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Java Platform New APIs: Putting It All Together
The new Java Development Kit APIs are rich with many
new and enhanced features and functionality. To the average
developer, it can be a daunting task to decide where each API fits
into the grand scheme of a business application--let alone
what each one does. To help you understand
how the APIs might work together, this article tells the story of
a fictional business--Duke's Bakery--and how the owner and
a Java programmer develop a robust, scalable, and
reliable application to run the day-to-day business.
Welcome to Duke's Bakery
Duke's Bakery is a large, busy, and well-known neighborhood
bakery with a loyal following. To continue their
personalized service while scaling the business to accommodate
the dozens of new customers they get every month, Duke's owner Kate
Cookie has hired Java programmer,
Madhavi Rao, to help upgrade their operations with a business
application. Kate and Madhavi prefer the Java platform because it not only
meets Kate's business needs for today, but offers important features
she will need as her business grows:
- The enhanced security architecture lets her safely
expand the business into electronic commerce so she can reach
people who do not live in her area.
- The Java platform architecture makes it easy and inexpensive
to expand the application as their business requirements change and grow.
- Internationalization support lets her comfortably
grow the business to reach the many ethnic communities in her
area and eventually expand overseas.
Right now, though, Duke's needs a clean and easy-to-use user interface
and back end so the administrative staff (some of whom have limited computer
experience) can track ordering, stock, and employee information.
Kate and Madhavi will draw on the following JDK 1.2 APIs to design and
create the business application:
Swing Components
Swing is ideal for creating the user interface. The components are highly
configurable and use images easily. Kate and Madhavi agree to display
sales,
customer, and vendor information using Swing components such
as tables, trees, labels, text fields, and text areas. They also decide to
include
photographs with the employee information
and use images of
baked goods in the user interface. For example, the
delicious and proprietary cake recipes that have made Duke's so popular
over the years can be viewed by choosing a button with a cake on it.
Because Swing components are separate from the data they display, two
components can
share the same data model. Madhavi decides to display sales data
both in a chart (drawn by a custom component that uses Java 2D)
and in a table.
Putting the sales data in a shared model
avoids duplicating data
and enables automatic updating of both components
when the data changes.
Having two views of the sales data can make it easier to understand,
helping Kate and her employees discover which bakery goods are the
most popular with their customers.
Duke's Bakery employees with permanent or temporary disabilities
aren't prevented from using the application,
thanks to the Swing components' support for accessibility.
For example,
if an employee's vision is impaired,
that employee could use a screen reader.
The Swing components
automatically provide the information that
accessibility tools such as screen readers need.
Java 2D
The Java 2D APIs provide ways to enhance the user interface with color,
graphics,
and images to make it easy to understand and use.
Kate is so excited about the possibilities, she has hired a graphic designer
to
help leverage the Java 2D functionality because she knows the less time her
employees spend learning and using the new system, the happier and more
productive
they are.
Kate and Madhavi want to use Java 2D to help customers choose a cake's
appearance. They decide to include a module in the application that uses
a color chooser for selecting icings, and 2D text for demonstrating the
appearance of the text on cakes for special occasions like birthdays and
anniversaries.
Cryptography
Duke's is working out relationships with some of their suppliers for
automated electronic ordering. The JDK 1.2 cryptography API and Java
Cryptography Extension (JCE 1.2) by separate download allow Duke's,
the suppliers, and their banks to use digital signatures and certificates
to
authorize and verify large orders with cash transfers in the thousands of
dollars.
JDBC
From Madhavi's point of view as a programmer, the Java platform is ideal.
The rich set of Java APIs gives her a lot to work with in designing and
writing this application. She will use JDBCTM
to access data in their current database. If they change databases or add
another
database, the existing JDBC code does not need to be changed.
JavaBeans
Madhavi will use JavaBeans to build
some of the general parts of the application. This way she can reuse
the code she writes for Kate in other similar business applications running
on the Java platform.
Distributed Computing
Because of Kate's plans to use online ordering with her vendors,
Madhavi must decide whether to use RMI or Java IDL for network
communications.
Because the vendors are also using the Java platform, she decides to use
RMI.
Java IDL would let her application use CORBA functionality to access
objects
written in languages other than the Java programming language (such as
C++),
but that is not necessary here. RMI is generally easier to use,
and Madhavi wants to encourage new vendors to use the Java platform
if they want an online purchasing arrangement with Duke's Bakery.
Of course, Madhavi will use Java servlets to implement an online
ordering system that customers can use on the premises and
eventually from their own computers at home.
Reference Objects and Collections
Madhavi considers using the Reference Objects API to create
soft references to objects that might be left in memory so the
garbage collector has the option of reclaiming the memory if
need be. This situation could arise when customers choose custom
cake decorations online. As they browse through and try the
multitude of decorating possibilities, a number of graphical and image
objects could be left in memory--especially if the customer or
employee does not remember to quit out of this part of the
application.
Madhavi also decides to use one of the
classes in the collections API to simulate a first in first out (FIFO)
queue.
This way, the application can manage the floor when customers take a number
and wait
their turn for service. Madhavi is considering adding a feature where
employees
in the back of the bakery are notified when more than 5 customers are waiting for
service.
Other APIs
Some of the other APIs are not so critical in this application. Kate does
not anticipate needing to access information on fields, methods, and
constructors in loaded classes (reflection); making native C calls (Java Native
Interface); extending the core Java platform (extensions), or playing sound (audio).
But when the application is written, she will bundle it and all its related
files into a Java ARchive (JAR) file for installation at the site.
Conclusion
Kate is thrilled with her new business application. Not only
does it help her handle current business and accommodate
growth, but she can maintain the personal touch that
made her business a success from the beginning.
Madhavi will use Duke's Bakery as a compelling reference in her
efforts to recruit other small business owners to use her
expertise to help them convert to the JDK 1.2 platform too.
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