Java Reference
In-Depth Information
BasicServer server
#
new
BasicServer(
new
PersistentDB(conneciton));
StubFactory factory
#
new
StubFactory(server);
(
new
Thread(factory)).start();
// instantiate the client components
CounterFrame counter
#
new
CounterFrame(
new SocketProxy("localhost"));
counter.show();
BarCodeReaderUI reader
#
new
BarCodeReaderUI();
reader.setLocation(100300);
reader.show();
reader.setListener(counter);
}
}
14.8
■
Extension
The reader can extend the supermarket support system in several ways:
Add the monitoring interface to the supermarket server.
■
Adapt the system to a web-based interface, consider the increment in
network traffic and the scalability limits.
■
Use RMI instead of sockets as a communication medium.
■
14.9
■
Assessment
Architectural model
. Since the nodes are client, server and database, the
architecture selected for the application is a three-tier model.
Paradigm
. The components that represent the three tiers of the archi-
tecture should be loosely coupled. This suggested an approach based on a
declarative communication paradigm. The communication between the
client and the server tiers is based upon an application-specific protocol,
which has been designed ad hoc. The interaction between the server and the
database uses the JDBC standard protocol.
Technology
. The application-specific protocol uses the socket technol-
ogy. It is based on a TCP
IP connection between client and server; this type
of connection guarantees the delivery of packets, thus relieving the applica-
tion protocol of this issue. Access to the database is based on JDBC, which is
a standard protocol supported by classes in the standard Java library.
