Advantages of a Smart MQTT Broker – Automation World

MQTT is becoming a popular protocol forIndustrial IoT (Internet of Things) data.Developed for connecting remotedevices to a central server, it is lightweight, efficient,and secure. However, IoT implementationsare growing larger and more complex, and demandis increasing for OT/IT connectivity. MQTT is nowbeing called on to aggregate and send diverse collectionsof data values over increasingly complexnetwork topologies.

To meet these challenges MQTT must getsmarter. As a transport protocol, MQTT specifiesthat messages are simply carriednot readlikea letter in the post. But that doesnt have to bethe case. What would happen if the letter carriercould read the mail? In other words, what if wegave an MQTT broker the ability to parse themessages it carries? It would be able to handlemessages more intelligently and include someinformation on the status of the data source orquality of the connection.

Data collectionA smart broker should be able to collect datain an intelligent way. For example, on largesystems data can come from a wide varietyof MQTT devices, each with its own messageformat. A broker that parses messages couldconvert these to a common message representationand make that available to all clients.Other data sources might include non-MQTTprotocols such as OPC UA, Modbus, DDE, andothers. A smart broker with protocol conversioncapabilities could act as a gateway for thisdata to any MQTT client or cloud ser vice.

Data consistencyIn real-time industrial systems, data consistencyfrom source to consumer is vital. Data thatsstale or out of correct time sequence can lead toincorrect decisions. Any disconnects or networkirregularities must be known.

Data can become inconsistent in several ways.If messages arrive at an MQTT broker faster thanthey can be delivered, some may be dropped. Ordata from multiple message streams may get sentto a client out of sequence. Also, if a data sourcegoes offline, the client may not know whether anunchanged value is current or stale.

A smart broker can ensure data consistencyby queueing incoming data in an intelligent way,passing on only the latest values. It can alsoparse timestamps on messages from differentdata streams to sequence them properly, as wellas pass along data and connection quality informationwith each value update.

Data securitySecurity is critical when accessing data from aproduction system. The MQTT push architecturethat connects outbound through firewalls isquite secure, but many corporate security policiesrequire isolating OT systems using a DMZ. This isproblematic for MQTT since messages must bepassed via two or more servers, while MQTT qualityof service guarantees are only valid for a singlesender-receiver hop. As a result, data at the endof a multi-hop daisy chain can become unreliable.

A smart broker that parses messages andconverts protocols can solve this problem byusing a tunnel. The device producing the MQTTdata would connect to one instance of the smartbroker. The message data, along with qualityand timestamp information, gets tunnelled viaa secure, TCP-enabled protocol to a secondinstance of the smart broker. That instance wouldconvert the data back into MQTT, with values,timestamps, and quality codes intact.

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Advantages of a Smart MQTT Broker - Automation World