View source for Set up CoAP Server

=Introduction=
In this chapter, we set up a CoAP/ MQTT server by using Open Source MQTT Broker : [https://www.emqx.io/ EMQX.IO].  And show how to communicate it with CoAP and MQTT. 

Below is the network structure. The end device use CoAP to connect our Emqx server via NB-IoT network. EMQ X broker will further process the data for the actually application.  

[[File:CoAP_1.png|600px|none|thumb|  Network structure ]]

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=Install CoAP server=
Set up example in Ubuntu 18.04
 sudo apt-get update 
 sudo apt-get upgrade
 wget https://www.emqx.io/downloads/broker/v3.2.7/emqx-ubuntu18.04-v3.2.7_amd64.deb  #download the installation package. 
 sudo dpkg –i emqx-ubuntu18.04-v3.2.4_amd64.deb  #install EMQX
 emqx start            # Start EMQX service
 emqx_ctl status   #check if EMQX is running
 ./bin/emqx_ctl plugins load emqx_coap # Run COAP service

<span CLASS=redtext> Notice: CoAP default port use 5683, if you install EMQX in a cloud server, make sure you open the UDP port 5683. So can receive the packets from NB-IoT.</span>

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=Test CoAP Server=
==Install Copper in Chrome==
1. Download Copper4Cr from [https://github.com/mkovatsc/Copper4Cr https://github.com/mkovatsc/Copper4Cr] and unpack it. 

2.  Run install.bat in the directory. 
[[File:CoAP_Test_1.png|600px|none|thumb|  Run install.bat ]]


3. Load the unpacked CoAP APP in Google Chrome:
[[File:CoAP_Test_2.png|600px|none|thumb| Install Copper APP ]]
[[File:CoAP_Test_3.png|600px|none|thumb| Install APP Successful ]]


4. Load the unpacked CoAP extension in Google Chrome:
[[File:CoAP_Test_4.png|600px|none|thumb| Install Copper Extension]]
[[File:CoAP_Test_5.png|600px|none|thumb| Install Extension Successful ]]


5. Replace the appID in file extension\endpoint\ClientPortChrome.js to Copper (Cu4Cr) Application ID
[[File:CoAP_Test_6.png|600px|none|thumb| Replace ID]]


6. Open the Copper extension. If you see below message, means install successfully. 
[[File:CoAP_Test_7.png|600px|none|thumb| Install Finished]]

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==Test CoAP connection==
Use Chrome Copper externsion to connect to the CoAP server. Input coap://COAP_SERVER_IP/mqtt/topic0?c=t1 to connect to the MQTT topic0 in CoAP server. Replace COAP_SERVER_IP with your COAP Server IP address, and refer [https://github.com/emqx/emqx-coap here] for the CoAP detail in EMQX. When connection ok, you can see below window.

[[File:CoAP_Test_8.png|600px|none|thumb| Connect to CoAP server]]

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==Test CoAP Uplink==
Try to use MQTT.fx to subscribe a the topic (topic0) in the server. And use CoAP to send a message to this topic, we can see the message arrive the topic0 and shown in MQTT.fx. 
[[File:CoAP_Test_9.png|600px|none|thumb| Use MQTT.fx to subscribe the topic]] 
[[File:CoAP_Test_10.png|600px|none|thumb| Use CoAP Exension to send a update to CoAP server]]
[[File:CoAP_Test_11.png|600px|none|thumb| MQTT.fx get the update of this topic on CoAP server]]
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==Test CoAP Downlink==
Try to use MQTT.fx to publish a message to the topic (topic0) in the server. CoAP extension will see this incomming message. 
[[File:CoAP_Test_12.png|600px|none|thumb| Use MQTT.fx to publish the topic]] 
[[File:CoAP_Test_13.png|600px|none|thumb| CoAP extension see the incoming message]]