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[FLaNK] Smart Weather Websocket Application - Kafka Consumer

tspannhw profile image Timothy Spann Originally published at datainmotion.dev on ・5 min read

[FLaNK] Smart Weather Websocket Application - Kafka Consumer

Part 2 of 2

This is based on Koji Kawamura's excellent GIST:

https://gist.github.com/ijokarumawak/60b9ab2038ef906731ebf4c0eee97176

As part of my Smart Weather Application, I wanted to display weather information as it arrives in a webpage using web sockets. Koji has an excellent NiFi flow that does it. I tweaked it and add some things since I am not using Zeppelin. I am hosting my webpage with NiFi as well.

https://www.datainmotion.dev/2020/11/flank-smart-weather-applications-with.html

We simply supply a webpage that makes a websocket connection to NiFi and NiFi keeps a cache in HBase to know what the client is doing. This cache is updated by consuming from Kafka. We can then feed events as they happen to the page.

Here is the JavaScript for the web page interface to websockets:

| |
| | function sendMessage(type, payload) { |
| | websocket.send(makeMessage(type, payload)); |
| | } |
| |

|
| | function makeMessage(type, payload) { |
| | return JSON.stringify({ |
| | 'type': type, |
| | 'payload': payload |
| | }); |
| | } |
| |

|
| | var wsUri = "ws://edge2ai-1.dim.local:9091/test"; |
| |

|
| | websocket = new WebSocket(wsUri); |
| | websocket.onopen = function(evt) { |
| |

|
| | sendMessage('publish', { |
| | "message": document.getElementById("kafkamessage") |
| | }); |
| |

|
| | }; |
| | websocket.onerror = function(evt) {console.log('ERR', evt)}; |
| | websocket.onmessage = function(evt) { |
| | var dataPoints = JSON.parse(evt.data); |
| |

|
| | var output = document.getElementById("results"); |
| | var dataBuffer = "

"; |
| | |
| | for(var i=0;i | | { |
| | dataBuffer += " " + dataPoints[i].location + |
| | dataPoints[i].station_id + "@" + dataPoints[i].latitude + ":" + |
| | dataPoints[i].longitude + "@" + dataPoints[i].observation_time + |
| | dataPoints[i].temperature_string + "," + dataPoints[i].relative_humidity + "," + |
| | dataPoints[i].wind_string +"
"; |
| |

|
| | } |
| | output.innerHTML = output.innerHTML + dataBuffer + "


"; |
| | }; |
| |

|
| |

Video Walkthrough: https://www.twitch.tv/videos/797412192?es_id=bbacb7cb39

*Source Code: * https://github.com/tspannhw/SmartWeather/tree/main

Kafka Topic

weathernj Schema

The schema registry has a live Swagger interface to it's REST API

NiFi Flow Overview

Ingest Via REST All US Weather Data from Zipped XML

As Data Streamings In, We Can Govern It

Ingested Data is Validated Against It's Schema Then Pushed to Kafka as Avro

We consume that Kafka data in store it in Kudu for analytics

We host a web page for our Websockets Application in NiFi with 4 simple processors.

Listen and Put Web Socket Messages Between NiFi Server and Web Application

Kafka Data is Cached for Websocket Applications

Set the Port for WebSockets via Jetty Web Server


Use HBase As Our Cache


We can monitor our Flink SQL application from the Global Flink Dashboard

*We can query our Weather data store in Apache Kudu via Apache Impala through Apache Hue *

Kudu Visualizations of Our Weather Data in Cloudera Visual Applications


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