aspnet information technology

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Session 21

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Review



ASP.NET is a collection of all the ASP.NET pages, the custom

controls, and modules



It provides the configuration files to customize the web site.



The ASP.NET configuration files are written in XML, which enables

the developer to modify them using an XML parser.



Two types of configuration files exist in ASP.NET:



<b>Machine.Config </b>



<b>Web.Config</b>



A hierarchical structure can be formed with every directory,

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Review Contd…



Within the configuration tags, the configuration information is

grouped into two categories:



<b>The configuration section handler declaration area </b>



<b>The configuration section settings area</b>

.



The process of validating the user name and password is known as

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Objectives



Trace an ASP.NET application



Debug an ASP.NET application



Explain Data and Output caching

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Tracing



The process of locating

errors in a code is known as

<b>tracing</b>



Tracing is a new feature of

ASP.NET, as previous

versions of ASP did not

support tracing



Tracing in ASP.NET is

provided at two levels:



Page-Level Tracing

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Page-Level Tracing



The intrinsic controls like Trace are used to write

custom debugging statements



These statements appear at the end of the output that is

delivered to the client



Apart from just inserting statements at the end of the

clients’ output, ASP.NET also provides a few methods

like Init and Pre-Render, which print messages in the

trace information block of the page



To enable page level debugging for a page, the following

page directive has to be included at the beginning of the

page code.

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Page-Level Tracing Example

<% @Page Trace="True" TraceMode="SortByCategory" %>
<html>

<head>

<title>Page level Tracing</title>
</head>

<body>

<h1>A Program to test Trace...</h1>
</body>

</html>

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Trace Information Categories

<b>Category </b>

<b>Description </b>

<b>Request Details </b> <b>Lists all the information of the request </b>

<b>Trace Information </b> <b>Lists information from standard and </b>
<b>custom trace statements </b>

<b>Control Tree </b> <b>Lists all of the items in the page </b>

<b>Cookies Collection </b> <b>Lists all of the cookies of the page with </b>
<b>their values </b>

<b>Header Collection </b> <b>Lists all the items of the HTTP header </b>

<b>Form Collection </b> <b>Lists all of the form elements and their </b>
<b>values being POSTed. </b>

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Trace Example

<% @ Page Trace="True" TraceMode="SortByTime" %>
<html>

<head>

<title>Trace Methods</title>
</head>

<body>

{

Trace.Warn ("Page Init Event: Message
from Page Init");

}

void Page_Load(Object Sender, EventArgs E)

{

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Trace Example - Output

</script>

<h1>A Program to test Trace...</h1>
</body>

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Checking Trace

<b>… </b>

<b>if(Trace.IsEnabled) </b>

<b>{ </b>

<b> Trace.Warn (“Inside the Init proc! ”); </b>

<b>} </b>

<b>… </b>

Sometimes at runtime, it may be necessary to check if trace

in an ASP.NET page is enabled

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Application Level Tracing



Used for tracing an entire application



Provides data about several requests to the pages of the

application at once



Allows the developer to view statistics and information on

the inputs of the page, and additional information with

respect to the entire application



Enables page-level tracing for all pages by default



Application level tracing can be enabled, by adding the

following line of code to the <system.web> section of

the web.config file

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Application Level Tracing

Example

</system.web>
</configuration>
Once this is coded, every
page will display trace
information.

Trace.axd file in the

application root directory
displays the information

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Trace Tag Parameters

<b>Parameter</b> <b>Description</b> <b>Default Value</b>

requestLimit Sets the number of trace requests to store

on the server 10

traceMode Sets whether the statistics should be
arranged according to time or category
(takes in value sortByCategory or

sortByTime)

sortByTime

pageOutput Sets whether the trace information is to
be displayed at the bottom of every page
(takes in either true or false)

False

Enabled Sets whether application level tracing is to

be enabled. (takes in values true or false) True
localOnly Sets whether Tracing is enabled for

