AF SDK Reference

AFChangeInfo Structure

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AFChangeInfo Structure

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Last UpdatedNov 18, 2025
8 minute read

The AFChangeInfo structure is used when returning information about objects that have changed in the server.

Namespace: OSIsoft.AF
Assembly: OSIsoft.AFSDK (in OSIsoft.AFSDK.dll) Version: 3.1.1.1182

Syntax

public struct AFChangeInfo : IEquatable<AFChangeInfo>

Public Structure AFChangeInfo
	Implements IEquatable(Of AFChangeInfo)

Dim instance As AFChangeInfo

public value class AFChangeInfo : IEquatable<AFChangeInfo>

[<SealedAttribute>]
type AFChangeInfo =  
    struct
        interface IEquatable<AFChangeInfo>
    end

The AFChangeInfo type exposes the following members.

Properties

	Name	Description
	Action	The AFChangeInfoAction that caused the object to be changed.
	ChangeTime	The time that the object was changed.
	Database	The AFDatabase containing the changed object.
	ID	The ID of the changed object.
	Identity	The AFIdentity of the changed object.
	IsValueUpdate	The update associated with this change is a value update.
	IsVersionAdded	The update associated with this change is because a version was added.
	ParentID	The ID of the parent of the changed object.
	VersionID	The VersionID of the changed object.

Methods

	Name	Description
	Equals(Object)	Determines whether the specified Object is equal to the current object. (Overrides ValueTypeEquals(Object).)
	Equals(AFChangeInfo)	Indicates whether the current object is equal to another object of the same type.
	FindObject(PISystem)	Finds the object represented by change information structure and automatically load from the server if not found.
	FindObject(PISystem, Boolean)	Finds the object represented by change information structure and optionally automatically load from the server if not found.
	GetHashCode	Gets the hash code for this instance of the object which is suitable for use in hashing algorithms and data structures like a hash table. (Overrides ValueTypeGetHashCode.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	Refresh	Refreshes the object represented by change information structure if it is currently loaded in the client.
	ToString	Returns a String that represents the current object. (Overrides ValueTypeToString.)

Operators

	Name	Description
	Equality	The equality operator (==) compares its operands to determine if they are equal.
	Inequality	The inequality operator (!=) compares its operands to determine if they are not equal.

Remarks

The AFChangeInfo structure is returned by the PISystem.FindChangedItems Overload and AFDatabase.FindChangedItems Overload methods. The actual object is not returned, but the information contained in the returned structure can be used to find the changed object.

Examples

// This example demonstrates getting changes made by other users
//  and refreshing the objects.

// Get the System and System Cookie
PISystem myPISystem = new PISystems().DefaultPISystem;
object sysCookie = myPISystem.GetFindChangedItemsCookie(searchSandbox: false);

// Wait for changes to be made...
//=======================================================

// Find changes made by other users.
List<AFChangeInfo> list = new List<AFChangeInfo>();
int resultsPerPage = 1000;
while (true)
{
    var results = myPISystem.FindChangedItems(false, true, resultsPerPage, sysCookie, out sysCookie);
    if ((results?.Count ?? 0) == 0) break;
    list.AddRange(results);
}

// Refresh objects that have been changed.
AFChangeInfo.Refresh(myPISystem, list);

// Find the objects that have been changed.
foreach (AFChangeInfo info in list)
{
    AFObject myObj = info.FindObject(myPISystem, false);
    Console.WriteLine("Found changed object: {0}", myObj);
}

' This example demonstrates getting changes made by other users
'  and refreshing the objects.

' Get the System and System Cookie
Dim myPISystem As PISystem = New PISystems().DefaultPISystem
Dim sysCookie As Object = myPISystem.GetFindChangedItemsCookie(searchSandbox:=False)

' Wait for changes to be made...
'=======================================================


' Find changes made by other users.
Dim list As New List(Of AFChangeInfo)()
Dim resultsPerPage As Integer = 1000
While True
    Dim results As IList(Of AFChangeInfo) _
        = myPISystem.FindChangedItems(False, True, resultsPerPage, sysCookie, sysCookie)
    If ((results Is Nothing) OrElse (results.Count = 0)) Then
        Exit While
    End If

    list.AddRange(results)
End While

' Refresh objects that have been changed.
AFChangeInfo.Refresh(myPISystem, list)

' Find the objects that have been changed.
For Each info As AFChangeInfo In list
    Dim myObj As AFObject = info.FindObject(myPISystem, False)
    Console.WriteLine("Found changed object: {0}", myObj)
Next

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

// This example demonstrates persisting and restoring the cookie
//  using the XmlSerializer. Other serializers could also be used.
//  Then the cookie is restored and used to get changes made while
//  the application was shut down.

