CoAP Device Access

Page Guide

Use CasesSuitable for low-power, weak-network, lightweight devices connecting to the platform over the CoAP protocol.

PrerequisitesThe device resource URI, message format, authentication Token, Message ID, and context handling method have been confirmed.

Debugging ToolsYou can use coap-cli or libcoap to verify GET, POST, PUT, and DELETE requests.

Acceptance CriteriaThe device can complete resource discovery, time query, device registration, property reporting, and command response.

1. CoAP Protocol Device Access

CoAP Roadmap

• CoAP message encoding and decoding: message header, options, message body
• CoAP data route registration
• CoAP observe mechanism
• CoAP message block handling
• CoAP authentication handling: Token, Message ID
• CoAP content context
• CoAP TransportService northbound interface

CoAP Southbound Interface

• .well-known/core: query the URI resources supported by the server
• /utc-time: query the server utc-time
• Other extensions (device registration, device online/offline, device property reporting, device)

CoAP Northbound Interface (TransportService, the interface class exposed to the business layer)

• Device command delivery
• Device property setting
• Device upgrade
• Device restart

CoAP TransportContext Context

• Forwarders (HTTP forwarding, MQTT broker forwarding)
• Message format adapters (Thing Model encoding, JSON, byte encoding, raw data)
• Scheduler
• Execution thread pool
• Request messages
• Response messages
• Session management

CoAP TransportHandler Handlers

• ReqDispatcher message dispatching

2. Test Tools

To test whether our code works correctly, we need a CoAP command line tool. There are currently two good tools available.

• CoAP-cli, a NodeJS-based CoAP command line tool whose core is built on the Node-CoAP library.
• libcoap, a CoAP command line tool written in C.

1. Node CoAP CLI

The installation command is as follows

npm install coap-cli -g

1.1 CoAP Command Line

In coap-cli, there are four methods in total, corresponding to the four different REST operations:

Commands:

get                    performs a GET request
put                    performs a PUT request
post                   performs a POST request
delete                 performs a DELETE request
Here, we use coap://vs0.inf.ethz.ch/ for a simple test

coap get coap://vs0.inf.ethz.ch/
(2.05)  ************************************************************
I-D
Let's test the smallest IoT system available today, the CoAP edition

coap get coap://iot-coap.phodal.com/id/1
(2.05)  [{"id":1,"value":"is id 1","sensors1":19,"sensors2":20}]

2. libcoap

2.1 Windows libcoap Installation

Use the pre-compiled libcoap image:

$ docker run -it --rm --name libcoap --network host heeejianbo/my-libcoap:1.0

By running the coap-client command inside it, we can check the version of the CoAP client currently in use:

$ coap-client
coap-client v4.3.1 -- a small CoAP implementation
Copyright (C) 2010-2022 Olaf Bergmann <bergmann@tzi.org> and others

Build: v4.3.1-4-g02b7647
TLS Library: OpenSSL - runtime 1.1.1t, libcoap built for 1.1.1t
(DTLS and TLS support; PSK, PKI, PKCS11, and no RPK support)

3. EMQX CoAP Gateway Test

3.1 PubSub Mode

• Publish a message

Use coap-client to publish a message to test/topic for testing:
coap-client -m post -e "Hello, CoAP" "coap://127.0.0.1/ps/test/topic?qos=0"

• Subscribe to messages

Create a CoAP subscriber and wait 60 seconds to receive messages on the test/topic topic:
coap-client -m get -s 60 -O 6,0x00 -o - -T "obstoken" "coap://127.0.0.1/ps/test/topic"

3.2 Connection Mode

• Create a connection The CoAP client can create a connection by requesting /mqtt/connection, for example:

coap-client -m post -e "" "coap://127.0.0.1/mqtt/connection?clientid=coaptest&username=admin&password=admin123"
coap-client -m post -e "" "coap://192.168.5.48/mqtt/connection?clientid=coaptest&username=admin&password=admin123"
After the connection is created successfully, a Token is returned.

• Disconnect

coap-client -m delete -e "" "coap://127.0.0.1/mqtt/connection?clientid=coaptest&token=3404490787"

• Heartbeat

coap-client -m put -e "" "coap://127.0.0.1/mqtt/connection?clientid=coaptest&token=3404490787"

• Send messages

Sending messages in connection mode requires the Token and ClientId parameters, for example:
coap-client -m post -e "Hi, this is libcoap" "coap://127.0.0.1/ps/coap/test?clientid=coaptest&token=3404490787"


coap-client -m post -e "[{\"id\": \"temperature\", \"value\": 17, \"remark\": \"test\" }]" "coap://192.168.5.48/ps//41/D1ELV3A5TOJS/property/post?clientid=coaptest&token=3404490787"
coap-client -m post -e "[{\"id\": \"switch\", \"value\": 1, \"remark\": \"test\" }]" "coap://192.168.5.48/ps//41/D1ELV3A5TOJS/function/post?clientid=coaptest&token=3404490787"
coap-client -m post -e "[{\"id\": \"height_temperature\", \"value\": 50, \"remark\": \"test\" }]" "coap://192.168.5.48/ps//41/D1ELV3A5TOJS/event/post?clientid=coaptest&token=3404490787"

• Subscribe to topics

coap-client -m get -s 60 -O 6,0x00 -o - -T "obstoken" "coap://127.0.0.1/ps/coap/test?clientid=coaptest&token=3404490787"
coap-client -m get -s 60 -O 6,0x00 -o - -T "obstoken" "coap://192.168.5.48/ps//41/D1ELV3A5TOJS/function/post?clientid=coaptest&token=3404490787"

• Unsubscribe

coap-client -m get -O 6,0x01 "coap://127.0.0.1/ps/coap/test?clientid=coaptest&token=3404490787"

4. FastBee CoAP Access Test

Test Commands

• Create a connection The CoAP client can create a connection by requesting /mqtt/connection, for example:

clientid = S-D1K031BE49X2-146-1

coap-client -m post -e "" "coap://192.168.5.48/connection?clientid=S-D1K031BE49X2-146-1&username=FastBee&password=P1N864X0420SN171"
After the connection is created successfully, a Token is returned.

• Disconnect

coap-client -m delete -e "" "coap://192.168.5.48/connection?clientid=S-D1K031BE49X2-146-1&token=CYG4UQRZKWY4SUT"

• Heartbeat

coap-client -m post -e "" "coap://192.168.5.48/keepalive?token=CYG4UQRZKWY4SUT"

• Send messages

Sending messages requires the Token parameter, for example:

coap-client -m post -e "[{\"rssi\": -43, \"firmwareVersion\": 1.2, \"userId\": 2, \"status\": 3, \"longitude\": 0, \"latitude\": 0}]" "coap://192.168.5.48/info/post?token=CYG4UQRZKWY4SUT"
coap-client -m post -e "[{\"id\": \"temperature\", \"value\": 17, \"remark\": \"test\" }]" "coap://192.168.5.48/property/post?token=CYG4UQRZKWY4SUT"
coap-client -m post -e "[{\"id\": \"switch\", \"value\": 1, \"remark\": \"test\" }]" "coap://192.168.5.48/function/post?token=CYG4UQRZKWY4SUT"
coap-client -m post -e "[{\"id\": \"height_temperature\", \"value\": 50, \"remark\": \"test\" }]" "coap://192.168.5.48/event/post?token=CYG4UQRZKWY4SUT"