Apt sdlc

Software Development Life Cycles
A look at Other Software Development Methodologies

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This material is primarily for the use of Orange and
Bronze Software Labs, Inc.

No part of this material may be reproduced or
transmitted in any form or by any means, electronic or
mechanical, including photocopying, recording, or by any
information storage and retrieval system, without
permission in writing from the publisher.

www.orangeandbronze.com

Overview
• Introduction to SDLC
• Types of Software Development Life Cycles
• Examples of Different Software Development Life
Cycles


Introduction to SDLC

The Software Development Life Cycle is the process,
involving multiple stages (from establishing feasibility to
carrying out post-implementation reviews), used to
convert a management need into an application system,
which is custom-developed or purchased, or is a
combination of both.


• SDLC is...
→ A model of a detailed plan on how to create, develop,
implement and deliver software
→ A complete plan outlining how a software will be born,

raised, and turned over to its eventual users


• Basic Pattern of General Life Cycle Models:
→ Planning
→ Requirements Definition and Analysis

→ Design

→ Development

→ Integration and Testing

→ Implementation

• Each phase produces output (deliverables) that will be
the input to the next phase.


Software Development Life Cycle Phases
• Planning
→ Helps the project team establish a bird's eye view of the
software to be built
→ Determines the basic project structure

→ Evaluates feasibility and risks involved in the project

→ Describes appropriate management and technical

approach to be taken


• Outputs:
→ Goals and Objectives of the Project
→ Configuration Management Plan

→ Quality Assurance Plan

→ Project Plan and Schedule

• High-level estimates


• Requirements Definition and Analysis
→ Goals are translated into a group of one or more
requirements
• Major functions / features
• Critical processes to be managed


• Outputs:
→ Requirements document
→ Requirements traceability document


• Design
→ Requirements identified are translated into design
→ Usually depicted or illustrated through the use of

diagrams and other supporting documents
• Ex. ERD, Activity Diagram, Tables of Business Rules


• Outputs:
→ Design documents / diagrams


• Development
→ Where design is translated into software artifacts
→ Results in a functional software that is traceable to the

requirements and design elements defined


• Outputs:
→ Functional software
→ Test Plans / Test Cases


• Integration and Testing
→ Software is migrated from development environment to
test environment
→ Execution of test cases / test suites

• Verify correctness and completeness of software
→ Preparation of cutover to production


• Outputs:
→ Integrated software
→ Implementation plan

→ Acceptance plan

• UAT / Final suite of test cases


• Implementation
→ Software is migrated to production environment
→ Initial production data is loaded to production

environment
→ All test cases are executed once again

• Verify correctness and completeness of software in
production environment
→ UAT must have satisfactory results before customer
formally accepts delivery


• Outputs:
→ Production application
→ Completed acceptance test suite

→ UAT sign off between client and project team


Types of Software Development Life Cycles
• Sequential Development
• Iterative and/or Incremental Development


• Sequential Development
→ A development strategy wherein a strict set of
development phases or stages is followed in a
sequential or linear order.
→ Only when one phase or stage is completed can

development move on to the succeeding phase or
stage.
→ Sometimes referred to as a classical or traditional

method of software development



Incremental development is distinctly different from
iterative development in its purpose and also from its
management implications. Teams get into trouble by
doing one and not the other, or by trying to manage
them the same way.