// Get the System and Database and their Cookie Values
PISystem myPISystem = new PISystems().DefaultPISystem;
AFDatabase myDB = myPISystem.Databases.DefaultDatabase;

object sysCookie = myPISystem.GetFindChangedItemsCookie(searchSandbox: false);
object dbCookie;
myDB.FindChangedItems(false, int.MaxValue, null, out dbCookie);

// Persist the cookie if you want to save to pick up changes
//  where you left off after restarting application.
string tmpDir = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
string sysCookieFile = Path.Combine(tmpDir, "AFSysCookie.xml");
string dbCookieFile = Path.Combine(tmpDir, "AFDbCookie.xml");
XmlSerializer serializer = new XmlSerializer(typeof(object[]));
using (var stream = File.Create(sysCookieFile))
{
    serializer.Serialize(stream, sysCookie);
}
using (var stream = File.Create(dbCookieFile))
{
    serializer.Serialize(stream, dbCookie);
}

// Shut down application, and wait for changes to be made...
//=======================================================

// After application restarts, reload persisted cookies.
using (var stream = File.OpenRead(sysCookieFile))
{
    sysCookie = serializer.Deserialize(stream);
}
using (var stream = File.OpenRead(dbCookieFile))
{
    dbCookie = serializer.Deserialize(stream);
}

// Find changes made while application not running.
List<AFChangeInfo> list = new List<AFChangeInfo>();
int resultsPerPage = 1000;
while (true)
{
    var results = myPISystem.FindChangedItems(false, resultsPerPage, sysCookie, out sysCookie);
    if ((results?.Count ?? 0) == 0) break;
    list.AddRange(results);
}
while (true)
{
    var results = myDB.FindChangedItems(false, resultsPerPage, dbCookie, out dbCookie);
    if ((results?.Count ?? 0) == 0) break;
    list.AddRange(results);
}

// Find the objects that have been changed.
foreach (AFChangeInfo info in list)
{
    AFObject myObj = info.FindObject(myPISystem, false);
    Console.WriteLine("Found changed object: {0}", myObj);
}

' This example demonstrates persisting and restoring the cookie
'  using the XmlSerializer. Other serializers could also be used.
'  Then the cookie is restored and used to get changes made while
'  the application was shut down.

' Get the System and Database and their Cookie Values
Dim myPISystem As PISystem = New PISystems().DefaultPISystem
Dim myDB As AFDatabase = myPISystem.Databases.DefaultDatabase

Dim sysCookie As Object = myPISystem.GetFindChangedItemsCookie(searchSandbox:=False)
Dim dbCookie As Object = Nothing
myDB.FindChangedItems(False, Integer.MaxValue, Nothing, dbCookie)

' Persist the cookie if you want to save to pick up changes
'  where you left off after restarting application.
Dim tmpDir As String = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData)
Dim sysCookieFile As String = Path.Combine(tmpDir, "AFSysCookie.xml")
Dim dbCookieFile As String = Path.Combine(tmpDir, "AFDbCookie.xml")
Dim serializer As XmlSerializer = New XmlSerializer(GetType(Object()))
Using stream As FileStream = File.Create(sysCookieFile)
    serializer.Serialize(stream, sysCookie)
End Using
Using stream As FileStream = File.Create(dbCookieFile)
    serializer.Serialize(stream, dbCookie)
End Using

' Shut down application, and wait for changes to be made...
'=======================================================


' After application restarts, reload persisted cookies.
Using stream As FileStream = File.OpenRead(sysCookieFile)
    sysCookie = serializer.Deserialize(stream)
End Using
Using stream As FileStream = File.OpenRead(dbCookieFile)
    dbCookie = serializer.Deserialize(stream)
End Using

' Find changes made while application not running.
Dim list As List(Of AFChangeInfo) = New List(Of AFChangeInfo)
Dim resultsPerPage As Integer = 1000
While True
    Dim results As IList(Of AFChangeInfo) _
        = myPISystem.FindChangedItems(False, resultsPerPage, sysCookie, sysCookie)
    If ((results Is Nothing) OrElse (results.Count = 0)) Then
        Exit While
    End If

    list.AddRange(results)
End While
While True
    Dim results As IList(Of AFChangeInfo) _
        = myDB.FindChangedItems(False, resultsPerPage, dbCookie, dbCookie)
    If ((results Is Nothing) OrElse (results.Count = 0)) Then
        Exit While
    End If

    list.AddRange(results)
End While

list.AddRange(myPISystem.FindChangedItems(False, Integer.MaxValue, sysCookie, sysCookie))
list.AddRange(myDB.FindChangedItems(False, Integer.MaxValue, dbCookie, dbCookie))

' Find the objects that have been changed.
For Each info As AFChangeInfo In list
    Dim myObj As AFObject = info.FindObject(myPISystem, False)
    Console.WriteLine("Found changed object: {0}", myObj)
Next

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

AF SDK Reference