SEMINAR REPORT

ON

(ASP)

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COMPUTER ENGINEERING DEPARTMENT COLLEGE OF TECHNOLOGY GB PANT UNIVERSITY OF AGRIL & TECHNOLOGY

SUBMITTED TO: SUBMITTED BY:

PROF. PRABHAKAR SHILPI GUPTA COMPUTER ENGG.DEPTT. ID NO. 27882 CP-1

CONTENTS

TOPIC PAGE NO.

1. INTRODUCTION 2

2. EVOLUTION OF ASP 3

3. SERVER-SIDE SCRIPTS –SYNTAX 4

4. FEATURES OF ASP 4

5. ADVANTAGES OF USING ASP 6

6. WHAT YOU NEED TO RUN ASP 6

7. ASP SCRIPTS 7

8. THE OBJECT MODEL 8

9. COOKIES 14

10. SUBROUTINES, FUNCTIONS AND INCLUDES 15

11. HANDLING USER INPUT: FORMS AND QUERYSTRINGS 17

12. GET AND POST METHODS 18

13. CONCLUDING REMARKS 19

14. REFERENCES 20

introduction

In the language of Microsoft, Active Server Pages is an open, compile-free application environment in which you can combine HTML, scripts, and reusable ActiveX server components to create dynamic and powerful Web-based business solutions. Active Server Pages enables server side scripting for IIS with native support for both VBScript and JScript.

In other words, Active Server Pages (ASPs) are Web pages that contain server-side scripts in addition to the usual mixture of text and HTML tags. Server-side scripts are special commands you put in Web pages that are processed before the pages are sent from the server to the web-browser of someone who's visiting your website. When you type a URL in the Address box or click a link on a webpage, you're asking a web-server on a computer somewhere to send a file to the web-browser (also called a "client") on your computer. If that file is a normal HTML file, it looks the same when your web-browser receives it as it did before the server sent it. After receiving the file, your web-browser displays its contents as a combination of text, images, and sounds. [1]

In the case of an Active Server Page, the process is similar, except there's an extra processing step that takes place just before the server sends the file. Before the server sends the Active Server Page to the browser, it runs all server-side scripts contained in the page. Some of these scripts display the current date, time, and other information. Others process information the user has just typed into a form, such as a page in the website's guestbook. And you can write your own code to put in whatever dynamic information you want. To distinguish Active Server Pages from normal HTML pages, Active Server Pages are given the ".asp" extension. [1]

EVOLUTION OF ASP

Although it may seem as though Microsoft’s Active Server Pages (ASP) technology has been around forever, it is actually a relatively new technology, introduced in 1996. Prior to ASP, developers were able to create active Web sites on a Microsoft platform using the Common Gateway Interface (CGI) and Internet Server Application Programming Interface (ISAPI), each of which played a part in the evolution of ASP. [2]

CGI was the first widely accepted technique of delivering dynamic Web content. CGI is effectively a method of extending the functionality of a Web server to enable it to dynamically generate HTTP responses using a program typically written in C or a scripting language such as Perl. Along came Microsoft’s Active Server platform, which addressed the technical limitations of CGI programming. The Active Server platform was, and really still is, a set of tools that developers can utilize to write Web applications. Microsoft’s Active Server platform didn’t however originally include Active Server Pages, ASP. Developers were forced to write ISAPI extensions or filters. [2]

As useful and powerful as ISAPI extensions and filters are, they can be difficult for novice programmers to develop. ISAPI DLLs must be written in C++; and, even though Visual C++ does provide a wizard to assist with the task, this proved to be quite a barrier. Recognizing this issue, Microsoft released several short-lived Active Platform development products that were actually based on ISAPI. These included dbWeb and Internet Database Connector (IDC), which evolved into ASP. [2]

In 1996, Microsoft released Active Server Pages and as they say “the rest is history.” ASP allows developers to execute code inline within a Web page. Although, ASP technology is still a relatively new way to create dynamic Web sites, during its short life span, it has evolved to become one of the foremost dynamic Web site development products. Since 1996, there have been several versions of ASP. In 1998, Microsoft introduced ASP 2.0 as part of the Windows NT 4.0 Option Pack. With ASP 2.0 and IIS 4.0, an ASP application and its associated components could be created in a memory space separate from the Web servers space to improve fault tolerance. In 2000, with the much anticipated release of Windows 2000(and IIS 5.0), Microsoft unveiled ASP 3.0. However, running on Windows 2000, ASP’s performance was greatly improved. [2]

