Client Server Architecture - Programming GPS and OpenStreetMap Applications with Java - page 144

enables programmers to inquire classes, which are not part of the start-up
procedure and which only appear at runtime.
From here on, the development will be coded directly into the new pack-
ages. The text will basically follow the call stacks and jump from client to
server according to their dialog. For the reader, this is somewhat a reverse-
engineering tutorial. The Java Tutorial used to have a final trail (although
it is not published anymore, the trail can still be found on the internet)
to collect previous trails and put them together into one application|this
can serve as a guideline for putting the ROAF together.

TheJavaTutorial>PuttingItAllTogether>Introduction

Now, it's time to put all that knowledge and programming
skill to use. You can chooseyourownproject, or you can follow
the description and analysis of some of the projects that we did.
A client/server application that implements the game of
BINGO. This example broadcasts information via a multicast
socket, builds its GUI with Swing components, uses multiple
synchronous threads, and communicates with RMI.

The software in Parts II and III was developed in roaf.book packages
related to Java Tutorial Trails. The remainder of this part rolls out the
server architecture with an application layer on top of it. It is much more
convenient and effective to follow the text by setting up clients and server
in advance and adding println statements in the source, while reading.

Please set up the application environment now as described in Section
13.2.1 to run the application as needed.

11.3 Four-layer Architecture

After separating client and server, the vision gets even more concrete. The
roaf.ros package was designed as the origin of all real objects. Each ab-
stract RealObject can be extended to specify an object representing the
real object; the server is the environment for the client objects.
Figure 11.1 shows the four main components of the client-server archi-
tecture. The RealObjectServer can be coded against abstract objects and
interfaces in the RO package. From a design perspective, it is vital to stick
to the package and not to apply any methods of the extending classes.
The figure supports the architect in defining guidelines. One guideline
for the real-object package was already defined to reflect human and scien-