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- Learning ASP

Contents:
  Disclaimer
  Introduction
  Installing Personal Web Server
  Your First ASP Page
  Getting Your Hands Dirty With VBScript
  Logging In Using ASP - Access2000



- Disclaimer

Warranty, Disclaimer and Copyright Policy

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express or implied, with respect to its quality performance or fitness for a particular 
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consequential damages arising out of the use of this material.
No patent liability is assumed with respect to the use of the information contained herein. 
Although every precaution has been taken in the preparation of this manual, assumes no 
responsibility for errors or omissions. Neither is any liability assumed for damages 
resulting from the use of the information contained herein. This information is provided 
with the understanding that is not engaged in rendering medical, legal, accounting or 
other professional service. If legal advice or other expert assistance is required, the 
services of a competent professional person should be sought.
By using this material, the user assumes complete responsibility for any and all damages 
resulting from that use. Use of this program and materials requires agreement to the terms 
of this warranty and disclaimer. If you do not agree to the terms of this warranty, do not 
use this material.



- Introduction

This text features Learning ASP Series. Web site maintenance is a job that never ends. 
You constantly need to keep your web site updated so that your visitors get a feeling that 
you are always evolving and dynamic. Once you have a quality web site, you have to 
promote it relentlessly. 
 


- Installing Personal Web Server

Welcome to the first chapter of your Basic ASP Learning Series.
By the time you are through with these chapters, you'll have learnt enough to make a small 
shopping cart in ASP.
Most of the chapters will be organized in a linear fashion, so that you always have to 
work according to your previously acquired knowledge. Sometimes I'll sound like writing 
the entire chapter in a bulleted form, but that'll be just to keep the unnecessary (I mean 
that is out of the scope of this reference) stuff out.

 Installing Personal Web Server
 Beginning of Chapter One

If you want to work with ASP (Active Server Pages) on your personal computer, you 
need to install the Personal Web Server (PWS). As the name indicates, it's a server. 
Unlike the normal HTML pages, dynamic pages (either created with CGI, PHP, ASP or 
Cold Fusion) require some sort of a server to carry on their business. Without a server, 
you can create a dynamic page, but you cannot view it decently in the run-time mode.
Since I mostly work with the Active Server Pages using PWS, I'll tell you how to install 
the PWS. It ships free with the Win98 CD, and should be in the add-ons folder.
From there, install the PWS on your computer. The installation program creates a folder, 
inetpub in the directly you specify during the installation. This inetpub, further has a 
folder, wwwroot. So if you install your PWS on your C drive, the wwwroot path should 
be C:\INETPUB\WWWROOT

All the files that you create, you store under wwwroot. What we generally do is, we 
create separate folders for separate projects under the wwwroot folder. So if I created 
bytesworth folder in wwwroot folder, the full path should be C:\INETPUB\WWWROOT\BYT
And when I have to view the page on my browser, I'll have to type 
http://localhost/byt as the URL.

After you've installed the PWS, it's icon appears on your desktop, and at the bottom right 
of your screen. Click or double-click on the icon. On the main window, you should see 
the message: Web publishing is on. Your Home page is available at http://servername
The servername is the name you use instead of localhost. But if you are confused about 
this name game, just use localhost and it should always work if you haven't been naughty 
and messing around with your computer's basic setup.

Before you proceed further, open the Windows Explorer, go to c:\inetpub\wwwroot and 
create a new folder here by the name of "learnASP" (how boringly predictable! So you 
can name it something else). We'll be storing ALL our files in this folder.
Hence, whenever we want to run a newly created file, we'd type in the location bar:
http://localhost/learnASP/newfile.asp and press Enter.

Ok, next, click on the Advanced tab. Select Enable Default Document
In the Default Document(s) box, type the list of file names you would like to use as your 
default file once the name of your site is type in the browser.

If you have no idea what's the default file, it is the file that answers your call when you 
type a specific URL without a specific file. For instance, if I type 
http://www.byt.com the file that actually gets loaded by default is 
DEFAULT.ASP. This depends on the setting. Some servers use INDEX.ASP or 
INDEX.HTML or INDEX.SHTML. It all depends on the file parsing set up on your web-
hosting server.

Then click on the Edit Properties button, after selecting the Home folder. There are three 
select boxes, viz., "Read", "Execute", "Script". Select all of them. The selections tell the 
server that we want to execute server side scripts in our ASP pages. ASP pages won't run 
if the server can't read and execute them.

Close the window, and your PWS is running. Of course do not run two servers 
simultaneously. So if you installed the Apache Web Server and left it running, and then 
loaded PWS, there is going to be some problem for you to sort out.



- Your First ASP Page

ASP pages (Active Server Pages page sounds a bit melodramatic but its easier to refer to 
them like this) are nothing but web pages. The difference is that they have an extension 
.ASP and you write the code in a Server Side Scripting language.

