Cache.xml

<Type Name="Cache" FullName="System.Web.Caching.Cache">
  <TypeSignature Language="C#" Value="public sealed class Cache : System.Collections.IEnumerable" />
  <TypeSignature Language="ILAsm" Value=".class public auto ansi sealed beforefieldinit Cache extends System.Object implements class System.Collections.IEnumerable" />
  <TypeSignature Language="DocId" Value="T:System.Web.Caching.Cache" />
  <TypeSignature Language="VB.NET" Value="Public NotInheritable Class Cache&#xA;Implements IEnumerable" />
  <TypeSignature Language="F#" Value="type Cache = class&#xA;    interface IEnumerable" />
  <TypeSignature Language="C++ CLI" Value="public ref class Cache sealed : System::Collections::IEnumerable" />
  <AssemblyInfo>
    <AssemblyName>System.Web</AssemblyName>
    <AssemblyVersion>1.0.5000.0</AssemblyVersion>
    <AssemblyVersion>2.0.0.0</AssemblyVersion>
    <AssemblyVersion>4.0.0.0</AssemblyVersion>
  </AssemblyInfo>
  <Base>
    <BaseTypeName>System.Object</BaseTypeName>
  </Base>
  <Interfaces>
    <Interface>
      <InterfaceName>System.Collections.IEnumerable</InterfaceName>
    </Interface>
  </Interfaces>
  <Docs>
    <summary>Implements the cache for a Web application. This class cannot be inherited.</summary>
    <remarks>
      <format type="text/markdown"><![CDATA[

## Remarks
 One instance of this class is created per application domain, and it remains valid as long as the application domain remains active. Information about an instance of this class is available through the `Cache` property of the <xref:System.Web.HttpContext> object or the `Cache` property of the <xref:System.Web.UI.Page> object.

> [!NOTE]
>  The <xref:System.Web.Caching.Cache> class is not intended for use outside of ASP.NET applications. It was designed and tested for use in ASP.NET to provide caching for Web applications. For other types of applications, such as console applications or Windows Forms applications, use the <xref:System.Runtime.Caching.ObjectCache> class.



## Examples
 The following example is a page that shows users the value assigned to an item in the cache, and then notifies them when the item is removed from the cache. It creates a `RemovedCallback` method, which has the signature of the `CacheItemRemovedCallback` delegate, to notify users when the cache item is removed, and it uses the <xref:System.Web.Caching.CacheItemRemovedReason> enumeration to tell them why it was removed. In addition, it uses the <xref:System.Web.Caching.Cache.Item%2A?displayProperty=nameWithType> property to add objects to the cache and retrieve the value of those objects. In the `AddItemToCache` method, it uses the <xref:System.Web.Caching.Cache.Add%2A?displayProperty=nameWithType> method to add an item to the cache. To use the `CacheItemRemovedCallback` delegate, you must add an item to the cache with this method or the <xref:System.Web.Caching.Cache.Insert%2A?displayProperty=nameWithType> method, so that ASP.NET can automatically make the proper method calls when the item is removed. The custom `RemoveItemFromCache` method uses the <xref:System.Web.Caching.Cache.Remove%2A?displayProperty=nameWithType> method to explicitly delete the item from the cache, causing the `RemovedCallback` method to be invoked.

> [!NOTE]
>  The instance of Cache that is accessed by the snippet below is a member of the <xref:System.Web.UI.Page> object that this sample inherits.

 [!code-aspx-csharp[System.Web.Caching Examples#1](~/snippets/csharp/VS_Snippets_WebNet/System.Web.Caching Examples/CS/cachecs.aspx#1)]
 [!code-aspx-vb[System.Web.Caching Examples#1](~/snippets/visualbasic/VS_Snippets_WebNet/System.Web.Caching Examples/VB/cachevb.aspx#1)]

 ]]></format>
    </remarks>
    <threadsafe>This type is thread safe.</threadsafe>
    <altmember cref="T:System.Web.HttpContext" />
    <altmember cref="T:System.Web.Caching.CacheDependency" />
    <altmember cref="T:System.Web.Caching.CacheItemRemovedCallback" />
    <related type="Article" href="https://learn.microsoft.com/previous-versions/aspnet/6hbbsfk6(v=vs.100)">Caching Application Data</related>
  </Docs>
  <Members>
    <Member MemberName=".ctor">
      <MemberSignature Language="C#" Value="public Cache ();" />
      <MemberSignature Language="ILAsm" Value=".method public hidebysig specialname rtspecialname instance void .ctor() cil managed" />
      <MemberSignature Language="DocId" Value="M:System.Web.Caching.Cache.#ctor" />
      <MemberSignature Language="VB.NET" Value="Public Sub New ()" />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; Cache();" />
      <MemberType>Constructor</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <Attributes>
        <Attribute FrameworkAlternate="netframework-4.0">
          <AttributeName Language="C#">[System.Runtime.TargetedPatchingOptOut("Performance critical to inline this type of method across NGen image boundaries")]</AttributeName>
          <AttributeName Language="F#">[&lt;System.Runtime.TargetedPatchingOptOut("Performance critical to inline this type of method across NGen image boundaries")&gt;]</AttributeName>
        </Attribute>
      </Attributes>
      <Parameters />
      <Docs>
        <summary>Initializes a new instance of the <see cref="T:System.Web.Caching.Cache" /> class.</summary>
        <remarks>To be added.</remarks>
      </Docs>
    </Member>
    <Member MemberName="Add">
      <MemberSignature Language="C#" Value="public object Add (string key, object value, System.Web.Caching.CacheDependency dependencies, DateTime absoluteExpiration, TimeSpan slidingExpiration, System.Web.Caching.CacheItemPriority priority, System.Web.Caching.CacheItemRemovedCallback onRemoveCallback);" />
      <MemberSignature Language="ILAsm" Value=".method public hidebysig instance object Add(string key, object value, class System.Web.Caching.CacheDependency dependencies, valuetype System.DateTime absoluteExpiration, valuetype System.TimeSpan slidingExpiration, valuetype System.Web.Caching.CacheItemPriority priority, class System.Web.Caching.CacheItemRemovedCallback onRemoveCallback) cil managed" />
      <MemberSignature Language="DocId" Value="M:System.Web.Caching.Cache.Add(System.String,System.Object,System.Web.Caching.CacheDependency,System.DateTime,System.TimeSpan,System.Web.Caching.CacheItemPriority,System.Web.Caching.CacheItemRemovedCallback)" />
      <MemberSignature Language="VB.NET" Value="Public Function Add (key As String, value As Object, dependencies As CacheDependency, absoluteExpiration As DateTime, slidingExpiration As TimeSpan, priority As CacheItemPriority, onRemoveCallback As CacheItemRemovedCallback) As Object" />
      <MemberSignature Language="F#" Value="member this.Add : string * obj * System.Web.Caching.CacheDependency * DateTime * TimeSpan * System.Web.Caching.CacheItemPriority * System.Web.Caching.CacheItemRemovedCallback -&gt; obj" Usage="cache.Add (key, value, dependencies, absoluteExpiration, slidingExpiration, priority, onRemoveCallback)" />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; System::Object ^ Add(System::String ^ key, System::Object ^ value, System::Web::Caching::CacheDependency ^ dependencies, DateTime absoluteExpiration, TimeSpan slidingExpiration, System::Web::Caching::CacheItemPriority priority, System::Web::Caching::CacheItemRemovedCallback ^ onRemoveCallback);" />
      <MemberType>Method</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.Object</ReturnType>
      </ReturnValue>
      <Parameters>
        <Parameter Name="key" Type="System.String" />
        <Parameter Name="value" Type="System.Object" />
        <Parameter Name="dependencies" Type="System.Web.Caching.CacheDependency" />
        <Parameter Name="absoluteExpiration" Type="System.DateTime" />
        <Parameter Name="slidingExpiration" Type="System.TimeSpan" />
        <Parameter Name="priority" Type="System.Web.Caching.CacheItemPriority" />
        <Parameter Name="onRemoveCallback" Type="System.Web.Caching.CacheItemRemovedCallback" />
      </Parameters>
      <Docs>
        <param name="key">The cache key used to reference the item.</param>
        <param name="value">The item to be added to the cache.</param>
        <param name="dependencies">The file or cache key dependencies for the item. When any dependency changes, the object becomes invalid and is removed from the cache. If there are no dependencies, this parameter contains <see langword="null" />.</param>
        <param name="absoluteExpiration">The time at which the added object expires and is removed from the cache. If you are using sliding expiration, the <paramref name="absoluteExpiration" /> parameter must be <see cref="F:System.Web.Caching.Cache.NoAbsoluteExpiration" />.</param>
        <param name="slidingExpiration">The interval between the time the added object was last accessed and the time at which that object expires. If this value is the equivalent of 20 minutes, the object expires and is removed from the cache 20 minutes after it is last accessed. If you are using absolute expiration, the <paramref name="slidingExpiration" /> parameter must be <see cref="F:System.Web.Caching.Cache.NoSlidingExpiration" />.</param>
        <param name="priority">The relative cost of the object, as expressed by the <see cref="T:System.Web.Caching.CacheItemPriority" /> enumeration. The cache uses this value when it evicts objects; objects with a lower cost are removed from the cache before objects with a higher cost.</param>
        <param name="onRemoveCallback">A delegate that, if provided, is called when an object is removed from the cache. You can use this to notify applications when their objects are deleted from the cache.</param>
        <summary>Adds the specified item to the <see cref="T:System.Web.Caching.Cache" /> object with dependencies, expiration and priority policies, and a delegate you can use to notify your application when the inserted item is removed from the <see langword="Cache" />.</summary>
        <returns>An object that represents the item that was added if the item was previously stored in the cache; otherwise, <see langword="null" />.</returns>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks
 Calls to this method will fail silently if an item with the same `key` parameter is already stored in the `Cache`. To overwrite an existing `Cache` item using the same `key` parameter, use the <xref:System.Web.Caching.Cache.Insert%2A> method.

