coap-router-full

A quick demo on how to leverage web router to build CoAP (Constrained Application Protocol) server.

Reference the source code

Github

1. Motivation

Currently I'm working on a Node.js based IoT (Internet of Things) platform. It allows Node.js powered DTU (Data Transfer Unit) to serve as CoAP server on smart devices like Raspberry PI.

When you design a Node.js based HTTP server, web router is one of your best choices to manage incoming requests from clients. Unfortunately, CoAP doesn't have one like Express Router, this project is to demonstrate how to leverage web router concept to simplify CoAP server implementation.

2.Usage

Inspired by many other JavaScript routers, coap-router does almost the same recursive routing as Express.Router.

Let's take a look at the example.

Example

./server.js

const coap = require("coap");
const app = require("./app");

const coapTiming = {
    ackTimeout: 0.25,
    ackRandomFactor: 1.0,
    maxRetransmit: 3,
    maxLatency: 2,
    piggybackReplyMs: 10
}
coap.updateTiming(coapTiming)
const server = coap.createServer(app);
var PORT = 5683
server.listen(PORT, () => {
    console.log(`The CoAP server is now running port ${PORT}.\n` + app.help);
});

./app.js

const Router = require("coap-router-full");
const app = Router();

app.help = `URL: coap://127.0.0.1:5683/
Usage:
 GET  / - Display this help document.
 GET  /test --- Test api get.
 POST /test --- Test api post.
 GET  /test/abc?de=fg --- Test api get with query string.
 POST /test/abc?de=fg -p "{'temp':100}" --- Test api post with query string and payload.`

app.code404 = 404
app.error404 = { msg: 'Not Found API' }

app.get("/", (req, res) => {
    res.status(200).end("Hello, world");
});

app.use("/test", require("./routes/test"));

module.exports = app;

./routes/test.js

const Router = require("coap-router-full");
const router = Router();

function Middleware(req, res, next) {
    console.log("Middleware.")
    next()
}

router.get("/", Middleware, (req, res) => {
    console.log("[ payload ]",req.payload)
    console.log("[ query ]",req.query)
    console.log("[ params ]",req.params)
    console.log("\n")

    res.status(200).json({ test: "test api get." });
});

router.post("/", (req, res) => {
    console.log("[ payload ]",req.payload)
    console.log("[ query ]",req.query)
    console.log("[ params ]",req.params)
    console.log("\n")

    res.status(200).json({ test: "test api post." });
});

router.post("/echo", (req, res) => {
    console.log("[ payload ]",req.payload)
    console.log("[ query ]",req.query)
    console.log("[ params ]",req.params)
    console.log("\n")

    let resp = { ...JSON.parse(req.payload) ,timestamp: new Date().getTime() }
    res.status(200).json(resp);
});

router.get("/:testparams", (req, res) => {
    console.log("[ payload ]",req.payload)
    console.log("[ query ]",req.query)
    console.log("[ params ]",req.params)
    console.log("\n")

    let resp = { timestamp: new Date().getTime() }
    res.status(200).json(resp);
});

router.post("/:testparams", (req, res) => {
    console.log("[ payload ]",req.payload)
    console.log("[ query ]",req.query)
    console.log("[ params ]",req.params)
    console.log("\n")

    let resp = { timestamp: new Date().getTime() }
    res.status(200).json(resp);
});

module.exports = router;

3. How to Install

3.1 Basic Requirements

• Node.js 6 or above
• UDP compatible network connected

3.2 Installation

$ npm install

or

$ npm i coap
$ npm i coap-router-full

4. How to Test

4.1 Install CoAP Client

Although there're dozens of CoAP clients available, one of the easiest ways is to install Node.js based client named coap-cli.

$ npm install coap-cli -g
$ coap

4.2 Tests

1. Start example server. By default the CoAP server is listening at port 5683.

   $ npm start

2. Get literal resource.

   $ coap get "coap://127.0.0.1:5683/"

3. TEST API.

   $ coap get "coap://127.0.0.1:5683/test"
   $ coap post "coap://127.0.0.1:5683/test"
   $ coap get "coap://127.0.0.1:5683/test/abc?de=fg"
   $ coap post "coap://127.0.0.1:5683/test/abc?de=fg" -p "{'temp':100}"
   $ coap post "coap://localhost/test/echo" -p "{'abc':123}"

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