Output Caching in asp.net

Recently one of my friend ask about output cache so I decided to put a post about how output cache works and what is the advantages and disadvantage of using output cache. Output cache is a technique to cache generated response from the asp.net pages or controls. Output Caching increases the performance drastically by reducing server round trips. We can use @OutputCache directive to controls output caching for a page or controls.

The @OutputCache includes following attributes.

• Duration: This attribute will explain how long output cache will be there for a page or control. It can be set in seconds. If you set 60 then it will not going to generate response from server until 60 second It will generate response from the cache it self. Here is example of duration where it will set 60 second for page.

<%@ OutputCache Duration="60" %>  

• VaryByParam: This attribute will determine cache entries based on get or post parameters. It will vary cache based on get or post parameters suppose you set product Id query string as VaryByParam it will create a different cache based on product Id. Following is a example how you can set the VaryByParam based on Product Id.
  

<%@ OutputCache Duration="Seconds" VaryByParam="ProductId"%>

• Location: This attribute will specify where the Item will be cached. Here are options available for that.
• Any: The output cache can be located at any browser from where request is generated or Server where request is processed or Proxy server participating in request.
  
• Client: The output cache will be located on browser client from where request is generated.
  
• Downstream: The output cache can be stored in any HTTP 1.1 cache-capable devices other than the origin server. This includes proxy servers and the client that made the request.
  
• Server: The output cache will stored in the server where generated request will be processed.
  
• ServerAndClient: The output cache will generated either on Browser where request generated or on server where generated request will be processed. Proxy servers are not allowed for this.
  
• None: None specifies that output cache will be disabled for this controls or Page.

Here is example of location.

<%@ outputcache duration="10"  Location="Server" %>

• VaryByCustom: This attribute is for different browsers where request is generated this means it will generate new instance of cache based on different browser versions.
  

<%@ OutputCache Duration="Seconds" VaryByCustom="Browser" %>

• VaryByHeader: This attribute allows to determine different instances of cache based on the headers. Here is example for it.
  

<%@ OutputCache VaryByHeader="Accept-Language" %>

Note: If you specify the output cache it will not fire server side events like click or selected index changed etc. So make sure the controls that you used in output cache will not have this kind of controls Or you have to handle this in other scenarios.

Hope this will help you.. Happy programming!!

Technorati Tags: Cache,OutputCache,ASP.NET

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Difference between sliding expiration and absolute expiration

ASP.net cache is great feature through which we can increase the performance of the our web application via reducing server round trips to database. We can cache any serializable data into the cache. There are so many ways to cache data but one of the simplest way to cache data like insert data into cache object. Here we must need to validate cache if any data is changed and there are so many ways from where we can set dependency to validate the cache like files,SQL Cache Dependency etc. We also can validate cache or expire via setting time to duration to its object. Like after the defined time our cache will expire and then it will again put new fresh data into the cache. This is called as time base expiration. We can put this kind of expiration via two way.

1. Absolute Expiration
2. Sliding Expiration

Absolute Expiration: Absolute expiration means It will expire cache after some time period set at the time of activating cache. This will be absolute expiration whether cache will be used or not It will expire the cache. This type of expiration used to cache data which are not frequently changing.

Sliding Expiration: Sliding expiration means It will expire cache after time period at the time of activating cache if any request is not made during this time period. This type of expiration is useful when there are so many data to cache. So It will put those items in the cache which are frequently used in the application. So it will not going to use unnecessary memory.

Here is the example how we can set the sliding expiration and absolute expiration.

string cacheData = "The data to be cached";
//Absolute Expiration
Cache.Insert("AbsoluteCacheKey", cacheData, null,
DateTime.Now.AddMinutes(1), System.Web.Caching.Cache.NoSlidingExpiration);
//Sliding Expiration
Cache.Insert("SlidingExpiration", cacheData, null,
System.Web.Caching.Cache.NoAbsoluteExpiration, TimeSpan.FromMinutes(1));

In above example I have created the a string to be cache that can be any serialized data. In the absolute expiration you can see that it will expires after one minute whether its accessed or not. While in sliding expiration it will expire cache if cache is not accessed within specified time.