Server-side scripts- Syntax

Server-side scripts are special commands you put in Web pages that are processed before the pages are sent from the server to the web-browser of someone who's visiting your website Server-side scripts typically start with <% and end with %>. The <% is called an opening tag, and the %> is called a closing tag. In between these tags are the server-side scripts. You can insert server-side scripts anywhere in your webpage - even inside HTML tags. [2]

FEATURES OF ASP

a) Database Connectivity

ActiveX data Objects (ADO) enable you to retrieve and store data in the database lying on the server side such as SQL Server. ADO is provided with the built-in objects like Connection, Recordset etc for any of the manipulation with the database. [3]

b) Ad Rotator

Ad Rotator allows you to display a different page each time this page is referenced from a browser. This technique is basically used in the sites having number of advertisements to display, every time the page is loaded and reloaded, every time when a page is loaded ASP uses the information in the Rotator Schedule File to select the graphic and insert it into the page. [3]

c) Content Rotator

Content Rotator is simplified version of Ad Rotator component. Add different texts and HTML codes in the Content Schedule File and the Content Rotator will automatically display different sections on the page.

d) Browser Capabilities

Different browsers have different capabilities for displaying web pages and their contents. e.g. some browser do not show item which are placed between different frames, or some do not support the graphics or images etc. Hence it becomes very difficult for a web designer/developer to make a flexible and compliant web page. To overcome this problem you use built-in component of ASP named Browser Capabilities. It provides the flexibility in the use of display of HTML contents, i.e. it can be used to display different HTML contents on different browsers, according to their capabilities. With the use of Browser Capabilities component, you can add/remove any contents, which you send to a browser depending upon the browser capabilities

e) Content Linking

It helps in linking of several HTML pages and ASP files. The linking further helps in ease of navigation through the ASP files or HTML pages in an application. e.g. different pages of an online book.

f) Page Counter

The page counter component enables you to count and display the number of times web page has been requested i.e. it keeps track of the number of visitors visiting your web site. E.g. you must have noticed a hit counter on a web page, displaying the visitor number and a message such as “Welcome to this Page. You are the 65,002 visitor”

g) Permission Checker Component

Permission Checker Component is used to display the pages to only those users who have the permissions to view that page. This feature is used to create web pages that are to be viewed only by the administrator or for remote administration of any site. [3]

h) Emailing Capability

SMTP server is used to send and receive the mails. STMP server use Pick Up directory for new email messages and also maintains the queue of email which server is not able to send it right now. STMP server also collects all the mails and places it in the Drop Directory.

i) File System Manipulation

Active Server pages include a rich set of methods, properties, and collection to work with the files. Active Server pages have a complete control over the file system i.e. reading and writing to a file, appending the data to the files, adding and deleting those files. [3]

AdvantageS of using ASP

1) ASP adds to the Client Side Scripting

ASP adds to the client scripting making all the database checks applied in the Client Side Script and submitting the data to the database in the Server Side Script. Hence increasing the power of Server Side Script ASP makes the Client Side Script most powerful. [3]

2) ASP is Compile Free

ASP Script is compile free. Earlier all the scripts were first compiled and then copied on the web server. Even a small change requires you to compile whole application while other ASP environment is Compile free. ASP DLL present on the Web Server processes the script and returns the result back to the Client. [3]

3) ASP Development is easy to use

ASP is quite easy to learn and only the knowledge of any of the scripting language like JavaScript/VBScript is required to write the script in ASP. [3]

4) ASP Environment is Extensible

ASP environment is fully extensible and can be easily be used with several built in tasks to create interactive pages like Rotating the Advertisement, Accessing the database at the Server Side etc. [3]

What you need to run ASP

Since the server must do additional processing on the ASP scripts, it must have the ability to do so. The only servers which support this facility are Microsoft Internet Information services & Microsoft Personal Web Server. [1]

Internet Information Services

This is Microsoft’s web server designed for the Windows NT platform. It can only run on Microsoft Windows NT 4.0, Windows 2000 Professional, & Windows 2000 Server. The current version is 5.0, and it ships as a part of the Windows 2000 operating system. [1]

Personal Web Server

This is a stripped-down version of IIS and supports most of the features of ASP. It can run on all Windows platforms, including Windows 95, Windows 98 & Windows Me. Typically, ASP developers use PWS to develop their sites on their own machines and later upload their files to a server running IIS. If you are running Windows 9x or Me, your only option is to use Personal Web Server 4.0. Personal web server is designed for individual use on a single PC .It can be used at the workgroup or LAN level .It does not have the performance of security that are necessary for a cooperate Webster open to outside world. It uses shared directories to great access to different parts of your web server. [1]

