as wireless sensor nodes up to smartphones andservers. This implies that CoAP is going to be used in many different applications and domains.
To read this external content in full, download the complete paper from the the author archives at the ETH's Institute for Pervasive Computing.