CacheItemPriority Enumeration (System.Web.Caching)

CacheItemPriority Enumeration

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Microsoft Visual Studio 2010/.NET Framework 4

Other versions are also available for the following:

.NET Framework Class Library

CacheItemPriority Enumeration

Specifies the relative priority of items stored in the Cache object.

Namespace: System.Web.Caching
Assembly: System.Web (in System.Web.dll)

Syntax

Visual Basic

Public Enumeration CacheItemPriority

public enum CacheItemPriority

Visual C++

public enum class CacheItemPriority

type CacheItemPriority

Members

	Member name	Description
	Low	Cache items with this priority level are the most likely to be deleted from the cache as the server frees system memory.
	BelowNormal	Cache items with this priority level are more likely to be deleted from the cache as the server frees system memory than items assigned a Normal priority.
	Normal	Cache items with this priority level are likely to be deleted from the cache as the server frees system memory only after those items with Low or BelowNormal priority. This is the default.
	AboveNormal	Cache items with this priority level are less likely to be deleted as the server frees system memory than those assigned a Normal priority.
	High	Cache items with this priority level are the least likely to be deleted from the cache as the server frees system memory.
	NotRemovable	The cache items with this priority level will not be automatically deleted from the cache as the server frees system memory. However, items with this priority level are removed along with other items according to the item's absolute or sliding expiration time.
	Default	The default value for a cached item's priority is Normal.

Remarks

When the Web server hosting an ASP.NET application runs low on memory, the Cache object selectively purges items to free system memory. When an item is added to the cache, you can assign it a relative priority compared to the other items stored in the cache. Items to which you assign higher priority values are less likely to be deleted from the cache when the server is processing a large number of requests, whereas items to which you assign lower priority values are more likely to be deleted. The default is Normal.

Note
Items can always be removed from the cache programmatically, regardless of their cache priority.

Examples

The following code example uses the Insert method to add an item to the Cache object with its priority parameter set to High.

Visual Basic

<%@ Page Language="VB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
    Public Sub Page_Load(sender As Object, e As EventArgs)
        Dim connectionString As String
        connectionString = "Data Source=localhost;Integrated Security=SSPI"
        Cache.Insert("DSN", connectionString, Nothing, DateTime.Now.AddMinutes(2), TimeSpan.Zero, CacheItemPriority.High, Nothing)
    End Sub
</script>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script language="c#" runat="server">
    public void Page_Load(Object sender, EventArgs e) {
        String connectionString;
        connectionString = "Data Source=localhost;Integrated Security=SSPI";
        Cache.Insert("DSN", connectionString, null, DateTime.Now.AddMinutes(2), TimeSpan.Zero, CacheItemPriority.High, null);
    }
</script>

Version Information

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference

System.Web.Caching Namespace

Cache

Other Resources

Caching Application Data