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Coap Broker Servers to Websocket Broker Servers

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A Coap broker server is not running on IoT devices. The main use case is for constrained devices (eg. microcontrollers) to send data streams over the web, and then proxying to websocket endpoints.

  1. Install
  2. Usage
  3. Discussion
  4. How To Report Bugs

Install

  1. Download dotcity-wot-framework.
  2. Run $ cd dotcity-wot-framework to change the directory.
  3. Run $ npm install to install the dependencies if you don't already have them.
  4. Run $ node servers/coap-proxy-websocket.js to start the WoT Coap proxy server.
  5. Run $ node servers/websocket-broker.js to start the WoT Websocket endpoint server.

By default, the Coap proxy server is running at coap://localhost:8000. The Websocket endpoint server is running at ws://localhost:8000.

The address of only ONE target endpoint set in Coap proxy server is localhost:8000. You can check code in servers/coap-proxy-websocket.js:

var server = new CoapBroker({
    port: port,
    host: host,
    endpoint: [
      'localhost:8000'
    ]
});

In this setting, Coap proxy server will proxy data to ws://localhost:8000. Of course, you can add other hosts, for example localhost:8001 in endpoint array to proxy data to multiple endpoints.

Prerequisites

  1. Node.js. Note: Node should be with a version above 0.10.x.

Usage

To send the data over the Internet, IoT devices should use the url below to establish a connection with the server.

coap://[hostname]/object/[name]/send

You must specify an object name and your hostname. For example:

coap://localhost:8000/object/frontdoor/send

To receive data from the server, the frontend should use the url below to establish a connection with the server.

ws://localhost:8000/object/[name]/viewer

Also, you need to specify the object name and hostname. For example:

ws://localhost:8000/object/frontdoor/viewer

An physical object has two significant resources, send and viewer. send is to send device data to the server over Coap connection. viewer could be used by web frontend to receive real-time data over the Websocket connection.

Tests

Proxy to one endpoint
  1. Open a new terminal and run $ cd tests to enter the directory of test scripts.
  2. Run $ node coap-send-data.js to start sending streaming data to WoT coap proxy server.
  3. Open a new terminal and run $ node websocket-viewer.js to start receiving streaming data over websocket.
Proxy to two endpoint
  1. Open a new terminal and run $ export export PORT=8001; node servers/websocket-broker.js to start the 2nd websocket endpoint at ws://localhost:8001.
  2. Add another endpoint in servers/coap-proxy-websocket.js, for example localhost:8001, and then start to run the Coap proxy server.
  3. Open a new terminal and run $ export export PORT=8001; node test/websocket-viewer.js to start the 2nd websocket viewer.

Discussion

There are various ways to get involved with .CITY Web of Things Framework. We're looking for help identifying bugs, writing documentation and contributing codes.

You can also find us in the #wotcity IRC channel on irc.freenode.net.

How to Report Bugs

Bugs are reported via https://github.com/wotcity/wotcity-wot-framework.