Java Reference
In-Depth Information
Here you see the class being run, and, sure enough, it displays our user-
name. We then run
su
to become root and (after setting that library path) run
it again—and, sure enough, it tells us we are “root.”
We'll talk more about JNI later in the topic, but now you know enough
to be dangerous.
5.8
I
NTRODUCING
RMI
Remote Method Invocation
(RMI) is a system for distributing application code
over multiple hosts. It is a small part of multitier computing. Much of this topic
will be devoted to the how's and why's of multitier client/server computing.
Here we are concerned only with the SDK tool
rmic
, the RMI compiler.
5.8.1
Remote Method Invocation is a basic client-server model for invoking Java
methods over a network.
A Brief Introduction to RMI
5.8.1.1
One of the most common problems in computing is how best to make an ap-
plication available to the largest number of users at the least cost. To this end
we have seen the development of “timeshare” systems with dumb terminals all
over the place. We have seen the evolution of distributed GUI systems with X
Windows and its network display system, and with tools like VNC (Virtual
Network Console).
16
We have seen the emergence of the PC, providing
autonomous computing at each worker's desktop. And finally we have seen the
desktop turning slowly back into a terminal (albeit a prettier one) with the
emergence of client-server computing.
What seems to have emerged from this progression is two major kinds of
software systems. One is the PC and associated hardware and software. Devel-
opments here have dramatically increased the power and productivity of indi-
vidual work. The PC revolution was indeed a real change throughout the world
of business and technology. But even with this, there are a host of applications
and business functions that require a collection of data and resources to be
available to
multiple
workers at the same time. This is the second major kind
History and Background
16.
http://www.realvnc.com/
