EXPERT TRACKING AND MAINTENANCE SYSTEM

IMPLEMENTATION

This chapter will discuss the design and implementation of the prototype system, namely Expert Tracking and Maintenance System. It will give an overview of the architecture of the web application. Later, this chapter will describe the prototype system architecture and finally samples of the modeling extension for the web-based graphical user interface design of the prototype system developed.

5.1     Architecture Of The Web Application

According to Conallen (1999) the architecture for a web site is rather straightforward. It contains three principal components that consist of a web server, a network connection and one or more client browsers. The web server distributes pages of formatted information to clients that request it. The request is made over a network connection and uses the HTTP protocol. Figure 5.1 shows the architecture of web application. Some web sites require clients to logon, and some allow anonymous access.

The information made available by a web site is typically stored, already formatted, in files. Clients request files by name, and when necessary, provide specific path information with the request. These files are termed pages, and represent the content of a web site.

In some situations the content of a page is not necessarily stored inside the file. It can be assembled at runtime from information stored in a database (or other information repository) and formatting instructions in a file. Alternatively, it can come from the output of a load-able module (CGI or ISAPI). The web server uses a page filter to interpret and execute the scripts in the page. Web sites employing this strategy are called dynamic sites.

 
 

 

 

 

 

 

 

 

 


Figure 5.1: Architecture of Web Application

Dynamic web sites offer certain advantages to web site designers. They make it easy to keep the content fresh and synchronized with data in a database. The overall look and feel of the web site is defined by a set of pages that contain code executed by the web server during a request for this page. In this context the file can either be a plain text file with scripts interpreted by the web server, or a compiled binary file that is executed by the web server.

A user interacts with a web site via a browser. A browser is an application that runs on a client machine, which connects to a server on a network and requests a page of information. Once the page request has been fulfilled the connection terminates. The browser knows how to communicate (via HTTP) to a web server, and how to render formatted information returned by the web server. Most pages of information contain links to other pages (possibly on other servers), which the browser user may easily request. Users navigate the web by clicking on links and requesting pages from web servers.

5.2     The Prototype System Architecture

The ETMS model proposed in this study can be implemented on several other platforms. However for the purpose of this study, the prototype was developed using the relational database in the web environment.

This study chooses Apache as the web server. Apache web server is one of the two-web servers that dominate the market. The other is Microsoft’s Internet Information Server (IIS).  Apache server is an open source, anyone with the skill can write code that extends the functionality of Apache (Greenspan & Bulger, 2000). 

For the middleware, this study chooses PHP. PHP will most often run as an Apache extension, known as the Apache module.  PHP belongs to a class of languages known as middleware. These languages work closely with the web server to interpret the requests made from the world wide web, process these requests, interacts with other programs on the server to fulfill the request, and then indicate to the web server exactly what to serve to the client’s browser. PHP is a cross-platform and it will run on Windows 2000/NT and Unix and with both IIS and Apache. PHP also works on Netscape, Roxen and other wide variety of systems. For the database, MySQL is chosen because it is free. MySQL will be extremely fast for small- to-medium-sized databases.

There are four types of actors that will use the system. The actors are the User, Managerial staff, Technical staff and Clerical staff. The system architecture contains four main subsystems and one relational database. The four main subsystems are the User management subsystem, Equipment Tracking subsystem, and Equipment Maintenance Subsystem and Equipment Assigning subsystem. The relational database, which is used to store the information, is MySQL. The subsystems will interact with the relational database when storing or retrieving information. The actors will also interact with the systems and its architecture.

5.3     Modeling Extension For The Web-Based Graphical User Interface Design

According to Connallen (1999), the latest generation of web applications is getting complex. Therefore it is important to have modeling to help manage the complexity.  Connallen (2000) stated that the UML has been widely accepted as the standard modeling language for software systems, and is the best option for modeling web application designs. The Web Application Extension (WAE) extends the UML notation with semantics and constraints enabling developers to model web-specific architectural elements using the Rational Unified Process or an alternative methodology. Using UML allows developers to model their web applications as a part of the complete system and the business logic that must be reflected in the application.

UML has defined a mechanism to allow certain domains to extend the semantics of specific model elements. The extension mechanism allows the inclusion of new attributes, different semantics and additional constraints. When collected together as Tagged Values, Stereotypes and Constraints they form an Extension to UML. Part of the extension mechanism of UML is the ability to assign different icons to stereotyped classes (Connallen, March 1999).

A list of prototype icons for the most common class stereotypes and the icon used in this implementation is shown in figure 5.2 below:

Class Stereotype

Common Icon

Icon used

Client page

Server page

Form

Target

Frameset

 

Figure 5.2: Prototype icons for the class stereotypes.

5.4            Modeling Extension For The Expert Tracking and Maintenance System

The modeling extension used in the Expert Tracking and Maintenance System are shown below.

5.4.1    Web Graphical User Interface for Main Menu

 

Figure 5.3 The Expert Tracking and Maintenance System’s Main Menu.

 

5.4.2    Web Graphical User Interface for user entry

Figure 5.4: web GUI for User entry.

5.4.3    Web Graphical User Interface for view user

Figure 5.5: web GUI for View User.

5.4.4    Web Graphical User Interface for user request entry

Figure 5.6: web GUI for User request entry.

5.4.5    Web Graphical User Interface for Maintenance

Figure 5.7: web GUI for Maintenance.

5.4.6    Web Graphical User Interface for Assigning the System

Figure 5.7: web GUI for assigning the system.

5.4.7    Web Graphical User Interface for Stock

Figure 5.7: web GUI for Stock.

5.4.8    Web Graphical User Interface for Technician

Figure 5.7: web GUI for Technician.

 

5.5  Summary

This chapter explains the architecture of a web application, the prototype system architecture and finally samples of the modeling extension for the web-based graphical user interface design of the prototype system.