Filter <filter>

Overview

The <filter> element of the <isapiFilters> collection configures an ISAPI filter to process client request data or server response data.

Compatibility

	IIS 7.0	IIS 6.0
Notes	The <filter> element of the <isapiFilters> collection is new in IIS 7.0.	The <isapiFilters> collection replaces the IIS 6.0 FilterEnableCache and FilterPath metabase properties.

Setup

To use the <isapiFilters> element, you must install the ISAPI Filters module on your IIS 7.0 server. To do so, use the following steps.

Windows Server 2008

1. On the taskbar, click Start, point to Administrative Tools, and then click Server Manager.
2. In the Server Manager hierarchy pane, expand Roles, and then click Web Server (IIS).
3. In the Web Server (IIS) pane, scroll to the Role Services section, and then click Add Role Services.
4. On the Select Role Services page of the Add Role Services Wizard, select ISAPI Filters, and then click Next.

   

5. On the Confirm Installation Selections page, click Install.
6. On the Results page, click Close.

Windows Vista

1. On the taskbar, click Start, and then click Control Panel.
2. In Control Panel, click Programs and Features, and then click Turn Windows Features on or off.
3. In the Windows Features dialog box, expand Internet Information Services, then World Wide Web Services, then Application Development Features.

   

4. Select ISAPI Filters, and then click OK.

How To

How to add an ISAPI filter

1. On the taskbar, click Start, point to Administrative Tools, and then click Internet Information Services (IIS) Manager.
2. In the Connections pane, go to the connection, site, application, or directory for which you want to configure page output caching.
3. In the Home pane, double-click ISAPI Filters.

   

4. In the Actions pane, click Add...
5. In the Filter name text box of the Add ISAPI Filter dialog box, type a friendly name for the ISAPI filter.
6. In the Executable box, type the file system path of the location of ISAPI filter file or click the ellipsis button (...) to navigate to the folder that contains the ISAPI filter file, and then click OK.

   

Configuration

Attributes

Attribute	Description
enableCache	Optional Boolean attribute. Specifies whether HTTP.sys caching is enabled (true) or disabled (false) for filtered server responses. The default value is false.
enabled	Optional Boolean attribute. Specifies whether the installed filter is enabled (true) or disabled (false). The default value is true.
name	Required string attribute. Specifies the unique name of the ISAPI filter.
path	Required string attribute. Specifies the full physical path of the ISAPI filter .dll file.
preCondition	Optional string attribute. Specifies conditions under which the ISAPI filter will run. The preCondition attribute can be one or more of the following possible values. If you specify more than one value, separate the values with a comma (,). Value Description bitness32 Specify the bitness32 value when the ISAPI filter is a 32-bit .dll file and IIS should load the filter only for worker processes that run in WOW64 mode (32-bit simulation) on a 64-bit operating system. bitness64 Specify the bitness64 value when the ISAPI filter is a 64-bit .dll file and IIS should load the filter only for worker processes that run in 64-bit mode. integratedMode Specify the integratedMode value when the ISAPI filter should use the integrated request-processing pipeline to process requests for managed content. ISAPIMode Specify the ISAPIMode value when the ISAPI filter should use the ASP.NET ISAPI extension, Aspnet_isapi.dll, to process requests for managed content. runtimeVersionv1.1 Specify the runtimeVersionv1.1 value when the ISAPI filter should load only for application pools that are configured to use .NET Framework version 1.1. runtimeVersionv2.0 Specify the runtimeVersionv2.0 value when the ISAPI filter should load only for application pools that are configured to use .NET Framework version 2.0.

Child Elements

None.

Configuration Sample

The following configuration example, when added to a Web.config file, adds an ISAPI filter named SalesQueryIsapi to a Web site or application. The sample names and enables the ISAPI filter with the name and enabled attributes. It also uses the enableCache attribute to disable HTTP.sys caching and the path attribute to specify the location of the ISAPI DLL.

