Skip to main content

Introduction

We will be using MQTT to send the results of the sensor to Grasshopper. The following diagram shows the overall workflow.

Workflow of MQTT and Grasshopper

  • MQTT is a lightweight messaging protocol that is used to send messages between devices.
  • MQTT is a publish-subscribe based messaging protocol.
  • MQTT is similar to ROS in the sense that it is used to send messages between devices.

Workflow (Source: Twilio)

Keywords​

  • Broker: A server that receives all messages from the clients and then routes the messages to the appropriate destination clients.
  • Client: A device that connects to the broker.
  • Publisher: A client that sends messages to the broker.
  • Subscriber: A client that receives messages from the broker.
  • Topic: A string that the broker uses to filter messages for each connected client.
  • QoS (Quality of Service): The level of guarantee that a message will be delivered. There are three levels of QoS: 0, 1, and 2. QoS 0 is the fastest but least reliable, while QoS 2 is the slowest but most reliable.

For more information about MQTT, here is a Youtube Playlist the explains more the basics.

MQTT Playlist