Software Layer and Components

The third layer of the Web Interaction Model is software. Software provides the underlying components that enable the display of Signs and Metaphors. It provides the structure needed to establish a site's Information Architecture. Various types of software are used for creating and managing resources available to users over the Internet. This lesson examines the ways software supports the various layers of the Web Interaction Model. You will not be expected to know every application in detail, but you should feel comfortable understanding the types of software available and their general capabilities. The diagram below illustrates the third layer of the Web Interaction Model:

Web software can be divided into four main categories:

1. Languages
2. Applications
3. Databases
4. Bundled software solutions

Note that these are not formal categories, but ways of understanding the different types of software. There is some overlap among these categories.

In Web site development, there are multiple levels and processes for software development. For example, software is used to create, use, and view other software components. To understand how these different categories of software relate to each other, it is helpful to think of a process that starts with languages and ends with a user interacting with a Web site, as shown in the following series of images below:

Every great piece of software starts with a customer's big idea. It is your job as a professional software developer to bring those ideas to life. But taking a vague idea and turning it into working code, code that satisfies your customer, is the challenge of understanding all of the benefits of SW development. By delivering software that is needed, on-time, and on-budget, you will be able to maximize profit for your company.

• Personal Software Process (PSP)
  PSP is based on the work of David Humphrey. PSP is a scaled down version of industrial software process. PSP is suitable for individual use. It is important to note that SEI CMM does not tell software developers how to analyse, design, code, test, or document software products, but assumes that engineers use effective personal practices. PSP recognises that the process for individual use is different from that necessary for a team. The quality and productivity of an engineer is to a great extent dependent on his process. PSP is a framework that helps engineers to measure and improve the way they work. It helps in developing personal skills and methods by estimating, planning, and tracking performance against plans, and provides a defined process which can be tuned by individuals.

Programming languages can be seen as building blocks for other software applications, databases, and bundled solutions.
A programming language formally defines logic to act on data. The logic provides the computer with instructions that result in specific kinds of operations. Different kinds of programming languages support different functions. Developers use programming languages to create what we generally call applications, as well as databases and bundled software solutions. Some languages commonly used for Web applications are shown below:
Programming languages support the upper layers of the Web Interaction Model in many ways. For example, languages for creating visual resources and screen functions, such as rollovers or animation, directly support the Signs and Metaphors layer. Similarly, the Information Architecture layer is supported by languages that provide data manipulation, logic, and navigation features, such as hypertext. In the next lesson, you will learn about applications that serve the end user and Web site support.