Caching in ASP.Net

   Caching in ASP.Net

When you store most frequently used data on to the temporary storage and providing to different clients request, then it is called as caching.

The main advantage of caching is to improve the performance of the web server by reducing the processing time.

When you are expecting more no. of requests to a web page within a particular time interval, also the web page is having database interaction and the data within the database is not changing frequently then apply the caching.

ASP 3.0 supports, entire page caching only at client side.

ASP.Net supports 3 types of caching,

a. Output Caching (Entire page Caching) 
b. Fragment Caching (Portion of web Page as Caching)

c. Data Caching (memory Variable Caching)

Output caching is also termed as entire page caching.

When you want to maintain multiple buffers content towards a single web page then we require varybyparam option.

To achieve this output caching go to html view,

<%@ outputcache duration=”seconds” varybyparam=”none”%>

User defined control.

Web user control will provide reusability of graphical interfaces and coding.

It will compile dynamically along with web page.

The extension of the file is .ascx

This is local to the application, so it will not appear in the toolbox.

Caching can be applied to web user control.

When you want to make use of web user control within a web page then .ascx file has to be registered with the web page.

i.e. under html view,

<%@ Register TagPrefix="uc1" TagName="WebUserControl1" Src="WebUserControl1.ascx"%>

      A web user control is similar to webform but can’t be called independently.

It has to be contained by web form.

When you apply caching on a portion of web page then it is called as fragment caching. This can be achieved under web user control.

Data caching

When you apply caching on the memory variables, then it is called as data caching. This can be classified into three types.

1.           Ordinary caching

2.           File based dependency data caching

3.           Time based dependency data caching

In asp.net the alternative for application memory is provided with data caching.

This will overcome all the drawbacks of application memory variable like,

1. Data caching is a thread safe as compared to application memory.

So the lock method will be applied implicitly to the variable, which is used for modification.

Application. Lock ()

Application. Unlock ()

(Not required in case of caching)

2. Data caching supports expiry policy for the data, which is not supported by application memory variable.

System.web.caching (namespace)

                                   

Cache class

CacheDependency Class

Ordinary data caching

Cache. Insert (“A”, 100)

Or

Cache (“A”) = 100

File based dependency data caching

When you want to provide expiry policy of data, based on time stamp of the file, then it is called as file based dependency data caching.

Time based dependency data caching

When you want to provide expiry policy of data, based on time, then it is called as time based dependency data caching.

Time can be based on two types.

1.           Absolute time will be considered from storage time.

2.           Sliding time will be considered from the last access.

When it comes to data caching, the content will be erased, when application demands for the memory.