 You cannot set both the `absoluteExpiration` and `slidingExpiration` parameters. If you intend the cache item to expire at a specific time, you set the `absoluteExpiration` parameter to the specific time, and the `slidingExpiration` parameter to <xref:System.Web.Caching.Cache.NoSlidingExpiration>.

 If you intend the cache item to expire after a certain amount of time has passed since the item was last accessed, you set the `slidingExpiration` parameter to the expiration interval, and the `absoluteExpiration` parameter to <xref:System.Web.Caching.Cache.NoAbsoluteExpiration>.



## Examples
 The following example creates an `AddItemToCache` method. When this method is called, it sets an `itemRemoved` property to `false` and registers an `onRemove` method with a new instance of the <xref:System.Web.Caching.CacheItemRemovedCallback> delegate. The delegate's signature is used in the `RemovedCallback` method. The `AddItemToCache` method then checks the value associated with the `Key1` key in the cache. If the value is `null`, the `Add` method places an item in the cache with a key of `Key1`, a value of `Value 1`, an absolute expiration of 60 seconds, and a high cache priority. It also uses the `onRemove` method as an argument. This allows the `RemovedCallback` method to be called when this item is removed from the cache.

> [!NOTE]
>  For examples of how to use the <xref:System.Web.Caching.CacheDependency> class and the <xref:System.Web.Caching.CacheItemRemovedCallback> delegate, see [Caching Application Data](https://learn.microsoft.com/previous-versions/aspnet/6hbbsfk6(v=vs.100)).

 [!code-csharp[System.Web.Caching Examples#3](~/snippets/csharp/VS_Snippets_WebNet/System.Web.Caching Examples/CS/cachecs.aspx#3)]
 [!code-vb[System.Web.Caching Examples#3](~/snippets/visualbasic/VS_Snippets_WebNet/System.Web.Caching Examples/VB/cachevb.aspx#3)]

 ]]></format>
        </remarks>
        <exception cref="T:System.ArgumentNullException">The <paramref name="key" /> or <paramref name="value" /> parameter is set to <see langword="null" />.</exception>
        <exception cref="T:System.ArgumentOutOfRangeException">The <paramref name="slidingExpiration" /> parameter is set to less than <see langword="TimeSpan.Zero" /> or more than one year.</exception>
        <exception cref="T:System.ArgumentException">The <paramref name="absoluteExpiration" /> and <paramref name="slidingExpiration" /> parameters are both set for the item you are trying to add to the <see langword="Cache" />.</exception>
        <altmember cref="T:System.Web.Caching.CacheDependency" />
        <altmember cref="T:System.Web.Caching.CacheItemPriority" />
        <altmember cref="T:System.Web.Caching.CacheItemRemovedCallback" />
        <related type="Article" href="https://learn.microsoft.com/previous-versions/aspnet/6hbbsfk6(v=vs.100)">Caching Application Data</related>
      </Docs>
    </Member>
    <Member MemberName="Count">
      <MemberSignature Language="C#" Value="public int Count { get; }" />
      <MemberSignature Language="ILAsm" Value=".property instance int32 Count" />
      <MemberSignature Language="DocId" Value="P:System.Web.Caching.Cache.Count" />
      <MemberSignature Language="VB.NET" Value="Public ReadOnly Property Count As Integer" />
      <MemberSignature Language="F#" Value="member this.Count : int" Usage="System.Web.Caching.Cache.Count" />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; property int Count { int get(); };" />
      <MemberType>Property</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.Int32</ReturnType>
      </ReturnValue>
      <Docs>
        <summary>Gets the number of items stored in the cache.</summary>
        <value>The number of items stored in the cache.</value>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks
 This property can be useful when monitoring your application's performance or when using ASP.NET tracing functionality.



## Examples
 The following example obtains the value of the `Count` property, converts it to a string, and assigns the string to the <xref:System.Web.UI.WebControls.Label.Text%2A> property of a <xref:System.Web.UI.WebControls.Label> Web server control, `Label1`.

 [!code-csharp[System.Web.Caching.Cache.Count#1](~/snippets/csharp/VS_Snippets_WebNet/System.Web.Caching.Cache.Count/CS/cachecountcs.aspx#1)]
 [!code-vb[System.Web.Caching.Cache.Count#1](~/snippets/visualbasic/VS_Snippets_WebNet/System.Web.Caching.Cache.Count/VB/cachecountvb.aspx#1)]

 ]]></format>
        </remarks>
      </Docs>
    </Member>
    <Member MemberName="EffectivePercentagePhysicalMemoryLimit">
      <MemberSignature Language="C#" Value="public long EffectivePercentagePhysicalMemoryLimit { get; }" />
      <MemberSignature Language="ILAsm" Value=".property instance int64 EffectivePercentagePhysicalMemoryLimit" />
      <MemberSignature Language="DocId" Value="P:System.Web.Caching.Cache.EffectivePercentagePhysicalMemoryLimit" />
      <MemberSignature Language="VB.NET" Value="Public ReadOnly Property EffectivePercentagePhysicalMemoryLimit As Long" />
      <MemberSignature Language="F#" Value="member this.EffectivePercentagePhysicalMemoryLimit : int64" Usage="System.Web.Caching.Cache.EffectivePercentagePhysicalMemoryLimit" />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; property long EffectivePercentagePhysicalMemoryLimit { long get(); };" />
      <MemberType>Property</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.Int64</ReturnType>
      </ReturnValue>
      <Docs>
        <summary>Gets the percentage of physical memory that can be consumed by an application before ASP.NET starts removing items from the cache.</summary>
        <value>The percentage of physical memory available to the application.</value>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks
 The <xref:System.Web.Caching.Cache.EffectivePercentagePhysicalMemoryLimit%2A> property returns the percentage of physical memory that is available to the application. When the available percentage becomes low, the cache algorithm begins removing items from the cache.

