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B.COM – COMPUTER – III YEAR - NOTES
WEB PROGRAMMING

INDEX – UNIT - IV

S.no: Title Page no:

1. Active Server Pages (ASP) Introduction 02 - 03

2. Scripting Languages and Script Engines 03 - 03

3. ASP Objects 04 - 13
i. ASP Response 04 - 05
ii. ASP Request 05 - 07
iii. ASP Application 07 - 07
iv. ASP Session 07 - 07
v. ASP Server 07 - 08
vi. ASP Error 08 - 09
vii. ASP FileSystem 09 - 09
viii. ASP TextStream 09 - 10
ix. ASP Drive 10 – 10
x. ASP File 11 - 11
xi. ASP Folder 11 - 12
xii. ASP Dictionary 12 - 12
xiii. ASP ADO 13 - 13

4. ASP Application 14 - 16

6. Conclusion 16 - 16

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Active Server Pages (ASP) Introduction

Active Server Pages (ASP), also known as Classic ASP or ASP Classic,
was Microsoft's firstserver-side script-engine for dynamically-generated web pages.
Initially released as an add-on toInternet Information Services (IIS) via the Windows NT
4.0 Option Pack (ca 1998), it was subsequently included as a free component of
Windows Server (since the initial release ofWindows 2000 Server). ASP.NET has
superseded ASP.

ASP 2.0 provided six built-in objects: Application, ASPError, Request, Response,
Server, and Session. Session, for example, represents a cookie-based session that
maintains the state of variables from page to page. The Active Scripting engine's
support of the Component Object Model (COM) enables ASP websites to access
functionality in compiled libraries such as DLLs.

Web pages with the .asp file extension use ASP, although some web sites disguise their
choice of scripting language for security purposes (e.g. still using the more
common .htm or .htmlextension). Pages with the .aspx extension use
compiled ASP.NET (based on Microsoft's .NET Framework), which makes them faster
and more robust than server-side scripting in ASP, which is interpreted at run-time;
however, ASP.NET pages may still include some ASP scripting. The introduction of
ASP.NET led to use of the term Classic ASP for the original technology.

Programmers write most ASP pages using VBScript, but any other Active Scripting
engine can be selected instead with the @Languagedirective or the <script
language="language" runat="server"> syntax. JScript (Microsoft's implementation
of ECMAScript) is the other language that is usually available. PerlScript (a derivative
of Perl) and others are available as third-party installable Active Scripting engines.
What is ASP?

• ASP stands for Active Server Pages
• ASP is a Microsoft Technology
• ASP is a program that runs inside IIS
• IIS stands for Internet Information Services
• IIS comes as a free component with Windows 2000
• IIS is also a part of the Windows NT 4.0 Option Pack
• The Option Pack can be downloaded from Microsoft
• PWS is a smaller - but fully functional - version of IIS
• PWS can be found on your Windows 95/98 CD

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ASP Compatibility

• To run IIS you must have Windows NT 4.0 or later
• To run PWS you must have Windows 95 or later
• ChiliASP is a technology that runs ASP without Windows OS
• InstantASP is another technology that runs ASP without Windows

What is an ASP File?

• An ASP file is just the same as an HTML file
• An ASP file can contain text, HTML, XML, and scripts
• Scripts in an ASP file are executed on the server
• An ASP file has the file extension ".asp"

How Does ASP Differ from HTML?

• When a browser requests an HTML file, the server returns the file
• When a browser requests an ASP file, IIS passes the request to the ASP engine.
The ASP engine reads the ASP file, line by line, and executes the scripts in the
file. Finally, the ASP file is returned to the browser as plain HTML

What can ASP do for you?

• Dynamically edit, change, or add any content of a Web page
• Respond to user queries or data submitted from HTML forms
• Access any data or databases and return the results to a browser
• Customize a Web page to make it more useful for individual users
• The advantages of using ASP instead of CGI and Perl, are those of simplicity
and speed
• Provide security - since ASP code cannot be viewed from the browser
• Clever ASP programming can minimize the network traffic

Note: Because ASP scripts are executed on the server, the browser that displays
the ASP file does not need to support scripting at all!

Scripting Languages and Script Engines
We have seen that Active Server Pages are really a combination of VBScript and HTML
tags. Processing these scripts on the server generates the dynamic HTML that can be
rendered in any browser. VBScript is the default scripting language, although you could
use JScript. All of our examples use the native VBScript. Everything within the <% %>is
written in VBScript, which has almost identical syntax to VB.

