MQTT Broker

Introduction

There is an executable file called TMQTTBroker.exe inside the product installation folder. To run it you need to double-click over the file. After running, you can see a blue icon in the Windows tray bar. MQTT Broker will run following the specification configured in the file TMQTTBroker.exe.config, you can find more information about it in the next section.

There is the possibility to run the Broker as Windows Service running the file InstallTMQTTBrokerAsService.exe also found in the product installation folder. This MQTT Broker accepts connection with MQTT Clients following the SparkplugB specification and pure MQTT Clients that do not use SparkplugB as the Mosquitto clients.

Also, it is possible to connect the TMQTTBroker with a runtime project where it can make available all namespaces and properties from the specific projects. In this case the project information will be available following the SparkplugB specification.

TMQQTBroker.exe.config

Before running the TMQTTBroker.exe the file TMQTTBroker.exe.config must be configured with the desire configuration.  It can be found in the product installation folder and you can open it  in any Text Editor. However, it is very important that the file name and extension (.exe.config) remains the same.

Open the TMQTTBroker.exe.config file, you are going to find all the possible configured parameters already there, but they will be in comments (between <!−−   −−> ). Then, to set a specific parameter you need to move the whole line of the parameter outside the comments (<!−−    −−>) but keep it into the section <configuration> <appSettings>.

Example of whole line to move:

<add key="ListeningPort" value="1883"/>

Running the MQTT Broker with the default configuration (without changing the .config file) it will assume the parameters below:

• Listening port: 1883
• UserNameAndPassword1: none
• CertificateFile: none
• CertificatePassword: none

See below the complete list of parameters found in the .config file and their respective description.

<appSettings>
<add key="ListeningPort" value="1883"/>
<add key="Backlog" value="100"/>
<add key="GroupId" value="TServer"/>
<add key="TimeUpdateTServers" value="500"/>
<add key="DisableRetainedFile" value="false"/>
<add key="CertificateFile" value=""/>
<add key="CertificatePassword" value=""/>
<add key="SslProtocols" value="Tls12"/>
<add key="UserNameAndPassword1" value="Test;#3B43F58BFF9AFF8CFF8BFFCDFF"/>
<add  key="ClientID1"  value="ClientID01;Topic1=*,Subscribe1=True,Publish1=True"/>
<add  key="ClientID2"  value="ClientID02;Topic1=*,Subscribe1=True,Publish1=True"/>
<add key="TServer1" value="<ProjectName>;localhost:3101"/>
<add  key="TagProperties"  value="Min;Max"/>
</appSettings>

• ListeningPort: Server listening port. Default is 1883 if it is not
• CertificateFile: Certificate file to use in the SSL
• CertificatePassword: Certificate password to use in the SSL
• SslProtocols: SSL protocol
• UserNameAndPassword1: UserName and Password required to Access Broker, following the syntax UserName;Password.

The password can be a string (no encryption) or an encrypted password. For encrypting a password you can use in any coder (ex. Visual Studio) the following code:

string Encrypted_password = T.Library.StringUtilities.ToHex(string <password>);

The encrypted password will be a hex character that will be an input in the .config file.  To  make  sure the Broker knows it is required to decrypt it in order to check  for matches you must add the  ’# ’ symbol before the password.

<add key="UserNameAndPassword1" value="<UserName>;< Password>" />
E.g.: <add key="UserNameAndPassword1" value="test;1234" />

No encrypted password:

Encrypted password:

<add key="UserNameAndPassword1" value="<UserName>;#<Encrypted_Password>" />
E.g.: <add key="UserNameAndPassword1" value="test;#21B4F78BFF9AFF8CFF8BFF" />

• Backlog: Sets the number of connections to keep backlog. Default: 100

• DisableRetainedFile: The broker stores the last retained message and the corresponding QoS for that topic. Valid value is true or false. Default is false.

• ClientID: This parameter can enable limitation for specific MQTT Clients related to For configuring more than one MQTT Client you need to create new whole line changing the last number to the next sequence number.

  
  

  add key="ClientID1" value="<MQTTClientID>; Topic1=<Topic>, Subscribe1=<True or False>, Publish1=<True or False>" />

  There are 4 internal parameters:

• value: Sets the MQTT Client Id;
• Topic: Specific Topic that will set the limitation;
• Subscribe: flag (true or false) that allows Client to subscribe to topic (can receive messages);

• Publish: flag (true or false) that allows Client to publish to topic (can write messages).

