• Active Server Pages
  • The Script Delimiters
  • The Scripting Host
  • Creating An ASP Page
• The ASP Interface
  • The ASP Intrinsic Objects
  • The Application Object
  • The ASPError Object
  • The ObjectContext Object
  • The Request Object
  • The Response Object
  • The Server Object
  • The Session Object
• Active Server Pages Samples
  • Say "Hello World!"
  • Accessing HTTP Server Variables
  • Reading the QueryString
  • Interactive Web Forms
  • Database Connections (ADO and ASP)
• Variants and Binary Data
  • To Read And Display Binary Large Objects (ADO and ASP)
• Appendix A
  • How To Set Up A System DSN
  • Why Not To Use A System DSN
  • How To Use The Native OLE DB Provider
• Appendix B
  • Book Resources
  • Online Resources
• AUTHOR AND COPYRIGHT

Active Server Pages (ASP)

Introduced in 1996, Active Server Pages (ASP) is an easy to learn server-side technology from Microsoft that has taken the web by storm. ASP is implemented as a set of objects with built-in features for fast and simple access to common services provided by the web-server for the Internet. As we will see, there are versatile reasons for using ASP as a server-side technology with ActivePerl.

To begin, if you in general are unfamiliar with server-side technologies, let's start at the core by describing the need-to-know about ASP. ASP is a feature that installs with Microsoft's Internet Information Services (IIS) web-server. No special interaction or configuration is needed afterwards, and it should run out of the box just as easily as IIS. Fundamentally, a server-side technology such as ASP puts no requirements on the client or browser, and, as a result, no browser-compatibility issues will ever occur, no browser plug-ins have to be installed, and the client does not need a local installation of ActivePerl.

Since there are no client requirements for ASP, it needs something on the server-side that tells it what to do with its features. A special implementation of a scripting language is therefore installed on the server and used in order to control and program ASP; PerlScript, which installs with ActivePerl, is suitable for the role as scripting language because it brings the power of Perl into the environment of ASP and there merges it with the services provided by ASP. There are only two things that you either may already know or will need to learn while using PerlScript:

• The Active Server Pages Object Model
• How Perl Works with Objects

On the Internet, ASP serves documents of its own filetype as opposed to familiar document types like HTML documents. This is so that the ASP document can be processed on the server side before returned to the client's browser. An ASP document has the file extension .asp, and it provides both existing features derived from ASP and the ability to execute script commands within the document. The file extension is by the webserver recognized in a special way which results in the underlying technology executing script commands that are within the file and treat other markup such as HTML in a standard fashion. The source code of your saved file's PerlScript script commands will by default never be available to the user when choosing to view the document source in the browser, so any script that you write can not be copied. The reason for this is because everything is processed on the server side and what is returned to the browser is a standard format such as HTML.

For a closure, it deserves to be repeated that if you are unfamiliar with object-oriented programming in Perl, it is strongly recommended that you sometime browse the Perl documentation on object-oriented programming to get a basic understanding of the aspects of an object and its origin. Next up, let's look at how to embed PerlScript commands within an ASP document.

The Script Delimiters

<%@ Language=PerlScript %>
<%
for($i=0; $i<=10; $i++) {
#
# Your Perl code here
#
}
%>

<SCRIPT Language=PerlScript RUNAT=Server>
    for($i=0; $i<=10; $i++) {
    #
    # Your Perl code here
    #
    }
</SCRIPT>

Creating An ASP Page

1) Create a file named PerlScript.asp
2) Edit it and enter "<HTML> Hello World </HTML>"
3) Save the file where you can access it by a URL such as http://localhost/. On IIS, the following path is often valid <device>:\inetpub\wwwroot\ where <device> is a hard-disk such as C:\ or D:\
4) Run the file in your browser by entering the URL pointing to PerlScript.asp; for example, http://localhost/PerlScript.asp

<%@Language=PerlScript%>
<HTML>
<TITLE> PerlScript Test </TITLE>
<%
for($i=0; $i<=10; $i+=2) {
$Response->Write("<FONT SIZE=$i COLOR=#000000>");
$Response->Write("Hello World! </FONT> <BR>");
}
%>
</HTML>

<HTML>
<TITLE> PerlScript Example </TITLE>
<script language=perlscript runat=server>
for($i=0; $i<=10; $i+=2) {