ASP Scripts It is an integral element necessary for process flow. ASP is built on a scripting engine. It enables to support multiple scripting languages such as VB, Jscript and VbScript. Support for other scripting languages, such as Perl, is also available. Server side scripting provides structure for ASP. JSP is included in detailed installations of ASP. [4]
Scripting Languages In order to increase the interactivity of HTML web page, some developers turn, to scripting adding code based functionality by combining the programming languages with HTM. VBScript is a scripting language based on Microsoft’s Visual basic for application (VBA). Although scripting represents advancement in interactivity, it has its limitations. Not all browsers recognize scripting. Among those is Netscape Navigator. In fact scripting alone is generally useful only for performing client side validations prior to submitting the form to the server. [4]

VBScript

Whatever scripting language you use, you can simply enclose script statements in special delimiters for ASP. The starting delimiter is <%, and the closing delimiter is %>.VBScript, however, is the more common language, partly because it has a simpler syntax to learn, but also because VB is just so ubiquitous in the Microsoft world. Using VBScript on the server in an ASP page really isn't very different from using VB in applications, or VBA in Microsoft Office, or VBScript on ordinary Web pages as a client-side technology. Nearly all VBScript commands are available for use with ASP except for those that interact with the user. Imagine the dilemma caused by a VBScript command to display a message box on the server. This would require someone to notice and dismiss it on the server before the system could proceed. Instead, the scripting language must interact with the user through HTML and the http protocol. [4]

JAVA Script JAVA Script is Netscape’s implementation of the ECMA (European Computers Manufacturers Associates) standard. [4]

THE OBJECT MODEL

ASP is a scripting environment revolving around its Object Model. An Object Model is simply a hierarchy of objects that you may use to get services from. In the case of ASP, all commands are issued to certain inbuilt objects that correspond to the Client Request, Client Response, the Server, the Session & the Application respectively. All of these are for global use. [1]

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The Request and Response objects contain collections (bits of information that are accessed in the same way). Objects use methods to do some type of procedure and properties to store any of the object's attributes (such as color, font, or size). [1]

The Request object

The Request object retrieves the values that the client browser passed to the server during an HTTP request.

Syntax

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Collections

Client Certificate
To get the certification fields from the request issued by the Web browser. The fields that you can request are specified in the X.509 standard

Cookies
The values of cookies sent in the HTTP request.

Form
The values of form elements in the HTTP request body.

QueryString
The values of variables in the HTTP query string.

ServerVariables
The values of predetermined environment variables.

Properties

TotalBytes
Read-only. Specifies the total number of bytes the client is sending in the body of the request.

Methods

BinaryRead
Retrieves data sent to the server from the client as part of a POST request. Variable parameters are strings that specify the item to be retrieved from a collection or to be used as input for a method or property. [1]

Note All variables can be accessed directly by calling Request (variable) without the collection name. In this case, the Web server searches the collections in the following order.

♣ QueryString
♣ Form
♣ Cookies
♣ ClientCertificate
♣ ServerVariables

If a variable with the same name exists in more than one collection, the Request object returns the first instance that the object encounters. It is strongly recommended that when referring to members of the ServerVariables collection the full name be used. For example, rather than Request (AUTH_USER) use Request.ServerVariables (AUTH_USER). [1]

The Response object

The Response object is used to send information to the user. The Response object supports only Cookies as a collection (to set cookie values). The Response object also supports a number of properties and methods.

Syntax

Response.collection|property|method

Collections

Cookies
Specifies cookie values. Using this collection, you can set cookie values.

Properties

Buffer
Indicates whether page output is buffered.

CacheControl
Determines whether proxy servers are able to cache the output generated by ASP.

Charset
Appends the name of the character set to the content-type header.

ContentType
Specifies the HTTP content type for the response.

Expires
Specifies the length of time before a page cached on a browser expires.

ExpiresAbsolute
Specifies the date and time on which a page cached on a browser expires.

IsClientConnected
Indicates whether the client has disconnected from the server.

Pics
Adds the value of a PICS label to the pics-label field of the response header.

Status
The value of the status line returned by the server.

Methods

AddHeader
Sets the HTML header name to value.

AppendToLog
Adds a string to the end of the Web server log entry for this request.

BinaryWrite
Writes the given information to the current HTTP output without any character-set conversion.

