REM This example shows how to subscribe to dataset messages extract data of a specific field.
REM
REM In order to produce network messages for this example, run the UADemoPublisher tool. For documentation, see
REM https://kb.opclabs.com/UADemoPublisher_Basics . In some cases, you may have to specify the interface name to be used.
REM
REM Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
REM OPC client and subscriber examples in Visual Basic on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VB .
REM Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
REM a commercial license in order to use Online Forums, and we reply to every post.

' The subscriber object, with events.
'Public WithEvents Subscriber7 As EasyUASubscriber

Private Sub EasyUASubscriber_SubscribeDataSet_ExtractField_Command_Click()
    OutputText = ""

    Const UAPublisherIdType_UInt64 = 4

    ' Define the PubSub connection we will work with.
    Dim subscribeDataSetArguments :  Set subscribeDataSetArguments = CreateObject("OpcLabs.EasyOpc.UA.PubSub.OperationModel.EasyUASubscribeDataSetArguments")
    Dim ConnectionDescriptor :  Set ConnectionDescriptor = subscribeDataSetArguments.dataSetSubscriptionDescriptor.ConnectionDescriptor
    ConnectionDescriptor.ResourceAddress.ResourceDescriptor.UrlString = "opc.udp://239.0.0.1"
    ' In some cases you may have to set the interface (network adapter) name that needs to be used, similarly to
    ' the statement below. Your actual interface name may differ, of course.
    ' ConnectionDescriptor.ResourceAddress.InterfaceName = "Ethernet"

    ' Define the filter. Publisher Id (unsigned 64-bits) is 31, and the dataset writer Id is 1.
    subscribeDataSetArguments.dataSetSubscriptionDescriptor.Filter.PublisherId.SetIdentifier UAPublisherIdType_UInt64, 31
    subscribeDataSetArguments.dataSetSubscriptionDescriptor.Filter.DataSetWriterDescriptor.DataSetWriterId = 1

    ' Define the metadata. For UADP, the order of field metadata must correspond to the order of fields in the dataset message.
    ' If the field names were contained in the dataset message (such as in JSON), or if we knew the metadata from some other
    ' source, this step would not be needed.
    ' Since the encoding is not RawData, we do not have to specify the type information for the fields.
    Dim metaData :  Set metaData = CreateObject("OpcLabs.EasyOpc.UA.PubSub.Configuration.UADataSetMetaData")
    '
    Dim field1 :  Set field1 = CreateObject("OpcLabs.EasyOpc.UA.PubSub.Configuration.UAFieldMetaData")
    field1.Name = "BoolToggle"
    metaData.Add(field1)
    '
    Dim field2 :  Set field2 = CreateObject("OpcLabs.EasyOpc.UA.PubSub.Configuration.UAFieldMetaData")
    field2.Name = "Int32"
    metaData.Add(field2)
    '
    Dim field3 :  Set field3 = CreateObject("OpcLabs.EasyOpc.UA.PubSub.Configuration.UAFieldMetaData")
    field3.Name = "Int32Fast"
    metaData.Add(field3)
    '
    Dim field4 :  Set field4 = CreateObject("OpcLabs.EasyOpc.UA.PubSub.Configuration.UAFieldMetaData")
    field4.Name = "DateTime"
    metaData.Add(field4)
    '
    Set subscribeDataSetArguments.dataSetSubscriptionDescriptor.DataSetMetaData = metaData
    
    ' Instantiate the subscriber object and hook events.
    Set Subscriber7 = New EasyUASubscriber

    OutputText = OutputText & "Subscribing..." & vbCrLf
    Subscriber7.SubscribeDataSet subscribeDataSetArguments

    OutputText = OutputText & "Processing dataset message events for 20 seconds..." & vbCrLf
    Pause 20 * 1000

    OutputText = OutputText & "Unsubscribing..." & vbCrLf
    Subscriber7.UnsubscribeAllDataSets

    OutputText = OutputText & "Waiting for 1 second..." & vbCrLf
    ' Unsubscribe operation is asynchronous, messages may still come for a short while.
    Pause 1000

    Set Subscriber7 = Nothing

    OutputText = OutputText & "Finished." & vbCrLf
End Sub

Private Sub Subscriber7_DataSetMessage(ByVal sender As Variant, ByVal eventArgs As EasyUADataSetMessageEventArgs)
    ' Display the dataset.
    If eventArgs.Succeeded Then
        ' An event with null DataSetData just indicates a successful connection.
        If Not (eventArgs.DataSetData Is Nothing) Then
            ' Extract field data, looking up the field by its name.
            Dim Int32FastValueData :  Set Int32FastValueData = eventArgs.DataSetData.FieldDataDictionary.Item("Int32Fast")
            OutputText = OutputText & Int32FastValueData & vbCrLf
        End If
    Else
        OutputText = OutputText & vbCrLf
        OutputText = OutputText & "*** Failure: " & eventArgs.ErrorMessageBrief & vbCrLf
    End If
End Sub
' Example output:
'
'Subscribing...
'Processing dataset message events for 20 seconds...
'6502 {System.Int32} @2019-10-06T10:02:01.254,647,600,00; Good
'6538 {System.Int32} @2019-10-06T10:02:01.755,010,700,00; Good
'6615 {System.Int32} @2019-10-06T10:02:02.255,780,200,00; Good
'6687 {System.Int32} @2019-10-06T10:02:02.756,495,900,00; Good
'6769 {System.Int32} @2019-10-06T10:02:03.257,320,200,00; Good
'6804 {System.Int32} @2019-10-06T10:02:03.757,667,300,00; Good
'6877 {System.Int32} @2019-10-06T10:02:04.258,405,000,00; Good
'6990 {System.Int32} @2019-10-06T10:02:04.759,532,900,00; Good
'7063 {System.Int32} @2019-10-06T10:02:05.260,257,200,00; Good
'7163 {System.Int32} @2019-10-06T10:02:05.761,261,800,00; Good
'7255 {System.Int32} @2019-10-06T10:02:06.262,176,800,00; Good
'7321 {System.Int32} @2019-10-06T10:02:06.762,839,800,00; Good
'7397 {System.Int32} @2019-10-06T10:02:07.263,598,900,00; Good
'7454 {System.Int32} @2019-10-06T10:02:07.764,168,900,00; Good
'7472 {System.Int32} @2019-10-06T10:02:08.264,350,400,00; Good
'...