 The <xref:System.Web.Caching.Cache.EffectivePercentagePhysicalMemoryLimit%2A> property can be set with the `percentagePhysicalMemoryUsedLimit` attribute of the [cache Element for caching (ASP.NET Settings Schema)](https://learn.microsoft.com/previous-versions/dotnet/netframework-4.0/ms228248(v=vs.100)) element in the application's configuration file. If the `percentagePhysicalMemoryUsedLimit` attribute is not set, the cache algorithm determines the maximum size of the cache, and the <xref:System.Web.Caching.Cache.EffectivePercentagePhysicalMemoryLimit%2A> property is calculated.

 <xref:System.Web.Caching.Cache.EffectivePercentagePhysicalMemoryLimit%2A> is introduced in the .NET Framework version 3.5.  For more information, see [Versions and Dependencies](/dotnet/framework/migration-guide/versions-and-dependencies).

 ]]></format>
        </remarks>
        <altmember cref="P:System.Web.Caching.Cache.EffectivePrivateBytesLimit" />
      </Docs>
    </Member>
    <Member MemberName="EffectivePrivateBytesLimit">
      <MemberSignature Language="C#" Value="public long EffectivePrivateBytesLimit { get; }" />
      <MemberSignature Language="ILAsm" Value=".property instance int64 EffectivePrivateBytesLimit" />
      <MemberSignature Language="DocId" Value="P:System.Web.Caching.Cache.EffectivePrivateBytesLimit" />
      <MemberSignature Language="VB.NET" Value="Public ReadOnly Property EffectivePrivateBytesLimit As Long" />
      <MemberSignature Language="F#" Value="member this.EffectivePrivateBytesLimit : int64" Usage="System.Web.Caching.Cache.EffectivePrivateBytesLimit" />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; property long EffectivePrivateBytesLimit { long get(); };" />
      <MemberType>Property</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.Int64</ReturnType>
      </ReturnValue>
      <Docs>
        <summary>Gets the number of bytes available for the cache.</summary>
        <value>The number of bytes available for the cache.</value>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks
 The <xref:System.Web.Caching.Cache.EffectivePrivateBytesLimit%2A> property returns the number of bytes that can be used by the application process. Once this limit is reached, the cache algorithm begins aggressively scavenging the cache.

 The <xref:System.Web.Caching.Cache.EffectivePrivateBytesLimit%2A> property can be set with the `privateBytesLimit` attribute of the [cache Element for caching (ASP.NET Settings Schema)](https://learn.microsoft.com/previous-versions/dotnet/netframework-4.0/ms228248(v=vs.100)) element in the application's configuration file. When the `privateBytesLimit` attribute is not set, the cache algorithm determines the maximum size of the cache, and the <xref:System.Web.Caching.Cache.EffectivePrivateBytesLimit%2A> property contains the size chosen by the algorithm.



## Examples
 <xref:System.Web.Caching.Cache.EffectivePercentagePhysicalMemoryLimit%2A>

 ]]></format>
        </remarks>
      </Docs>
    </Member>
    <Member MemberName="Get">
      <MemberSignature Language="C#" Value="public object Get (string key);" />
      <MemberSignature Language="ILAsm" Value=".method public hidebysig instance object Get(string key) cil managed" />
      <MemberSignature Language="DocId" Value="M:System.Web.Caching.Cache.Get(System.String)" />
      <MemberSignature Language="VB.NET" Value="Public Function Get (key As String) As Object" />
      <MemberSignature Language="F#" Value="member this.Get : string -&gt; obj" Usage="cache.Get key" />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; System::Object ^ Get(System::String ^ key);" />
      <MemberType>Method</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.Object</ReturnType>
      </ReturnValue>
      <Parameters>
        <Parameter Name="key" Type="System.String" />
      </Parameters>
      <Docs>
        <param name="key">The identifier for the cache item to retrieve.</param>
        <summary>Retrieves the specified item from the <see cref="T:System.Web.Caching.Cache" /> object.</summary>
        <returns>The retrieved cache item, or <see langword="null" /> if the key is not found.</returns>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Examples
 The following example demonstrates how to retrieve the value cached for an ASP.NET text box server control.

 [!code-csharp[Classic Cache.Get Example#1](~/snippets/csharp/VS_Snippets_WebNet/Classic Cache.Get Example/CS/source.cs#1)]
 [!code-vb[Classic Cache.Get Example#1](~/snippets/visualbasic/VS_Snippets_WebNet/Classic Cache.Get Example/VB/source.vb#1)]

 ]]></format>
        </remarks>
        <related type="Article" href="https://learn.microsoft.com/previous-versions/aspnet/6hbbsfk6(v=vs.100)">Caching Application Data</related>
      </Docs>
    </Member>
    <Member MemberName="GetEnumerator">
      <MemberSignature Language="C#" Value="public System.Collections.IDictionaryEnumerator GetEnumerator ();" />
      <MemberSignature Language="ILAsm" Value=".method public hidebysig instance class System.Collections.IDictionaryEnumerator GetEnumerator() cil managed" />
      <MemberSignature Language="DocId" Value="M:System.Web.Caching.Cache.GetEnumerator" />
      <MemberSignature Language="VB.NET" Value="Public Function GetEnumerator () As IDictionaryEnumerator" />
      <MemberSignature Language="F#" Value="member this.GetEnumerator : unit -&gt; System.Collections.IDictionaryEnumerator" Usage="cache.GetEnumerator " />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; System::Collections::IDictionaryEnumerator ^ GetEnumerator();" />
      <MemberType>Method</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.Collections.IDictionaryEnumerator</ReturnType>
      </ReturnValue>
      <Parameters />
      <Docs>
        <summary>Retrieves a dictionary enumerator used to iterate through the key settings and their values contained in the cache.</summary>
        <returns>An enumerator to iterate through the <see cref="T:System.Web.Caching.Cache" /> object.</returns>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks
 Items can be added to or removed from the cache while this method is enumerating through the items.



## Examples
 The following example creates an <xref:System.Collections.IDictionaryEnumerator> object, `CacheEnum`, using the `GetEnumerator` method. The enumerator moves through the cache, converts the value of each cached item to a string, and then writes the values to a Web Forms page.

