Understanding Agile Methods & Project Management in Software Development, Essays (university) of Software Engineering

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Chapter 3 – Agile Software Development

Topics covered

 Agile methods

 Agile development techniques

 Agile project management

 Scaling agile methods

Agile development

 Program specification, design and implementation are

inter-leaved

 The system is developed as a series of versions or

increments with stakeholders involved in version

specification and evaluation

 Frequent delivery of new versions for evaluation

 Extensive tool support (e.g. automated testing tools)

used to support development.

 Minimal documentation – focus on working code

Plan-driven and agile development

Agile methods

Agile methods

 Dissatisfaction with the overheads involved in software

design methods of the 1980s and 1990s led to the

creation of agile methods. These methods:

 Focus on the code rather than the design

 Are based on an iterative approach to software development

 Are intended to deliver working software quickly and evolve this

quickly to meet changing requirements.

 The aim of agile methods is to reduce overheads in the

software process (e.g. by limiting documentation) and to

be able to respond quickly to changing requirements

without excessive rework.

The principles of agile methods

Module 2 Agile Software Development 10 Principle Description Customer involvement Customers should be closely involved throughout the development process. Their role is provide and prioritize new system requirements and to evaluate the iterations of the system. Incremental delivery The software is developed in increments with the customer specifying the requirements to be included in each increment. People not process The skills of the development team should be recognized and exploited. Team members should be left to develop their own ways of working without prescriptive processes. Embrace change Expect the system requirements to change and so design the system to accommodate these changes. Maintain simplicity Focus on simplicity in both the software being developed and in the development process. Wherever possible, actively work to eliminate complexity from the system. Estelito R. Medallada, Jr.

Agile method applicability

 Product development where a software company is

developing a small or medium-sized product for sale.

 Virtually all software products and apps are now developed

using an agile approach

 Custom system development within an organization,

where there is a clear commitment from the customer to

become involved in the development process and where

there are few external rules and regulations that affect

the software.

Extreme programming

 A very influential agile method, developed in the late

1990s, that introduced a range of agile development

techniques.

 Extreme Programming (XP) takes an ‘extreme’ approach

to iterative development.

 New versions may be built several times per day;

 Increments are delivered to customers every 2 weeks;

 All tests must be run for every build and the build is only

accepted if tests run successfully.

The extreme programming release cycle

Extreme programming practices (b)

Module 2 Agile Software Development 16 Pair programming Developers work in pairs, checking each other’s work and providing the support to always do a good job. Collective ownership The pairs of developers work on all areas of the system, so that no islands of expertise develop and all the developers take responsibility for all of the code. Anyone can change anything. Continuous integration As soon as the work on a task is complete, it is integrated into the whole system. After any such integration, all the unit tests in the system must pass. Sustainable pace Large amounts of overtime are not considered acceptable as the net effect is often to reduce code quality and medium term productivity On-site customer A representative of the end-user of the system (the customer) should be available full time for the use of the XP team. In an extreme programming process, the customer is a member of the development team and is responsible for bringing system requirements to the team for implementation. Estelito R. Medallada, Jr.

XP and agile principles

 Incremental development is supported through small,

frequent system releases.

 Customer involvement means full-time customer

engagement with the team.

 People not process through pair programming, collective

ownership and a process that avoids long working hours.

 Change supported through regular system releases.

 Maintaining simplicity through constant refactoring of

code.

User stories for requirements

 In XP, a customer or user is part of the XP team and is

responsible for making decisions on requirements.

 User requirements are expressed as user stories or

scenarios.

 These are written on cards and the development team

break them down into implementation tasks. These tasks

are the basis of schedule and cost estimates.

 The customer chooses the stories for inclusion in the

next release based on their priorities and the schedule

estimates.

A ‘prescribing medication’ story