Do we know what's Server Side Scripting? This doesn't actually matter if we delve into 
such nitty-gritty, but let's sound a bit philosophically intellectual. Now, there are two 
sorts of scripting languages:
Server Side (the hosting server where all the pages and programs reside)
Client Side (the web surfer using the browser - actually the browser is the client)

No, we are not talking about some corporate politics with all this "siding" talk. Ok, before 
I begin with my bad sense of humor, "Client Side Scripting" is what we generally see 
when we code basic Java Scripts in our web pages to validate HTML forms or 
implementing those cool image rollover effects or opening custom popup windows etc. 

When you view the source of an HTML page, and if the Java Script has been written in 
the page itself (they have external Java Scripts too, but then that's a different story), then 
you can see the script with all it's gory details. A simple example of a Client Side Script 
written in Java Script is:
<Script Language = "JavaScript1.2"> 
function welcome() 
{ 
alert("Welcome to the Incredible world of Amrit Hallan!!"); 
} 
</script>
And then you can use it when the page loads:
<body onload="welcome();">
</body>

A Server Side Script, on the other hand, does not manifest itself when you try to use the 
"View Source" option of your browser. It is a server side matter so unless you have the 
actual access to the server, you cannot view the portion containing the server side coding. 
But yes, the rest of the HTML matter is visible.
A typical ASP page looks like: 
<%@Language=VBScript%> 
<% Option Explicit %> 
<html> 
<head> 
<title> 
</title> 
</head> 
<body> 
<% 
Dim SayThis 
SayThis = "Finally, I'm learning ASP!" 
Response.Write SayThis 
%> 
</body> 
</html>

Provided you've configured your PWS in an amicable manner, this docile file should 
show up without fuss. You can copy/paste this page as it is using your preferred editor, 
and save the file as "basic.asp".
As you know, a basic HTML web page begins with the <html> tag, when you begin to 
work with an ASP page, try to make the first line as:
<%@Language=VBScript%> 
<% Option Explicit %>
The first line tells the concerned authorities that the following code is going to contain 
VBScript syntax.
The second line forces us to declare every variable before we use it. We'll come back to 
this later when we are in a more aware state of mind.

My preferred script for ASP is VBScript, so most of my ponderings will be in this 
language. A few daredevils write their ASP pages in Perl too, but personally I feel it is an 
overkill and they are just trying to either show off or the features they want to use only 
exist in Perl. For that matter, even C++ is used for making ASP pages.

Anyway, done with the first line, are we?

As you can observe, we have all the quintessential HTML tags in an ASP page too, but 
they are only necessary if you intend to display the page to your visitors. If the page just 
includes a script that performs some programming function and then loads some other 
page, you can simply have the pure ASP code with first line as <% and the last line is 
%>.



- Getting Your Hands Dirty With VBScript

 Beginning of Chapter Three
I know some people don't like VBScript for being Microsoft-Centric, but it's very easy to 
get familiar with, and once you know how to create your ASP pages in VBScript, you can 
move on to any programming language of your choice.

First thing first: HTML tags and ASP scripts don't socialize well, and although it is not a 
politically correct agenda, you have to segregate them. Whenever you are writing the 
VBScript code for ASP, enclose the code within <% %>.
So if you want to initialize a VBScript variable, do it like this:
<% 
Dim name 
name = "Tutan Khamen" 
%>

For instance, if you want to use the variable "name" in your HTML (ASP, actually) page, 
all you have to do is:
<%@Language=VBScript%> 
<% Option Explicit %> 
<html> 
<head> 
<title>Testing a VBSCript</titlegt; 
</head> 
<body> 
<% 
Dim name 
name = "Tutan Khamen" 
%>
<%=name%>! An ancient Egyptian mummy!
</body> 
</html>
Another example:
<%@Language=VBScript%> 
<% Option Explicit %> 
<html> 
<head> 
<title>Testing a VBSCript</title> 
</head> 
<body> 
<% 
Dim number1, number2 
number1 = 33 
number2 = 44 
%>

The product of <%=number1%> and <%=number2%> is <%=number1 * number2%>
</body> 
</html>
So now its amply clear that whenever you want to insert Server Side code, or a part of it, 
you enclose it within <% %>.
You can try making short programs and test run the page.



- Logging In Using ASP - Access2000

After receiving a few queries about how to store passwords using ACCESS and ASP, and 
then use them as "logins", I thought, well, why not write in a separate article, instead of 
attaching multiple ASP files that are full of confusing comments and variables only to be 
decipherable by my brain?

I'm assuming you've installed, and are running PWS (Personal Web Server) on your 
machine, if you are not already working on a server that supports ASP.
First of all, create a database, for instance, customers. Define a table with all the fields 
you require (include email and password).
After the database has been created, you need to create a DNS in order to access this 
database through your ASP pages.

If you have never created it, this is how you do it:
Go to the Control Panel (My Computer - Control Panel), and click on the icon that should 
be saying "ODBC Data Sources (32bit)". In the resulting window, select the "System 
DSN" tab. Then click on the "Add..." button. From the given list of Database drivers, 
select "Microsoft Access Driver (*.mdb)" and click the "Finish" button. You reach a 
place where you have to enter the "Data Source Name". Enter it, anything, for instance, 
"customers". Then click the "Select..." button. This lets you select the Access database 
you created. Press Ok, press Ok, and press Ok. Your DSN is created.
In the first part, I'll write about storing the passwords.

