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Academic Open Internet Journal |
Volume 14, 2005 |
Establishing of a Web-based
Information System
Using Java Instruments
Practical Course
Daniela Ananieva Orozova
Bourgas Free University –
orozova@bfu.bg
Abstract: A
general approach for establishing a Web-based information
systems using Java instruments is discussed. The training covers a development of a project,
shown in the process of its development, following the classical technology
of life cycle.
Proposed is a practical training course on Internet applications development, conducted
in a practical training during
a course on network programming at Bourgas Free University, and a general
approach for establishing of a Web-based information system is described.
This practical training course is integrated with a lecture course on “network
programming”. The course includes and highlights basic elements of Java language.
After their discussion the students are offered to work out project referring
to various applied aspects. Each project represents a simplified model of
a real task for establishing of a Web-based information system.
At the beginning of the practical course, for the sake of the successful realization of
such a project, the students should have a basic knowledge
in object oriented programming, be acquainted with the Java’s basic characteristics,
have a general knowledge of Internet organization and beginners’ knowledge
referring to HTML. At the end of the course the students should have a completed
vision for the basic approach for establishing of network and Web-applications
using Java instruments.
During the course the attention shall
be drawn to basic concepts of Java such as: input-output flows, the instruments
for establishing of multithreading applications, implementing client/server
applications, communication of TCP sockets. It is good to demonstrate the
instruments for sending of single packages between two applications using
UDP protocol and demonstrate the access to the resources of URL, establishing
java.net package classes.
The lecture course discusses the basic
concepts and fundamental terms connected with the Web-programming, languages
for data description and the technologies for a dynamic generation of Web-contents.
The project presents in detail the technology of Java servelets, the techniques
for extraction of user stated parameters and instruments for user sessions
management, as well using a server for Web-applications. The technology Java
Server Pages (extension of the servelets, allowing a Java code to be built
in a HTML document) and tags relevant to it are commented. Finally the complete
concept for Web-applications of J2EE platform is
be clarified.
The students have to demonstrate their
acquired skills for working with threads in the practical course and use the
technologies for working with applets, serveletes or Java Server Pages (JSP),
implementing simple network applications, which are of real interest. They
should complete the task and establish a proper visual interface implementing
the Java instruments.
There are two basic technologies for establishing of information systems based on different approaches – life cycle [1] and prototype [2].
·
With prototype approach the
implementation of the working concepts represents a series of prototypes approximations
to the requirements of the project, so the last prototype assumes the status
of a main sample.
·
Following the classical technology
of the life cycle the implementation goes trough some basic phases: analysis,
specification, designing, developing, testing, exploatation and maintenance.
Hereafter the separate phases of the
process are commented as well as the project progress keeping to the requirements
of the classical technology of the life cycle.
A Web-application represents a software
system with a Web-based user interface, working on an Internet or a local
network Web-server. Each Web-application includes two parts [5]:
-
Client – a
combination of dynamically generated documents, visualized by the user’s Web-browser
and represent the user interface of the application.
-
Server – All the servelets
or JPS pages responding to the client’s request: processing user’s data and
depending on it dynamically generating HTML or other format, to be visualized
by the browser.
The tasks and the data information
flow analysis is performed at the beginning, according
to the classical technology of information systems development. The specification
of the tasks using sample statistics and establishing of ER- diagram, defining
the structures for data presentation, the input forms and documents follow
then. During the design process the normalized relational scheme of the
database with primary and foreign keys, data restrictions as well as definitions
of the virtual tables. The data required for the application are stored in
the database (DB) on a server. The data
establishing, modification and access on the server is performed by Java-applications
and Java Server Pages. Then the basic stages of this implementation follows.
- Task analysis
This stage of the project developing includes analysis
of the application field, definition of the concepts in use and the relations
between them, clarifying the aims of development, division into subtasks,
determining the available resources and system requirements. Here are determined
the methods for solving the problems and the structures for representation
of all types of data and knowledge, as well as data restrictions.
1.1.
Decomposition of the task – as a result,
there can arise multiple subtasks, substituting the original one and subtasks,
controlled by the original task. The information flow diagram [3] is established.
1.2.
Definition of all object classes of
and structures for data presentation, and as a result an ER-diagram is established.
1.3.
Imposing restrictions on data correctness
and validity rules as well as default values.
- Database scheme design and realization
The creation of a detailed project
of a normalized scheme of a relational database is based on the already established
ER-diagram and user’s restrictions
on the data. Next is the creation of Java-applications, implementing the DB
scheme with Java code using built in SQL queries from the data description
language.
2.1.
The connections between the relations
– the connections of the type one to one ( 1:1),
one to many ( 1: r) and many to many ( r: R) are analyzed. The connections
of last type in the relational model of data are broken in connections of
the type (1:r) as it is shown on fig.1.
