mjCoAP: An Open-Source Lightweight Java CoAP Library for Internet of Things Applications - Interoperability and Open-Source Solutions for the Internet of Things - page 127

Fig. 2. A complex IoT application scenario for real-time environmental monitoring
based on the mjCoAP library.

The Raspberry Pi is connected to an IPv4 network via IEEE 802.3 and to an IPv6
(6LoWPAN) constrained network using IEEE 802.15.4, acting as 6LoWPAN
border router (6LBR), by means of a Zolertia Z1 node connected via USB and
running Contiki OS in order to provide a network interface to the 6LoWPAN
network.

Table 2. List of hardware and software used for the real-time environmental monitoring
IoT application with corresponding connectivity.

Device Connectivity Operating system CoAP implementation

Raspberry Pi IPv4/IEEE 802.3 Raspbian mjCoAP

IPv6/IEEE 802.15.4 Raspbian Erbium

Arduino Yun IPv4/IEEE 802.11 OpenWrt-Yun mjCoAP

Intel Galileo IPv4/IEEE 802.3 Linux mjCoAP

Zolertia Z1 IPv6/IEEE 802.15.4 Contiki OS Erbium

The central element of the architecture is the Raspberry Pi, which is also
denoted as “ IoT Gateway ”, as it provides several features that are needed to
enable full operativity by all network nodes. The mjCoAP library has been used
to develop an HTTP-to-CoAP Cross-Proxy, following the set of rules specified in
the HTTP-to-CoAP mapping draft [ 12 ]. A RD has also been implemented using
mjCoAP. The IoT Gateway runs an HTTP-to-CoAP proxy and a RD, as well