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Developing your first enterprise beans
Writing distributed enterprise applications has always
been a significant challenge, but this once Herculean task has been
somewhat ameliorated with the advancement of component-based programming
in general. For example, by increasing program modularity, you can now
compose a behemoth application from multiple functionally independent
modules. This not only enables you to assemble complex systems using an
assembly-line approach, but also greatly increases the reusability of the
modules themselves.
Although using components enhances the modularity and
natural distribution of applications in general, they still present some
interesting challenges. For example, in days of old, when a monolithic
program failed, it was simply restarted as a unit. But, today, with a
modular system, when a failure of any one component occurs, the challenge
is to ensure faults are isolated to limit their propagation and that it
does not corrupt others. This is more complicated than it sounds with
distributed applications, however, as the components can reside anywhere
on the network. In addition, because enterprises are essentially
heterogeneous environments, the presence of multiple operating systems and
platforms that host the different components adds a new level of
complexity.
Clearly, a technology like Java, with its promise of
the "write once run anywhere," can significantly mitigate many
of the problems associated with enterprise distributed systems
development. This seminar report is devoted to understanding the
implications and architecture of an enabling server-side component
technology-Enterprise JavaBeans (EJBs)-and presents examples of how to use
this technology to implement real-life, distributed enterprise solutions
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