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ASP Objects
ASP Response
ASP Request
ASP Application
ASP Session
ASP Server
ASP Error
ASP FileSystem
ASP TextStream
ASP Drive
ASP File
ASP Folder
ASP Dictionary
ASP ADO
ASP Response Object
The ASP Response object is used to send output to the user from the server.
The ASP Response object is used to send output to the user from the server. Its
collections, properties, and methods are described below:
Collections
Collection Description
Cookies Sets a cookie value. If the cookie does not exist, it will be created,
and take the value that is specified

Properties
Property Description
Buffer Specifies whether to buffer the page output or not
CacheControl Sets whether a proxy server can cache the output generated by
ASP or not
Charset Appends the name of a character-set to the content-type header
in the Response object
ContentType Sets the HTTP content type for the Response object
Expires Sets how long (in minutes) a page will be cached on a browser
before it expires
ExpiresAbsolute Sets a date and time when a page cached on a browser will
expire
IsClientConnected Indicates if the client has disconnected from the server
Pics Appends a value to the PICS label response header
Status Specifies the value of the status line returned by the server

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Methods
Method Description
AddHeader Adds a new HTTP header and a value to the HTTP response
AppendToLog Adds a string to the end of the server log entry
BinaryWrite Writes data directly to the output without any character
conversion
Clear Clears any buffered HTML output
End Stops processing a script, and returns the current result
Flush Sends buffered HTML output immediately
Redirect Redirects the user to a different URL
Write Writes a specified string to the output

ASP Request Object
The ASP Response object is used to send output to the user from the server.
The ASP Response object is used to send output to the user from the server. Its
collections, properties, and methods are described below:
Collections
Collection Description
Cookies Sets a cookie value. If the cookie does not exist, it will be created,
and take the value that is specified

Properties
Property Description
Buffer Specifies whether to buffer the page output or not
CacheControl Sets whether a proxy server can cache the output generated by
ASP or not
Charset Appends the name of a character-set to the content-type header
in the Response object
ContentType Sets the HTTP content type for the Response object
Expires Sets how long (in minutes) a page will be cached on a browser
before it expires
ExpiresAbsolute Sets a date and time when a page cached on a browser will
expire
IsClientConnected Indicates if the client has disconnected from the server
Pics Appends a value to the PICS label response header
Status Specifies the value of the status line returned by the server

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Methods
Method Description
AddHeader Adds a new HTTP header and a value to the HTTP response
AppendToLog Adds a string to the end of the server log entry
BinaryWrite Writes data directly to the output without any character
conversion
Clear Clears any buffered HTML output
End Stops processing a script, and returns the current result
Flush Sends buffered HTML output immediately
Redirect Redirects the user to a different URL
The Request object is used to get information from a visitor.

When a browser asks for a page from a server, it is called a request. The Request
object is used to get information from a visitor. Its collections, properties, and methods
are described below:

Collections
Collection Description
ClientCertificate Contains all the field values stored in the client certificate
Write
Writes a specified string to the output
The Request object is used to get information from a visitor.

When a browser asks for a page from a server, it is called a request. The Request
object is used to get information from a visitor. Its collections, properties, and methods
are described below:

Collections
Collection Description
ClientCertificate Contains all the field values stored in the client certificate
Cookies Contains all the cookie values sent in a HTTP request
Form Contains all the form (input) values from a form that uses the post
method
QueryString Contains all the variable values in a HTTP query string
ServerVariables Contains all the server variable values

Properties
Property Description
TotalBytes Returns the total number of bytes the client sent in the body of
the request

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Methods
Method Description
BinaryRead Retrieves the data sent to the server from the client as part of a
post request and stores it in a safe array

ASP Application Object
A group of ASP files that work together to perform some purpose is called an
application. The Application object is used to tie these files together.

An application on the Web may consists of several ASP files that work together to
perform some purpose. The Application object is used to tie these files together.

The Application object is used to store and access variables from any page, just like the
Session object. The difference is that ALL users share ONE Application object (with
Sessions there is ONE Session object for EACH user).

The Application object holds information that will be used by many pages in the
application (like database connection information). The information can be accessed
from any page. The information can also be changed in one place, and the changes will
automatically be reflected on all pages.

ASP Session Object
A Session object stores information about, or change settings for a user session.

When you are working with an application on your computer, you open it, do some
changes and then you close it. This is much like a Session. The computer knows who
you are. It knows when you open the application and when you close it. However, on
the internet there is one problem: the web server does not know who you are and what
you do, because the HTTP address doesn't maintain state.

ASP solves this problem by creating a unique cookie for each user. The cookie is sent
to the user's computer and it contains information that identifies the user. This interface
is called the Session object.

The Session object stores information about, or change settings for a user session.

Variables stored in a Session object hold information about one single user, and are
available to all pages in one application. Common information stored in session
variables are name, id, and preferences. The server creates a new Session object for
each new user, and destroys the Session object when the session expires.