– Alistair Cockburn (2008)


Definition:
• Incremental development is a strategy for staging and
scheduling the integration of the different parts of a
system being developed. Each part of the system is
developed at its own time or pace and are then
integrated as they are completed.
→ The word increment fundamentally means “add onto”


Definition:
• Iterative development is a strategy for scheduling a
certain amount of time for rework or revisions in order
to improve the quality of the different parts of the
system being built.
→ The word iterate fundamentally means “re-do”


SDLC Examples
• Waterfall Model
• Rapid Application Development (RAD)
• Spiral Model


Waterfall Model


Waterfall Model
• Characteristics
→ Phases are executed in sequential order
→ Each phase must be completed before proceeding to

the next
→ A formal review is conducted at the end of each phase

to determine completion
→ No overlap between phases

→ Software is not seen until the end of the project

→ Changes are limited and tightly controlled


Waterfall Model
• Phases
→ Requirements Specification
→ Design

→ Construction / Implementation / Coding

→ Integration

→ Testing and Debugging / Verification

→ Installation

→ Maintenance


Waterfall Model
• Advantages
→ Puts emphasis on documentation
→ Straightforward and more disciplined approach

→ Provides a structured approach

→ Provides easily markable milestones

→ Generally suited for stable projects


Waterfall Model
• Criticism / Disadvantages
→ Rigid structure
→ Impossible to achieve perfection

→ “Measure twice, cut once” does not always work

→ Planning control and risk management are not covered

within the model


Waterfall Model
→ Very specific skill sets required for each phase
→ High amounts of risk and uncertainty

→ Poor model for:

• Complex and object-oriented projects
• Long and ongoing projects
• Projects where requirements are at a moderate to high
risk of changing


Rapid Application Development (RAD)


• Characteristics
→ Iterative development through prototyping
→ Iterative and incremental

→ Aimed at speeding up application development

→ Compromises functionality and performance in

exchange for faster development


• Phases
→ Requirements Planning
→ User Design

→ Construction /

Development
→ Cutover / Deployment

→ Learning


• Advantages
→ Fast and efficient way of delivering software
→ Generally improves:

• User-Designer communication
• User cooperation
• User commitment


→ The process may become so fast that proper testing
(especially security testing) may not be done
→ Prototypes delivered may not always result in a

production application
→ Quality indicators such as consistency, standardization,

reusability, and reliability are easily overlooked


Spiral Model


Spiral Model
• Characteristics
→ Iterative model with emphasis on risk analysis
→ Combines elements of design and prototyping-in-stages

→ Aims to combine advantages of top-down and bottom-

up concepts
→ Intended for large, expensive and complex projects


Spiral Model
• Phases
→ Planning
• Determine objectives, alternatives, and constraints
→ Risk Analysis
• Identify and resolve risks
• Evaluate possible alternatives


Spiral Model
• Phases
→ Engineering
• Develop deliverables
→ Evaluation
• Verify that deliverables are correct
• Plan the next iteration


Spiral Model
• Advantages
→ High amount of risk analysis
→ Good for large and mission-critical projects

→ Software is produced early


Spiral Model
→ Can be costly
→ Risk analysis requires high expertise

→ Success is highly dependent on risk analysis

→ Does not work well with smaller projects


References
• Lewallen, R. (2005, July 13). Software Development Life
Cycle Models. Message posted to
http://codebetter.com/blogs/raymond.lewallen/archive/20
• Becerra, G. (2004). Software Life Cycle: Theory and
Summary. Retrieved from
http://pages.cpsc.ucalgary.ca/~ayala/SENG/seng611/Assign
• Purcell, J. (2007). Comparison of Software
Development Life Cycle Methodologies. Retrieved from
http://www.giac.org/resources/whitepaper/application/21


References
• Davis, W. S., Yen, D. C. (1998). Rapid Application
Development (RAD). In The Information Systems:
Analysis and Design. Retrieved August 6, 2008, from
http://www.hit.ac.il/staff/leonidM/information-systems/ch
• Cockburn, A. (2008). Using Both Incremental and
Iterative Development. CrossTalk The Journal of
Defense Software Engineering, May 2008 Issue.
Retrieved April 11, 2008, from
http://www.stsc.hill.af.mil/crosstalk/2008/05/0805Cockbur


References
• Steele, J. (2001). The Software Development Life Cycle
(SDLC). Retrieved from
http://www.elucidata.com/refs/sdlc.pdf
•


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