XMLDA.NET Sample Application

ASP.NET Application with Visual Basic code behind that uses DataBind subscriptions

DataBind subscriptions are defined from a ListBuilder created XML file. The DataBind subscriptions work in combination with the ASP.NET DataBind feature to update a CheckBox from a binary OPC-DA or XML-DA server item value, a ListBox with an array item value and TextBoxes with integer values.

   'Shared OpcURL As String = "http://localhost/OpcXmlGateway/OpcDaGateway.asmx"
   Shared OpcURL As String = "OCSTK.DA.Sim.32"
   Private Shared OpcSrv As XmlServer
 
   '-----------------------------------------------------------------------------------------
   Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
      ' Put user code to initialize the page here
      If Not IsPostBack Then
         chkStopped.Checked = False
         OpcSrv = New XmlServer(OpcURL)
         Dim err As OPCError()
         Dim subscr As DataBindSubscription()
         OpcSrv.DataBindFromXmlFile(Me, "AspDemo1.xml", "Demo1", Nothing, 1000, Nothing, subscr, err)
      End If
      DataBind()
   End Sub

   '------------------------------------------------------
   ' method used in DataBind definitons
   Public Function GetOpcItemValue(ByVal SubscrID As String) As Object
      If OpcSrv Is Nothing Then
         Return ""
      End If
      Return OpcSrv.GetBindValue(SubscrID)
   End Function

   '------------------------------------------------------
   Private Sub btnRefresh_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRefresh.Click
      ' only postback handling is required
   End Sub

   Private Sub chkStopped_CheckedChanged(ByVal sender As System.Object, _
                              ByVal e As System.EventArgs) Handles chkStopped.CheckedChanged
      Dim err As OPCError()
      OpcSrv.DataBindCancel(Nothing, Nothing, err)
   End Sub