Clear
Erases any buffered HTML output.

End
Stops processing the .asp file and returns the current result.

Flush
Sends buffered output immediately.

Redirect
Sends a redirect message to the browser, causing it to attempt to connect to a different URL.

Write
Writes a variable to the current HTTP output as a string. This can be done by using the construct

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or the shortcut command. [1]

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The Server object

The Server object provides access to methods and properties on the server. Most of these methods and properties serve as utility functions.

Syntax

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Properties

ScriptTimeout
The amount of time that a script can run before it times out.

Methods

CreateObject
Creates an instance of a server component. This component can be any component that you have installed on your server (such as an ActiveX ).

HTMLEncode
Applies HTML encoding to the specified string.

MapPath
Maps the specified virtual path, either the absolute path on the current server or the path relative to the current page, into a physical path.

URLEncode
Applies URL encoding rules, including escape characters, to the string. [1]

The Session object

You can use the Session object to store information needed for a particular user-session. Variables stored in the Session object are not discarded when the user jumps between pages in the application; instead, these variables persist for the entire user-session.
The Web server automatically creates a Session object when a Web page from the application is requested by a user who does not already have a session. The server destroys the Session object when the session expires or is abandoned. One common use for the Session object is to store user preferences. For example, if a user indicates that they prefer not to view graphics, you could store that information in the Session object. [1]

Note: Session state is only maintained for browsers that support cookies.

Syntax

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Collections

Contents
Contains the items that you have added to the session with script commands.

StaticObjects
Contains the objects created with the <OBJECT> tag and given session scope.

Properties

CodePage
The codepage that will be used for symbol mapping.

LCID
The locale identifier.

SessionID
Returns the session identification for this user.

Timeout
The timeout period for the session state for this application, in minutes.

Methods

Abandon
This method destroys a Session object and releases its resources.

Events
Scripts for the following events are declared in the global.asa file. [1]
Session_OnEnd
Session_OnStart

The Application object

The Application object can store information that persists for the entire lifetime of an application (a group of pages with a common root). Generally, this is the whole time that the IIS server is running. This makes it a great place to store information that has to exist for more than one user (such as a page counter). The downside of this is that since this object isn't created anew for each user, errors that may not show up when the code is called once may show up when it is called 10,000 times in a row. In addition, because the Application object is shared by all the users, threading can be a nightmare to implement. You can use the Application object to share information among all users of a given application. An ASP-based application is defined as all the .asp files in a virtual directory and its subdirectories. Because the Application object can be shared by more than one user, there are Lock and Unlock methods to ensure that multiple users do not try to alter a property simultaneously. [1]

Syntax

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Collections

Contents
Contains all of the items that have been added to the Application through script commands.

StaticObjects
Contains all of the objects added to the session with the <OBJECT> tag.

Lock
The Lock method prevents other clients from modifying Application object properties.

Unlock
The Unlock method allows other clients to modify Application object properties.

Events

Application_OnEnd
Application_OnStart
Scripts for the preceding events are declared in the global.asa file.

Remarks

You can store values in the Application Collections. Information stored in the Application collections is available throughout the application and has application scope. [1]

Cookies

An important ASP feature is the ability to use cookies to store and retrieve information. The Request object has a Cookie collection, and you can use this in your processing.Note that cookies are actually stored on the user's computer, and not the server. This often gives cookies a bit of a bad name. Most Web browsers give a user the option of disabling cookies, so these can't always be relied upon. Where cookies can be most useful is when they work in conjunction with a database. For example, you might make a site where you require people to register. You would store all the user's details in a database on your server. To make logging in easier every time the user visits, you might store a cookie on their computer containing just their username and password. If the cookie is accepted, you can read it each time the user goes to your site, and log them in automatically - getting all the rest of their details from your database. If the cookie is not accepted, then the user will need to log in manually each time they revisit your site. [3] The Response.Cookies command is used to create cookies:

<%
Response.Cookies("firstname")="Alex"
Response.Cookies("firstname").Expires="May 10,2002"
%>

Note: The Response.Cookies command must appear BEFORE the <html> tag! The "Request.Cookies" command is used to retrieve a cookie value: [3]

<% fname=Request.Cookies("firstname") response.write("Firstname=" & fname)
%>

SUBROUTINES, FUNCTIONS AND INCLUDES

Subroutines

Subroutines are defined via the Sub keyword.

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A subroutine may accept parameters too, which can be of any type.

