Iterative development and The Unified process

Need for a process ?

Need an approach for:

•Building

•Deploying

•Maintaining

UP : example process (in this course)

The Unified Process

The Unified Process has emerged as a popular and iterative software development process for object oriented systems.

In particular, the Rational Unified Process, as modified at Rational Software, is widely practiced and adopted by industry.

Why UP?

Think and Design with Objects Apply UML Use Design Patterns Apply to Agile approaches Incremental requirements analysis Writing use cases

Most Important Concept in UP

The critical idea in the Rational Unified Process is

Iterative, Incremental development.

Iterative Development is successively enlarging

and refining a system through multiple

iterations, using feedback and adaptation.

The Most Important Concept

Each iteration will include requirements,

analysis, design, and implementation.

Iterations are timeboxed.

Incremental : system grows over time

Example: Building a House

Incremental: Start with a modest house, keep adding rooms and upgrades to it.

Iterative: On each iteration, the house is re-designed and built a new.

Each iteration involves :• Choosing small subset of requirements.• Quick design, implementation and testing• User quickly see partial system• Rapid , early feedback ( ex: usability tests from users)

•Yes , that´s exactly what I asked for ………….•I try it , what I really want is something slightely different…

• Modify and Adapt understanding of the requirements or design , then involve the user again

Iterations

Iterations

Each phase has iterations, each having the purpose of producing a demonstrable piece of software. The duration of iteration may vary from two weeks or less up to six months.

Inception Elaboration Construction Transition

Iterations Iterations IterationsIterations

The iterations and the phases

Iterations

Each phase can be further broken down into iterations

UP phases

ManagementEnvironment

Business Modeling

Implementation

Test

Analysis & Design

Preliminary Iteration(s)

Iter.#1

PhasesProcess Workflows

Iterations within phases

Supporting Workflows

Iter.#2

Iter.#n

Iter.#n+1

Iter.#n+2

Iter.#m

Iter.#m+1

Deployment

Configuration Mgmt

Requirements

Elaboration TransitionInception Construction

time

Another approach :Waterfall Model

Requirements

Design

Implementation

Test

All or most of the requirements are defined before development begins

Developer receives problem statement (what should the system).

Developer works in isolation for some extended time period.

Developer delivers result.

Developer hopes client is satisfied.

Why Not Waterfall? Requirements are not stable/unchanging.

The market changes—constantly.

The technology changes.

The goals of the stakeholders change.

• Less project failure

• Early rather than late mitigation high

risks

• Early visible progress

• Early feedback, user engagement ,

adaptation and refinements of

requirements

• Better understanding through iterations

• Managed complexity

Benefits to iterative developement

Unified Process best practices

Get high risk and high value first Constant user feedback and engagement Early cohesive core architecture Test early. Apply use cases where needed. Do some visual modeling with UML. Manage change requests and

configuration

Inception :

• Approximate vision.

• Business case .

•Scope. (we model the system not the business)

• Vague estimates.

Ask yourself : is the system feasible ? Should we go on or stop?

Elaboration• Refined vision

• Iterative implementation of core architecture

•High risks issues are mitigated

•Most requirements are identified !!

• More realistic estimates

UP phases

Construction • Iterative implementation of remaining lower risk and elements

• Preparation for deployment

Transition•Beta tests, deployment

UP disciplines:• Business modeling: domain model artifacts to visualize

concepts in application domain

• Requirements: Use case model and supplementary Specification artifacts to capture functional and non functional requirements.

• Design : domain model artifacts to design software objects.

UP phases

Construction• Iterative impelmentation of the low risks,easier par

• Preparation for deployement Transition

• Beta Tests

• Deployment

UP phases

ManagementEnvironment

Business Modeling

Implementation

Test

Analysis & Design

Preliminary Iteration(s)

Iter.#1

PhasesProcess Workflows

Iterations within phases

Supporting Workflows

Iter.#2

Iter.#n

Iter.#n+1

Iter.#n+2

Iter.#m

Iter.#m+1

Deployment

Configuration Mgmt

Requirements

Elaboration TransitionInception Construction