  <add  key="ClientID1"  value="MQTTClientTest;Topic1=*,Subscribe1=True,  Publish1=True"/>
  
  <add  key="ClientID2"  value="32443fsa6546fa;Topic1=*,Subscribe1=True,  Publish1=False"/>
  
  <add  key="ClientID3"  value="7323rt304343r4;Topic1=*,Subscribe1=False,Publish1=True"/>

The parameters below are used to make the TMQTTBroker connecting with a running project (TServer).

• TServer: Project Name and TServer IP Address and Port Number. For connection with more than one runtime project you need to create new whole line changing the last number to the next sequence

add key="TServer1" value="<ProjectName>;<TServerIPAddress>:<TServerPort> " />

E.g.
<add key="TServer1" value="ProjectTest1;localhost:3101" />
<add key="TServer2" value="ProjectDemo;localhost:3201" />
<add key="TServer3" value="ProjectMQTT;192.168.1.10:3101" />

• TimeUpdateTSevers: Time between update TServer; Default
• GroupId: Alias that will be used in the Topic
• TagProperties: List of Tag properties that will be sent to MQTT Client when they change values.

<add  key="TagProperties"  value="Minl;Max;AlarmState;Acked"  />

Topologies

There are two ways the TMQTTBroker can be implemented. It can be used as simple gateway to exchange data between any MQTT Clients or through a direct connection with runtime projects and publishing project data for MQTT Clients using SparkplugB specification.

Simple Gateway

 In this scenario the TMQTTBroker only will exchange data between MQTT Clients following the SparkplugB specification or not. Then, the Clients are responsible to subscribe and publish topics to the Broker. Any topic format is supported in this scenario.

Connected to Runtime project

 In this scenario the TMQTTBroker will connect with one or several runtime projects through the TServer. It will publish the project data only for topics following SparkplugB specification.

The topic is configured following the syntax below:

spBv1.0/<Group_Id>/<message_type>/<Project_Name>/<MQTT_Device_Name>

Where :

• Group Id: is a name configured in the .config
• Message Type: The following message type elements are defined for the Sparkplug specifi- cation. Almost of the Clients that support SparkplugB should set the message type automat-
• NBIRTH – Birth certificate for MQTT EoN
• NDEATH – Death certificate for MQTT EoN
• DBIRTH – Birth certificate for
• DDEATH – Death certificate for
• NDATA – Node data
• DDATA – Device data
• NCMD – Node command
• DCMD – Device command
• STATE – Critical application state
• Project Name: is the same name configured in the .config
• MQTT Device Name: it can be a namespace or object from the runtime project. The individual objects should be avoided and uses the namespaces for performance

Examples of namespaces: Tag, Script, Device, Info, Script, Server, Security, Alarm, Historian DataSets, TemplatesName and MainTag for arrays.

Examples of objects: Tag.Test, Server.Second, etc.

Example of topic:

spBv1.0/TServer/DBIRTH/Project1/Tag

spBv1.0/TServer/DDATA/Project1/Tag

Gateway + Connected to Project

In this scenario the TMQTTBroker will work as the last two scenarios together. As simple gateway exchange any data between the MQTT Clients and publishing data projects to the topics that match the project configuration in the TMQTTBroker.exe.config.

Examples of Communication

MQTT driver (without SparkPugB)

To set up a communication between the TMQTTBroker and the MQTTdriver, the first step is to create a Channel using this protocol.

In the Engineering Environment, go to Edit > Devices > Channels and find the desired protocol inside the list.

MQTT protocol

In Nodes tab the primary station is configured in the syntax below:

<BrokerURL> ; <port> ; [Username] ; [Password] ; [X509Certificate] ; [QoS]

Node configuration

Where, Username, Password, X509Certificate and QoS are optional.

In Points tab you need to configure the Topic in which your variable may publish or subscribe to messages (according to its AccessType). More information on each item is available in the MQTT driver documentation.

Points configuration

Mosquitto Client (without SparkPlugB)

The TMQTT Broker can have other clients connect to it in the same way as others Brokers available (e.g: mosquitto).

In order to test it, you can use mosquitto (as a publisher or subscriber). The syntax required to publish a message and subscribe to a topic with mosquitto is:

mosquitto_pub -p <portNumber> -t <Topic> -m <Message>
mosquitto_sub -p <portNumber> -t <Topic>

An example of its implementation is:

mosquitto_sub -p 1883 -t Furnace/Temperature/Value
mosquitto_pub -p 1883 -t Furnace/Temperature/Value -m 22

MQTTSpB driver (SparkPlugB)

To set up a communication between MQTT + SparkPlug Driver and the TMQTT Broker, the first step is to create a Channel using this protocol.

