Published: Wednesday, December 05, 2001
How to Build a Low-Budget Web Service with Classic ASP
By Jason Salas
Introduction
With the increasing interest in XML Web Services platforms from the various major vendors (i.e., Microsoft's
.NET Framework, Sun's J2EE, IBM's WebSphere), many people have expressed an interest in getting their content
to be shared by site owners and entities external to their organization. This ranges in function from the
simple co-branding marketing service all the way up to an advanced e-commerce app that allows for the
exchange of data between partners in a B2B relationship. And up until this point, accessing data from
resources not within the same Web or network was extremely difficult to do, if not completely impossible.
Also, a concern of yours being a service provider should be what clients who
use your remote content use for their apps. There are a plethora of
platforms in use by remote clients, and it's unconscionable for you as a
developer to create a custom solution for each. And much to my chagrin (and
Microsoft's), not everyone out there uses ASP, so performing screen scraping
with VBScript's XMLHTTP object is not feasible for everyone, likewise with
complex DCOM solutions with remote procedure calls (RPCs). Fortunately, the
portability of the resultant JavaScript text file solves this, being nearly
universally compatible with whatever the client is running on their end.
This results in better chances for you to get your information out and
about.
(For more information on screen scraping, see: Treating
Another Web Site's Web Page as Data On Your Own Site.)
While the demands are going to be great for advanced access to data through XML Web services, not many
companies have been so quick to migrate to the technology...but this doesn't mean you can't pull off something
similar with classic ASP. In fact, there's already an article here on 4Guys that shows how to create
Web Services in classic ASP using Microsoft's SOAP Toolkit. (Read Creating Web Services with ASP.)
In this article, I will show how to create a much simpler Web Service that utilizes a JavaScript file and some
clever ASP code.
Working in the NeverNeverLand of high technology (Guam), especially in these tough economic times, I represent
the "low-budget-to-no-budget" class of devs. The company I work for isn't directly involved in technology,
and as such we've got very little to spend on IT. So I came up with a solution that does work...but is a
little more scaled down than your normal Web Service solution. What we're going to write emulates the concept
of the XML Web service, using JavaScript and classic ASP.
Your Most Powerful Asset - Information (or Understanding Why Web Services Rule)
It's a very competitive advantage if you can offer your content to partners for use on their own sites, and
it serves you very well. Large, dominating sites such as MSNBC.COM do this to stay ahead of the competition
in the online news game by offering their headlines and story abstracts to other sites. The end result is
that the content provider ultimately gets the traffic, which is a win for justifying traffic levels, which leads
to revenue gains. And smaller sites love to incorporate remote content on their pages to stimulate traffic
increases by way of association with larger entities. But the added overhead due to additional database
connections is an unwanted headache for developers.
So, our "Web service" consists of a very simple script which works with the following:
- JavaScript text files (files with a
.JS extension) are "portable" in the sense that they can
be referenced from within the HTML source code of a remote client page, with their contents being displayed.
Thus, we can write a very simple code construct to get content portable.
- Publishing the
.JS files can be done by writing a script which connects to a database,
writes a new text file outputting JavaScript code, and saves it to the server (overwriting the previous
file with the same name).
- This service never relies on external clients directly connecting to your database, so there isn't an
additional overhead concern other than the made by you when running the script. This prevents your main
site from being bogged down. That's the beauty of it - you can control how many times the script is
invoked if you embedded the script in an administration page, which would be executed by a staffer in
your organization. So you could literally have tens, hundreds, or thousands of clients using your service
and the load would at be the same minimal level, because you're essentially only connecting to your
database once!
- The code construct we'll be using for our JavaScript file (
portablecontent.js) is as follows:
<!--
document.writeln('<a target="_blank" ' +
'href="http://www.yourdomainname.com/filename.asp?id=8675309">' +
'<b>Senators debate during session sale of GTA</b>' +
'</a><br>');
document.writeln('The privatization of the Guam Telephone Authority is being touted ' +
'as a top priority of the Gutierrez administration, as its sale is ' +
'expected to bring some major </a><br>');
.....more content as needed.....
//-->
|
This has benefits for the client, in that:
- The outputted JavaScript file will conform to CSS rules, so it's somewhat customizable by the client to
match the flow and theme of their page(s).
- The script also truncates a "description" field and appends
... if the string is too long.
This saves you from having to modify your table structure in an existing database.
