Protocols

MQTT

Characteristics - MQTT

Information Model Requirements

• The first Node after the root node must be of type Event .

• The following Node Types can be used under the Event Node:

  • Variables with a Simple Data Type represents the key-value pairs.

  • Variables with a Custom Data Type represent objects that can contain key-value pairs.

  • With Lists you can aggregate multiple variables.

• In case of publishing a topic, the Information Model determines the structure of the payload.

• In case of subscribing to a topic make sure that the Information Model structure matches the payload.

How to configure the MQTT Channel

1. Select the MQTT (JSON) as Channel Type.

2. Click the Configure button.

3. Select the root model node

4. Enter host and port of the MQTT Broker used.

5. Specify a path to a folder on your local machine. The temp directory inside the SMARTUNIFIER Manager can be also used.

6. Select Username and password in order to manually enter the credentials or select Username and password credentials reference to add it from the Credentials Manager. If there are no credentials needed (e.g., test.mosquitto.org) select None.

7. Select the event node in the tree on the left.

8. Enable either producer or consumer depending on the use case and enter a topic name.

9. Click the Apply button.

Certificates

Encrypted connection using TLS security is supported. Follow the steps below to encrypt the connection.

1. Enable Hostname Verification (optional)

2. Enable the Tls Configuration checkbox

• Enter the path to the CA (certificate authority) certificate of the CA that has signed the server certificate

Note

Make sure the CA certificate is valid.

3. Enable the Client checkbox

• Enter the path to the client certificate. The client certificate identifies the client just like the server certificate identifies the server.

• Enter the path to the private client key.

• If applicable select to enter a password or to add from the Credentials Manager.

• Select the protocol from the Drop-Down.

Disconnected Buffer

In case the connection is lost, messages can be buffered offline when the Disconnected Buffer is enabled. Follow the steps below to enable the DisconnectedBuffer.

1. Enable the DisconnectedBuffer checkbox.

2. Set the Buffer Size - defines the amount of messages being hold e.g., 5000.

3. (Optional) Enable PersistBuffer.

4. (Optional) Enable DeleteOldestMessage.

Description of configuration properties:

Property	Description	Example
host	URL of the MQTT Broker.	test.mosquitto.org
port	Port of the MQTT Broker.	1883
reconnectInterval	Time interval to reconnect to the MQTT Broker after loss of connection in seconds	5
connectionTimeout	Time interval the connection times out in seconds	60
keepAliveInterval	Time the session persists in seconds	60
persistenceFolder	Path to a folder for the persistence store of the MQTT	temp
clientId	Identifies an MQTT client which connects to an MQTT Broker	MyClientID
username	Client username	Username
password	Client password	Password
hostnameVerification	Hostname Verification	true, false
tls	Encryption	true, false
producers	Data producer	true, false
consumer	Data consumer	true, false
protocol	TLS protocol version	TLSv1.1, TLSv1.2
disconnectedBuffer	Offline buffering of data	true, false
bufferSize	Amount of message allowed in the buffer	5000
persistBuffer	Buffer persistence	true, false
deleteOldestMessage	Delete oldest message in buffer	true, false

OPC-UA

Characteristics - OPC-UA

OPC (Open Platform Communications) enables access to machines, devices and other systems in a standardized way. To learn more about the standard visit the OPC-UA website.

Information Model Requirements

• The following Node Types can be used to model data structures:

  • Variables with a Simple Data Type.

  • Variables with a Custom Data Type.

OPC-UA Client

1. Select OPC-UA Client as Channel Type.

2. Click the Configure button.

1. Make sure the root model node is selected to configure the OPC-UA Client

2. Enter an applicationName

3. Configure the serverTcpConfiguration

• Enter an ipAdress

• Enter the port

• Define an endpoint

• Set a requestTimeOut

6. Configure the defaultSubscriptionAttribute

• Define a publishingInterval

7. Configure monitoringParameters

• Set a samplingInterval

• Enter a queueSize

• Enable discardOldest depending on the use case

8. Select the complex variable node.

9. Enable the complexVariables

10. Assign OPC-UA data block variables to corresponding variables in the Information Model by selecting the variable in the tree

11. Assign data block

• Enable the variables checkbox

• Enter the nodeId

REST

REST Server

The following sample configuration shows how variables can be made accessible over a REST server.

1. Select the root model node in the tree on the left.

2. Enter a path prefix.

3. Configure the REST Server endpoint.

• Enter the IP.

• Enter the port.

• Enter the Content-Type.

4. Check the webapp checkbox and provide the WAR-file if you want to host an application.

5. Click the Apply button and save the Channel by clicking the Save button on the upper right corner.

Description of configuration properties:

Property	Description	Example
pathPrefix	Prefix for the URL	e.g., demo
Port	Port of the REST server	e.g., 9002, 9000, ...
IP	IP address of the REST server	http://localhost
DefaultContentType	Is used to indicate the media type of the resource	application/json, application/xml, text/html, text/csv
webapp	Possibility to host an application	true, false

REST Client

The following sample configuration shows a GET request using url parameters.

1. Select the root model node in the tree on the left

2. Select the content type - defines the media type of the associated representation

3. Set the wait timeout

4. Select the Command node

5. Enable the Command routes checkbox for the configuration of the following fields:

   • Enter the URL - If url parameters are used then add each parameter in the following syntax ${id}

   • Select the HTTP method.

6. (Optional - If url parameters are used) Select the custom variable and enable the command routes checkbox

7. Select the content type

Description of configuration properties:

Property	Description	Example
URL	URL of the REST Server.	http://localhost:8081/api/v1/dataPoint/${id}
HttpMethod	HTTP method for the action performed by the Client.	GET, POST, PUT
HeaderName and Header Value	To provide server and client with additional information	Retry-After: 12
Default Content Type	Is used to indicate the media type of the resource.	application/json
Content Type Parameter Nodes	Type of the Parameter	Parameters
WaitTimeoutDuration	Timeout in seconds until request is failing	10