THREE TIER ARCHITECTURE

LEVEL III

The work station (client) represents the third level, and it relies on a browser as the executive program environment.

Windows-like GUI (Graphical User Interface) is implemented using HTML and JavaScript. The OS used on the client is Windows, with Internet Explorer 6.0+ as the corresponding browser.

The development of the client part of the application relies on the use of JAVA, HTML, JavaScript. The connection with the database utilizes a JDBC driver.

 

LEVEL II

The second level is the applicative/Web Server. The program uses the Tomcat Application Server, Apache Web Server and Jasper Reports.

The middle level and the reports are structured in a way to be portable and transferable to different database servers (currently Oracle and Informix have been used).

 

LEVEL I

The first level is the DB Server, with Oracle RDBMS currently being used.

The business logic is partly implemented with PLSQL procedures, and mostly through mid-level (LEVEL II) Java classes.

For the development of Stored Procedures, procedural languages adequate to the database server are used, e.g. Oracle/SQL etc.

 

Products developed using this architecture:  asw:dominus, asw:credis and asw:temporis

The advantages of the three tier architecture include:

• Web access (allowing operation from distant locations)
• Reduced administration on the works stations (browser installation)
• Simple and efficient system maintenance
• System scalability, adaptability to complex organizational and locational structures

 

Both architecture layouts are shown in the figure:

 

TWO TIER ARCHITECTURE

Client

• Work station

Either Windows or Linux OS can be used for the client. GUI based on the use of Java Swing architecture.

The client part of the application is developed using Java programming language. The graphic library used is Java Swing. A JDBC driver is used for communications with the database.

 

Server

• DB Server, currently Oracle RDBMS and PostgreSQL
• Stored Procedures

The business logic is implemented in the PLSQL procedures. Oracle PL/SQL procedural language is used for the development of the server part.

 

Products implemented using this architecture

ITCC, LPH and the retail subsystem asw:mercantis (POS and Back Office functions) have a two tier structure.

The subsystem is based on the Java programming language and operates within a Client-Server architecture.
The advantage of the two tier architecture:

• universality of the Java language
• transparency of solutions on various different platforms
• support for handling special POS devices (Java POS standards)
• central distribution of program solutions with local copies (Web start technology developed by SUN)

Development: Java WebStart
Using Java Web Start technology, independent Java applications can be distributed through the network with a single click.

Java Web Start also ensures a flexible and intense upgrading of the applications on Java technology.