- The remote site manager never has to do anything modification-wise. He/she just references the JavaScript
file and then never touches it again. The remote site manager also has peace of mind about not sacrificing
traffic to their own if the user clicks away, because we'll open a new browser window by using the HTML
attribute
_blank within the <A> tag.
The only assumption is that you will have a file sitting on your server with the path (you can edit this to
match your own site's settings) http://www.yourdomainname.com/filename.asp?id=8675309.
There is one concern you'll want to watch out for, however (I learned this the hard way), in that single
quotation marks " ' " in ASCII format represent a line break in JavaScript, and this in
turn will generate an error on the client's page, making for an ugly and dysfunctional service. And with much
database-driven content being generated by forms - transmitting data in ASCII - this could run into problems.
Fortunately, Unicode characters don't have this problem. As a workaround, I employ VBScript's Replace function
to check for the existence of ASCII-type single-quotes, swapping each one with a Unicode single-quote, which
is acceptable in JavaScript. (Note: To make this script run right, I had to type in the ASCII single quote
character using NotePad, and the Unicode single-quote character using MS Word.)
Get the Word Out - Promoting your "Web Service"
You can then promote the heck out of your new "Web service" by having interested users insert the following HTML
into their Web page(s):
<!-- START PORTABLE HEADLINES -->
<table border="0" cellpadding="0" cellspacing="0" width="100%"><
tr><td width="100%"><font face="Arial" size="2">
<script language="JavaScript"
src="http://www.domainname.com/dirname/portablecontent.js">
</script></font>
</td></tr>
</table>
<!-- END PORTABLE HEADLINES -->
|
Plan your Code, Code your Plan
The code needed to create this .JS file is fairly simple and straightforward. All we need to
do is first open a text file to dump out the JavaScript contents to. This text file is opened and manipulated
using the FileSystemObject object. To learn more about this object, be sure to check out the
FileSystemObject FAQs on ASPFAQs.com.
Next, a connection to the database is made, and the headlines and their information are loaded into a Recordset.
This Recordset is iterated through, and each record's contents are outputted as a line in the JavaScript file,
checking to see if the description is longer than 165 characters - if it is, only the first 165 characters (and
perhaps some more, up until the next word) are displayed, followed by a ....
That's essentially all there is to it! The code is not extremely long, but to lengthy to place in this article.
Therefore, you can view the source code in
a separate window. Feel free to modify this code however you see fit, such as just displaying headline
information and forgoing the description. You can see an example of the output my script generates
here; to the right is an image of the
headlines as they might appear on a Web site utilizing this Web service I created.
The only drawback with this approach is that the script must be run whenever you wish to update the JavaScript
file. Fortunately there are a couple of articles here on 4Guys that examine how to schedule the execution of
an ASP script. See Scheduling the Execution of an ASP Script and
Automating Tasks with WSH.
.NET Web Services Allow for Greater Flexibility and Choice
The only limitation is that with a system such as this, the client has very little say in what he/she can do
with the resultant data (e.g., filtering for content, subscription-driven services, etc.). The client can
modify formatting for presentation purposes, but that's about it. MSNBC has a very powerful portable product that
it makes available to its affiliate stations across the U.S. wherein site managers can pick-and-choose which
newsfeeds they wish to receive as MSNBC updates its site.
This is the big draw of XML Web services with the .NET Framework - the service provider exposes access to the
data to the client, and the client decides what to do with it to best fit his situation.
But for now, this is just an example of one of the many things you can do to drive more traffic to your site
by leveraging the single-most important asset you've got - information. To learn more about Web Services with
ASP.NET, check out this Web Service Tutorial.
Happy Programming!
By Jason Salas
Jason Salas is Web Development Manager for KUAM.COM,
one of Guam's most popular Web sites. He also writes business and technology-oriented columns for KUAM.COM,
and hosts the weekly segment "Tech Talk" on KUAM-TV, a whimsical look at what's new on the technical front and
the Internet subculture. He has worked in the information technology industry for more than 11 years as a
salesperson, marketing manager, developer, consultant, and author. He also owns IntelliBiz, a consulting
company focusing on developing XML Web services. He is a graduate of Simon Sanchez High School, has a
Bachelor's degree in Marketing from the University of Guam, a degree in Music Theory with Emphasis in Guitar
from the Sutton Institute in Texas, and a Master's degree in Management of Applied Technologies from the University
of Phoenix. He is also a Microsoft Certified Professional.