Before this, let's make an include file to create and initialize the session variables that we 
are going to need (we can use cookies, but some clever folks disable cookies on their 
browsers).
File name: sessions.inc
<%
if session("email")="" then
  session("email")="notlogged"
  session("pass")=""
end if
%>

This file you can include in every page as
<!--#include file="sessions.inc"-->
so that you can use them whenever you need them.

Now accepting login and password.
For this you require a normal HTML form. You can have "n" number of fields in a form, 
but here, our primary concern is, getting the email as login, and the accompanying 
password.
Here's the form:
<p>Please enter your details:>/p>
<form name="login_info" method="post" action="storelog.asp" onsubmit="return 
validate(this);"> 
Enter Email: >input type="edit" name="email" size="15"><br> 
Enter Password: >input type="password" name="pass" size="15"><br> 
<input type="submit" value="Submit"> 
</form>
We validate the form before it proceeds to the "action" file so that there is very little 
server-side processing. A simple validation:

Note: Put the following Javascript above the <body> tag.
<script language="JavaScript">
function validate()
{
  var res=true;
  allok=true;
  // Checking that the email has been entered.
  if(document.login_info.email.value=="" || 
document.login_info.email.value==null)
    {
      alert("Sorry, you cannot register without an email address.");
      res=false;
      allok=false;
      document.login_info.email.focus();
    }
   // Checking that the password is right.
   if(allok==true)
   // I'm using allok here because if allok is false, no use checking 
for the next field.
   {

     if(document.login_info.pass.value.length < 6 || 
        document.login_info.pass.value=="" ||
        document.login_info.pass.value==null)
     {
         alert("Your password has to be at least six characters 
long.");
         res=false;
         document.login_info.pass.focus();
     }
  }
return res;

}
</script>

So now when the user clicks on "Submit", he/she goes to "storelog.asp" In between, you 
can have a file to confirm the form fields and give the user an option to modify them 
before finally saving.

A few things. In order to use a database through ASP, you need to have a DNS created 
for that database on the server.
STORELOG.ASP should somewhat look like this:
<%
dim sEmail, sPass, noError
noError="y"
sEmail=request.form("email")
sPass=request.form("pass")

' The following lines setup a connection to the DNS we created above

Dim toDatabase 'To connect to the DNS
Dim toRecordset 'To connect to the individual tables

Set toDatabase = Server.CreateObject("ADODB.Connection")
toDatabase.Open "customers"

Set toRecordset = Server.CreateObject("ADODB.Recordset")
toRecordset.Open "logins", toDatabase, 2

' 2 = Opens the recordset in "Write Mode"

' Let us say "logins" is some table you created in the database.

toRecordset.AddNew
toRecordset("email")=sEmail
toRecordset("password")=sPass
on error resume next
toRecordset.Update
if err.number<>0 then
' do something if some error occurs.
' one error could be that the email already exists in the
database.
  noError="n"
end if

toRecordset.Close

Set toRecordset = Nothing

toDatabase.Close

Set toDatabase = Nothing

if noError="y" then
' If the info was saved smoothly.

  session("email")=sEmail
  session("pass")=sPass
end if

' Here you can display some message that the record has been
saved.
%>
This saves the login information of a new customer. Now, how do we use it in the future? 
First, the login form, that could be on any page.

Remember you can use somewhat same validation Javascript here too, so I'm not 
repeating it, but just mentioning it.
<p>Please login by entering your email and password.</p>
<form name="login" method="post" action="login.asp" 
onsubmit="return validate(this);"> 
Enter Email: <input type="edit" name="email" size="15"><br> 
Enter Password: <input type="password" name="pass" size="15"><br> 
<input type="Submit" value="Submit"> 
</form>
LOGIN.ASP
At the top of the page, along with other ASP commands, include this too:
<% response.buffer=true %>

This is required if you want to send the user to some page after he/she has successfully 
logged in.
<%
dim sEmail, sPass, noError
noError="y"
sEmail=request.form("email")
sPass=request.form("pass")

' The following lines setup a connection to the DNS we created
above

Dim toDatabase 'To connect to the DNS
Dim toRecordset 'To connect to the individual tables

Set toDatabase = Server.CreateObject("ADODB.Connection")
toDatabase.Open "customers"

fndSQL="select * from logins where email='" & sEmail & "' and 
password='" & sPass & "'"

Set toRecordset=toDatabase.execute(fndSQL)

if toRecordset.eof then
  response.write "Your details are not in the database, please try 
again, or register yourself."
else
  session("email")=toRecordset("email")
  session("pass")=toRecordset("password")
end if

toRecordset.Close

Set toRecordset = Nothing

toDatabase.Close

Set toDatabase = Nothing

response.redirect "To some URL"
%>

From now onwards, whenever you want to perform some action that should only be 
performed if the user is logged in, just check the value is session("email"), like:
<%
if session("email")<>"notlogged" then
' do things for the logged in customer
else
' tell the customer that he she is not logged in.
end if
%>


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Networked Dynamic Information Technology - www.NetDit.com
Empowering Articles for Web Developers