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Using the TALtech Bar Code ActiveX Plus with Active Server Pages
System Requirements
Discussion
This example is designed to demonstrate how to generate server side
bar codes using the TALtech Bar Code ActiveX control (Plus version).
It uses an
ASP generated HTML form to collect information from the client about
the type of bar code they wish to create - including the bar code symbology,
the text to be encoded, the text for the comment, etc. When the user
completes the form, their information is submitted to the server for
processing.
The ASP page then reads in the client supplied parameters, generates
the bar code and saves it as an image file on the server. It then generates
HTML code containing an Image tag which references the newly created
bar code image. The generated HTML code is then passed back to the users
browser
which displays the resulting bar code.
How to use this Example
It is not impossible that this example will work right "out of the
box" with little or no modifications on your part, but don't be surprised
if it does not. We have tested it on a Windows 98 machine running Personal
Web Server 4.0, a Windows 2000 Server running IIS 5, and a Windows 98
Second Edition machine running Personal Web Server 4.0. However, this
example is fairly complicated, there are many elements to it and therefore
some of it may not work on your server. Usually if a line causes the script
to fail an error is generated and appears in the Browser window identifying
which line caused the problem, but it may still take some time to figure
out why it is not working. So instead of taking this example and working
backwards to fix the problems you encounter, we recommend you start a
new application that uses just the basics and then build upon it, borrowing
code and ideas from our example until you have rebuilt the application
in such a way that not only does it work on your server, but it also does
exactly what you want it to do:
- Start with "Step1.asp" (included in the the example files).
This code generates a barcode (using the default settings) with a hard
coded filename (barcode1.png). and displays this image on the page.
(The image will be huge because it is not being scaled to match your
screen resolution - more on this later).
- If you see the image, then add an HTML Form that allows the user to
specify properties of the bar code and the code required to set those
properties. If this step does not work then there is no point having
any other code!
See: Troubleshooting ActiveX and ASP Problems
page to help you figure out what is wrong.
- Once that is working you can add code that manages the filenames -
not necessarily the way we chose - perhaps you would give the user the
ability to name his own files.
- Add any other features you need.
Note: The ASP code in this example is recursive. In other words the page
contains logic so that it appears as a form prompting for information
about the bar code that you want to generate the first time you view it.
After you submit the form, the page will rewrite itself to display the
resulting barcode.
Follow these steps to try to run the example "straight out of the
box".
- Configure your Web Server to run
ASP and make sure your Web Server is running.
- Install TAL Barcode ActiveX Plus (or Demo) on your Web Server.
 Download
all the files discussed in this example. This is a self extracting
Zip file containing:
- "Barcode.asp" - the main (more advanced) example discussed
here.
- "Step1.asp" - a bare bones troubleshooting or starter
file.
- "Useful Code Snippets.txt" - Prewritten and tested code
that you should be able to cut and paste into your application to
enhance it with the minimum of editing:
- Data Validation functions - catch errors before they happen
by checking that the barcode message is suitable for the symbology
selected.
- Code to Determine the client's Operating System, Browser and
Version - What if the client wants to create a .png file but
is
using Netscape 4 which cannot display it?
- Code to delete the old image files from your server.
- Code to verify that the image you just tried to create was actually
created - Avoid broken links that make your site look bad!
- "fnum.txt" - a simple text file that will be used to
track the file number.
- Double click on the downloaded file to extract the files. (By default
they will be extracted to your temp folder ("C:\Windows\temp"
on Windows 95/98 machines and "C:\temp" on Windows NT/2000
machines)
- Using Windows Explorer, copy the files into the root directory of
your web server (usually "C:\Webshare\wwwroot" or "C:\InetPub\wwwroot").
- Open your Web browser and type in "http://your.server.name/barcode.asp"
into the address line, change the properties that interest you on the
form, and submit it. You should be rewarded with a barcode. If you are
not, see: Troubleshooting ActiveX and ASP Problems.
View the Source Code behind Barcode.asp
(fully commented).
Note: The form contains more features than the supplied ASP Code
supports: Only the Message, Comment, Symbology and Image Format properties
will be set by the ASP Code. As an exercise to help you understand how
the example works you may find it useful to make the other properties
on
the
form function too - this will help you learn to use both the ActiveX
Control and ASP.
Related Links
Introduction to Active Server Pages
Printing From Active Server Pages
Using TALtech Bar Code ActiveX Plus with PERL
CGI Scripts
See a fully working ASP example
of the TAL Bar Code ActiveX
Troubleshooting ActiveX and ASP Problems
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