 [!code-csharp[Cache.GetEnumerator#1](~/snippets/csharp/VS_Snippets_WebNet/Cache.GetEnumerator/CS/getenumcs.aspx#1)]
 [!code-vb[Cache.GetEnumerator#1](~/snippets/visualbasic/VS_Snippets_WebNet/Cache.GetEnumerator/VB/getenumvb.aspx#1)]

 ]]></format>
        </remarks>
      </Docs>
    </Member>
    <MemberGroup MemberName="Insert">
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <Docs>
        <summary>Inserts an item into the <see cref="T:System.Web.Caching.Cache" /> object. Use one of the versions of this method to overwrite an existing <see langword="Cache" /> item with the same <paramref name="key" /> parameter.</summary>
      </Docs>
    </MemberGroup>
    <Member MemberName="Insert">
      <MemberSignature Language="C#" Value="public void Insert (string key, object value);" />
      <MemberSignature Language="ILAsm" Value=".method public hidebysig instance void Insert(string key, object value) cil managed" />
      <MemberSignature Language="DocId" Value="M:System.Web.Caching.Cache.Insert(System.String,System.Object)" />
      <MemberSignature Language="VB.NET" Value="Public Sub Insert (key As String, value As Object)" />
      <MemberSignature Language="F#" Value="member this.Insert : string * obj -&gt; unit" Usage="cache.Insert (key, value)" />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; void Insert(System::String ^ key, System::Object ^ value);" />
      <MemberType>Method</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.Void</ReturnType>
      </ReturnValue>
      <Parameters>
        <Parameter Name="key" Type="System.String" />
        <Parameter Name="value" Type="System.Object" />
      </Parameters>
      <Docs>
        <param name="key">The cache key used to reference the item.</param>
        <param name="value">The object to be inserted into the cache.</param>
        <summary>Inserts an item into the <see cref="T:System.Web.Caching.Cache" /> object with a cache key to reference its location, using default values provided by the <see cref="T:System.Web.Caching.CacheItemPriority" /> enumeration.</summary>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks
 This method will overwrite an existing cache item whose key matches the `key` parameter. The object added to the cache using this overload of the `Insert` method is inserted with no file or cache dependencies, a priority of <xref:System.Web.Caching.CacheItemPriority.Default>, a sliding expiration value of <xref:System.Web.Caching.Cache.NoSlidingExpiration>, and an absolute expiration value of <xref:System.Web.Caching.Cache.NoAbsoluteExpiration>.



## Examples
 The following example demonstrates how to insert an item into an application's cache.

 [!code-csharp[Classic Cache.Insert Example#1](~/snippets/csharp/VS_Snippets_WebNet/Classic Cache.Insert Example/CS/source.cs#1)]
 [!code-vb[Classic Cache.Insert Example#1](~/snippets/visualbasic/VS_Snippets_WebNet/Classic Cache.Insert Example/VB/source.vb#1)]

 ]]></format>
        </remarks>
        <exception cref="T:System.ArgumentNullException">The <paramref name="key" /> or <paramref name="value" /> parameter is <see langword="null" />.</exception>
        <related type="Article" href="https://learn.microsoft.com/previous-versions/aspnet/6hbbsfk6(v=vs.100)">Caching Application Data</related>
      </Docs>
    </Member>
    <Member MemberName="Insert">
      <MemberSignature Language="C#" Value="public void Insert (string key, object value, System.Web.Caching.CacheDependency dependencies);" />
      <MemberSignature Language="ILAsm" Value=".method public hidebysig instance void Insert(string key, object value, class System.Web.Caching.CacheDependency dependencies) cil managed" />
      <MemberSignature Language="DocId" Value="M:System.Web.Caching.Cache.Insert(System.String,System.Object,System.Web.Caching.CacheDependency)" />
      <MemberSignature Language="VB.NET" Value="Public Sub Insert (key As String, value As Object, dependencies As CacheDependency)" />
      <MemberSignature Language="F#" Value="member this.Insert : string * obj * System.Web.Caching.CacheDependency -&gt; unit" Usage="cache.Insert (key, value, dependencies)" />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; void Insert(System::String ^ key, System::Object ^ value, System::Web::Caching::CacheDependency ^ dependencies);" />
      <MemberType>Method</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.Void</ReturnType>
      </ReturnValue>
      <Parameters>
        <Parameter Name="key" Type="System.String" />
        <Parameter Name="value" Type="System.Object" />
        <Parameter Name="dependencies" Type="System.Web.Caching.CacheDependency" />
      </Parameters>
      <Docs>
        <param name="key">The cache key used to identify the item.</param>
        <param name="value">The object to be inserted in the cache.</param>
        <param name="dependencies">The file or cache key dependencies for the inserted object. When any dependency changes, the object becomes invalid and is removed from the cache. If there are no dependencies, this parameter contains <see langword="null" />.</param>
        <summary>Inserts an object into the <see cref="T:System.Web.Caching.Cache" /> that has file or key dependencies.</summary>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks
 This method will overwrite an existing cache item whose key matches the `key` parameter. The object added to the cache using this overload of the `Insert` method is inserted with a priority of <xref:System.Web.Caching.CacheItemPriority.Default>, a sliding expiration value of <xref:System.Web.Caching.Cache.NoSlidingExpiration>, and an absolute expiration value of <xref:System.Web.Caching.Cache.NoAbsoluteExpiration>.



## Examples
 The following example demonstrates how to insert an item into an application's cache with a cache dependency on an XML configuration file.

 [!code-csharp[Classic Cache.Insert1 Example#1](~/snippets/csharp/VS_Snippets_WebNet/Classic Cache.Insert1 Example/CS/source.cs#1)]
 [!code-vb[Classic Cache.Insert1 Example#1](~/snippets/visualbasic/VS_Snippets_WebNet/Classic Cache.Insert1 Example/VB/source.vb#1)]

 ]]></format>
        </remarks>
        <exception cref="T:System.ArgumentNullException">The <paramref name="key" /> or <paramref name="value" /> parameter is <see langword="null" />.</exception>
        <altmember cref="T:System.Web.Caching.CacheDependency" />
      </Docs>
    </Member>
    <Member MemberName="Insert">
      <MemberSignature Language="C#" Value="public void Insert (string key, object value, System.Web.Caching.CacheDependency dependencies, DateTime absoluteExpiration, TimeSpan slidingExpiration);" />
      <MemberSignature Language="ILAsm" Value=".method public hidebysig instance void Insert(string key, object value, class System.Web.Caching.CacheDependency dependencies, valuetype System.DateTime absoluteExpiration, valuetype System.TimeSpan slidingExpiration) cil managed" />
      <MemberSignature Language="DocId" Value="M:System.Web.Caching.Cache.Insert(System.String,System.Object,System.Web.Caching.CacheDependency,System.DateTime,System.TimeSpan)" />
      <MemberSignature Language="VB.NET" Value="Public Sub Insert (key As String, value As Object, dependencies As CacheDependency, absoluteExpiration As DateTime, slidingExpiration As TimeSpan)" />
      <MemberSignature Language="F#" Value="member this.Insert : string * obj * System.Web.Caching.CacheDependency * DateTime * TimeSpan -&gt; unit" Usage="cache.Insert (key, value, dependencies, absoluteExpiration, slidingExpiration)" />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; void Insert(System::String ^ key, System::Object ^ value, System::Web::Caching::CacheDependency ^ dependencies, DateTime absoluteExpiration, TimeSpan slidingExpiration);" />
      <MemberType>Method</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.Void</ReturnType>
      </ReturnValue>
      <Parameters>
        <Parameter Name="key" Type="System.String" />
        <Parameter Name="value" Type="System.Object" />
        <Parameter Name="dependencies" Type="System.Web.Caching.CacheDependency" />
        <Parameter Name="absoluteExpiration" Type="System.DateTime" />
        <Parameter Name="slidingExpiration" Type="System.TimeSpan" />
      </Parameters>
      <Docs>
        <param name="key">The cache key used to reference the object.</param>
        <param name="value">The object to be inserted in the cache.</param>
        <param name="dependencies">The file or cache key dependencies for the inserted object. When any dependency changes, the object becomes invalid and is removed from the cache. If there are no dependencies, this parameter contains <see langword="null" />.</param>
        <param name="absoluteExpiration">The time at which the inserted object expires and is removed from the cache. To avoid possible issues with local time such as changes from standard time to daylight saving time, use <see cref="P:System.DateTime.UtcNow" /> rather than <see cref="P:System.DateTime.Now" /> for this parameter value. If you are using absolute expiration, the <paramref name="slidingExpiration" /> parameter must be <see cref="F:System.Web.Caching.Cache.NoSlidingExpiration" />.</param>
        <param name="slidingExpiration">The interval between the time the inserted object is last accessed and the time at which that object expires. If this value is the equivalent of 20 minutes, the object will expire and be removed from the cache 20 minutes after it was last accessed. If you are using sliding expiration, the <paramref name="absoluteExpiration" /> parameter must be <see cref="F:System.Web.Caching.Cache.NoAbsoluteExpiration" />.</param>
        <summary>Inserts an object into the <see cref="T:System.Web.Caching.Cache" /> with dependencies and expiration policies.</summary>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks
 This method will overwrite an existing `Cache` item with the same `key` parameter.

