public int addItems(
        final int dwCount, // Data count
        final OPCITEMDEF[] pItemArray, // Items array to create
        final PointerByReference pResults, // Results' handles
        final PointerByReference pErrors // Error's pointers
        ) {
      return this._invokeNativeInt(
          3, new Object[] {this.getPointer(), dwCount, pItemArray, pResults, pErrors});
    }
We define the OPC DA Classes and interfaces here like C's .h file.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/connector/protocol/opcda/OpcDaHeader.java