Introduction to Software Engineering

Introduction to Software Engineering

Software engineering is concerned with all aspects of software production from the early stages of system specification through to maintaining the system after it has gone into use. In this chapter, we will explain the following:

• The definition of computer science and software engineering and how the two are different

• Software engineering is similar to other engineering disciplines and what that means for software engineers

• The unique challenges of software engineering

• Software development models and processes and their component parts, software development

 Practices

Software systems are perhaps the most intricate and complex . . . of the things humanity makes. – Fred Brooks (Brooks, 1995)

As a discipline, software engineering has progressed very far in a very short period of time, particularly when compared to classical engineering field (like civil or electrical engineering). In the early days of computing, not much more than 50 years ago, computerized systems were quite small. Most of the programming was done by scientists trying to solve specific, relatively small mathematical problems. Errors in those systems generally had only “annoying” consequences to the mathematician who was trying to find “the answer.” Today we often build monstrous systems, in terms of size and complexity. What is also notable is the progression in the past 50 years of the visibility of the software from mainly scientists and software developers to the general public of all ages. “Today, software is working both explicitly and behind the scenes in virtually all aspects of our lives, including the critical systems that affect our health and well-being.” (Pfleeger, 1998)

Despite our rapid progress, the software industry is considered by many to be in a crisis. Some 40 years ago, the term “Software Crisis” emerged to describe the software industry’s inability to provide customers with high quality products on schedule. “The average software development project overshoots its schedule by half; larger projects generally do worse. And, some three quarters of all large systems are “operating failures” that either do not function as intended or are not used at all.” (Gibbs, 1994) While the industry can celebrate that software touches nearly all aspects of our daily lives, we can all relate to software availability dates (such as computer games) as moving targets and to computers crashing or locking up. We have many challenges we need to deal with as we continue to progress into a more mature engineering field, one that predictably produces high-quality products.

 Software Development

Software engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software; that is, the application of engineering to software (IEEE, 1990). The “systematic, disciplined, quantifiable approach” is often termed a software process model (in the general sense) or a software development process (in the specific sense). Specific software development processes consist of a particular set of software development practices which are often performed by the software engineer in a predetermined order. Software development practices, models, and methodologies will be introduced in the next two subsections.

Software Development Practices

Engineers adopt a systematic and organized approach to their work. As you learn software engineering, you should be exposed to many specific practices (or techniques) for developing software. By software development practice we refer to a requirement employed to prescribe a disciplined, uniform approach to the software development process (IEEE, 1990), in other words, a well-defined activity that contributes toward the satisfaction of the project goals; generally the output of one practice becomes the input of another practice. First, we provide one list of software development practices (but this list may vary depending upon the process and its associated terminology):

• Requirements engineering

• System analysis

• High-level design/architecture

 • Low-level design

• Coding

• Integration

• Design and code reviews

• Testing

• Maintenance

• Project management

 • Configuration management