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Data Source - MQTT Buffer

MQTT Buffer

MQTT (originally an initialism of MQ Telemetry Transport) is a lightweight, publish-subscribe, machine-to-machine network protocol. It is designed for connections with remote locations that have devices with resource constraints or limited network bandwidth. It must run over a transport protocol that provides ordered, lossless, bi-directional connections—typically TCP/IP.

To create a connection to the MQTT Real-Time Buffer Data Source: Right-click on the Data Sources group, then click “MQTT”, and then select “MQTT Buffer”.

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To successfully buffer and retrieve data from a real-time MQTT data source, the following properties need to be configured.

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  • Name (String)
 Name to identify the data source.
  • Quality of Service (Dropdown)

Each connection to the broker can specify a quality of service (QoS).

These are classified in increasing order of overhead:

  • At most once – the message is sent only once and the client and broker take no additional steps to acknowledge delivery (fire and forget).
  • At least once – the message is re-tried by the sender multiple times until acknowledgment is received (acknowledged delivery).
  • Exactly once – the sender and receiver engage in a two-level handshake to ensure only one copy of the message is received (assured delivery).
  • Protocol (Dropdown)
 Specifies if the payload received will conform to the SparkplugB specification or if it is a custom payload. If a custom payload is defined, one can configure whether the payload is in JSON format or not. 
  • Server(String)
 Location of the MQTT Broker. This can be a local server name or a cloud-hosted endpoint address (Server Name, IP Address, or URL).
  • Username (String)
 If security is enabled, supply the Username with access to the broker.
  • Password (String)
 If security is enabled, supply the Password associated with the Username.
  • Use TLS (Boolean)
 Set to True if the TLS protocol is used to communicate with the MQTT Broker.
  • Topic (String)

Topic to subscribe to on the MQTT Broker
  • Tag Delimiter (String)

Defines how to build the namespace hierarchy. Depends on how tag names are structured in the topic. By default (see screenshot), the namespace will be split in the tree structure on a . or / encountered in the tag name.

For example, if the topic contains a tag named "Juice Factory.Boiler/Flow Totalizer", this will be represented in the namespace as :

Folder: Juice Factory

   Subfolder: Boiler

       Tag: Flow Totalizer