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JavaBeans is a new component
architecture for Sun's Java language. Like the language from which
JavaBeans draws its name, it is portable across many platforms; any
environment supporting a JDK 1.1 interpreter will be capable of using
JavaBeans.
For Java developers, and amateur applet authors, JavaBeans offers the
ability to write applications quickly and easily, by using a palette of
components that can be assembled to form a larger application.
User-interface components, such as trees, lists, or graphical buttons can
make applications come alive, without the need for writing custom
components for each and every application. Networking protocols can be
encapsulated in a component, allowing developers to simply plug in email
and web support into their applications. Literally any component you can
imagine can be written as a JavaBean, and then plugged into an
application.
- JavaBeans support properties, allowing an application to read and
modify their values.
- JavaBeans support events, allowing vendors to create their own
unique events.
- JavaBeans support the BeanInfo interface, allowing vendors to
specify exactly which properties and methods are available, and icons
for beans which can be displayed on a toolbar.
- JavaBeans are highly configurable, and the state of a bean can be
saved and restored through 'serialization'.
ActiveX is a competing object technology, developed by Microsoft for
its Windows platform. ActiveX objects are similar to the OCX components,
and allow vendors to create components that can be used in products such
as Visual C++, Visual
Basic and Borland Delphi.
ActiveX controls can be created in a variety of languages, such as
Visual Basic Control Creation Edition, or Visual C++. The task of creating
controls, however, is often more difficult than the simplicity of
JavaBeans.
Java stacks up very well indeed! JavaBeans are highly portable, and can
run on any platform that has a Java Virtual Machine that is JDK1.1
compliant. ActiveX controls can execute on the Windows platform, and most
use Win32 specific calls that would render them unsuitable for automatic
porting to other platforms. While ActiveX is now being pushed as an open
standard, it will be some time (if ever) before we see truly portable
ActiveX controls.
There is also a common misperception amongst developers that JavaBeans
can only be used in Java applications, and thus are not integratable with
other products, such as Visual
Basic and Delphi. This is
not so! Any existing JavaBean can be instantly converted into an ActiveX
control, through the use of the JavaBeans
ActiveX Bridge.
The bridge takes an existing JavaBean, and registers it as an ActiveX
control that can be used in any ActiveX compatible application or
programming language. Not only is the JavaBean architecture portable
across platforms, it's portable across other languages!
JavaBeans have a significant competitive advantage over ActiveX -
JavaBeans can be instantly converted into ActiveX controls via the bridge,
but ActiveX controls cannot be easily converted into JavaBeans. JavaBeans
also offer the security and robustness that developers have come to know
and love, whereas ActiveX controls remain dangerous (despite the
innovation of digital signatures), as they have low level access to
features of the operating system. JavaBeans used in applets are bound by
the same restrictions (file and network access) as their applet hosts, yet
ActiveX controls that are signed have a much larger potential to wreak
havoc on the system. Coupled with their lack of portability, ActiveX
components have a smaller target audience, and there is a perception that
they can be dangerous when executed indiscriminately from the web.
For the serious component vendor, or application developer, JavaBeans
is an important new technology that must be learnt to stay ahead. ActiveX
has its place, for now, but with the introduction of the JavaBeans Bridge,
it would be prudent to learn the JavaBeans architecture while it remains
in its infancy. |
