PIServer.FindChangedPIPoints Method

Public Function FindChangedPIPoints ( 
	maxCount As Integer,
	cookie As Object,
	<OutAttribute> ByRef nextCookie As PIPointChangesCookie,
	Optional filterPoints As IEnumerable(Of PIPoint) = Nothing
) As IList(Of PIPointChangeInfo)

Dim instance As PIServer
Dim maxCount As Integer
Dim cookie As Object
Dim nextCookie As PIPointChangesCookie
Dim filterPoints As IEnumerable(Of PIPoint)
Dim returnValue As IList(Of PIPointChangeInfo)

returnValue = instance.FindChangedPIPoints(maxCount, 
	cookie, nextCookie, filterPoints)

public:
IList<PIPointChangeInfo>^ FindChangedPIPoints(
	int maxCount, 
	Object^ cookie, 
	[OutAttribute] PIPointChangesCookie^% nextCookie, 
	IEnumerable<PIPoint^>^ filterPoints = nullptr
)

member FindChangedPIPoints : 
        maxCount : int * 
        cookie : Object * 
        nextCookie : PIPointChangesCookie byref * 
        ?filterPoints : IEnumerable<PIPoint> 
(* Defaults:
        let _filterPoints = defaultArg filterPoints null
*)
-> IList<PIPointChangeInfo> 

' Get the PIServers collection for the current user and default PIServer.
Dim myPIServer As PIServer = New PIServers().DefaultPIServer

' Cookie used to get changes since the last call
Dim cookie As PIPointChangesCookie = Nothing

Try
    ' Try to open the file containing the persisted cookie
    Using reader As New StreamReader("cookie.dat")
        Dim json = reader.ReadToEnd()
        cookie = JsonConvert.DeserializeObject(Of PIPointChangesCookie)(json)
    End Using

Catch fileNotFoundEx As FileNotFoundException
    ' Cookie has never been persisted
Catch serializationEx As SerializationException
    ' Cookie could not be read
Catch securityEx As SecurityException
    ' No permission to read file
Catch ioEx As IOException
    ' Some other I/O Exception occurred
End Try

' If the cookie is null, initialize it to start monitoring changes
If cookie IsNot Nothing Then
    myPIServer.FindChangedPIPoints(Integer.MaxValue, Nothing, cookie)
End If

' Perform the operation 100 times...
For loopIndex As Integer = 1 To 100 Step 1
    Dim piPointName As String = $"testPoint_{loopIndex}"

    ' Create a new point which should cause a change
    Dim testPoint As PIPoint = myPIServer.CreatePIPoint(piPointName)

    ' Edit the point's name which should cause a change
    testPoint.Name = $"{piPointName}_Renamed"

    ' Delete the point which should cause a change
    myPIServer.DeletePIPoint(testPoint.Name)

    ' Log the changes that have occurred since the last call
    Dim changes As IList(Of PIPointChangeInfo) = myPIServer.FindChangedPIPoints(
            Integer.MaxValue, cookie, cookie)

    If changes IsNot Nothing Then
        For Each change As PIPointChangeInfo In changes
            Console.WriteLine("ID: {0} Action: {1}", change.ID, change.Action)
        Next
    End If

    ' Sleep for three seconds, don't peg the CPU
    System.Threading.Thread.Sleep(3000)
Next

Try
    ' Persist cookie so that the process can pick up changes where it left off
    Using writer As New StreamWriter("cookie.dat")
        Dim serializer = New JsonSerializer()
        serializer.Serialize(writer, cookie)
    End Using

Catch serializationEx As SerializationException
    ' Cookie could not be written
Catch securityEx As SecurityException
    ' No permission to write this file
Catch ioEx As IOException
    ' Some other I/O Exception occurred
End Try

No code example is currently available or this language may not be supported.

No code example is currently available or this language may not be supported.