ASP.NET - Cache Dependency

Asked By Mahesh B on 05-Jan-12 03:41 AM

Hi
can anyone give me example of cache dependency

Jitendra Faye replied to Mahesh B on 05-Jan-12 03:49 AM

ASP.NET allows you to use the http://msdn.microsoft.com/en-us/library/system.web.caching.sqlcachedependency.aspx class to create a cache item dependency on a table or row in a database. When a change occurs in the table or in a specific row, the item that has a dependency is invalidated and removed from the cache. You can set a dependency on a table in Microsoft SQL Server 7.0, SQL Server 2000, and SQL Server 2005. If you are using SQL Server 2005 you can also set a dependency on a specific record.

Using caching with a SQL dependency can dramatically increase application performance in certain scenarios.

For this you have to make following changes-

 <caching> <sqlCacheDependency enabled = "true" pollTime = "1000" > <databases> <add name="Northwind" connectionStringName="NorthwindConnectionString1" pollTime = "1000" /> </databases> </sqlCacheDependency> </caching>

follow this link for example-

http://msdn.microsoft.com/en-us/library/ms178604.aspx
http://msdn.microsoft.com/en-us/library/e3w8402y.aspx

kalpana aparnathi replied to Mahesh B on 05-Jan-12 03:53 AM

hi,



// Insert the cache item.

CacheDependency dep = new CacheDependency(fileName, dt);

cache.Insert("key", "value", dep);

// Check whether CacheDependency.HasChanged is true.

if (dep.HasChanged)

Response.Write("<p>The dependency has changed.");

else Response.Write("<p>The dependency has not changed."

);





Thanks,

Riley K replied to Mahesh B on 05-Jan-12 04:04 AM

Here is a simple example

protected void Page_Load(object sender, EventArgs e)

{

string fileContent = Cache["SampleFile"] as string;

if (string.IsNullOrEmpty(fileContent))

{

using (StreamReader sr = File.OpenText(Server.MapPath("~/SampleFile.txt")))

{

fileContent = sr.ReadToEnd();

Cache.Insert("SampleFile", fileContent, new System.Web.Caching.CacheDependency(Server.MapPath("~/SampleFile.txt")));

}

TextBox1.Text = fileContent;

}

the application checks the cache for an item in the cache named SampleFile and assigns the value to the fileContent variable.

Regards