Apple WebObjects 5 - Manual (Page 63)

C H A P T E R 5
Direct to Web Applications
Limitations 63
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Apple Computer, Inc. January 2002
■ It allows you to focus on business logic instead of on the user interface.
Also, Direct to Web applications are constructed using well-tested Apple
technology, which increases the stability of applications and reduces the time
required to test applications before deploying them.
Limitations
Direct to Web is an HTML-based technology. As a result, Direct to Web user
interfaces are highly portable but suffer the limited interactivity provided by HTML
forms.
Because Direct to Web generates your applications for you, the applications have a
number of additional limitations.
First, the programming model is indirect. You provide a model and Direct to Web
assembles the application for you. The Web page generation is performed by a
“magic box.” You don’t have to know what’s going on. This makes it really easy to
get started programming with Direct to Web. But for certain customizations, the
learning curve gets very steep very fast.
The machinery for generating Web pages is an entirely new layer on top of the
WebObjects HTML-based application technology. This layer adds complexity that
regular HTML-based applications don’t have, and you might have to learn the
details of it to get certain results. In fact, making fundamental changes to a Direct to
Web application can be a lot of work. Note, however, that you can typically reuse
this work in later applications.
Another disadvantage is that modifying the layout of a Direct to Web template is
more involved and harder to do than laying out a WebObjects component because
Direct to Web templates are more complex than most WebObjects components.