lec_3 (process models2)
TRANSCRIPT
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o tware ng neer ng
Process Models - II
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General Process Models
n Waterfall model.n Prototype model.
n .
n Evolutionary models: Incremental model.
e sp ra mo e .
Concurrent development model.
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Motivation for Evolutionary Models
n Business Requirements are often change as development
proceeds.
n Software evolves over a period of time.
n Tight market deadlines make the completion of a comprehensive
software product impossible.
n Making a straight line to an end is unrealistic.
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Evolutionary Models
n Evolutionary models are iterative.
n
completion of an increment.n Unlike the prototype model, the segment is a part of the
pro uc on sys em.
n Suitable scenario: The core re uirements of a roduct are well understood.
Details of the product extension have yet to be defined.
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General Process Models
n Waterfall model.n Prototype model.
n .
n Evolutionary models: Incremental model.
e sp ra mo e .
Concurrent development model.
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Incremental Model
n Iterative in nature as illustrated by its name.
.
n An increment (usable piece) is delivered in a cycle.n A increment is based on its redecessor increment.
n Unlike prototype, an operational product is the focus of
increments.
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Incremental Model
System/informationengineering
increment 1
1st increment
ana ys s design code testincrement 2
2nd increment
analysis design code testincrement 3 3rd increment
analysis design code testincrement 4
delivery of4th increment
calendar time
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Incremental Model
n Steps:
address basic requirements.
plan for the next increment.
Objectives of the plan:
To better meets the needs of customers.
To address the modification to core product.
o e ver a ona ea ure an unc ona y.
The process is repeated until the completion.
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Incremental Model
n Suitable scenario:
the business deadline.
Fewer people is available to implement an early.
Additional staff can be added to implement the next
increments. Increments can be planned to manage technical
risks.
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General Process Models
n Waterfall model.n Prototype model.
n .
n Evolutionary models: Incremental model.
e sp ra mo e .
Concurrent development model.
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Spiral Model
n Evolutionary process model.
.
n Produces software in a series of incremental releases.n Having potential for rapid development.
n Realistic approach to the development of a large scalesystem.
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Spiral: Structure
Spiral model is divided into number of framework activities calledas Tasks Regions
PlanningRisk Analysis
Customer
Communication
Engineering
Construction & ReleaseCustomerEvaluation
,
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How Its Used
n Region and task sets are adapted to the characteristics ofthe project to be undertaken.
n o ware eng neers move aroun e sp ra .
n Early passes result in product specification.
and then more sophisticated software.
n Project plan is adjusted in each pass from customers.
n And number of iteration is adjusted by project manager.
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Characteristics of the Model
n Developers and customers understand and react to risk
.
n Prototyping is used to reduce risk.n Classical life cycle approach is followed with iterative
approach.
n Technical risk is considered in order to reduce in all.
n Risk assessment expertise is demanded and relies on
this ex ertise for success.n The evolutionary approach is difficult to control.
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General Process Models
n Waterfall model.n Prototype model.
n .
n Evolutionary models: Incremental model.
e sp ra mo e .
Concurrent development model.
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Concurrent Development Model
n Also called as Concurrent Engineeringn A series of framework activities, tasks and associated
.
n All activities exist concurrently, but reside in differentstate awaiting changes, under development, none, &.
n Suitable for system engineering projects.
n Events enerated at one oint in the rocess networktrigger transitions among the states.
Customer Communication Activities and tasks
Analysis Activity Under
development
Under
revision
Done
one Awaiting Changes Base Line
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Weakness in Evolutionary P.M.
n Project planning because of the uncertain number of
.
n Maximum evolutions speed has not been fixed.
n ocuses on ex es an ex ens es ra er an on
the high quality.
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Rational Unified Process
n Rational Unified Process (RUP) is an iterative
the Rational Software Corporation, a division of IBMsince 2003.
n RUP is not a single concrete prescriptive process, but
rather an adaptable process framework, intended to be
tailored b the develo ment or anizations and software
project teams that will select the elements of the
process that are appropriate for their need
n e roo s o a ona rocess go ac o e or g na
spiral model of Barry Boehm. The Rational Approach
was developed at Rational Software in the 1980s and
1990s.
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Grady Booch speaks
n People are more important than any
process.
n Good people with a good process will
out erform ood eo le with no rocessany time.
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The Most Important Concept
n The critical idea in the Rational Unified.
n Iterative Development is successively
multiple iterations, using feedback and.
n Each iteration will include requirements,
, , .n Iterations are timeboxed.
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Phases in RUP
RUP is divided into four phases, named:
ncep on
Elaboration
Construction
Transition
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Rational Unified Process
Inception Elaboration Construction Transition
PhasesCore Workflows
Requirements
Design
Implementation
Testing
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Iterations
Each phase has iterations, each having the
purpose of producing a demonstrable piece of
software. The duration of iteration may vary
.
Iteration
s
Iteration
s
Iteration
s
Iteration
s
Inception Elaboratio
n
Constructio
n
Transition
The iterations and the phases fig 1
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The Agile Manifesto
n Individuals and interactions
ver processes an oo s
n Working software ver compre ens ve ocumen a on
n Customer collaboration Over contract negotiation
n Responding to change
Over following a plan
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Unified Process best practices
n Get high risk and high value first
n ons an user ee ac an engagemen
n Early cohesive core architecture
n Test early, often, and realistically
n Apply use cases where neededn Do some visual modeling with UML
n Manage requirements and scope creep
n Manage change requests and configuration
I i
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Inception
n The life-cycle objectives of the project are
,
are considered.
Boundary conditions
Acceptance criteria
and some requirements are established.
El b i
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Elaboration
n An analysis is done to determine the
Risks
Stability of vision of what the product is to
become
Stability of architecture Expenditure of resources.
C i
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Construction
n The Construction phase is a engineering
process.
n It emphasizes
managing resources
Controlling operations to optimize Costs
Schedules
quality.
n This phase is broken into several
iterations.
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Transition
n The transition phase is the phase where
e pro uc s pu n e an s o s en
users.
n It involves issues of
marketing, packaging, installing, configuring,supporting the user-community, making
corrections, etc.
Th R i l U ifi d P
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The Rational Unified Process
n RUP is a method of mana in OO Software
Development
n It can be viewed as a Software Development
ramewor w c s ex ens e an ea ures:
Iterative Development
Component-Based Architectural Vision
Visual Modelin of S stems Quality Management
Change Control Management
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Advantages of RUP
The RUP puts an emphasis on addressing very.
It does not assume a fixed set of firmre uirements at the ince tion of the ro ect, butallows to refine the requirements as the project
evolves. oes no pu e er a s rong ocus on
documents or ceremonies
itself, and its quality.
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Drawbacks of RUP
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Assignment # 2 (20 marks)
Compare & Contrast SPMn Identify advantages and disadvantages of each
process model (excluding RUP)
n Compare and contrast the software process
models (excluding RUP)
n Submission date : 26th March, 2008 Document
Presentation
n
Th k Y
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Thank You
n Thank you