 If the `slidingExpiration` parameter is set to <xref:System.Web.Caching.Cache.NoSlidingExpiration>, sliding expiration is disabled. If you set the `slidingExpiration` parameter to greater than <xref:System.TimeSpan.Zero>, the `absoluteExpiration` parameter is set to <xref:System.DateTime.Now%2A> plus the value contained in the `slidingExpiration` parameter. If the item is requested from the cache before the amount of time specified by the `absoluteExpiration` parameter, the item will be placed in the cache again, and `absoluteExpiration` will again be set to `DateTime.Now` plus the value contained in the `slidingExpiration` parameter. If the item is not requested from the cache before the date in the `absoluteExpiration` parameter, the item is removed from the cache. The item added to the cache using this overload of the insert method is inserted with a priority of <xref:System.Web.Caching.CacheItemPriority.Default>.



## Examples
 The following example demonstrates how to insert an item into an application's cache with an absolute expiration.

> [!NOTE]
>  Since this form of the `Insert` method supports cache dependencies, if the item has no dependencies, you must declare the `dependency` parameter as `null` (`Nothing` in Visual Basic) in the comma-delimited list of parameters.

 [!code-csharp[Classic Cache.Insert2 Example#1](~/snippets/csharp/VS_Snippets_WebNet/Classic Cache.Insert2 Example/CS/source.cs#1)]
 [!code-vb[Classic Cache.Insert2 Example#1](~/snippets/visualbasic/VS_Snippets_WebNet/Classic Cache.Insert2 Example/VB/source.vb#1)]

 The following example demonstrates how to insert an item into the cache with a sliding expiration.

 [!code-csharp[Classic Cache.Insert2 Example#2](~/snippets/csharp/VS_Snippets_WebNet/Classic Cache.Insert2 Example/CS/source.cs#2)]
 [!code-vb[Classic Cache.Insert2 Example#2](~/snippets/visualbasic/VS_Snippets_WebNet/Classic Cache.Insert2 Example/VB/source.vb#2)]

 ]]></format>
        </remarks>
        <exception cref="T:System.ArgumentNullException">The <paramref name="key" /> or <paramref name="value" /> parameter is <see langword="null" />.</exception>
        <exception cref="T:System.ArgumentOutOfRangeException">You set the <paramref name="slidingExpiration" /> parameter to less than <see langword="TimeSpan.Zero" /> or the equivalent of more than one year.</exception>
        <exception cref="T:System.ArgumentException">The <paramref name="absoluteExpiration" /> and <paramref name="slidingExpiration" /> parameters are both set for the item you are trying to add to the <see langword="Cache" />.</exception>
        <altmember cref="T:System.DateTime" />
        <altmember cref="T:System.TimeSpan" />
        <related type="Article" href="https://learn.microsoft.com/previous-versions/aspnet/6hbbsfk6(v=vs.100)">Caching Application Data</related>
      </Docs>
    </Member>
    <Member MemberName="Insert">
      <MemberSignature Language="C#" Value="public void Insert (string key, object value, System.Web.Caching.CacheDependency dependencies, DateTime absoluteExpiration, TimeSpan slidingExpiration, System.Web.Caching.CacheItemUpdateCallback onUpdateCallback);" />
      <MemberSignature Language="ILAsm" Value=".method public hidebysig instance void Insert(string key, object value, class System.Web.Caching.CacheDependency dependencies, valuetype System.DateTime absoluteExpiration, valuetype System.TimeSpan slidingExpiration, class System.Web.Caching.CacheItemUpdateCallback onUpdateCallback) cil managed" />
      <MemberSignature Language="DocId" Value="M:System.Web.Caching.Cache.Insert(System.String,System.Object,System.Web.Caching.CacheDependency,System.DateTime,System.TimeSpan,System.Web.Caching.CacheItemUpdateCallback)" />
      <MemberSignature Language="VB.NET" Value="Public Sub Insert (key As String, value As Object, dependencies As CacheDependency, absoluteExpiration As DateTime, slidingExpiration As TimeSpan, onUpdateCallback As CacheItemUpdateCallback)" />
      <MemberSignature Language="F#" Value="member this.Insert : string * obj * System.Web.Caching.CacheDependency * DateTime * TimeSpan * System.Web.Caching.CacheItemUpdateCallback -&gt; unit" Usage="cache.Insert (key, value, dependencies, absoluteExpiration, slidingExpiration, onUpdateCallback)" />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; void Insert(System::String ^ key, System::Object ^ value, System::Web::Caching::CacheDependency ^ dependencies, DateTime absoluteExpiration, TimeSpan slidingExpiration, System::Web::Caching::CacheItemUpdateCallback ^ onUpdateCallback);" />
      <MemberType>Method</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
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      <ReturnValue>
        <ReturnType>System.Void</ReturnType>
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      <Parameters>
        <Parameter Name="key" Type="System.String" Index="0" FrameworkAlternate="netframework-2.0;netframework-3.0;netframework-3.5;netframework-4.0;netframework-4.5;netframework-4.5.1;netframework-4.5.2;netframework-4.6;netframework-4.6.1;netframework-4.6.2;netframework-4.7;netframework-4.7.1;netframework-4.7.2;netframework-4.8;netframework-4.8.1" />
        <Parameter Name="value" Type="System.Object" Index="1" FrameworkAlternate="netframework-2.0;netframework-3.0;netframework-3.5;netframework-4.0;netframework-4.5;netframework-4.5.1;netframework-4.5.2;netframework-4.6;netframework-4.6.1;netframework-4.6.2;netframework-4.7;netframework-4.7.1;netframework-4.7.2;netframework-4.8;netframework-4.8.1" />
        <Parameter Name="dependencies" Type="System.Web.Caching.CacheDependency" Index="2" FrameworkAlternate="netframework-2.0;netframework-3.0;netframework-3.5;netframework-4.0;netframework-4.5;netframework-4.5.1;netframework-4.5.2;netframework-4.6;netframework-4.6.1;netframework-4.6.2;netframework-4.7;netframework-4.7.1;netframework-4.7.2;netframework-4.8;netframework-4.8.1" />
        <Parameter Name="absoluteExpiration" Type="System.DateTime" Index="3" FrameworkAlternate="netframework-2.0;netframework-3.0;netframework-3.5;netframework-4.0;netframework-4.5;netframework-4.5.1;netframework-4.5.2;netframework-4.6;netframework-4.6.1;netframework-4.6.2;netframework-4.7;netframework-4.7.1;netframework-4.7.2;netframework-4.8;netframework-4.8.1" />
        <Parameter Name="slidingExpiration" Type="System.TimeSpan" Index="4" FrameworkAlternate="netframework-2.0;netframework-3.0;netframework-3.5;netframework-4.0;netframework-4.5;netframework-4.5.1;netframework-4.5.2;netframework-4.6;netframework-4.6.1;netframework-4.6.2;netframework-4.7;netframework-4.7.1;netframework-4.7.2;netframework-4.8;netframework-4.8.1" />
        <Parameter Name="onUpdateCallback" Type="System.Web.Caching.CacheItemUpdateCallback" Index="5" FrameworkAlternate="netframework-2.0;netframework-3.0;netframework-3.5;netframework-4.0;netframework-4.5;netframework-4.5.1;netframework-4.5.2;netframework-4.6;netframework-4.6.1;netframework-4.6.2;netframework-4.7;netframework-4.7.1;netframework-4.7.2;netframework-4.8;netframework-4.8.1" />
      </Parameters>
      <Docs>
        <param name="key">The cache key that is used to reference the object.</param>
        <param name="value">The object to insert into the cache.</param>
        <param name="dependencies">The file or cache key dependencies for the item. When any dependency changes, the object becomes invalid and is removed from the cache. If there are no dependencies, this parameter contains <see langword="null" />.</param>
        <param name="absoluteExpiration">The time at which the inserted object expires and is removed from the cache. To avoid possible issues with local time such as changes from standard time to daylight saving time, use <see cref="P:System.DateTime.UtcNow" /> instead of <see cref="P:System.DateTime.Now" /> for this parameter value. If you are using absolute expiration, the <paramref name="slidingExpiration" /> parameter must be set to <see cref="F:System.Web.Caching.Cache.NoSlidingExpiration" />.</param>
        <param name="slidingExpiration">The interval between the time that the cached object was last accessed and the time at which that object expires. If this value is the equivalent of 20 minutes, the object will expire and be removed from the cache 20 minutes after it was last accessed. If you are using sliding expiration, the <paramref name="absoluteExpiration" /> parameter must be set to <see cref="F:System.Web.Caching.Cache.NoAbsoluteExpiration" />.</param>
        <param name="onUpdateCallback">A delegate that will be called before the object is removed from the cache. You can use this to update the cached item and ensure that it is not removed from the cache.</param>
        <summary>Inserts an object into the <see cref="T:System.Web.Caching.Cache" /> object together with dependencies, expiration policies, and a delegate that you can use to notify the application before the item is removed from the cache.</summary>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks
 The <xref:System.Web.Caching.Cache.Insert%2A> method enables you to insert a new item in the cache and provide a delegate that is called before the item is removed from the cache. In the delegate, you can update the cached item and thereby prevent it from being removed from the cache.

