CoAP is a web protocol for constrained environments, and also designed in consideration of interoperability with HTTP. However, lack of best practices of implementing proxies that provide HTTP-CoAP translation obstructs verication and spread of new Web of Things services based on interactions between HTTP and CoAP devices. In this paper, we introduce a HTTP-CoAP proxy implementation. It does not require any congurations on clients. It also can be easily added on top of conventional HTTP servers by utilizing CGI.

1. Zero Configuration
HTTP-CoAP Proxy based on CGI
Jongsoo Jung, Jeehoon Lee, Haeyong Kim, Gyusang Shin, and Seontae Kim
Embedded Software Research Department
Electronics and Telecommunications Research Institute (ETRI), Korea
{jsjeong, zardu22, haekim, gsshin, stkim10}@etri.re.kr
Motivation Proxies for HC Translation
Interception Forward Reverse
HTTP, a de-facto REST protocol is CoAP, an emerging REST protocol
Actual CoAP
widely used in computers, phones, for constrained devices will realize Destination Proxy Proxy
resource
and tablets, currently. Not compatible Internet of Things in the near future.
with each other Actual CoAP Actual CoAP Sub resource of
Request target
resource Resource the proxy
Configuration No Client Proxy
Embedded
HC Proxy (CGI)
mapping or
Apache2 URI mapping Homogeneous Not necessary additional
complex
Linux mapping
System Overview
GET
http://{Proxy address}/cgi/coap/
GET
coap://{CoAP URI path}
Why CGI?
{CoAP URI path}/sensor/temperature /sensor/temperature If the proxy should be implemented for
the actual embedded devices such as
Internet
Constrained
Network
the border router, CGI will be an
efficient solution because the CGI
HTTP Client
HTTP/1.1 200 OK … HC Proxy 0x62450405… CoAP Server
programming can be implemented
20 (℃) (2.05 … 20 (℃))
lightly using C language.