Extranets
- Database-driven sites
A database-driven web site provides the widest range of extranet-related
possibilities. This page discusses:
Whether you need a database-driven web site, and how you link to it as part
of your extranet will largely be determined by:
- whether your web server is in-house or hosted by an ISP
- the objectives of your extranet
- the level of interactivity you think you will require
- the degree of automation required to minimise ongoing costs
- the time delay you are prepared to accept between something happening on
your web site and your internal systems knowing about it
- your in-house information processing workflows
Extranet development
technologies
Data-driven web sites typically use a combination of HTML pages (with or
without JavaScript), e-mail, forms and PERL and/or PHP scripting to create a
"front end" for the database and manipulate the data.
Products such as Cold Fusion - our preferred database web site development
tool - allow us to create systems that "react" to the values stored in
the site database as a result of visitor activity. In turn, these reactions
interact with products like Cold Fusion to provide a more personalised
experience for the site visitor - i.e. the visitor drives the database and the
database determines the the options that are
presented to the visitor.
For businesses used to running Microsoft products we can provide
data-base-driven sites using Microsoft Access and/or
Microsoft SQL Server. For clients that prefer Unix/Linux
we tend to use MySQL. There are many many alternatives to these database tools -
at the end of the day the choice of database depends on whether you want to
run with MS-Windows technology or Unix/Linux technology.
Data Uploading / Downloading
options
Although you have a wide range of "front end" tools and
"back-end" database technologies to choose from when developing a
database-driven extranet:
- Without an in-house web server (it might be physically
located on the other side of the planet), you still need to consider how your
internal systems will interact with the
server on a timely basis in order to provide a high level of service to your
clients
- You also need to consider ways of minimising the effort required to maintain a
good level of in-house task automation.
Getting data from the server to your desktop machine ready to go into your
office machine is pretty much the same as it is for "Brochureware"
sites. Your basic tools are:
- Action-specific e-mail messages
- Per Session or Persistent FTP for small files
- PERL / PHP Scripts
Because the size of your database is likely to grow quite large, continuing
to use FTP to download the entire database on a regular basis is not a feasible
thing to do if your server is not on your internal network.
The most practical solution is to use automated PERL / PHP scripts to extract transactions
as they occur and pull these transactions into your in-house system.
For example, you could
run a download scripts every 5 minutes if you are working to tight deadlines - which means
that your site data is never more than 5 minutes out of synch with your in-house
database.
You end up with two versions of your database - one on your site which your
ISP should back up every 24 hours - and one on your internal system which should
also be (automatically) backed up at least once every 24 hours.
Important: Despite the convenience, you cannot rely on e-mail
systems for high transaction volume levels. At best, e-mail can be used as
a backup system for PERL / PHP scripts that periodically extract transactions
from your web site database, and/or as a way of letting you know about
occasional or non-critical, low transaction rate, events.
The Timeliness of Web Site
Data Updates
If you need to react
quickly to visitor actions on your web site then you need to give serious
consideration to running an in-house web server.
In-house web servers operate in pretty
much the same way as shared or dedicated servers - with one major difference -
they are able to be quickly accessed as if they were part of your normal
in-house network.
This means that the data on your web
server can be maintained via the same database as the rest of your in-house
systems. Your web site becomes an integral part of your in-house system and data
updates can occur in "real" time.
This can be particularly important when
web site visitors are interacting with information from:
- Inventory / Stock Levels
- Dynamic Price Lists
- Live Production Schedules
Aside from the cost of hardware and systems software for your web server, the
major cost is making sure that your web server is operational 24/7.
Some server technologies are more stable than others - for example there is
strong evidence to suggest that Linux/Unix web servers are more stable than
servers running Microsoft technology.
However, even the most stable software can stop functioning. If you are
considering running an in-house server, issues like a continuous power supply
and the need to set up "hot" backup servers need to be factored in
to your planning. This increases the costs of doing business via the web but it
can be a more cost effective solution for (usually) larger companies.
Proper system architecture and design can reduce the need to operate an
in-house web server.
- For example, if the inventory level preparing on your web site needs to be
closely monitored, you could use a permanent high speed data line to a web
server housed by your ISP.
- If a leased line is too expensive you might want to consider setting minimum
stock levels and automatic re-order levels for your web site inventory based on
historical demand trends for each product on your web site.
To summarise, there are many ways to provide a high level of "timeliness" for
your web site - the best solution only becomes apparent once you establish
criteria for your site. You ignore the issue of timeliness at your own peril -
if you underestimate your needs, customers will complain about your service - if
you overestimate your needs, you will be spending money you don't have to.
On-site Data Maintenance
In addition you also have the option of maintaining your site directly - i.e.
you can build maintenance screens and reporting options into your web site.
Security options normally prevent unauthorised access to maintenance and site
reporting.
Data maintenance via on-site tools
is feasible for small volumes of data, but is normally not cost-effective once
your site traffic grows - especially if you have a slow Internet connection.
- Your team has to resort to cut and paste (a.k.a. "screen
scraping") techniques to move large amounts of data.
- If you do not have a fast connection to your web site, maintenance can
be a very slow process.
- The cost of developing web-based tools may be far higher than developing
a custom in-house system
One valid option is to use PERL/PHP scripts to download large volumes of
non-sensitive data and "cut and paste" sensitive relatively low volume
data such as credit card numbers etc.
Once traffic grows the only realistic way to maintain your web site data is
to set up your own in-house extranet server and access it directly via your
internal network.
See
also: Server
options | E-Mail
Only systems | Brochureware Sites
| Peer-to-Peer options
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