ASP Server Object
The Server object is used to access properties and methods on the server.

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The ASP Server object is used to access properties and methods on the server. Its
properties and methods are described below:

Properties
Property Description
ScriptTimeout Sets or returns the maximum number of seconds a script can run
before it is terminated

Methods
Method Description
CreateObject Creates an instance of an object
Execute Executes an ASP file from inside another ASP file
GetLastError() Returns an ASPError object that describes the error condition that
occurred
HTMLEncode Applies HTML encoding to a specified string
MapPath Maps a specified path to a physical path
Transfer Sends (transfers) all the information created in one ASP file to a
second ASP file
URLEncode Applies URL encoding rules to a specified string

ASP ASPError Object
The ASPError object was implemented in ASP 3.0 and is available in IIS5 and later.

The ASPError object is used to display detailed information of any error that occurs in
scripts in an ASP page.

Note: The ASPError object is created when Server.GetLastError is called, so the error
information can only be accessed by using the Server.GetLastError method.

The ASPError object's properties are described below (all properties are read-only):

Properties
Property Description
ASPCode Returns an error code generated by IIS
ASPDescription Returns a detailed description of the error (if the error is ASP-
related)
Category Returns the source of the error (was the error generated by ASP?
By a scripting language? By an object?)
Column Returns the column position within the file that generated the

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error
Description Returns a short description of the error
File Returns the name of the ASP file that generated the error
Line Returns the line number where the error was detected
Number Returns the standard COM error code for the error
Source Returns the actual source code of the line where the error
occurred

ASP FileSystemObject Object
The FileSystemObject object is used to access the file system on a server.

The FileSystemObject object is used to access the file system on a server.

This object can manipulate files, folders, and directory paths. It is also possible to
retrieve file system information with this object.

The following code creates a text file (c:\test.txt) and then writes some text to the file:

<%
dim fs,fname
set fs=Server.CreateObject("Scripting.FileSystemObject")
set fname=fs.CreateTextFile("c:\test.txt",true)
fname.WriteLine("Hello World!")
fname.Close
set fname=nothing
set fs=nothing
%>

The FileSystemObject object's properties and methods are described below:
Properties
Property Description
Drives Returns a collection of all Drive objects on the computer

ASP TextStream Object
The TextStream object is used to access the contents of a text file.

The TextStream object is used to access the contents of text files.

The following code creates a text file (c:\test.txt) and then writes some text to the file
(the variable f is an instance of the TextStream object):

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<%
dim fs,f
set fs=Server.CreateObject("Scripting.FileSystemObject")
set f=fs.CreateTextFile("c:\test.txt",true)
f.WriteLine("Hello World!")
f.Close
set f=nothing
set fs=nothing
%>

To create an instance of the TextStream object you can use the CreateTextFile or
OpenTextFile methods of the FileSystemObject object, or you can use the
OpenAsTextStream method of the File object.

The TextStream object's properties and methods are described below:

Properties
Property Description
AtEndOfLine Returns true if the file pointer is positioned immediately before the
end-of-line marker in a TextStream file, and false if not
AtEndOfStream Returns true if the file pointer is at the end of a TextStream file,
and false if not
Column Returns the column number of the current character position in an
input stream
Line Returns the current line number in a TextStream file

ASP Drive Object
The Drive object is used to get information about a local disk drive or a network share.

The Drive object is used to return information about a local disk drive or a network
share. The Drive object can return information about a drive's type of file system, free
space, serial number, volume name, and more.

Note: You cannot return information about a drive's content with the Drive object. For
this purpose you will have to use the Folder object.

To work with the properties of the Drive object, you will have to create an instance of the
Drive object through the FileSystemObject object. First; create a FileSystemObject
object and then instantiate the Drive object through the GetDrive method or the Drives
property of the FileSystemObject object.

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ASP File Object
The File object is used to return information about a specified file.

To work with the properties and methods of the File object, you will have to create an
instance of the File object through the FileSystemObject object. First; create a
FileSystemObject object and then instantiate the File object through the GetFile method
of the FileSystemObject object or through the Files property of the Folder object.

The following code uses the GetFile method of the FileSystemObject object to
instantiate the File object and the DateCreated property to return the date when the
specified file was created:

Example

<%
Dim fs,f
Set fs=Server.CreateObject("Scripting.FileSystemObject")
Set f=fs.GetFile("c:\test.txt")
Response.Write("File created: " & f.DateCreated)
set f=nothing
set fs=nothing
%>

ASP Folder Object
The Folder Object is used to return information about a specified folder.

The Folder object is used to return information about a specified folder.

