MQTT Topic Tree Design best practices, tips & examples

By Maximilian Batz | 2019-05-29

Generic MQTT Background With MQTT the sender and receiver are not aware of each other – the broker handles the messaging. This allows the messages to be separated in space, time, and intensity. The sender can send at the speed it wants, and the time it wants. The receiver can pick up the messages at…

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VerneMQ: econnrefused & Webhook example

By Maximilian Batz | 2019-05-20

Webhooks activate webhooks like this in your vernemq.conf.local (.local when running on docker, so that settings at bottom of the file will persist): plugins.vmq_webhooks = on vmq_webhooks.js_auth_on_register.hook = auth_on_register vmq_webhooks.js_auth_on_register.endpoint = http://container_picockpit:1200/example/path Note that if your webhook is not accessible (econnrefused), the db based authentication will also fail … ! If you get errors like…

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envoy serving a static response

By Maximilian Batz | 2019-05-20

Besides routing and redirecting you can serve static responses with Envoy. In this case I want to serve a forbidden response (403) route_config:   virtual_hosts:   – name: picockpit     domains: [“picockpit.local:443”, “picockpit.local”]     routes:       – match: { prefix: “/demo” }         direct_response:           status: 403           body:             inline_string: “Forbidden.”        – match: {prefix: “/”}         route: {cluster: target_picockpit} It can also serve…

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Python Paho MQTT client self-signed certificates websockets, howto

By Maximilian Batz | 2019-05-19

Using Paho in Python with websockets and self-signed certificates for a https:// websocket connection has a couple of pitfalls, so I’m addressing this with some sample code here: import ssl import time import paho.mqtt.client as mqtt class PCPMQTTClient:     def on_connect(self, client, userdata, flags, rc):         self.connection_status = rc         if rc == 0:             self.connected_flag = True             self.connection_error_flag…

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VerneMQ Docker overwrites my configuration

By Maximilian Batz | 2019-05-19

Situation You edit vernemq.conf, only to find that your configuration is overwritten by VerneMQ on the next start (using the official Docker container). Specifically, the section with the listeners at the end of the file is “forced upon you”. Solution VerneMQ is started using a script (start_vernemq). The script can be seen here: https://github.com/vernemq/docker-vernemq/blob/master/bin/vernemq.sh The…

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envoy not connecting to VerneMQ for MQTT over websockets, error code 503

By Maximilian Batz | 2019-05-19

Some quick background information for anyone running into the same issues, and how to debug them. Error code 503 This is the error code I am getting: Error during WebSocket handshake: Unexpected response code: 503. Set envoy logging to debug Here’s my docker-compose.yaml for envoy: version: ‘3.7’ services:   envoy:     build:       context: ./       dockerfile: Dockerfile     container_name:…

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envoy websockets per route configuration, JavaScript test setup

By Maximilian Batz | 2019-05-19

In my article yesterday I discussed the configuration & test of envoy for proxying websockets at length. Today I would like to add some additional information. correct syntax for websocket upgrade per route You can enable websocket upgrade per route. No need to add it globally: – name: envoy.http_connection_manager    config:      #upgrade_configs:      #  – upgrade_type: websocket     …

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envoy, docker and websockets – debugging and configuration

By Maximilian Batz | 2019-05-18

Websockets are an exciting technology, allowing you to upgrade a HTTP connection to a long-running persistent binary connection, which you can use to send bi-directional messages. As an aside, the MQTT protocol can be transported using websockets – which is the only (?) way for a JavaScript client delivered by the website, for instance. In…

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correct way to instantiate Paho Client in JavaScript for wss (secure websocket)

By Maximilian Batz | 2019-05-17

The Paho documentation is unfortunately quite fragmented at the moment, and some links on Eclipse’s website do not work. Here are some working links (as of 05/2019): https://www.eclipse.org/paho/clients/js/ https://www.eclipse.org/paho/files/jsdoc/index.html https://github.com/eclipse/paho.mqtt.javascript And here’s a fantastic website by Steve: http://www.steves-internet-guide.com/using-javascript-mqtt-client-websockets/ There is an important breaking change in the Paho namespace, where you will run into trouble using…

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