You are on page 1of 16

1

B.COM – COMPUTER – III YEAR - NOTES

WEB PROGRAMMING
INDEX – UNIT - IV
S.no:

Title Active Server Pages (ASP) Introduction Scripting Languages and Script Engines ASP Objects
ASP ASP ASP ASP ASP ASP ASP ASP ASP ASP ASP ASP ASP Response Request Application Session Server Error FileSystem TextStream Drive File Folder Dictionary ADO

Page no: 02 - 03 03 - 03 04 - 13
04 - 05 05 - 07 07 - 07 07 - 07 07 - 08 08 - 09 09 - 09 09 - 10 10 – 10 11 - 11 11 - 12 12 - 12 13 - 13

1. 2. 3.
i. ii. iii. iv. v. vi. vii. viii. ix. x. xi. xii. xiii.

4. 6.

ASP Application Conclusion

14 - 16 16 - 16

http://www.saif4u.webs.com

2

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 ASP.NET has superseded ASP.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

http://www.saif4u.webs.com

3 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.

http://www.saif4u.webs.com

4

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

http://www.saif4u.webs.com

5 Methods Method AddHeader AppendToLog BinaryWrite Clear End Flush Redirect Write Description Adds a new HTTP header and a value to the HTTP response Adds a string to the end of the server log entry Writes data directly to the output without any character conversion Clears any buffered HTML output Stops processing a script, and returns the current result Sends buffered HTML output immediately Redirects the user to a different URL 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 Cookies Properties Property Buffer CacheControl Charset ContentType Expires ExpiresAbsolute IsClientConnected Pics Status Description Specifies whether to buffer the page output or not Sets whether a proxy server can cache the output generated by ASP or not Appends the name of a character-set to the content-type header in the Response object Sets the HTTP content type for the Response object Sets how long (in minutes) a page will be cached on a browser before it expires Sets a date and time when a page cached on a browser will expire Indicates if the client has disconnected from the server Appends a value to the PICS label response header Specifies the value of the status line returned by the server Description Sets a cookie value. If the cookie does not exist, it will be created, and take the value that is specified

http://www.saif4u.webs.com

6 Methods Method AddHeader AppendToLog BinaryWrite Clear End Flush Description Adds a new HTTP header and a value to the HTTP response Adds a string to the end of the server log entry Writes data directly to the output without any character conversion Clears any buffered HTML output Stops processing a script, and returns the current result 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 ClientCertificate Cookies Form QueryString ServerVariables Properties Property TotalBytes Description Returns the total number of bytes the client sent in the body of the request http://www.saif4u.webs.com Description Contains all the field values stored in the client certificate Contains all the cookie values sent in a HTTP request Contains all the form (input) values from a form that uses the post method Contains all the variable values in a HTTP query string Contains all the server variable values

7 Methods Method BinaryRead Description 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. http://www.saif4u.webs.com

8 The ASP Server object is used to access properties and methods on the server. Its properties and methods are described below: Properties Property ScriptTimeout Methods Method CreateObject Execute GetLastError() HTMLEncode MapPath Transfer URLEncode Description Creates an instance of an object Executes an ASP file from inside another ASP file Returns an ASPError object that describes the error condition that occurred Applies HTML encoding to a specified string Maps a specified path to a physical path Sends (transfers) all the information created in one ASP file to a second ASP file Applies URL encoding rules to a specified string Description Sets or returns the maximum number of seconds a script can run before it is terminated

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

http://www.saif4u.webs.com

9 error Description File Line Number Source Returns a short description of the error Returns the name of the ASP file that generated the error Returns the line number where the error was detected Returns the standard COM error code for the error 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 Drives Description 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):

http://www.saif4u.webs.com

10

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

http://www.saif4u.webs.com

11

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)

http://www.saif4u.webs.com

12

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

http://www.saif4u.webs.com

13

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

http://www.saif4u.webs.com

14

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.

http://www.saif4u.webs.com

15

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:

http://www.saif4u.webs.com

16

<% Application.Lock 'do some Application.Unlock %>

application

object

operations

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

http://www.saif4u.webs.com