In the Engineering Environment, go to Edit > Devices > Channels and find the desired protocol inside the list.

MQTT+Sparkplug B protocol.

In column ProtocolOptions, there are some fields that must be filled.

• Type;
  • Application Node;
  • Scada IIoT Host;
  • EoN

• ClientID;
• TagProperties;

Channel configuration

More information on each item is available in the MQTT + SparkPlugB driver documentation. In Nodes tab the primary station is configured in the syntax below:

<BrokerURL> ; <port> ; [Username] ; [Password] ; [X509Certificate] ; [SslProtocol] ; [WebSocket] ; [ScadaIIoTHostID]

Node configuration

The topics are configured using the following syntax.

<GroupId>;<EdgeNodeId>;<DeviceId>;<QoS>

Point configuration

Using Third Party MQTT Clients – MQTT fx (SparkplugB)

It is possible to set up a communication between TMQTT Broker with Third Parties MQTT Clients. In this example we will use MQTT.fx.

To configure this client the following steps are required:

Step 1: TMQTT Broker must be running (look for icon in Windows TaskBar).

TMQTT Broket icon

Step 2: In the Client, go to Extras > Edit Connections Profiles. In the opened Window you will fill the properties according to your Broker (e.g.: Broker Address and Broker Port). Then, click on connect.

Configure MQTT Fx client

Step 3: In subscribe Tab the Topic will follow the syntax below:

spBv1.0/<Group_Id>/<message_type>/<Project_Name>/<MQTT_Device_Name>

Let’s imagine an example, in which the Project Name is ’Project1’ and we have an integer tag called ’Tag.Integer1’.

In this situation, to correctly subscribe to the Tag, first you need to create a Device Birth Certificate (to start the communication channel).

spBv1.0/TServer/DBIRTH/Project1/Tag.Integer1 // create channel for this specific tag
// or
spBv1.0/TServer/DBIRTH/Project1/Tag // create channel for all tags

After the device certificate is created, the subscription for data becomes available. The following topic is required to fetch data:

spBv1.0/TServer/DDATA/Project1/Tag.Integer1
// or 
spBv1.0/TServer/DDATA/Project1/Tag

Topics client is subscribed to

There are some other data that can exchange between the running project and TMQTT Broker. Some examples can be seen below.

spBv1.0/TServer/DDATA/Project1/Devices // Channel, Node and Points info spBv1.0/TServer/DDATA/Project1/Alarms // All properties spBv1.0/TServer/DDATA/Project1/Dataset // DB Status, etc spBv1.0/TServer/DDATA/Project1/Script // Tasks info spBv1.0/TServer/DDATA/Project1/Historian // All properties spBv1.0/TServer/DDATA/Project1/Server // All properties spBv1.0/TServer/DDATA/Project1/Info // TProject, License and Module info
spBv1.0/TServer/DDATA/Project1/Security // User, Permission and Policies info

Step 4: After subscribing for the desired topics, the exchanged data can be seen in the top-right

Exchanged data

Step 5: To correctly format the received data, copy the message and paste it in any JSON formatter (e.g.: https://jsonformatter.org/json-pretty-print). The result should be something like the code below.

{
"timestamp": 1580152490182, "metrics": [
{
"name":  "Integer1", "timestamp": 1580152489659, "dataType": "Int32", 
"value": 30
}
],
"seq": 1
}

Appendix

MQTT

As defined in http://mqtt.org/:

”MQTT is a machine-to-machine (M2M)/”Internet of Things” connectivity protocol. It was de- signed as an extremely lightweight publish/subscribe messaging transport. It is useful for connec- tions with remote locations where a small code footprint is required and/or network bandwidth is at a premium. For example, it has been used in sensors communicating to a broker via satellite link, over occasional dial-up connections with healthcare providers, and in a range of home automation and small device scenarios. It is also ideal for mobile applications because of its small size, low power usage, minimised data packets, and efficient distribution of information to one or many receivers (more...)”.

Sparkplug B

As defined in https://www.bevywise.com/blog/sparkplug-b-mqtt-simulation/.

Sparkplug provides an open and freely available specification for how Edge of Network (EoN) gate- ways or native MQTT enabled end devices and MQTT Applications communicate bi-directionally within an MQTT Infrastructure. One of the unique aspects of MQTT is that it was originally  designed for real time SCADA systems to help reduce data latency over bandwidth limited and often unreliable network infrastructure. Similarly the intent of the Sparkplug specification is to take full advantage of MQTT’s native Continuous Session Awareness capability as it applies to real time SCADA/IIoT solutions.