Message Queuing Telemetry Transport (MQTT) Adding a Data Source User Guide

1. After logging into the Kuika platform, open the project you will work on from the “Apps” screen.
2. Go to the “Data Sources” (1) module. In the Data Sources module, you can view the data sources, actions and tables in the application you have developed, add a new data source, a new action and a new table.

3. To add a new data source to your application, click the “+” (2) icon next to the “Sources” heading on the left side of the Data Sources module.

4. Select “MQTT” (1) as the Data Sources data source type and enter a name (2).
5. Then click on the “CREATE” (3) button.

HiveMQ Cloud is an IoT platform using the MQTT protocol. You can create a cluster using HiveMQ Console and connect with a web client.

In order to use the MQTT protocol on the Kuika platform, you need to create a user on HiveMQ and obtain the necessary connection information. You will use the username and password you created when adding MQTT in Kuika.

You can do this step by step as follows:

1. Login to HiveMQ Cloud Console

• Navigate to HiveMQ Cloud Console in your browser.
• If you do not have an account, click on the “Sign Up” button to register.
• If you have an account, log in by clicking the “Login” button. Access the HiveMQ Console by entering your username and password.

2. Create a New Cluster

• After logging in, go to the “Clusters” section on the main page.
• Click on “Create Cluster”.
• Give a name for the cluster (for example “MyFirstCluster”).
• Select the location of the cluster. For example, “Europe” or “North America”.
• You can choose a free plan (Free Plan) or a paid plan according to your needs.
• After confirming the settings, click on the “Create” button. The cluster will be created and will provide the necessary information for you to connect.

3. Connecting with Web Client

• Once the cluster has been created, find the “Web Client” tab in the left menu in the HiveMQ Cloud Console and click on it.
• When the Web Client opens, you will need to fill in the following information to connect:some text
  • Host: The connection URL given when creating the cluster (usually *.hivemq.cloud).
  • Port: 8883 (SSL) or 1883 (for unsecured connections).
  • Client ID: A unique ID must be used for each connection; a random ID can be entered.
  • Username and Password: Enter the username and password you created on the HiveMQ Cloud Console.
• After entering all the information, click the “Connect” button.
• Once connected, you can start sending and receiving messages over MQTT. Once connected, you can publish (publish) or listen (subscribe) to messages on a specific topic.

Topic

• In MQTT, a topic is a UTF-8 string that filters messages for a connected client. A topic consists of one or more levels separated by a slash (/), and these levels follow a hierarchical structure. A topic allows clients to easily access the data they are interested in.
• Example:
  • home/living_room/temperature: This topic refers to the temperature data of the living room in the house.
  • vehicles/car/speed: This topic can represent vehicle speed data.
• By subscribing to a particular Topic, clients can receive messages published on that Topic or send messages to that Topic.

Quality of Service (QoS)

In MQTT, Quality of Service (QoS) determines the level of reliability of message delivery. There are three different QoS levels:

1. QoS 0 (at most once):

• Allows messages to be sent to the receiver at most once. No acknowledgement is expected when messages are transmitted over the cable. Therefore, it can be used if some data loss is not a problem.

Only available if the transmitter and receiver are connected by cable.

• Usage Area: Situations that are constantly updated, such as temperature, and where data loss can be tolerated.

2. QoS 1 (at least once):

• Guarantees that the sender transmits the message at least once. The message can be resent until confirmation is received from the receiver. May result in the same data being sent more than once.
• Usage Area: Situations where it is critical that data is not lost, but some repetition is acceptable (e.g. alarm notifications).

3. QoS 2 (exactly once):

• Reliable level and ensures that the message is delivered only once. The sent message is finalized with acknowledged packets. Therefore there is no data loss or retransmission, but it takes longer.
• Usage Area: Situations where sensitive data transfer is required and data duplication is undesirable (e.g. financial transactions).

Retain

• Retain means that a message is saved and then forwarded to newly connected clients. If a message is sent with the retain flag, it is saved in the MQTT Broker and every new client that connects to that Topic is first forwarded this retained message.
  • Example: When a message “User” is sent with retain true, the broker stores this message. Afterwards, several different messages may have been sent with retain false. When you log in again, you will see the retained message “User” first. To delete this retained message, an empty (zero byte) message must be sent with retain true. This will unregister the “User” message and you will not see any retained message the next time you log in.

The Retain feature allows certain data to be quickly forwarded to newly connected clients and is useful when the latest status information needs to be retained.

1. After clicking the “CREATE” button, configure the connection information on the screen that opens:

• Use TLS: Protects the security and confidentiality of the transmitted data by ensuring that the MQTT connection is encrypted and secure.
• Protocol: MQTT is a messaging protocol that runs on TCP/IP for data transmission and supports TLS for secure connections. The default is “WebSocket”.
• Port: The default ports for MQTT are: 1883 (for unsecured connections) and 8883 (for secure connections, when TLS is used).
• Host: Host specifies the address of the MQTT server. It can be an IP address or a domain name (for example, mqtt.example.com).
• Basepath: MQTT does not require a base path as it usually works over ports, but some MQTT servers may use a basepath when connecting over WebSocket (for example, /mqtt).
• Username: The username used to establish a connection to the MQTT server. On a server that requires authentication, this username is used to authenticate the connection.
• Password: The password used with the username to access the MQTT server and is required for authentication.

2. After configuring the connection settings, click on the “Test” button in the upper right corner to check if the connection is working correctly.

3. Then you can configure your connection settings by clicking the “CREATE” button. The actions and parameters to be used in the project are automatically created in the Create process.

• Go to the “Properties” panel on the right sidebar in the UI Design module.

• Add Subscribe action so that when the user enters the page, he/she is automatically subscribed to a specific topic. In this example, “kuika/test” is used as the topic.
• With this subscribe action, the user is authorized to see the messages coming to the specified Topic.
• You can make additions to the Action section. For example:some text
  • Add a Notify action to show the message from the “ADD ACTION” button on the right sidebar.
  • To make the message appear in a Text Input component, use the Set Value Of action to print the message into the Text Input.

Add the Publish Action to a Button

• Add a “Button” from the Elements panel on the left side and connect the Publish action to this button.
• With the Publish action, you can send a message to the Topic you specify. For example, when you send a message to the user/guide Topic, all users subscribed to this Topic will see the message.