 This method will overwrite an existing `Cache` item with the same `key` parameter.

 You cannot set both the `absoluteExpiration` and `slidingExpiration` parameters. If you intend the cache item to expire at a specific time, you set the `absoluteExpiration` parameter to the specific time, and the `slidingExpiration` parameter to <xref:System.Web.Caching.Cache.NoSlidingExpiration>.

 If you intend the cache item to expire after a set period of time since the item was last accessed, you set the `slidingExpiration` parameter to the expiration interval, and you set the `absoluteExpiration` parameter to <xref:System.Web.Caching.Cache.NoAbsoluteExpiration>.

 ]]></format>
        </remarks>
        <exception cref="T:System.ArgumentNullException">The <paramref name="key" />, <paramref name="value" />, or <paramref name="onUpdateCallback" /> parameter is <see langword="null" />.</exception>
        <exception cref="T:System.ArgumentOutOfRangeException">You set the <paramref name="slidingExpiration" /> parameter to less than <see langword="TimeSpan.Zero" /> or the equivalent of more than one year.</exception>
        <exception cref="T:System.ArgumentException">The <paramref name="absoluteExpiration" /> and <paramref name="slidingExpiration" /> parameters are both set for the item you are trying to add to the <see langword="Cache" />.

 -or-

 The <paramref name="dependencies" /> parameter is <see langword="null" />, and the <paramref name="absoluteExpiration" /> parameter is set to <see cref="F:System.Web.Caching.Cache.NoAbsoluteExpiration" />, and the <paramref name="slidingExpiration" /> parameter is set to <see cref="F:System.Web.Caching.Cache.NoSlidingExpiration" />.</exception>
        <altmember cref="T:System.Web.Caching.CacheItemUpdateCallback" />
      </Docs>
    </Member>
    <Member MemberName="Insert">
      <MemberSignature Language="C#" Value="public void Insert (string key, object value, System.Web.Caching.CacheDependency dependencies, DateTime absoluteExpiration, TimeSpan slidingExpiration, System.Web.Caching.CacheItemPriority priority, System.Web.Caching.CacheItemRemovedCallback onRemoveCallback);" />
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      <MemberSignature Language="DocId" Value="M:System.Web.Caching.Cache.Insert(System.String,System.Object,System.Web.Caching.CacheDependency,System.DateTime,System.TimeSpan,System.Web.Caching.CacheItemPriority,System.Web.Caching.CacheItemRemovedCallback)" />
      <MemberSignature Language="VB.NET" Value="Public Sub Insert (key As String, value As Object, dependencies As CacheDependency, absoluteExpiration As DateTime, slidingExpiration As TimeSpan, priority As CacheItemPriority, onRemoveCallback As CacheItemRemovedCallback)" />
      <MemberSignature Language="F#" Value="member this.Insert : string * obj * System.Web.Caching.CacheDependency * DateTime * TimeSpan * System.Web.Caching.CacheItemPriority * System.Web.Caching.CacheItemRemovedCallback -&gt; unit" Usage="cache.Insert (key, value, dependencies, absoluteExpiration, slidingExpiration, priority, onRemoveCallback)" />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; void Insert(System::String ^ key, System::Object ^ value, System::Web::Caching::CacheDependency ^ dependencies, DateTime absoluteExpiration, TimeSpan slidingExpiration, System::Web::Caching::CacheItemPriority priority, System::Web::Caching::CacheItemRemovedCallback ^ onRemoveCallback);" />
      <MemberType>Method</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.Void</ReturnType>
      </ReturnValue>
      <Parameters>
        <Parameter Name="key" Type="System.String" />
        <Parameter Name="value" Type="System.Object" />
        <Parameter Name="dependencies" Type="System.Web.Caching.CacheDependency" />
        <Parameter Name="absoluteExpiration" Type="System.DateTime" />
        <Parameter Name="slidingExpiration" Type="System.TimeSpan" />
        <Parameter Name="priority" Type="System.Web.Caching.CacheItemPriority" />
        <Parameter Name="onRemoveCallback" Type="System.Web.Caching.CacheItemRemovedCallback" />
      </Parameters>
      <Docs>
        <param name="key">The cache key used to reference the object.</param>
        <param name="value">The object to be inserted in the cache.</param>
        <param name="dependencies">The file or cache key dependencies for the item. When any dependency changes, the object becomes invalid and is removed from the cache. If there are no dependencies, this parameter contains <see langword="null" />.</param>
        <param name="absoluteExpiration">The time at which the inserted object expires and is removed from the cache. To avoid possible issues with local time such as changes from standard time to daylight saving time, use <see cref="P:System.DateTime.UtcNow" /> rather than <see cref="P:System.DateTime.Now" /> for this parameter value. If you are using absolute expiration, the <paramref name="slidingExpiration" /> parameter must be <see cref="F:System.Web.Caching.Cache.NoSlidingExpiration" />.</param>
        <param name="slidingExpiration">The interval between the time the inserted object was last accessed and the time at which that object expires. If this value is the equivalent of 20 minutes, the object will expire and be removed from the cache 20 minutes after it was last accessed. If you are using sliding expiration, the <paramref name="absoluteExpiration" /> parameter must be <see cref="F:System.Web.Caching.Cache.NoAbsoluteExpiration" />.</param>
        <param name="priority">The cost of the object relative to other items stored in the cache, as expressed by the <see cref="T:System.Web.Caching.CacheItemPriority" /> enumeration. This value is used by the cache when it evicts objects; objects with a lower cost are removed from the cache before objects with a higher cost.</param>
        <param name="onRemoveCallback">A delegate that, if provided, will be called when an object is removed from the cache. You can use this to notify applications when their objects are deleted from the cache.</param>
        <summary>Inserts an object into the <see cref="T:System.Web.Caching.Cache" /> object with dependencies, expiration and priority policies, and a delegate you can use to notify your application when the inserted item is removed from the <see langword="Cache" />.</summary>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks
 This method will overwrite an existing `Cache` item with the same `key` parameter.