<configuration>
   <system.webServer>
      <isapiFilters>
         <filter 
            name="SalesFilter" 
            enabled="true" 
            enableCache="false" 
            path="C:\Inetpub\filters\SalesFilter.dll" />
      </isapiFilters>
   </system.webServer>
</configuration>

Sample Code

The following examples configure an ISAPI filter named SalesQueryIsapi on the server. Each of the examples use the name property to specify a name for the  ISAPI filter, the enableCache property to disable HTTP.sys caching, and the path property to specify the location of the ISAPI DLL.

AppCmd.exe

appcmd.exe set config -section:system.webServer/isapiFilters /+"[name='SalesQueryIsapi',path='c:\Inetpub\www.contoso.com\filters\SalesQueryIsapi.dll',enabled='True',enableCache='True']" /commit:apphost

C#

using System;
using System.Text;
using Microsoft.Web.Administration;

internal static class Sample
{
   private static void Main()
   {
      using (ServerManager serverManager = new ServerManager())
      {
         Configuration config = serverManager.GetApplicationHostConfiguration();
         ConfigurationSection isapiFiltersSection = config.GetSection("system.webServer/isapiFilters");
         ConfigurationElementCollection isapiFiltersCollection = isapiFiltersSection.GetCollection();

         ConfigurationElement filterElement = isapiFiltersCollection.CreateElement("filter");
         filterElement["name"] = @"SalesQueryIsapi";
         filterElement["path"] = @"c:\Inetpub\www.contoso.com\filters\SalesQueryIsapi.dll";
         filterElement["enabled"] = true;
         filterElement["enableCache"] = true;
         isapiFiltersCollection.Add(filterElement);

         serverManager.CommitChanges();
      }
   }
}

VB.NET

Imports System
Imports System.Text
Imports Microsoft.Web.Administration

Module Sample
   Sub Main()
      Dim serverManager As ServerManager = New ServerManager
      Dim config As Configuration = serverManager.GetApplicationHostConfiguration
      Dim isapiFiltersSection As ConfigurationSection = config.GetSection("system.webServer/isapiFilters")
      Dim isapiFiltersCollection As ConfigurationElementCollection = isapiFiltersSection.GetCollection
      Dim filterElement As ConfigurationElement = isapiFiltersCollection.CreateElement("filter")
      filterElement("name") = "SalesQueryIsapi"
      filterElement("path") = "c:\Inetpub\www.contoso.com\filters\SalesQueryIsapi.dll"
      filterElement("enabled") = True
      filterElement("enableCache") = True
      isapiFiltersCollection.Add(filterElement)
      serverManager.CommitChanges()
   End Sub
End Module

JavaScript

var adminManager = new ActiveXObject('Microsoft.ApplicationHost.WritableAdminManager');
adminManager.CommitPath = "MACHINE/WEBROOT/APPHOST";
var isapiFiltersSection = adminManager.GetAdminSection("system.webServer/isapiFilters", "MACHINE/WEBROOT/APPHOST");
var isapiFiltersCollection = isapiFiltersSection.Collection;

var filterElement = isapiFiltersCollection.CreateNewElement("filter");
filterElement.Properties.Item("name").Value = "SalesQueryIsapi";
filterElement.Properties.Item("path").Value = "c:\\Inetpub\\www.contoso.com\\filters\\SalesQueryIsapi.dll";
filterElement.Properties.Item("enabled").Value = true;
filterElement.Properties.Item("enableCache").Value = true;
isapiFiltersCollection.AddElement(filterElement);

adminManager.CommitChanges();

VBScript

Set adminManager = createObject("Microsoft.ApplicationHost.WritableAdminManager")
adminManager.CommitPath = "MACHINE/WEBROOT/APPHOST"
Set isapiFiltersSection = adminManager.GetAdminSection("system.webServer/isapiFilters", "MACHINE/WEBROOT/APPHOST")
Set isapiFiltersCollection = isapiFiltersSection.Collection

Set filterElement = isapiFiltersCollection.CreateNewElement("filter")
filterElement.Properties.Item("name").Value = "SalesQueryIsapi"
filterElement.Properties.Item("path").Value = "c:\\Inetpub\\www.contoso.com\\filters\\SalesQueryIsapi.dll"
filterElement.Properties.Item("enabled").Value = True
filterElement.Properties.Item("enableCache").Value = True
isapiFiltersCollection.AddElement filterElement

adminManager.CommitChanges()