1. TK2023 Object-Oriented Software Engineering
CHAPTER 2
INTRODUCTION TO THE UNIFIED PROCESS

2. INTRODUCTION
A software development process describes an approach to building, deploying and possibly maintaining software.

3. Requirements
Design
Implementation
Testing
Maintenance

5. This course is about object-oriented software development
This course is about object-oriented software development. In particular, it focuses on the Unified Process (UP).
UP is a software development process framework which combines commonly accepted best practices into a cohesive and well-documented description.
The Rational Unified Process (RUP) is a detailed refinement of the UP. It is a process product developed and maintained by IBM.

6. This chapter is an introduction to the UP which covers the following:
Iterative Development
Embracing Change
Phases
Disciplines

7. ITERATIVE DEVELOPMENT
A very important "best practice" promoted by the UP is the iterative and incremental development approach to software development.
In this approach, development is organized into a series of short, fixed-length iterations.
The outcome of each iteration is a tested, integrated, and executable system.
Each iteration is a "mini-project"; it includes its own requirement analysis, design, implementation and testing activities.

8. The iterative lifecycle is based on the successive enlargement and refinement of a system through multiple iterations, with cyclic feedback and adaptation as core drivers to converge upon a suitable system.
The system grows incrementally over time, iteration by iteration.

9. Feedback from
Requirements
Requirements
iteration N leads to
Design
Design
refinement and
Time
adaptation of the
Implementation
&
Implementation
&
requirements and
Test
&
Integration
Test
&
Integration
design in iteration
&
More Design
&
More Design N + 1 .
Final Integration
Final Integration
&
System Test
&
System Test 3
weeks (
for example )
Iterations are fixed in
The system grows
length , or
timeboxed .
incrementally .

10. Each iteration tackles a small subset of requirements
Each iteration tackles a small subset of requirements. The output of an iteration is an executable but incomplete system. It is not an experimental or throw-away prototype. It is also not ready to deliver into production but it is a production-grade subset of the final system.
Note that it is also possible for an iteration to improve existing software instead of handling new requirements. For example, an iteration may focus on the performance of a subsystem.

11. EMBRACING CHANGE
Reality: Change is inevitable in software development. Normally, clients are not clear about what they really want.
UP balances the need to agree upon and stabilize a set of requirements with the reality of changing requirements.

12. In the UP, each iteration results in an executable release developed based on a small subset of requirements.
Using that release, early feedback can be obtained through users, stakeholders, developers and tests. From the feedback, requirements can be clarified, corrected or even added. Risky and critical design decisions can be resolved early rather than late.

14. ITERATION LENGTH
The length of an iteration is important. The UP recommends an iteration length of between two and six weeks.
Iteration length too short => can be difficult to obtain meaningful throughput and feedback.
Iteration length too long => increases complexity and feedback is delayed which defeats the purpose of iterative development.
The length for each iteration is fixed. Date slippage is discouraged.

15. ADVANTAGES OF ITERATIVE DEVELOPMENT
Early rather than late mitigation of high risks (technical, requirements, objectives, usability, etc)
Early visible progress
Early feedback, user engagement, and adaptation, leading to a refined system that more closely meets the real needs of the stakeholders.
Managed complexity
The learning within an iteration can be methodically used to improve the development process itself, iteration by iteration.

16. PHASES IN UNIFIED PROCESS
Inception
Approximate vision, business case, scope, vague estimates
This phase is like a feasibility phase. Adequate investigation is done to support a decision to continue or stop
Elaboration
Refined vision, iterative implementation of the core architecture, resolution of high risks, identification of most requirements and scope, more realistic estimates.
In this phase, the core architecture is iteratively implemented, and high risk issues are mitigated.

17. Construction Transition
Iterative implementation of the remaining lower risk and easier elements, and preparation for deployment.
Transition
Beta tests, deployment.

18. inc.
elaboration
construction
transition
iteration
phase
development cycle
release
A stable executable
subset of the final
product. The end of
each iteration is a
minor release.
increment
The difference
(delta) between the
releases of 2
subsequent
iterations.
final production
At this point, the
system is released
for production use.
milestone
An iteration end-
point when some
significant decision
or evaluation occurs.

19. DISCIPLINES IN UNIFIED PROCESS
In the UP, an artifact is the general term for any work product: code, Web graphics, database schema, text documents, diagrams, models, etc.
In the UP, a discipline is a set of activities (and related artifacts) in one subject area. For example, the Requirements discipline refers to the set of activities and artifacts within requirements analysis.

20. DISCIPLINES AND PHASES
During one iteration, work goes on in most or all disciplines. However, the relative effort across these disciplines changes over time.
Sample
incep-
transi-
elaboration
construction
UP Disciplines
tion
tion
The relative effort in
Business Modeling
disciplines shifts
across the phases.
Requirements
This example is
Design
suggestive, not literal.
Implementation
...
...

21. DISCIPLINES AND PHASES
A four-week iteration (for example).
A mini-project that includes work in most
disciplines, ending in a stable executable.
Note that
although an
iteration includes
Sample
work in most
UP Disciplines
disciplines, the
relative effort and
Business Modeling
emphasis change
Focus
over time.
Requirements
of this
book
This example is
Design
suggestive, not
literal.
Implementation
Test
Deployment
Configuration & Change
Management
Project Management
Environment
Iterations