Kafka connect and python OPC

[kalyagin-private]

Hello!

I'm encountering an issue while setting up a connection between Kafka Connect and an OPC UA server using Docker Compose. Here are the details of my setup:

I am using Docker Compose to run the following services:

• Kafka
• Kafka Connect
• OPC UA Server (from [FreeOpcUa/python-opcua](https://github.com/FreeOpcUa/python-opcua))

Here is my Kafka Connect configuration:

{
    "connector.class": "org.apache.plc4x.kafka.Plc4xSourceConnector",
    "connectionString": "opcua:tcp://172.25.0.10:4841",
    "jobs.jobA.interval": "5000",
    "default.topic": "plcTestTopic",
    "sources": "machineA",
    "sources.machineA.jobReferences": "jobA",
    "tasks.max": "1",
    "jobs": "jobA",
    "bootstrap.servers": "kafka:9092",
    "key.converter.schemas.enable": "true",
    "jobs.jobA.tags": "running",
    "sources.machineA.connectionString": "opcua:tcp://172.25.0.10:4841",
    "jobs.jobA.tags.running": "ns=1;s=mvp_1|TEST_TAG_12345678901234567890_0001.Number;STRING",
    "name": "opc-test",
    "value.converter.schemas.enable": "true",
    "value.converter": "org.apache.kafka.connect.storage.StringConverter",
    "key.converter": "org.apache.kafka.connect.storage.StringConverter"
}

The connection between Kafka Connect and the OPC UA server is established successfully, but I am receiving the following error messages:

2025-07-03 18:33:36 [2025-07-03 14:33:36,375] ERROR Data type - class org.apache.plc4x.java.opcua.readwrite.VariantNull is not supported (org.apache.plc4x.java.opcua.protocol.OpcuaProtocolLogic)
2025-07-07 18:33:36 [2025-07-03 14:33:36,376] WARN Handling error responses: {running=UNSUPPORTED} (org.apache.plc4x.java.scraper.triggeredscraper.TriggeredScraperTask)

In the OPC UA server UI, the data type for the tag is specified as Double. Here is a screenshot of the tag configuration:

I have attempted to change the type in the tag description from STRING to REAL and INT, but none of these changes resolved the issue.

I am using PLCX 0.12 version.

Could you please help me understand:

1. What might be causing this error?
2. What data type should I use in the configuration?
3. What could be the mistake in my current setup?

Any guidance or suggestions would be greatly appreciated.

[chrisdutz]

Have you tried the current development version 0.13.0-SNAPSHOT? It has been quite some time since our last release and a lot of fixes have already gone into the OPC-UA driver.

[kalyagin-private]

No, I did not. I found only 0.12.0 version jars on mvnrepository.
As I understand, I should compile on my own, should not I?

[chrisdutz]

Snapshots should be available from repository.apache.org