Hope this will help you for better understanding of asp.net caching technique. Happy programming!!!

Technorati Tags: Cache,Absolute,Sliding

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LinqDatasource A Great Control for declarative programming

I have used data source control many times and its great it provides us great features for declarative binding. LinqDataSource Control is a great control and it allows us to bind linq queries without writing any code declaratively. Let’s create a example in that example I am not going to write a single line of code and we are going to create view,Update and Delete functionality.

So first we need a table which will have data. So, I am going to use the same table which I have used in my old posts. Below is the table structure for this example.

Let’s insert some data for that table structure. I have already inserted it in previous example. Just like below.

Now, To bind a linqdatasource we need a Linq-To-SQL Data context class Let’s create it via Project->Right Click->Add New Item –>Go to data tab->Linq-To-SQL classes Just like following.

After that I have just dragged user data to my data context just like following.

After creating Our Linq-To-SQL Classes Let’s just Add the A grid View control to my default.aspx page and apply some default format like this.

Now Let’s add a LinqDataSource from the toolbox like following.

Now select the data source and click configure data source as we can see as below.

After clicking on the Configure Data source a wizard will appear which will allow us to select Linq-to-SQL Context class just like following.

After clicking on next it will allow us to select the Linq-To-SQL Table. In our case it is a Users table so select user table just like following and select * for all columns.

Click finish now our Linq Data Source is Ready Now select the grid view and select Linq Data source we just created like below.

Now our grid view is ready We just need to select Enable Sorting and Enable Paging to give default sorting and paging functionality to grid view. Now do to aspx file and you will see that grid view control is created. I have set two more properties AutoGenerateDeleteButton and AutoGenerateEditButton property of grid view to true as we need to create update and delete functionality also. Just like below.

<asp:GridView ID="GridView1" runat="server" CellPadding="4" ForeColor="#333333"
GridLines="None" AllowPaging="True" AllowSorting="True"
AutoGenerateColumns="False" DataSourceID="LinqDataSource1"
AutoGenerateDeleteButton="True" AutoGenerateEditButton="True"
DataKeyNames="UserId" >
<AlternatingRowStyle BackColor="White" />
<Columns>
<asp:BoundField DataField="UserId" HeaderText="UserId"
SortExpression="UserId" ReadOnly="True" />
<asp:BoundField DataField="UserName" HeaderText="UserName"
SortExpression="UserName" />
<asp:BoundField DataField="FirstName" HeaderText="FirstName"
SortExpression="FirstName" />
<asp:BoundField DataField="LastName" HeaderText="LastName"
SortExpression="LastName" />
</Columns>
<EditRowStyle BackColor="#2461BF" />
<FooterStyle BackColor="#507CD1" Font-Bold="True"
ForeColor="White" />
<HeaderStyle BackColor="#507CD1" Font-Bold="True"
ForeColor="White" />
<PagerStyle BackColor="#2461BF" ForeColor="White"
HorizontalAlign="Center" />
<RowStyle BackColor="#EFF3FB" />
<SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True"
ForeColor="#333333" />
<SortedAscendingCellStyle BackColor="#F5F7FB" />
<SortedAscendingHeaderStyle BackColor="#6D95E1" />
<SortedDescendingCellStyle BackColor="#E9EBEF" />
<SortedDescendingHeaderStyle BackColor="#4870BE" />
</asp:GridView>

Then go to Linq Data source and set EnableDelete and EnableUpdate property to true as we need this functionality. Just like following.

<asp:LinqDataSource ID="LinqDataSource1" runat="server"
ContextTypeName="Blog.MyBlogDataContext"
EntityTypeName="" TableName="Users"
EnableDelete="True" EnableUpdate="True">
</asp:LinqDataSource>

That’s it now everything is ready lets run the example and see how its works here is the update example and its working fine as should.

So It’s very easy to create this kind of functionality. Hope this help you.. Happy Programming..

Technorati Tags: Linq-To-Sql,LinqDataSource,Linq,ASP.NET,Datasource

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