1.3_An introduction to software engineering

Software devel as an engineering activity

• Software development has many things in common with the discipline of engineering, and is said to be:
• The application of a systematic disciplined, quantifiable approach to the development, operation and maintenance of software; that is the application of engineering to software.
• the study of approaches as in (1).
• (IEEE 1990)
• Carrying out a systematic, disciplined and quantifiable approach implies management, and assumes that project management is a necessary activity within the discipline of software development

An engineering approach

Typical activities for SD

• 
• Legenda: problems will be broken into chunks, bringing them back together is known as integration and it is sometimes seen a a separate activity

Activities for development

Agile development

• 
• An umbrella term that describes a set of practices that encourage a simpler, lightweight, faster and nimbler software development that adapts to changes in customer requirements.

Dealing with risk

• Assessing risks and taking steps to reduce them are important activities in software development - this is known as risk management.
• The major risks are around the requirements. Do you understand them? have you got them all? do they change too frequently?
• An agile approach involves customers throughout the process and making it easier to address changes in requirements.
• There is always a trade off between what can be delivered on time and to budget against functionality. One way to choose is to estimate the risk of not delivering each feature.
• 

Traceability

• If a plan driven process is followed, a requirement specification is produced that identifies what the supposed software must do and the environment in which it should work. It allows for the tracing of the history of each requirement from its origin to the various activities to the final operational software system
• Traceability is essential for dispute resolution. The amount of documentation should be inline with the desired level of traceabilty.
• The agile approach emphasises the balance between the amount of documentation and the pay off it brings. The involvement of stakeholders will determine the level required.
• Keeping a project notebook is a disciplined approach to organising thoughts and actions. It may be required as evidence, helps you to review what you did, how long it took and facilitates learning.

Summary

• Large projects are prone to problems due to their size and complexity
• Software is easy to change and easy to introduce new errors
• Software development is similar to engineering when it involves a defined process with clear activities, each of which has a product that can be tested against user requirements.
• A basic process for the development of software is a set of rules that define how a software development project should be carried out. It involves a number of activites and a life cycle model that shows the order of how they are carried out.
• A disciplined approach implies that some effort has been made to record activities, I must be sufficient for the level of traceabilty required.
• An agile approach puts the emphasis on people rather than on processes or documenation, quickly working software, and on the acceptance that systems change.