nes-proj/examples/coap

A Quick Introduction to the Erbium (Er) CoAP Engine

EXAMPLE FILES

• coap-example-server.c: A CoAP server example showing how to use the CoAP layer to develop server-side applications.
• coap-example-client.c: A CoAP client that polls the /actuators/toggle resource every 10 seconds and cycles through 4 resources on button press (target address is hard-coded).
• plugtest-server.c: The server used for draft compliance testing at ETSI IoT CoAP Plugtests. Erbium (Er) participated in Paris, France, March 2012 and Sophia-Antipolis, France, November 2012 (configured for native).

PRELIMINARIES

• Get the Copper (Cu) CoAP user-agent from https://addons.mozilla.org/en-US/firefox/addon/copper-270430

TMOTE SKY HOWTO

The CoAP example no longer fits in the limited ROM of the Tmote Sky. Please use a platform with larger ROM instead.

NATIVE HOWTO

With the target native you can test your CoAP applications without constraints, i.e., with large buffers, debug output, memory protection, etc. The plugtest-server is thought for the native platform, as it requires an 1280-byte IP buffer and 1024-byte blocks.

    make TARGET=native plugtest-server
    sudo ./plugtest-server.native

Open new terminal

    make connect-native

• Start Copper and discover resources at coap://[fdfd::ff:fe00:10]:5683/
• You can enable the ETSI Plugtest menu in Copper's preferences

Under Windows/Cygwin, WPCAP might need a patch in \usr\include\w32api\in6addr.h:

21,23c21
< #ifdef __INSIDE_CYGWIN__
<     uint32_t __s6_addr32[4];
< #endif
---
>     u_int __s6_addr32[4];
36d33
< #ifdef __INSIDE_CYGWIN__
39d35
< #endif

DETAILS

Erbium implements the Proposed Standard of CoAP. Central features are commented in coap-example-server.c. In general, coap supports:

• All draft-18 header options
• CON Retransmissions (note COAP_MAX_OPEN_TRANSACTIONS)
• Blockwise Transfers (note COAP_MAX_CHUNK_SIZE, see plugtest-server.c for Block1 uploads)
• Separate Responses (no rest_set_pre_handler() required anymore, note coap_separate_accept(), _reject(), and _resume())
• Resource Discovery
• Observing Resources (see EVENT_ and PERIODIC_RESOURCE, note COAP_MAX_OBSERVERS)

TODOs

• Dedicated Observe buffers
• Optimize message struct variable access (directly access struct without copying)
• Observe client
• Multiple If-Match ETags
• (Message deduplication)