 You cannot set both the `absoluteExpiration` and `slidingExpiration` parameters. If you intend the cache item to expire at a specific time, you set the `absoluteExpiration` parameter to the specific time, and the `slidingExpiration` parameter to <xref:System.Web.Caching.Cache.NoSlidingExpiration>.

 If you intend the cache item to expire after a certain amount of time has passed since the last access to the item, you set the `slidingExpiration` parameter to the expiration interval, and the `absoluteExpiration` parameter to <xref:System.Web.Caching.Cache.NoAbsoluteExpiration>.



## Examples
 The following example demonstrates how to assign an item high priority when you insert it into your application's `Cache` object.

> [!NOTE]
>  For more information about how to use this method with the <xref:System.Web.Caching.CacheItemRemovedCallback> delegate, see [How to: Notify an Application When an Item Is Removed from the Cache](https://learn.microsoft.com/previous-versions/aspnet/7kxdx246(v=vs.100)).

 [!code-csharp[Classic Cache.Insert3 Example#1](~/snippets/csharp/VS_Snippets_WebNet/Classic Cache.Insert3 Example/CS/source.cs#1)]
 [!code-vb[Classic Cache.Insert3 Example#1](~/snippets/visualbasic/VS_Snippets_WebNet/Classic Cache.Insert3 Example/VB/source.vb#1)]

 ]]></format>
        </remarks>
        <exception cref="T:System.ArgumentNullException">The <paramref name="key" /> or <paramref name="value" /> parameter is <see langword="null" />.</exception>
        <exception cref="T:System.ArgumentOutOfRangeException">You set the <paramref name="slidingExpiration" /> parameter to less than <see langword="TimeSpan.Zero" /> or the equivalent of more than one year.</exception>
        <exception cref="T:System.ArgumentException">The <paramref name="absoluteExpiration" /> and <paramref name="slidingExpiration" /> parameters are both set for the item you are trying to add to the <see langword="Cache" />.</exception>
        <altmember cref="T:System.DateTime" />
        <altmember cref="T:System.TimeSpan" />
        <altmember cref="T:System.Web.Caching.CacheItemPriority" />
        <altmember cref="T:System.Web.Caching.CacheItemRemovedCallback" />
        <related type="Article" href="https://learn.microsoft.com/previous-versions/aspnet/6hbbsfk6(v=vs.100)">Caching Application Data</related>
      </Docs>
    </Member>
    <Member MemberName="Item">
      <MemberSignature Language="C#" Value="public object this[string key] { get; set; }" />
      <MemberSignature Language="ILAsm" Value=".property instance object Item(string)" />
      <MemberSignature Language="DocId" Value="P:System.Web.Caching.Cache.Item(System.String)" />
      <MemberSignature Language="VB.NET" Value="Default Public Property Item(key As String) As Object" />
      <MemberSignature Language="F#" Value="member this.Item(string) : obj with get, set" Usage="System.Web.Caching.Cache.Item" />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; property System::Object ^ default[System::String ^] { System::Object ^ get(System::String ^ key); void set(System::String ^ key, System::Object ^ value); };" />
      <MemberType>Property</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <Attributes>
        <Attribute FrameworkAlternate="netframework-4.0">
          <AttributeName Language="C#">[get: System.Runtime.TargetedPatchingOptOut("Performance critical to inline this type of method across NGen image boundaries")]</AttributeName>
          <AttributeName Language="F#">[&lt;get: System.Runtime.TargetedPatchingOptOut("Performance critical to inline this type of method across NGen image boundaries")&gt;]</AttributeName>
        </Attribute>
        <Attribute FrameworkAlternate="netframework-4.0">
          <AttributeName Language="C#">[set: System.Runtime.TargetedPatchingOptOut("Performance critical to inline this type of method across NGen image boundaries")]</AttributeName>
          <AttributeName Language="F#">[&lt;set: System.Runtime.TargetedPatchingOptOut("Performance critical to inline this type of method across NGen image boundaries")&gt;]</AttributeName>
        </Attribute>
      </Attributes>
      <ReturnValue>
        <ReturnType>System.Object</ReturnType>
      </ReturnValue>
      <Parameters>
        <Parameter Name="key" Type="System.String" />
      </Parameters>
      <Docs>
        <param name="key">A <see cref="T:System.String" /> object that represents the key for the cache item.</param>
        <summary>Gets or sets the cache item at the specified key.</summary>
        <value>The specified cache item.</value>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks
 You can use this property to retrieve the value of a specified cache item, or to add an item and a key for it to the cache. Adding a cache item using the <xref:System.Web.Caching.Cache.Item%2A> property is equivalent to calling the <xref:System.Web.Caching.Cache.Insert%2A?displayProperty=nameWithType> method.



## Examples
 The following example uses the `Item` property to retrieve the value of a cached object associated with the `Key1` key. It then uses the <xref:System.Web.HttpResponse.Write%2A?displayProperty=nameWithType> method to write the value and introductory text and the B HTML element to a Web Forms page.

 [!code-csharp[System.Web.Caching Examples#5](~/snippets/csharp/VS_Snippets_WebNet/System.Web.Caching Examples/CS/cachecs.aspx#5)]
 [!code-vb[System.Web.Caching Examples#5](~/snippets/visualbasic/VS_Snippets_WebNet/System.Web.Caching Examples/VB/cachevb.aspx#5)]

 The following example demonstrates using this property to insert the value of a text box into the cache.

 [!code-csharp[Classic Cache.this Example#2](~/snippets/csharp/VS_Snippets_WebNet/Classic Cache.this Example/CS/source.cs#2)]
 [!code-vb[Classic Cache.this Example#2](~/snippets/visualbasic/VS_Snippets_WebNet/Classic Cache.this Example/VB/source.vb#2)]

 ]]></format>
        </remarks>
        <related type="Article" href="https://learn.microsoft.com/previous-versions/aspnet/6hbbsfk6(v=vs.100)">Caching Application Data</related>
      </Docs>
    </Member>
    <Member MemberName="NoAbsoluteExpiration">
      <MemberSignature Language="C#" Value="public static readonly DateTime NoAbsoluteExpiration;" />
      <MemberSignature Language="ILAsm" Value=".field public static initonly valuetype System.DateTime NoAbsoluteExpiration" />
      <MemberSignature Language="DocId" Value="F:System.Web.Caching.Cache.NoAbsoluteExpiration" />
      <MemberSignature Language="VB.NET" Value="Public Shared ReadOnly NoAbsoluteExpiration As DateTime " />
      <MemberSignature Language="F#" Value=" staticval mutable NoAbsoluteExpiration : DateTime" Usage="System.Web.Caching.Cache.NoAbsoluteExpiration" />
      <MemberSignature Language="C++ CLI" Value="public: static initonly DateTime NoAbsoluteExpiration;" />
      <MemberType>Field</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.DateTime</ReturnType>
      </ReturnValue>
      <Docs>
        <summary>Used in the <paramref name="absoluteExpiration" /> parameter in an <see cref="M:System.Web.Caching.Cache.Insert(System.String,System.Object)" /> method call to indicate the item should never expire. This field is read-only.</summary>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks
 When used, this field sets the `absoluteExpiration` parameter equal to <xref:System.DateTime.MaxValue>, which is a constant representing the largest possible `DateTime` value, 12/31/9999 11:59:59 PM.



