Topics include:

• The general elements of a software engineering discipline
• The phases of any significant software development project
• Personnel involved
• Ongoing activities regardless of the phase
• Software process models
• The importance of a disciplined process

For experienced software developers, the component-level process is often less conspicuous, involving well-established and automated patterns of thinking. This does not diminish its importance.

Software developers need good automated thinking habits to free their minds for dealing with more complex issues.

In smaller organizations, people may play multiple roles.

Next we show the major software development roles.

The following software development activities cannot be isolated to a single phase, and are repeated throughout the development process.

• Risk Analysis
• Planning
• Verification and Validation
• Documentation

Risk analysis is a management activity that attempts to identify aspects of the development process that have a significant chance of failing.

After risks are identified, managers have several options:

• Cancellation of the project
• Change in goals or how resources are allocated

Planning is a management activity that determines the specific project goals and allocates adequate resources for the various phases:

• Time: calendar time or person-months
• People: full-time equivalents
• Work and meeting space
• Development hardware and software

• Allocate more time or people
• Allocate more skilled people
• Devote time to training people

All phases of development should involve ensuring that the products of the various phases meet their objectives.

• Validation: the process of ensuring that the requirements and designs solve the customer's problem
• Verification: the process of ensuring that the design and implementation conform to the requirements through:
  • Reviews and code walk-throughs
  • Testing:
    • Black-box testing: Testing how software meets its client-oriented specifications, without regard to implementation
    • White-box testing: Using knowledge of implementation to exercise all paths of control in programs
  • Formal or analytic verification

Documentation provides instructions and information needed for the installation, use, and maintenance of software.

• User Documentation: Important, but not the only kind
• Code Documentation: Because of the importance of maintenance, the documentation of components for use by other developers is essential

• Help the project manager and his or her team to decide:
  • What work should be done
  • In what sequence to perform the work
• The models should be seen as aids to thinking, not rigid prescriptions of the way to do things
• Each project ends up with its own unique plan

• Does not acknowledge the importance of working out the requirements and the design before implementing a system
• There is no explicit recognition of the need for systematic testing and other forms of quality assurance
• The above problems make the cost of developing and maintaining software very high

However, the phase transitions must be controlled, or the process will be chaotic as shown below.

• Suggests that software engineers should work in a series of stages
• Each stage should involve quality assurance (verification and validation)
• Accounts for the importance of requirements, design and quality assurance
• Recognizes, to a limited extent, that you sometimes have to step back to earlier stages

• Implies that you should attempt to complete a given stage before moving on to the next stage
  • Does not account for the fact that requirements constantly change
  • Means that customers cannot use anything until the entire system is complete
• Makes no allowances for prototyping
• Implies that you can get the requirements right by simply writing them down and reviewing them
• Implies that once the product is finished, everything else is maintenance

• In practice, neither users nor developers know in advance all the factors that affect desired outcome
• Thus considerable "thrashing" between one activity and back may take place in order to gain knowledge about the problem
• One way to control such thrashing: develop a partial product and allow customers and developers to examine it for feasibility
• Advantage: revisions made at requirements stage rather than the more costly testing stage
• The partially developed product is a prototype

In the Prototyping Model, the prototype becomes the product:

• After requirements gathering and planning, the project should be broken into separate subprojects, or phases
• Each phase can be released to customers when ready
• Parts of the system will be available earlier than when using a strict waterfall approach
• However, it continues to suggest that all requirements be finalized at the start of development

Incremental Development: Deliver complete modules one at a time

Iterative Development: Deliver incomplete modules in a bundle and improve them over time

• Helps developers better understand what they are doing
• Helps managers make more accurate predictions about how long a project will take
  • Predictability is crucial for setting reasonable goals and planning resource allocation.

• The values of the client
• The concepts that are important to the client
• Software patterns for achieving the desired behavior
• Implementation methods

• One of the development team members has changed jobs so that a replacement is needed, or
• The project is behind schedule so management has allocated more people to work on the project.

Will he/she be as effective as the other team members?

Not likely.

• Often, the result is that the project slips further behind schedule.
• The reason: The new people do not have a mental road map.
• In order to acquire it, experienced team members will have to dedicate some time to bringing them up to speed.

This may seem obvious, but managers have to go through a similar process to learn how to manage effectively.

A lot of facts are obvious, but that does not mean that you will see them when they are important:

• You do not see things that are obvious until you have had experiences that stress their importance.
• You also need to recognize that they are important.

• A reasonable estimate of cost can be given to the purchaser
• Internally, managers can anticipate needs and coordinate between multiple projects.

• With an undisciplined process, there is too much variation in how long it takes to accomplish a task among previous projects, and a reliable estimate cannot be made for new projects
• With a disciplined process, managers develop a better sense of how long it takes to accomplish various kinds of tasks and what kinds of skills are needed.