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Parameters do not have defined types; their usage determines the type. All parameter types are variants by default. Subroutines cannot return a value; that is, they can only be called, their value cannot be used. To return values to calling programs, we use Functions. [5]

Functions

Functions are defined similar to Subroutines:
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As seen above, the function Add adds two numbers and returns their result. We can call this function as:
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which will produce the sum as the output. More complex processing may be done inside function bodies. [5]
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Includes

Server Side Includes or SSI is a very simple programming language but it also has a very limited number of instructions. We will consider only one option SSI allows us to use within our asp scripts: include/virtual

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As we have the #include <stdio.h> statement in C, we have the #include directive here. The purpose is exactly similar: #INCLUDE actually includes the said file at the given location. Any script that is present within that file is automatically executed.
Include files are typically used to store application-wide functions and procedures, as well as various utility functions, e.g. IsValidEmail (...) a function that checks if a given string is a valid email address. You can put such functions in just 1 file, and include that on each one of your pages. Or, you may use this functionality to insert headers & footers on every page. Putting all the standard content in one file, you simply include that file in each of your pages, so you do not need to copy & paste it everywhere. Updates are easier too, since you can modify just one file and not worry about forgetting to update another. [5]

HANDLING USER INPUT: FORMS & QUERYSTRINGS

What good is a language that won’t allow you to read user input effectively! HTML, the good old markup language provides the user with forms to enter his data in, and an ASP programmer, can write scripts to process the input. [1]

The Request.Form Collection

When you have an HTML form, say,

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You have within it a number of elements, each with a unique name. The fields in the form above are FirstName (Text), LastName (Text), Sex (Option: M or F), and Address (Multiline Text). The last input type is “submit” that is a button required to submit the user input to your script. On clicking the Submit button, the contents of each of these fields are posted to the script that you specified in the FORM Action attribute. In the above example, it is “process. asp”. [1]

The form processing script can access these input values as below:

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Once you have this value, you can process it as you need – enter it into a database, mail it to yourself, - anything you want.

Note: METHOD specified in the FORM tag must be POST if you want to use the Request.Form collection to process it.

The Request.QueryString Collection

Quite often, you might have seen page URL’s like the one below:

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This is a direct link to a card that your friend sent you. You just need to click on the link, and the card shows up. You do not need to identify yourself or enter any code number anywhere. All the information that the site needs, is encoded in the string,

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This is known as the Query String and forms part of a URL. You can pass multiple values too, using something like:

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The Request.QueryString Collection helps you sort this stuff out and extract only what you need – the values of the variables themselves. So to access the data contained in the variable FirstName above, you would use:

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This again, is a regular variable that you can assign to another, or do arithmetic on. The Request.QueryString collection gives you access to yet another class of variables – those passed via a FORM with its METHOD = “get.” However, there is a limit to the amount of data that can be passed on via the QueryString and you are expected to use a form for more data. [1]

GET and POST methods

The METHOD by which the form is submitted may be one of the two: GET or POST.

When to use GET?

Any data that you pass via a GET can be retrieved in your script by using the Request.QueryString collection. GET may be used for small amounts of data – the reason being that, the data items are appended to the URL by your browser, and obviously, you cannot have an infinitely long URL (with the QueryString).

When to use POST?

It should be used almost always. Stick to POST for your forms, and be sure to use the Request.Form collection to access them (and not the Request.QueryString collection.) [3]

Concluding remarks

Although, ASP technology is still a relatively new way to create dynamic Web sites, during its short life span, it has evolved to become one of the foremost dynamic Web site development products. This is probably due to the ease with which complex pages and applications can be created, combined with the ability to use custom components and existing Microsoft and third party commercial components through the Component Object Model (COM/COM+) architecture. While ASP is powerful and incredibly simple to use, it does have the drawbacks like ASP code can get complicated very quickly and ASP has no actual component model. Microsoft, realizing that ASP does possess some significant shortcomings, has developed ASP.NET. But still ASP provides a simple and secure means for building dynamic Web pages. ASP is a powerful tool for Web developers. If you have access to an IIS server or Chili!Soft ASP server you can make your sites dynamic, personalized, and interactive quickly and easily. [2]

REFERENCES

1. http://www.manastungare.com/asp

2. http://www.hp.com/technicalreferences/EBOOK_PDF_ASP_NETDAT

3. ASP (Active Server Pages) –avenue to excellent careers –ATEC Computer Education

4. http://www.stardeveloper.com/asp_searchengine

5. http://www.atectimes.com/asp_tutorial

6. http://www.stardeveloper.com

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