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FIX: Dynamic Caching may incorrectly delete recently cached objects from a caching server that is running Forefront Threat Management Gateway 2010 or Internet Security and Acceleration Server 2006

Article ID: 2694478 - View products that this article applies to.

SYMPTOMS

When you use Dynamic Caching for a web server, Dynamic Caching may incorrectly delete recently cached objects from a caching server that is running Forefront Threat Management Gateway 2010 or Internet Security and Acceleration Server 2006when concurrent requests are made for the same object and when the object is currently not cached.

For example, consider the following scenario:

Two requests (request1 and request2) for the same object are made to a caching server that is running Forefront Threat Management Gateway 2010 or Internet Security and Acceleration Server 2006.
The object is currently not cached on the caching server.
The request is for a Dynamic URL that contains a special character such as a question mark (?).
Dynamic Caching is enabled on a cache rule that applies to the destination URL for the object.
Because the object does not exist in the cache of the caching server, both request1 and request2 are sent to the web server of the object.
When the response for the object by request1 is received, the object is added to the cache of the caching server.
If the response for for the object by request2 arrives while the cache is being updated for the object request1, the cache entry [?] is marked incorrectly for deletion.
After the cache is updated by request1, the cache entry is deleted.

In this scenario, the next request for the same object may cause additional requests to the web server. However, you expect the request instead to be served from the cache.

Note The cache is updated and works as expected unless all the conditions in this scenario are met.

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RESOLUTION

To resolve this problem, apply one of the following fixes:

Forefront Threat Management Gateway 2010

Internet Security and Acceleration Server 2006

After you apply the fix, run the following script to enable the fix:

Const SE_VPS_GUID = "{143F5698-103B-12D4-FF34-1F34767DEabc}"
Const SE_VPS_VALUE = "DeleteEntryForForceCache"

Sub SetValue()

' Create the root object.
Dim root ' The FPCLib.FPC root object
Set root = CreateObject("FPC.Root")

' Declare the other objects that are needed.
Dim array ' An FPCArray object
Dim VendorSets ' An FPCVendorParametersSets collection
Dim VendorSet ' An FPCVendorParametersSet object

' Obtain references to the array object
' and to the network rules collection.
Set array = root.GetContainingArray
Set VendorSets = array.VendorParametersSets

On Error Resume Next
Set VendorSet = VendorSets.Item( SE_VPS_GUID )

If Err.Number <> 0 Then
Err.Clear

' Add the item
Set VendorSet = VendorSets.Add( SE_VPS_GUID )
CheckError
WScript.Echo "New VendorSet added... " & VendorSet.Name

Else
WScript.Echo "Existing VendorSet found... value- " & VendorSet.Value(SE_VPS_VALUE)
End If

if VendorSet.Value(SE_VPS_VALUE) <> true Then

Err.Clear
VendorSet.Value(SE_VPS_VALUE) = true

If Err.Number <> 0 Then
CheckError
Else
VendorSets.Save false, true
CheckError

If Err.Number = 0 Then
WScript.Echo "Done with " & SE_VPS_VALUE & ", saved!"
End If
End If
Else
WScript.Echo "Done with " & SE_VPS_VALUE & ", no change!"
End If

End Sub

Sub CheckError()

If Err.Number <> 0 Then
WScript.Echo "An error occurred: 0x" & Hex(Err.Number) & " " & Err.Description
Err.Clear
End If

End Sub

SetValue

Forefront Threat Management Gateway 2010

To resolve this problem, install the hotfix package that is described in the following Microsoft Knowledge Base article:

2689195

(http://support.microsoft.com/kb/2689195/ )

Rollup 2 for Forefront Threat Management Gateway (TMG) 2010 Service Pack 2

Internet Security and Acceleration Server 2006

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, go to the following Microsoft website:

http://support.microsoft.com/contactus/?ws=support

(http://support.microsoft.com/contactus/?ws=support)

Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

You must have Microsoft Internet Security and Acceleration Server 2006 Service Pack 1 (SP1) installed to apply this hotfix.

Restart information

You may have to restart the computer after you apply this hotfix.

Replacement information

This hotfix does not replace a previously released hotfix.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Collapse this tableExpand this table