lec_3 (process models2)

7/29/2019 Lec_3 (Process Models2)

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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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n .


e sp ra mo e .



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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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n .


e sp ra mo e .



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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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n .


e sp ra mo e .



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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

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