The paper describes the author's experience teaching database web application
programming with templates. The templates are each individual complete
database programming examples. Presenting them one by one in class, letting
students compile and run by themselves, and then modifying them to their
homework assignments. Based on the templates they were able to accomplish
their homework and finally database application projects. Database web
application programming was the last topic of our database course. It was
a fun part of the term project.
Due to the vast popularity development of the Internet applications,
web database application programming has become one of the topics in the
undergraduate database course. How to enhance it into the already crowded
traditional database course is a raised question. After trial and errors,
the author found an effective way to teach the emerged technology. The
solution is to use the designed programming templates and . Given the appropriate
connectivity resources and programming templates, students can learn both
non-web and web programming and create their own projects using CGI or
JDC in two weeks. The prerequisite is that students should have the knowledge
of the database design, SQL language, and at least one programming language
During the four semesters of academic year of 1998-1999 the author taught
web application programming with CGI (Common Gateway Interface) programming
in Pre-compiler C in Oracle7. With the release of Oracle 8i, the author
started teaching JDBC (Java Database Connectivity) in the fall of 1999.
Both CGI and JDBC were implemented within the Oracle DBMs environment.
The focus of the paper is to describe how to teach CGI and JDBC with programming
2. Teaching CGI (Common Gateway Interface) with Proc
CGI is a programming method that lets the Form on Web pages communicate
with programs on an HTTP server . The interface is precisely called:
a gateway. It receives the information from the server and creates a child
process that handles or stores this information for the CGI program. CGI
enables you to add applications to your web pages, retrieve real time data,
and communicate with other individuals. With CGI, you can provide a method
by which visitors to your site can access your databases, store information,
and execute external programs. In CGI programming, a request is made for
a URL from a location served by the HTTP server. CGI is a method that lets
Web pages communicate with programs on an HTTP server. Prior to the advent
of Java, this was the only way to get web pages to interact with .
When using HTML for the interface, the author can define various fields
that enable the user to enter data. This data is sent to a CGI program
when the user clicks a submit button. Once the data sent, the CGI program
generates a new HTML page describing the result and returns it to the userís
browser to be displayed. You can use any language to write CGI scripts.
Perl (Practical Extraction and Report Language) is best overall to use
for creating CGI program with C and Visual BASIC. HTML form provides the
only method by which a visitor can interact with your CGI scripts.
CGI Program was written with Pro-c and compiled with proc-compiler in
Oracle7 on Salaries system. The generated c code was compiled with GCC
compiler to generate executable cig code. The executable cgi runs on the
web server when URL in the Action in the form is called.
3. Teaching JDBC with Java
JDBC (Java database Connectivity) contains Java classes and interfaces
that provide low-level access to databases. The most common task of an
applet using the JDBC driver to connect to and query a database. The most
prominent and mature approach for accessing relational DBMSs from Java
appears to be JDBC .
With JDBC Java can be used as the host language for writing database
applications. JDBC is a standard Java classes library, to query and modify
relational data. The JDBC driver acts like a translator. It receives the
client applications request in Java methods, translates it into a format
that the database can understand, then presents the request to the database
using the database native protocol. The response is received by the JDBC
driver, translated back into Java data format, and presented to the client
application. JDBC defines a set of interfaces and classes to be used for
communicating with a database. This set of interfaces and classes are all
contained in the java.sql package. The entire java.sql package is included
in the Java core just as the java.awt or java.lang packages are.
All databases speak SQL. The goal of JDBC API is to give the Java programmer
the ability to write applets and applications to access any SQL database
servers. The JDBC API consists of a set of classes and interfaces written
in the Java programming language that provide a standard API for tool/database
JDBC driver API defines two things. On one side, the JDBC API specifies
how information is to be presented to your application. It tells your application
what can be expected from the database. Conversely the JDBC API also define
what the database can expect from your application. Essentially, it defines
the common ground between the database and application. It defines what
commands can be executed, how to execute them, and how data will be formatted.
Oracle8 provides native support for Java in the DBMS. That is, Oracle
has developed its own Java VM that integrates with the database mechanisms
closely high performance. In addition, the database system natively supports
JDBC and SQLJ. The oracle 8i comes with a web server; so the database system
can be an http listener.
The JDBC API makes it easy to send SQL statements to a relational database
systems and supports all dialects of SQL. The value of the JDBC API is
that an application can access any source and run on any platform with
API (Application Programming Interface) is added to Java 1.1. Using the
JDBC API you can access a wide variety of different SQL database using
exactly the same syntax in an application and applets.
Seven basic steps to querying databases are: Import the java.sql package,
Load and register the Driver, Establish connection, Create a statement,
Execute a statement: statement executes SQL statements, Retrieve the results,
Close the statement and connection
4. Programming Templates
Programming templates are typical database programming examples prepared
by the instructor. Teaching with templates are listed as following steps:
Demonstrate non-web application programming examples and explain how
they work in class.
The typical templates are listed as follows:
Explain the syntax of database connectivity and embedded SQL.
Let students run the templates before they start their homework assignments.
Encourage students to do the homework by following the given examples
in the classroom as templates.
Repeat Step 1 to Step 4 to teach web application programming by providing
web application programs.
Assign students to a project to write a complete database application
Table 2 Programmer's point of view
Two disadvantages of Proc CGI programs are:
HTML form has to be defined and wrapped in the proc code, which makes
code more complicated.
The size of the executable is very large. One executable cgi program
with one query has the file size as large as 1 megabytes because the calls
to Oracle library were embedded in the file.
Although CGI program has a lot of disadvantages, it is still a popular
and general way to create web applications. Once students learned how to
create using one language, they will be able to pick up any other language
to write a CGI program. Some of my students learned using pro-c writing
a CGI program in the course. They picked up Perl or and Ada to write a
CGI program by themselves.
It is more complicated to define GUI interface with JDBC unless using
predefined Java beans or Java Swing.
Java program is machine independent. It can be compiled with any Java
compiler as long as it follows JDK standard. Driver can be changed. The
compiled output Java class saved on the disk can be called by an applet
which is embedded into a page of HTML. When a web browser reads the page
with the embedded applet, it downloads the applet over the network to the
local system, and runs the applet in a Java VM which is built into the
browser. Therefore the output of the Java program is displayed on the Internet.
Java replaces some uses of CGI by allowing truly dynamic web pages doing
the process on the client instead of server. Java has built-in capabilities
to prevent memory corruption, program crashes, and viruses. Thus it is
robust and secure. Java contains multiple threads to carry out many tasks
in parallel. On the whole, JDBC application programming has the bright
future. The Java Server Page (JSP) is the newly developed technology, which
will help computer professionals to develop more standard web applications
more efficiently in the real world.
 Connolly, T & Begg, C.& Strachan A. Database systems: A
practical Approach to design, Implementation, and management, Addison Wesley,
 Catlell R. & Hamilton G., JDBC database access with Java, Addison
 Hall Marty, Core Web Programming, Prentice Hall, 1997