process models ii

8/6/2019 Process Models II

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Farooq Ahmed, FAST-NU, Lahore

Software Process Models II


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Unified Process Model

Object-oriented

Use-case driven

Architecture-centric Iterative and Incremental

Combines the best features of Rumbugh, Boochand Jacobson's methods


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UPM Phases

Inception

Elaboration

Construction Transition


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Agile Models Agile: Quick, Active

Adaptability to change

Basic Principles & Values

Individuals and interactions over processes and tools

Working software over comprehensive documentation

Customer collaboration over contract negotiation

Responding to change over following a plan

while there is value in the items on the right, agile value the items on the leftmore

Basic characteristics

Light-weight

Short development cycle

Incremental

Feedback-oriented

Agile is not adhoc


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Key Assumptions

It is difficult to predict in advance whichrequirements will persist and which will change and so are customer priorities

For many types of software, design andconstructionis interleaved (constructionis usedto prove the design)

Analysis, design, construction and testing arenot as predictable as we might like


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Agile Manifesto

Customer satisfactionby rapid delivery of useful software

Welcome changing requirements, even late in development

Working software is delivered frequently (weeks rather than months)

Working software is the principal measure of progress

Sustainable development, able to maintain a constant pace

Close, daily co-operationbetweenbusiness people and developers

Face-to-face conversationis the best form of communication (co-location)

Projects are built around motivated individuals, who should be trusted

Continuous attention to technical excellence and good design

Simplicity

Self-organizing teams

Regular adaptation to changing circumstances


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Extreme Programming


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Key XP Practices

User-stories

CRC cards & Spike Prototypes

Refactoring Improving the design of existing code

Pair Programming

Test first approach

Write unit tests before writing the code

Automated tools and test suites

Pair Programming Example(taken from Wikipedia)


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SCRUM


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Key Features of SCRUM

More of a management methodology than anengineering methodology

Canbe applied to other areas as well not just

software development

Doesn't prescribe any specific techniques forsoftware engineering

User-stories may be used for requirements


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OtherAgile Models

ASD

Dynamic Systems Development

Feature Driven Development Crystal


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Factors forAgile Success

Competence

Common Focus

Deliver working increments to customers Collaboration

Decision-making ability

Fuzzy Problem-solving ability Continually deal with ambiguity

Mutual trust and respect

Self-organization


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Problems with Agile

Generally suitable for small projects with small teams(< 10 co-located resources)

Customer collaborationis v.important. If customerscannot collaborate, dont use this

Generally works with experienced programmers A mentor experienced in agile methodology is a must Useful in an environment where requirements may

change v. frequently Financial forecasting is difficult to acheive, because of

lack of a definitive plan


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concerned or dealing with a specific subject, purpose, or end.

a committee formed ad hoc to deal with the issue.

Point to Take-away

Agile is not adhoc

process models ii

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