$Response->Write("<FONT SIZE=$i COLOR=#000000>");
$Response->Write("Hello World! </FONT> <BR>");

}
</script>
</HTML>

<HTML>
<TITLE> PerlScript Example </TITLE>
<% @Language=PerlScript %>
<% for($i=0; $i<=10; $i+=2) {
%>
<FONT SIZE=<%=$i%> COLOR=#000000>
Hello World!
</FONT>
<BR>
<% } >%
</HTML>

The ASP Programming Interface

Providing an interface to common tasks for a web programmer, ASP simplifies web-programming by making the simple tasks even easier. The features of ASP are implemented and exposed as objects, and, in addition, a scripting language is enabled to not only use those features of the ASP host, the language can certainly use its own features, too.

The ASP Intrinsic Objects

Application

# Set an application variable
#
$Application->Contents->SetProperty('Item', 'myName', 'Tobias');

# Access an application variable
#
$Application->Contents->Item('myName');

ASPError


# Return the ASPError object
#
$ASPError = $Server->GetLastError();

# Output the error's description
#
$Response->Write( $ASPError->{Description} );

Session

$Session->Contents->Remove('myName');

<%
my($name) = $Request->Form('Yourname')->Item();
$name = $Server->HTMLEncode($name);
%>

<%
if($name eq 'Enter Your name here') {
$Response->Write("Please type your name in the box below and then press the button");
}
else {
$Response->Write("Hello $name");
}
%>

<CENTER>
<FORM ACTION="wform.asp" METHOD="POST">
<INPUT TYPE="Textfield" NAME="Yourname" MAXLENGTH="30" VALUE="Enter Your Name Here">
<INPUT TYPE="SUBMIT" VALUE="Click Me">
</FORM>
</CENTER>

<%
# Create an instance of the ADO Connection object
#
$Conn = $Server->CreateObject("ADODB.Connection");

# Open a system DSN
#
$Conn->Open( "ADOSamples" );

# Execute an SQL Query
#
$RS = $Conn->Execute( "SELECT * FROM Orders" );

# Read a property to get the number of columns
# present in the Recordset returned from the
# query.
#
$count = $RS->Fields->{Count};

# Print out the names of each column
#
for ( $i = 0; $i < $count; $i++ ) {
$Response->Write( $RS->Fields($i)->Name );
$Response->Write("<BR>");
};

# Loop the Recordset until there are no more records
#
while ( ! $RS->{EOF} ) {
for ( $i = 0; $i < $count; $i++ ) {
$Response->Write(" ");
$Response->Write($RS->Fields($i)->{Value});
$Response->Write("<BR>");
};

# Move to the next record
#
$RS->MoveNext();
};

# Close the Recordset
#
$RS->Close();
$Conn->Close();
%>

Variants and Binary Data

At times, you will be working with binary data that is passed to PerlScript from a COM object or passed from PerlScript to a COM object. In Windows Script, the data comes in a data type called a Variant. The Variant resembles of Perl's scalar variables because it was designed for holding most types of data. And most of the time, Perl is able to determine what type of Variant that is being returned to it from a COM object; however, with binary data, it sometimes becomes necessary to define what the variant is exactly for a type, so the "Win32::OLE::Variant"-module provides functionality for this conversion and much more. For example, if you have a GIF image stored in the variable $image, and you want to output it to the screen by using the Response object's "BinaryWrite()"-method, you must convert it to a VT_UI1 variant before it is passed to the "BinaryWrite()"-method simply because a VT_UI1 variant is expected by the method.

use Win32::OLE::Variant;

# Tell the browser a GIF image is on its way
#
$Response->{ContentType} = "image/GIF";

# Send the GIF as a VT_UI1 Variant
#
$Response->BinaryWrite(Win32::OLE->Variant(VT_UI1, $image));

To Read And Display Binary Large Objects (ADO and ASP)

The following example will demonstrate how ADO can be used to read a Binary Large Object from SQL Server, and how ASP is used to output the BLOB as an image.

