18.1 Struts and JavaServer Faces
You might be wondering, "What does JavaServer Faces have to do with Jakarta
Struts?" The truth is, quite a bit. First and
foremost, Craig McClanahan has a hand in both. As mentioned several
times already, he is the creator of Struts and still participates as
its steward, but he is also one of the technical leads on the
JavaServer Faces JSR-127, along with Ed Burns. However, the key
similarity between JSF is that both attempt to solve the same
problem. That is, they are both Java frameworks for building
web-based applications, with one big exceptionJSF is an actual
specification, along the lines of JDBC, JNDI, EJB and so forth. Like
other Java specifications, Sun and the JSR committee provide a set of
APIs that describe the contract between a client and a provider of
the technology. With JSF, the actual implementation of the JSF
specification is left to the vendor to implement. |
In many specifications, a reference implementation is provided with
the API to help ensure adherence to the specification and
compatibility between providers. |
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In contrast to JSF, Struts is based on a proprietary framework and
API. Actions and forms built for use within a Struts application must
be modified (or even rewritten) when switching to a different
framework. There's also only one provider of
Struts:Apache and the Struts development community. With JSF, there
will be multiple implementations.JSF's goal is to provide a way to build UIs
(buttons, checkboxes and other widgets) that are client-independent.
It does this by utilizing a rendering kit that contains
client-dependent parts of the UI. The rendering kit detects the
client in use and renders the widgets appropriately. JSF also
supports the ability to create custom widgets, much like Java Swing.
In fact, you can build completely new rendering kits if there are
none available for your client type.
18.1.1 Do We Really Need Another UI Framework?
An often asked and completely valid question is: "Do
we really need a new UI framework?" In fact, many
would argue that we have too many already! These questions do need to
be asked, but one must keep an open mind when asking them. Contrary
to how one group or another might try to market a framework
(commercial or open source), no single framework can contain every
feature that every application might demand; this holds true for all
types of frameworks. The more important question is:
"Does JSF bring anything new to the
mix?"
18.1.2 The Big-Picture Benefits of JSF
JSF does include several features currently found in existing UI
frameworks. However, along with these features, it also includes
things that can't be obtained from a single
framework. Let's spell out several niceties of JSF
and why you might consider using it by itself or in conjunction with
the Struts framework.The goal of JSF is
to provide reusable server components for creating user interfaces.
As such, it provides the following benefits for Java developers:- An extensible UI component model
- An event handling model
- A pluggable rendering model
- A presentation validation framework (for both client and server side
validation) - A simple page navigational model
- Internationalization (I18N) support
- Integrated support for accessibility
These benefits alone make JSF as powerful, if not more so, than many
of the UI frameworks available today. Add to that a standardization
which guarantees that multiple vendors will provide implementations,
and JSF starts to become a very attractive option. |
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