How to invoke OpenWhisk Actions for certain IoT Device Events

Serverless Computing is often useful in event-driven Internet of Things (IoT) scenarios. For example when IoT sensors exceed a certain temperature actions are invoked to fix the issue.

OpenWhisk is IBM’s serverless computing offering in Bluemix. In order to implement a use case like above with the experimental OpenWhisk service, at this point you need to deploy a non-serverless application which receives MQTT events from IoT devices and invokes the appropriate OpenWhisk actions. While such a model seems to defeat the purpose of a serverless architecture, it allows developers to add their own filtering logic. For example rather than invoking hundreds of actions for hundreds of device events, you can invoke the potentially processing-intensive actions only for certain events, for example when the temperature is too hot.

Below is a simple sample how you could do this. Here is a sample action.

function main(params) {
   params = JSON.stringify(params);
   return { "message": "you sent me " + params };
}

For testing purposes you can invoke events via MQTT tools.

The following code shows a Node.js application that can be deployed via Cloud Foundry or Docker on Bluemix.

var cfenv = require("cfenv");
var appEnv = cfenv.getAppEnv();
var express = require('express');
var app = express();
app.get('/', function (req, res) {
   res.send('up');
});
app.listen(appEnv.port, appEnv.bind, function() {
   console.log('listening on port ' + appEnv.port);
});

var openwhisk = require('openwhisk');
var ow = openwhisk({ api: 'https://openwhisk.ng.bluemix.net/api/v1/', 
   api_key: 'xxx:xxx', 
   namespace: 'niklas_heidloff@de.ibm.com_dev' });

var Client = require("ibmiotf");
var appClientConfig = {
   "org" : "1o56n8",
   "id" : 'myapp',
   "auth-key" : "a-1o56n8-xxx",
   "auth-token" : "xxx"
}
var appClient = new Client.IotfApplication(appClientConfig);
appClient.connect();

appClient.on("connect", function () {
   // change this for the device events you're interested in   
   appClient.subscribeToDeviceEvents("TestDeviceType","+","+","json");
});

appClient.on("deviceEvent", function (deviceType, deviceId, eventType, format, payload) {
   // add your own filter logic here    
   payload = JSON.parse(payload);
   ow.actions.invoke({ actionName: "openwhisk",
      params: payload }).then(result => {
         console.log('success', result);
      })
});

The Node application uses iot-nodejs for the MQTT part and openwhisk as a convenience library to invoke actions.

{
  "name": "mqtt-to-openwhisk",
  "version": "1.0.0",
  "description": "",
  "main": "app.js",
  "dependencies": {
    "ibmiotf": "^0.2.12",
    "openwhisk": "2.0.0",
    "express": "4.13.4",
    "cfenv": "1.0.3"
  },
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "node app.js"
  },
  "author": "",
  "license": ""
}

Invoked actions show up in the OpenWhisk dashboard.

As alternative to deploying a Node application you could also use Node-RED, the incoming IoT node and the openwhisk node.

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