Catching is a technique to store frequent use data and information into the memory temporarily. As the information and data is storeed in the memory, if this is requested again, instead of requesting server, data and information is fetch from the memory . This makes an website faster in performance . Some pages are dynamically generated , these are cost heavy CPU usage and time consuming. If this is catched , CPU usage reduce and delivery faster to the client.
Catching still possible
- Object lifetimes not expired
- An application has not released memories
- Error or exception did not occurred during catching.
In this chapter we will go to several kind of catching technique
- Catching web forms
- Catching part of forms
- Catching application data
- Monitor catching performance
Below is the example of the same.
Example 1
<%@
Page
Language="C#"
AutoEventWireup="true"
CodeFile="Default.aspx.cs"
Inherits="_Default"
EnableViewState="false"
%>
<%@
OutputCache
Duration="60"
VaryByParam="*"
%>
<!DOCTYPE
html
PUBLIC
"-//W3C//DTD
XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html
xmlns="http://www.w3.org/1999/xhtml">
<head
runat="server">
<title></title>
</head>
<body>
<form
id="form1"
runat="server">
<div>
</div>
<asp:Button
ID="Button1"
runat="server"
Text="Submit"
/>
</form>
</body>
</html>
using
System;
using
System.Web;
using
System.Web.UI;
using
System.Web.UI.WebControls;
public
partial
class
_Default
: System.Web.UI.Page
{
protected
void
Page_Load(object
sender, EventArgs
e)
{
Response.Write(DateTime.Now.ToString("h:mm:ss
tt"));
}
}
(Notice that Time is same after postback)
The above example catch the waveform for 20 second .Output cache has two parameter , duration and VaryByParam. Duration tell the time limit the page should be kept in the memory and VaryByParam allowed to multiple resource that could be kept in the memory.
Example
<%@
Page
Language="C#"
AutoEventWireup="true"
CodeFile="Default.aspx.cs"
Inherits="_Default"
EnableViewState="false"
%>
<%@
OutputCache
Duration="60"
VaryByParam="DropDownList1"
%>
<!DOCTYPE
html
PUBLIC
"-//W3C//DTD
XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html
xmlns="http://www.w3.org/1999/xhtml">
<head
runat="server">
<title></title>
</head>
<body>
<form
id="form1"
runat="server">
<div>
<asp:DropDownList
ID="DropDownList1"
runat="server">
<asp:ListItem>India</asp:ListItem>
<asp:ListItem>USA</asp:ListItem>
<asp:ListItem>UK</asp:ListItem>
<asp:ListItem>Brazil</asp:ListItem>
<asp:ListItem>Australia</asp:ListItem>
</asp:DropDownList>
</div>
<asp:Button
ID="Button1"
runat="server"
Text="Submit"
/>
</form>
</body>
</html>
using
System;
using
System.Web;
using
System.Web.UI;
using
System.Web.UI.WebControls;
public
partial
class
_Default
: System.Web.UI.Page
{
protected
void
Page_Load(object
sender, EventArgs
e)
{
Response.Write(DateTime.Now.ToString("h:mm:ss
tt"));
}
}
HttpCachePolicy class to control output caching, below is some commonly used method of
HttpCachePolicy class
ByValueParam : Catch multiple response from singular
form.
ByValueHeader : Catch multiple response from a single form based on http header.
SetVaryByCustom: Catch it multiple response depending on string.
SetExpires : How long the catch you would be in memory.
SetCacheability : The location what to save information client host server proxy server ect.
ByValueHeader : Catch multiple response from a single form based on http header.
SetVaryByCustom: Catch it multiple response depending on string.
SetExpires : How long the catch you would be in memory.
SetCacheability : The location what to save information client host server proxy server ect.
HttpCacheability is an enumaration for where the data / information will be stored.
| * | Option | Stored Location |
|---|---|---|
| Any | HttpCacheability.Server | Any ,Client ,Proxy & Host |
| Client | HttpCacheability.Private | Client |
| DownStream | HttpCacheability.Public | Client or Proxy |
| Server | HttpCacheability.ServerAndNoCache | Host Server |
| Server and Client | HttpCacheability.ServerAndPrivate | Host Server & Client |
Here is the use of HttpCacheability enumeration.The following syntax tell that Response will be catched for 60 second and it would be catched to Client or ProxyServer
Response.Cache.SetExpires(DateTime.Now.AddSeconds(60));
Response.Cache.SetCacheability(HttpCacheability.Public);
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