[PLC4X-291] DefaultPlcSubscriptionField cannot be cast to class OpcuaField

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.8.0
• Fix Version/s: 0.9.0
• Component/s: API
• Assignee: Unassigned
• Reporter: Souquières Adam
• Created: 07/Apr/21 16:06
• Updated: 03/Aug/21 20:46
• Resolved: 03/Aug/21 20:46

Description

@Test
public void shoudlWorkWithSubscriptionRequest() throws PlcConnectionException, InterruptedException {

  var plcConnection = new PlcDriverManager().getConnection("opcua:tcp://localhost:62541/Quickstarts/ReferenceServer")
      
  // Connection OK : lets subscribe
  var subBuilder = plcConnection.subscriptionRequestBuilder();

  subBuilder.addChangeOfStateField("machine1", "ns=2;s=Fabrication_Id_1:STRING");

  var subscriptionRequest = subBuilder.build();
  var subResponse = subscriptionRequest.execute();

  subResponse.whenComplete(
      (response, ex) -> {
          System.out.println("Result : "+ response + " - "+ex);
          
        for (String subscriptionName : response.getFieldNames()) {
          final var subscriptionHandle = response.getSubscriptionHandle(subscriptionName);
          subscriptionHandle.register(System.out::println);
        }
      });
  
  Thread.sleep(1000000000);
}

The code above always return this specific exception in the whenComplete callback:

java.lang.ClassCastException: class org.apache.plc4x.java.spi.model.DefaultPlcSubscriptionField cannot be cast to class org.apache.plc4x.java.opcua.protocol.OpcuaField (org.apache.plc4x.java.spi.model.DefaultPlcSubscriptionField and org.apache.plc4x.java.opcua.protocol.OpcuaField are in unnamed module of loader 'app')

 

Dependencies used in this maven project are :

<dependency> <groupId>org.apache.plc4x</groupId> <artifactId>plc4j-api</artifactId> <version>0.8.0</version> </dependency> <dependency> <groupId>org.apache.plc4x</groupId> <artifactId>plc4j-driver-opcua</artifactId> <version>0.8.0</version> <scope>runtime</scope> </dependency>

 

Diagnosis :

It appears that DefaultPlcSubscriptionField is composed of a PlcField/OpcuaField on api side, but expected as an direct OpcuaField on driver side.
I do not have the general knowledge of the design of this repository so i'm not confident enough to propose you a pull request.

Fix proposal :
-> Add already existing getField from DefaultPlcSubscriptionField in PlcSubscriptionField interface and assume the composition strategy for PlcSubscriptionField + Modify OpcuaTcpPlcConnection to get real field from this new method ( may have an impact on other driver implementation too !)

I stay available to give you some more information.

 

Issue Links

• duplicates: PLC4X-289 ClassCast exception when using SubscriptionRequest with OPCA Driver implémentation
• duplicates: PLC4X-290 java.lang.ClassCastException: DefaultPlcSubscriptionField cannot be cast to class OpcuaField