A Quick Introduction to the Erbium (Er) REST Engine
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Compile the Example
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./run.sh

OSD-Merkur Board
----------------------
write the images to the OSD-Merkur Board:

./flash.sh

EXAMPLE FILES
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er-example-server.c: A RESTful server example showing how to use the REST layer to develop server-side applications (at the moment only CoAP is implemented for the REST Engine).
er-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).
er-plugtest-server.c: The server used for draft compliance testing at ETSI IoT CoAP Plugtest in Paris, France, March 2012 (configured for minimal-net).

PRELIMINARIES
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-  Make sure rpl-border-router has the same stack and fits into mote memory:
   You can disable RDC in border-router project-conf.h (not really required as BR keeps radio turned on).
   #undef NETSTACK_CONF_RDC
   #define NETSTACK_CONF_RDC     nullrdc_driver
-  For convenience, define the Cooja addresses in /etc/hosts
   aaaa::0212:7401:0001:0101	cooja1
   aaaa::0212:7402:0002:0202	cooja2
   ...
-  Get the Copper (Cu) CoAP user-agent from https://addons.mozilla.org/en-US/firefox/addon/copper-270430/
-  Optional: Save your target as default target
   $ make TARGET=sky savetarget

COOJA HOWTO
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Server only:
1) $ make TARGET=cooja server-only.csc
2) Open new terminal
3) $ make connect-router-cooja
4) Start Copper and discover resources at coap://cooja2:5683/
-  Choose "Click button on Sky 2" from the context menu of mote 2 (server) after requesting /test/separate
-  Do the same when observing /test/event

With client:
1) $ make TARGET=cooja server-client.csc
2) Open new terminal
3) $ make connect-router-cooja
4) Wait until red LED toggles on mote 2 (server)
5) Choose "Click button on Sky 3" from the context menu of mote 3 (client) and watch serial output

DETAILS
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Erbium currently implements draft 08 (name "er-coap-07" stems from last technical draft changes).
Central features are commented in er-example-server.c.
In general, apps/er-coap-07 supports:
* All draft 08 header options
* CON Retransmissions (note COAP_MAX_OPEN_TRANSACTIONS)
* Blockwise Transfers (note REST_MAX_CHUNK_SIZE, see er-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 PRERIODIC_RESOURCE, note COAP_MAX_OBSERVERS)

REST IMPLEMENTATIONS
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The Makefile uses WITH_COAP to configure different implementations for the Erbium (Er) REST Engine.
* WITH_COAP=7 uses Erbium CoAP 08 apps/er-coap-07/.
  The default port for coap-07/-08 is 5683.
* WITH_COAP=3 uses Erbium CoAP 03 apps/er-coap-03/.
  The default port for coap-03 is 61616.
  er-coap-03 produces some warnings, as it not fully maintained anymore.
* WITH_COAP=0 is a stub to link an Erbium HTTP engine that uses the same resource abstraction (REST.x() functions and RESOURCE macros. 

TODOs
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* Observe client
* Multiple If-Match ETags
* (Message deduplication)