Datasheet

Displaying Data on the Web
11
•
Disadvantages
Although there are many advantages to making a web site data-driven, some of them come at a price,
and a data-driven site is not always the right solution to your problem. There are several hurdles that
must be overcome in order to provide a richer experience to the end user, and it's important that you
consider them before taking the plunge:
❑ Development. A large number of web sites that are now data-driven started out being static, and
there are still many static sites being created to this day. The nature of the content you want to
present is not always suited to a data-driven site, and the creation of a data-driven system
requires extra time and skills, resulting in a product that is more complex, and (inevitably)
more prone to errors. These costs have to be weighed up against the advantages that such a
system provides.
❑ Performance. The performance of data-driven web sites is an issue that crops up regularly. If a
site is entirely static, then there are no constraints on the way the system is organized, or on
how it can expand to cater for higher volumes of users. The simplest way to increase
performance is to buy a faster processor and more memory. When that stops being viable,
multiple versions of the site can be created, and users redirected to whichever one is under
least load. This can continue in a linear fashion, with the same increase in performance each
time a new web server is added.
With a data-driven site, this is not the case, because the entire system is dependent upon one
resource: the database. If it's not carefully designed, the database can create a bottleneck in
the system, whereby the rest of the application is held up while it waits for information to be
retrieved. Removing this bottleneck is a difficult problem to solve – having multiple
synchronized databases is one of the few real solutions, but it can prove very expensive, and
the overheads involved in this synchronization are significant.
❑ Cost. In addition to the technical considerations mentioned above, there are also associated
commercial issues. For a relatively static site, the time required to create a database and write
the code to access it may be longer than it would take just to edit some HTML pages. Also,
enterprise-class database systems are themselves expensive. Considering Microsoft's data
storage solutions alone, it's well known that producing a solution using SQL Server
(Microsoft's enterprise-level database server) provides many benefits over Access (its desktop
database), such as higher performance and better support for industry standards, but comes
with a price tag to match.
Data Sources
So: you've already considered some or all of the issues in the above lists, and you're still with us, which
means that it's reasonable to assume you want to write a data-driven web application. The first question
that needs to be answered, then, is where the information that will eventually end up on the user's
screen is going to come from. Depending on factors such as the type of data, what operations are to be
performed on the data, and the amount of use that is going to be made of the system, there are a
multitude of options available. This section describes the reasons for and against using three of the most
common data source types, along with an overview of the other types available.