Introduction

• Two kinds of software product:

  • Generic: Stand-alone systems produced by a development organization for the open market.

  • Customized (bespoke): Commissioned and developed for a particular customer. A software contractor designs and implements software for that customer.

• SWE is an engineering discipline 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.

  • Engineering discipline: You have to apply theory, methods and tools effectively and try to discover solutions to problems. You also work within organizational and financial constraints.

  • All aspects of software production: Not just the technical processes of software development, but also the software project management and development of tools, methods and theories to support software development.

• Importance of SWE:

  • More and more individuals rely on software systems. We need to make reliable and trustworthy systems economically and quickly.

  • It is usually cheaper to use software engineering methods and techniques in the long run rather than just write programs. Failure to do so leads to higher testing, QA and long-term maintenance costs.

• Three reasons software systems fail:

  • Overbudget

  • Not meeting schedule

  • Not meeting expectations

• Four fundamental software process activities:

  • Software specification: Create a vision for the product. Customers and engineers define the software that is to be produced and the constraints on its operations

  • Software development: Software is designed and programmed

  • Software validation: Software is checked to ensure that it is what the customer requires

  • Software evolution: Software is changed to reflect changing customer and market requirements

• General issues that affect software:

  • Heterogeneity: Systems are required to operate as distributed systems across different platforms

  • Business and social change: Businesses and society are changing incredibly quickly as emerging economies develop and new technologies become available.

  • Security and trust: Trust is essential for software, we have to make sure malicious users cannot attack the software.

  • Scale: Software has to be developed across a very wide range of scales, from small embedded systems to Internet-scale cloud-based systems for a global community.

• Application types:

  • Stand-alone applications: Run on a local computer, and include all necessary functionality. Don't need to be connected to a network.

  • Interactive (transaction-based) applications: Applications that execute on a remote computer and are accessed by users from their own PC. These include web applicatoins such as e-commerce applications.

  • Embedded control systems: Software control systems to control and manage hardware devices. Most common

  • Batch Processing Systems: Process data in large batches. Eg. Bursar

  • Entertainment (media) systems: Primarily for personal use and to entertain the user

  • Modeling and Simulation Systems: Systems developed by scientists and engineers to model physical processes or situations

  • Data Collection Systems: Collet data from their environment using sensors and send to other systems for processing.

  • Systems of Systems: Systems composed of a number of other software systems