To work with the properties and methods of the Folder object, you will have to create an
instance of the Folder object through the FileSystemObject object. First; create a
FileSystemObject object and then instantiate the Folder object through the GetFolder
method of the FileSystemObject object.

The following code uses the GetFolder method of the FileSystemObject object to
instantiate the Folder object and the DateCreated property to return the date when the
specified folder was created:

<%
Dim fs,fo
Set fs=Server.CreateObject("Scripting.FileSystemObject")
Set fo=fs.GetFolder("c:\test")
Response.Write("Folder created: " & fo.DateCreated)

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set fo=nothing
set fs=nothing
%>

Output:

Folder created: 10/22/2008 10:01:19 AM

ASP Dictionary Object
The Dictionary object stores information in name/value pairs.

The Dictionary object is used to store information in name/value pairs (referred to as
key and item). The Dictionary object might seem similar to Arrays, however, the
Dictionary object is a more desirable solution to manipulate related data.

Comparing Dictionaries and Arrays:

• Keys are used to identify the items in a Dictionary object
• You do not have to call ReDim to change the size of the Dictionary object
• When deleting an item from a Dictionary, the remaining items will automatically
shift up
• Dictionaries cannot be multidimensional, Arrays can
• Dictionaries have more built-in functions than Arrays
• Dictionaries work better than arrays on accessing random elements frequently
• Dictionaries work better than arrays on locating items by their content

The following example creates a Dictionary object, adds some key/item pairs to it, and
retrieves the item value for the key gr:

<%
Dim d
Set d=Server.CreateObject("Scripting.Dictionary")
d.Add "re","Red"
d.Add "gr","Green"
d.Add "bl","Blue"
d.Add "pi","Pink"
Response.Write("The value of key gr is: " & d.Item("gr"))
%>

Output:

The value of key gr is: Green

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ASP ADO

ADO can be used to access databases from your web pages.

Accessing a Database from an ASP Page

The common way to access a database from inside an ASP page is to:

1. Create an ADO connection to a database
2. Open the database connection
3. Create an ADO recordset
4. Open the recordset
5. Extract the data you need from the recordset
6. Close the recordset
7. Close the connection

What is ADO?

• ADO is a Microsoft technology
• ADO stands for ActiveX Data Objects
• ADO is a Microsoft Active-X component
• ADO is automatically installed with Microsoft IIS
• ADO is a programming interface to access data in a database

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ASP Application
A group of ASP files that work together to perform some purpose is called an
application.

Application Object

An application on the Web may consists of several ASP files that work together to
perform some purpose. The Application object is used to tie these files together.

The Application object is used to store and access variables from any page, just like the
Session object. The difference is that ALL users share ONE Application object (with
Sessions there is ONE Session object for EACH user).

The Application object holds information that will be used by many pages in the
application (like database connection information). The information can be accessed
from any page. The information can also be changed in one place, and the changes will
automatically be reflected on all pages.

Store and Retrieve Application Variables

Application variables can be accessed and changed by any page in an application.

You can create Application variables in "Global.asa" like this:

<script language="vbscript" runat="server">
Sub Application_OnStart
application("vartime")=""
application("users")=1
End Sub
</script>

In the example above we have created two Application variables: "vartime" and "users".

You can access the value of an Application variable like this:

There are
<%
Response.Write(Application("users"))
%>
active connections.

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Loop Through the Contents Collection

The Contents collection contains all application variables. You can loop through the
Contents collection, to see what's stored in it:

<%
dim i
For Each i in Application.Contents
Response.Write(i & "<br />")
Next
%>

If you do not know the number of items in the Contents collection, you can use the
Count property:

<%
dim i
dim j
j=Application.Contents.Count
For i=1 to j
Response.Write(Application.Contents(i) & "<br />")
Next
%>

Loop Through the StaticObjects Collection

You can loop through the StaticObjects collection, to see the values of all objects stored
in the Application object:

<%
dim i
For Each i in Application.StaticObjects
Response.Write(i & "<br />")
Next
%>

Lock and Unlock

You can lock an application with the "Lock" method. When an application is locked, the
users cannot change the Application variables (other than the one currently accessing
it). You can unlock an application with the "Unlock" method. This method removes the
lock from the Application variable:

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<%
Application.Lock
'do some application object operations
Application.Unlock
%>

Conclusion

ASP technology is a server-side programming developed to enable dynamic web
pages. With its build-in objects and ActiveX components, ASP developers can create a
dynamic web page and make use of database access. Now that you have basic
knowledge
about ASP, it is better to have a hands-on experience, which is the best way to learn to
learn how to write an ASP file. Enjoy and good luck!

KNOWLEDGE IS POWER

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