<%@Language=PerlScript%> <%
use Win32::OLE::Variant;

# One note, 40 as bytes to read per GetChunk()-call is not
# a good number to choose for a real application. I emphasize
# _not_. Instead, whatever you choose depends much on your
# system and the power of it; however, 4000 is a much more
# realistic real-world number compared to 32.
#
my($blob_size, $read_size, $bytes_to_read) = (0, 0, 32);

# Let's create the Connection object used to establish the connection
#
$conn = $Server->CreateObject('ADODB.Connection');

# Open a connection using the SQL Server OLE DB Provider
#
$conn->Open(<<EOF);
Provider=SQLOLEDB;
Persist Security Info=False;
User ID=sa;Initial Catalog=pubs
EOF

# Execute the query which returns the BLOB from our database
#
$rs = $conn->Execute("SELECT logo FROM pub_info WHERE pub_id='0736'");

# Get the size of the BLOB
#
$blob_size = $rs->FieldS('logo')->{ActualSize};

# And here's the routine for reading in the blob. Alternatively you can
# make a control statement that says if the $blob_size is less than
# 4096, it should just swallow it in one chunk, but the routine below
# is good to have handy
#
while($read_size < $blob_size) {

$buffer .= $rs->Fields('logo')->GetChunk($bytes_to_read);
$read_size += $bytes_to_read;
if($read_size+$bytes_to_read > $ blob_size) {

$bytes_to_read = $blob_size - $read_size;

}

}

# Make a VT_UI1 variant of the retrieved Chunks
#
$image = new Win32::OLE::Variant(VT_UI1, $buffer);

# Tell the browser that the content coming is an image of the type GIF
#
$Response->{ContentType}="image/gif";

# Do a binarywrite of the VT_UI1 variant image
#
$Response->BinaryWrite($image);
%>

Why Not To Use A System DSN

With the ActiveX Data Objects (ADO), the layer that connectes to a database is called the OLE DB layer. It is the very closest to the physical database, and directly connecting to OLE DB is ADO. Most databases will have what is called an OLE DB Provider, and if you have worked with ODBC, the OLE DB provider is OLE DB's equivalent of the ODBC driver. In ADO, ideally you should connect via ADO directly to OLE DB and from OLE DB directly to the physical database or other data store. A System DSN is for ODBC data sources and it causes OLE DB to wrap an ODBC driver within itself, which adds an overhead and reduces performance.

How To Use The Native OLE DB Provider

There are a number of things you can do to get the native provider set up. When you have it set up, you simply replace the name of the system DSN with the string that has been produced in order to connect to the data store using the native OLE DB provider. First, try to create an Universal Data Link file by doing the following:

1) Create a file named connectionstring.udl
2) Right-click on it
3) Choose Properties
4) Choose the OLE DB Provider to use
5) Define what source to connect to and possibly a username and password
6) Click "Test Connection"
7) Open the file in "Notepad"
8) Highlight the connectionstring and press CTRL+C to copy it into memory
9) Paste it into your ADO application by pressing CTRL+V

Provider=Microsoft.Jet.OLEDB.4.0;
User ID=Somebody;
Data Source=c:\\access.mdb;
Persist Security Info=False

Provider=SQLOLEDB;
Persist Security Info=False;
User ID=sa;
Initial Catalog=Northwind

Online Resources

• Microsoft Data Access Components; MDAC includes ADO, OLE DB, and every component needed for getting your databases out on the Internet.
• Windows 95 users will have to download the NT Option Pack from Microsoft and install Personal Web Server which ships with it. Win 98 already has it on its CD.
• The ASP PerlScript mailinglist is pretty much where the most questions and answers on PerlScript and ASP circulate.
• PerlScript Community is a Deja community for users who want to find users that PerlScript.
• The Perl-Win32-ASP FAQ. Maintained by Matthew Sergeant.

AUTHOR AND COPYRIGHT

Copyright (c) 2000 Tobias Martinsson. All Rights Reserved.

When included as part of the Standard Version of Perl, or as part of its complete documentation whether printed or otherwise, this work may be distributed only under the terms of Perl's Artistic License. Any distribution of this file or derivatives thereof outside of that package require that special arrangements be made with copyright holder.

Irrespective of its distribution, all code examples in this file are hereby placed into the public domain. You are permitted and encouraged to use this code in your own programs for fun or for profit as you see fit. A simple comment in the code giving credit would be courteous but is not required.

Active Server Pages is copyright (c) Microsoft Corporation. All rights reserved.