## Examples
 The following example demonstrates how to use the `NoAbsoluteExpiration` field to disable absolute expirations when inserting an item in the `Cache`.

 [!code-csharp[Classic Cache.NoAbsoluteExpiration Example#1](~/snippets/csharp/VS_Snippets_WebNet/Classic Cache.NoAbsoluteExpiration Example/CS/source.cs#1)]
 [!code-vb[Classic Cache.NoAbsoluteExpiration Example#1](~/snippets/visualbasic/VS_Snippets_WebNet/Classic Cache.NoAbsoluteExpiration Example/VB/source.vb#1)]

 ]]></format>
        </remarks>
        <altmember cref="T:System.DateTime" />
        <altmember cref="M:System.Web.Caching.Cache.Insert(System.String,System.Object)" />
      </Docs>
    </Member>
    <Member MemberName="NoSlidingExpiration">
      <MemberSignature Language="C#" Value="public static readonly TimeSpan NoSlidingExpiration;" />
      <MemberSignature Language="ILAsm" Value=".field public static initonly valuetype System.TimeSpan NoSlidingExpiration" />
      <MemberSignature Language="DocId" Value="F:System.Web.Caching.Cache.NoSlidingExpiration" />
      <MemberSignature Language="VB.NET" Value="Public Shared ReadOnly NoSlidingExpiration As TimeSpan " />
      <MemberSignature Language="F#" Value=" staticval mutable NoSlidingExpiration : TimeSpan" Usage="System.Web.Caching.Cache.NoSlidingExpiration" />
      <MemberSignature Language="C++ CLI" Value="public: static initonly TimeSpan NoSlidingExpiration;" />
      <MemberType>Field</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.TimeSpan</ReturnType>
      </ReturnValue>
      <Docs>
        <summary>Used as the <paramref name="slidingExpiration" /> parameter in an <see cref="M:System.Web.Caching.Cache.Insert(System.String,System.Object)" /> or <see cref="M:System.Web.Caching.Cache.Add(System.String,System.Object,System.Web.Caching.CacheDependency,System.DateTime,System.TimeSpan,System.Web.Caching.CacheItemPriority,System.Web.Caching.CacheItemRemovedCallback)" /> method call to disable sliding expirations. This field is read-only.</summary>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks
 When used, this field sets the `slidingExpiration` parameter to the <xref:System.TimeSpan.Zero?displayProperty=nameWithType> field, which has a constant value of zero. The cached item expires in accordance with the `absoluteExpiration` parameter associated with the `Insert` or `Add` method call.



## Examples
 The following example demonstrates how to use the Insert method to add an item to the <xref:System.Web.Caching.Cache> object using the `NoSlidingExpiration` field.

 [!code-csharp[Classic Cache.NoSlidingExpiration Example#1](~/snippets/csharp/VS_Snippets_WebNet/Classic Cache.NoSlidingExpiration Example/CS/source.cs#1)]
 [!code-vb[Classic Cache.NoSlidingExpiration Example#1](~/snippets/visualbasic/VS_Snippets_WebNet/Classic Cache.NoSlidingExpiration Example/VB/source.vb#1)]

 ]]></format>
        </remarks>
        <altmember cref="F:System.TimeSpan.Zero" />
        <altmember cref="M:System.Web.Caching.Cache.Insert(System.String,System.Object)" />
      </Docs>
    </Member>
    <Member MemberName="Remove">
      <MemberSignature Language="C#" Value="public object Remove (string key);" />
      <MemberSignature Language="ILAsm" Value=".method public hidebysig instance object Remove(string key) cil managed" />
      <MemberSignature Language="DocId" Value="M:System.Web.Caching.Cache.Remove(System.String)" />
      <MemberSignature Language="VB.NET" Value="Public Function Remove (key As String) As Object" />
      <MemberSignature Language="F#" Value="member this.Remove : string -&gt; obj" Usage="cache.Remove key" />
      <MemberSignature Language="C++ CLI" Value="public:&#xA; System::Object ^ Remove(System::String ^ key);" />
      <MemberType>Method</MemberType>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.Object</ReturnType>
      </ReturnValue>
      <Parameters>
        <Parameter Name="key" Type="System.String" />
      </Parameters>
      <Docs>
        <param name="key">A <see cref="T:System.String" /> identifier for the cache item to remove.</param>
        <summary>Removes the specified item from the application's <see cref="T:System.Web.Caching.Cache" /> object.</summary>
        <returns>The item removed from the <see langword="Cache" />. If the value in the key parameter is not found, returns <see langword="null" />.</returns>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Examples
 The following example creates a `RemoveItemFromCache` method. When this method is called, it uses the <xref:System.Web.Caching.Cache.Item%2A> property to check whether the cache contains an object that is associated with a `Key1` key value. If it does, the `Remove` method is called to remove the object.

 [!code-csharp[System.Web.Caching Examples#4](~/snippets/csharp/VS_Snippets_WebNet/System.Web.Caching Examples/CS/cachecs.aspx#4)]
 [!code-vb[System.Web.Caching Examples#4](~/snippets/visualbasic/VS_Snippets_WebNet/System.Web.Caching Examples/VB/cachevb.aspx#4)]

 ]]></format>
        </remarks>
        <related type="Article" href="https://learn.microsoft.com/previous-versions/aspnet/6hbbsfk6(v=vs.100)">Caching Application Data</related>
      </Docs>
    </Member>
    <Member MemberName="System.Collections.IEnumerable.GetEnumerator">
      <MemberSignature Language="C#" Value="System.Collections.IEnumerator IEnumerable.GetEnumerator ();" />
      <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance class System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() cil managed" />
      <MemberSignature Language="DocId" Value="M:System.Web.Caching.Cache.System#Collections#IEnumerable#GetEnumerator" />
      <MemberSignature Language="VB.NET" Value="Function GetEnumerator () As IEnumerator Implements IEnumerable.GetEnumerator" />
      <MemberSignature Language="F#" Value="abstract member System.Collections.IEnumerable.GetEnumerator : unit -&gt; System.Collections.IEnumerator&#xA;override this.System.Collections.IEnumerable.GetEnumerator : unit -&gt; System.Collections.IEnumerator" Usage="cache.System.Collections.IEnumerable.GetEnumerator " />
      <MemberSignature Language="C++ CLI" Value=" virtual System::Collections::IEnumerator ^ System.Collections.IEnumerable.GetEnumerator() = System::Collections::IEnumerable::GetEnumerator;" />
      <MemberType>Method</MemberType>
      <Implements>
        <InterfaceMember>M:System.Collections.IEnumerable.GetEnumerator</InterfaceMember>
      </Implements>
      <AssemblyInfo>
        <AssemblyName>System.Web</AssemblyName>
        <AssemblyVersion>1.0.5000.0</AssemblyVersion>
        <AssemblyVersion>2.0.0.0</AssemblyVersion>
        <AssemblyVersion>4.0.0.0</AssemblyVersion>
      </AssemblyInfo>
      <ReturnValue>
        <ReturnType>System.Collections.IEnumerator</ReturnType>
      </ReturnValue>
      <Parameters />
      <Docs>
        <summary>Returns an enumerator that can iterate through the <see cref="T:System.Web.Caching.Cache" /> object collection.</summary>
        <returns>An enumerator that can iterate through the <see cref="T:System.Web.Caching.Cache" /> object collection.</returns>
        <remarks>
          <format type="text/markdown"><![CDATA[

## Remarks

This member is an explicit interface member implementation. It can be used only when the <xref:System.Web.Caching.Cache> instance is cast to an <xref:System.Collections.IEnumerable> interface.

          ]]></format>
        </remarks>
      </Docs>
    </Member>
  </Members>
</Type>