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Debugging an Application



In spite of the tracing options provided by ASP.NET, bugs

may still creep into the programming logic of an

application



ASP.NET provides high-end debugging, that enables the

developer to step through the code line by line, and see

how the actual execution takes place



In order to configure the ASP.NET application to debug, a

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Debugging an Application

<configuration>

<system.web>

<b><compilation debug="true"/> </b>

</system.web>

</configuration>

After configuring the application
for debug mode, the application
needs to be invoked by requesting
one of the application pages

After requesting a page, the

debugger has to be launched by
typing DbgClr.exe in the Run

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Debug window with the code

 After invoking the debugger, the ASP.NET source file that needs to be debugged
should be opened

 The next step is to open the Processes dialog box, by clicking on the Tools

menu, and then clicking on Debug processes. The show system processes option
should be checked. The Aspnet_wp.exe process should also be attached.

 To set a breakpoint in an ASP.NET page, the left-hand margin on a line

containing an executable statement or method has to be clicked

 A red dot appears where the breakpoint is set.

 Moving the mouse over the breakpoint facilitates ensuring that the breakpoint,

is appropriately mapped to the correct application instance in the

Aspnet_wp.exe process

 The <b>Watch </b>window can be used to see the intrinsic objects on the page, like

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Caching



Caching is a technique used to increase performance,

by keeping frequently accessed data in memory



In the case of a web application, caching is used to retain

pages or data across HTTP requests, and reuse them

without the expense of recompiling them

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Output Caching



Output caching refers to caching the dynamic response

generated by a request



It is useful when the contents of an entire page are to

be cached



While a page is cached by the output cache, subsequent

requests for that page are served from the cached page

without executing the code that created it



The extent to which the cache will be stored in memory

can be set



The @OutputCache directive should be added at the

beginning of a page to cache a web page



The output cache directive takes in a duration

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Output Caching Example

<b><%@ </b>OutputCache Duration="120<b>" </b>VaryByParam="none"<b> %></b>

<html>

TimeGen.Text = DateTime.Now.ToString ("G");
}

</script>
<body>

<h1>Use of Output Cache</h1>

<p><i>This page was generated on:</i>
<asp:label id="TimeGen" runat="server"/>
</body>

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Output Caching Example

More flexibility and control can be provided to the ASP.NET applications, by even
programmatically setting the duration of the cache

This can be achieved by importing the System.Web.HttpCachePolicy class, from
which the SetExpires(DateTime) method can be used.

Response.Cache.SetExpires(DateTime.Now.AddSeconds(120));
Another caching method is called <b>Sliding Expiration</b>, where the expiration
period is renewed by the value specified every time the page is accessed.

To make this sliding expiration policy, where the expiration time out resets each
time the page is requested, the SlidingExpiration property (of the class) can be
set as follows

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Data Caching



Data caching provides a simple dictionary interface, that

allows programmers to easily place objects in, and

retrieve them from the cache



Placing an item in the cache is just like adding an item to

a dictionary



The syntax for doing this is as follows

Cache["mykey"] = myValue;



To retrieve the value, following syntax can be used

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Data Caching Example

<%@ Import Namespace="System.Data" %>

<%@ Import Namespace="System.Data.SqlClient" %>
<html>

<head>

<title>Caching Data</title>
</head>

DataView mySource;

<b>mySource = (DataView) Cache ["MyCache"]; </b>
<b>if (mySource == null) </b>

SqlConnection myConnection = new SqlConnection

("server=SQLDB; database=Northwind; uid=sa; pwd =password");

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Data Caching Example

SqlDataAdapter myCommand = new SqlDataAdapter ("select * from
customers", myConnection);

DataSet myds = new Dataset();

myCommand.Fill(myds, "employee");

mySource = new DataView (myds.Tables["employee"]);<b> </b>
<b> Cache ["MyCache"] = mySource; </b>

<b> CacheMsg.Text = "Dataset created from Table";</b>
}

else
{

<b> </b> <b> CacheMsg.Text = "Dataset retrieved from Cache"; </b>

}

MyDataGrid.DataSource =mySource;
MyDataGrid.DataBind();

}

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Data Caching Example

<body>

<h3><font face="Verdana">Caching Data</font></h3>
<ASP:DataGrid id="MyDataGrid" runat="server" />

<p>

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