Development Methodologies

Iterative Development Process

Sometimes also called the "Waterfall Model", this development process:

follows a set of steps in a specific order
allows iteration

Iteration

If a development team choose to make use of an iterative methodology, they will repeat stages like design, implementation and testing regularly.

Iteration can take place:

between stages
within stages

We spend a lot of time collecting the complete requirements. Then working out the main steps to then refine these down into smaller problems. Only then designing and coding a piece of software.

Agile Development Process

The Agile model is a further evolution of the software development process.

The main difference is in the amount of client/developer interaction. And that the requirements are constantly being gathered in Agile development as opposed to the traditional method of gathering them all at the beginning.

Features:

have a strong emphasis on communication and team work
draw on some principles of rapid application development, namely prototyping and regular communication with the client
have a strong emphasis on leadership and project management within the software development team
have face-to-face communication as a key principle

Sprints

Agile methods draw on the waterfall method in relation to sprints. A sprint is a planned delivery schedule for an aspect of the system.

Within a sprint the principles of analysis, design, implementation and testing are used.

Prototyping is also likely, particularly during the early phase of a sprint.

Sprints are carried out for each area of development.

Rather than following a rigid set of steps for the development of the entire system, several steps are repeated in one sprint and then carried out again in the next sprint.

Agile vs Iterative

Client Interaction

Iterative

Client is heavily involved at the start and end points of development.
They will sign off the specification.
Specification is fixed for the remainder of the project
At the end of development they will evaluate that it is fit for purpose and meets the specification.
This feedback can then be used redesign any aspects not met (very time heavy).

Agile

Client is involved throughout the entire process.
They will give feedback on each prototype as it is produced to meet requirements at that stage.
Feedback is acted upon at that stage to improve the software
Goals can be changed throughout the project.

Teamwork

Iterative

Independent specialist teams work in isolation on each phase of the project

Agile

Teams consisting of a range of specialists collaborate and communicate.

Documentation

Iterative

Comprehensive documentation produced throughout the project.

Agile

Concise documentation kept to a minimum.

Measurement of Progress

Iterative

Progress measured against milestones set out during analysis.

Agile

Progress measured by work completed in each sprint, or by time taken to produce prototypes or working components.

Adaptive vs Predictive

Iterative

Predictive methodology - the analysis phase used to predict the development pathway.

Agile

Adaptive methodology - allows for ongoing changes to be made as the project requires.

Testing

Iterative

Testing is carried out when the implementation phase of the project is complete.

Agile

Ongoing testing - carried out during each development sprint.

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