Brokers

There are several brokers that we are going to try:
- test.mosquito.org
- local broker
- serverles brokers (HiveMQ, EMQX, etc)
- managed brokers (Blynk, Antares, etc)

Playing with test.mosquitto.org

Eclipse Mosquitto provides a simple broker in the cloud that we can use for testings. In fact, test.mosquitto.org can be considered as another serverless broker. We will use port number 1883 for unencrypted-unauthenticated connections.

Local broker

It is possible to install a broker in our own computer. In this case, our IoT devices connect to our computer directly. Internet connection becomes unnecessary.

Setup the local broker

These are some good documentations on how to install the broker on Linux and Windows systems. We must make sure that we allow anonymous connectios to the broker.

Linux system:

https://docs.vultr.com/install-mosquitto-mqtt-broker-on-ubuntu-20-04-server

Windows system:

https://cedalo.com/blog/how-to-install-mosquitto-mqtt-broker-on-windows/ -- follow step 1, 2, 5, 7, 8, 9, and 10. For step 5, follow only up to the point where we allow anonymous connections.

Clients

One way to create a client is by simulating the client from the same computer. Here, we can use the mosquitto_pub and mosquitto_sub commands by using the following formats.

  • mosquitto_pub -m PAYLOAD -t TOPIC
  • mosquitto_sub -t TOPIC

To connect from our IoT devices, we can adapt the provided Arduino MQTT client template to connect to our local broker. Please note that our local broker accepts anonymous connections.

Assignment

Adapt the provided Arduino MQTT client template to connect to your local broker.

HiveMQ

Create and run the broker

First, create a HiveMQ account for free and sign in to that account. After that, click Create New Cluster >> Manage Cluster.

|650

In HiveMQ, clients must have accounts and passwords. Therefore, we need to create at least one username and password which can be done from the Access Management menu. |600

EMQX (assignment)

EMQX also provide a free serverless broker similar to HiveMQ.
Now, let us setup a connection to EMQX broker from an Arduino MQTT client. This will become our class assignment.

Blynk