Download CD Content
The purpose of this chapter is to provide an introduction to the subject matter of the book, with samples of the code and the diagrams you will read about and produce.
The Web is a significant technological, economic, and cultural phenomenon. For relatively little cost and modest efforts, people can disseminate (publish) text, images, and multimedia to anyone with a computer with a connection to the Web. Furthermore, these computer connections are becoming increasingly widespread and powerful. The initial and still most common Web offerings were and are basically information. They are “read-only” for the viewer, termed the visitor, to the site. After review of the basics, this book explains how to build complex Web applications that incorporate reading and writing to databases and files. Examples of these types of applications are e-commerce sites and sites that gather information for research.
The Web is constructed using complex and still evolving software, hardware, and communication technologies. Products from different companies and organizations work together not perfectly, but fairly successfully based on published technical standards. In this text, we focus on what is termed middleware; namely, software products that bridge between ordinary Web pages to be interpreted and displayed on the visitor’s computer (called the client) and operating systems and database systems resident on the server computer (your computer or, more typically, your organization’s computer, which you have established as a node on the Web). We do not cover all the products that provide these functions. However, we have chosen to present two distinct sets:
PHP Hypertext Preprocessor (PHP), formerly named Personal Home Page, and database management system MySQL
The first set is open source. Open source refers to a worldwide movement in which software is made available as source code so that anyone can examine the internal workings and make suggestions for changes. Open-source software is also available for free, although many people and organizations find it easier to purchase it together with installation, maintenance, and other services. The second choice constitutes an example of proprietary software. The vendor for ASP and Access is the Microsoft Corporation. Proprietary software is generally sold only in its executable (also called compiled) form and the original source code is not revealed.
It should be noted that multi-user computer applications existed before the Web, and Web applications involving server-side resources existed before PHP or ASP came into existence. PHP and ASP offer ease of use for the developer and improved robustness and security for the owner of the server. If you have not used the older products, do not expect to appreciate fully these claims, although we do provide some reasons. Just as there were applications before these middleware products came into existence, new products are coming into use every day. Hopefully, what you gain from using this book will help you evaluate and master the new products.
Building a complex Web application is not just programming code. It involves analysis of the technical environment, consultation with the many groups of people to be involved in the project, and extensive planning. Entire courses and numerous books exist on systems analysis, systems design, usability, and other information technology and business topics. In this book, we introduce you to the planning and documenting aspects through methods of diagramming the information content of a database (entity-relationship diagram), the processes of an application (data flow diagram), and the flow of control of the scripts (storyboard).