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158 Chapter 4 Web Application Concepts
All this leads to the conclusion that it might be wiser to use something else except in
the most basic scenarios, where you know that your audience is used to these dialogs
and you don’t need permission levels or idle timeouts.
PHP Authentication
PHP native authentication, on the other hand, makes it possible to use arbitrary login
screens and authentication procedures, as it’s form-based. For authentication to work,
you also need session-management functions. Once the user is logged in, you need to
remember this state across multiple requests.
You can write your own authentication library using the PHP session-management
functions introduced earlier, or you can use the PHPLib.With its Auth class you can
manage authentication, and using the Perm class lets you set up complete authorization
levels. For details on how this works, see Chapter 6.
Why Usability Matters
You might wonder why a section about usability is included in a book about software
development.We feel it’s a necessity for any serious developer to know about basic
principles for information architecture, user interface engineering, and usability.
As Web applications get larger and more complex,Web developers are challenged
more than ever to create effective and functional Web sites, and usability becomes a
key feature of these sites.
What is usability? The characteristic of how easy it is to learn and use an information
system is referred to as the system’s usability. As the developer of an application, it’s
probably easy for you to use it—but you may be surprised at how difficult other users
find your system. Initially, they’re completely unfamiliar with it and might try to use it
for different things than you intended!
While usability engineers have tried to integrate usability issues into an early stage
of software development, this effort hasn’t been very successful. But usability needs to
play an important role from the beginning of each project—starting to think about
usability in the beta test phase is insufficient.We think usability should be placed on
the same level as other traditional characteristics for software quality—such as correctness,
maintainability, and reliability.As soon as you, as a software developer, understand
the importance of usability in determining the quality of an application, you’ll strive
to enhance the user experience. How you can achieve better usability in your applications
may vary from project to project, but some key principles form the heart of all
user-centered development:
n Early focus on users, directly involving them in the design process
n Early and continuing evaluation of the application
n Empirical measurement of usability, even in early stages of the development
n Iterative design and development
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