Process and Method:
An Introduction to the
Rational Unified Process
Traditional Structured Analysis
Described by W. W. Royce, 1970, IEEE WESCON, Managing the
development of large software systems.
Decomposition in terms of Function and Data
Modularity available only at the file level
– cf. C language's static keyword (=="file scope")
Data was not encapsulated:
– Global Scope
– File Scope
– Function Scope (automatic, local)
Waterfall Method of Analysis and Design
– Analysis Specification
• Design Specification
– Coding from Design Specification
» Unit Testing
» System Testing
» UAT Testing
» Ship It (????)
Measuring rod is in the form of formal
Waterfall Process Assumptions
Requirements are known up front before design
Requirements rarely change
Users know what they want, and rarely need visualization
Design can be conducted in a pure abstract space, or trial
rarely leads to error
The technology will all fit nicely into place when the time
comes (the apocalypse)
The system is not so complex. (Drawings are for wimps)
Structured Analysis Problems
Reuse is complicated because Data is strewn throughout
many different functions
– Reuse is usually defined as code reuse and is
implemented through cutting and pasting of the same
code in multiple places. What happens when the logic
• coding changes need to be made in several different
• changing the function often changes the API which
breaks other functions dependent upon that API
• data type changes need to be made each time they are
used throughout the application
Waterfall Process Limitations
Big Bang Delivery Theory
The proof of the concept is relegated to the very end of a long singular
cycle. Before final integration, only documents have been produced.
Late deployment hides many lurking risks:
– technological (well, I thought they would work together...)
– conceptual (well, I thought that's what they wanted...)
– personnel (took so long, half the team left)
– User doesn't get to see anything real until the very end.
– System Testing doesn't get involved until later in the process.
The Rational Unified Process
RUP is a method of managing OO Software Development
It can be viewed as a Software Development Framework
which is extensible and features:
– Iterative Development
– Requirements Management
– Component-Based Architectural Vision
– Visual Modeling of Systems
– Quality Management
– Change Control Management
Online Repository of Process Information
and Description in HTML format
Templates for all major artifacts, including:
– RequisitePro templates (requirements tracking)
– Word Templates for Use Cases
– Project Templates for Project Management
Process Manuals describing key processes
An Iterative Development Process...
Recognizes the reality of changing requirements
– Capers Jones’s research on 8000 projects
• 40% of final requirements arrived after the analysis phase, after
development had already begun
Promotes early risk mitigation, by breaking down the system into mini-
projects and focusing on the riskier elements first
Allows you to “plan a little, design a little, and code a little”
Encourages all participants, including testers, integrators, and technical
writers to be involved earlier on
Allows the process itself to modulate with each iteration, allowing you
to correct errors sooner and put into practice lessons learned in the
Focuses on component architectures, not final big bang deployments
An Incremental Development Process...
Allows for software to evolve, not be produced in one
Allows software to improve, by giving enough time to the
evolutionary process itself
Forces attention on stability, for only a stable foundation
can support multiple additions
Allows the system (a small subset of it) to actually run
much sooner than with other processes
Allows interim progress to continue through the stubbing
Allows for the management of risk, by exposing problems
earlier on in the development process
Goals and Features of Each Iteration
The primary goal of each iteration is to slowly chip away
at the risk facing the project, namely:
– performance risks
– integration risks (different vendors, tools, etc.)
– conceptual risks (ferret out analysis and design flaws)
Perform a “miniwaterfall” project that ends with a delivery
of something tangible in code, available for scrutiny by the
interested parties, which produces validation or correctives
Each iteration is risk-driven
The result of a single iteration is an increment--an
incremental improvement of the system, yielding an
Identification of the risks
The prototype or pilot project
– Booch’s “Tiger Team”
Early testing and deployment as opposed to
late testing in traditional methods
The Development Phases
Overriding goal is obtaining buy-in from all interested
Initial requirements capture
Cost Benefit Analysis
Initial Risk Analysis
Project scope definition
Defining a candidate architecture
Development of a disposable prototype
Initial Use Case Model (10% - 20% complete)
First pass at a Domain Model
Requirements Analysis and Capture
– Use Case Analysis
• Use Case (80% written and reviewed by end of phase)
• Use Case Model (80% done)
– Sequence and Collaboration Diagrams
– Class, Activity, Component, State Diagrams
– Glossary (so users and developers can speak common vocabulary)
– Domain Model
• to understand the problem: the system’s requirements as they exist
within the context of the problem domain
– Risk Assessment Plan revised
– Architecture Document
Focus is on implementation of the design:
– cumulative increase in functionality
– greater depth of implementation (stubs fleshed out)
– greater stability begins to appear
– implement all details, not only those of central
– analysis continues, but design and coding predominate
The transition phase consists of the transfer of the system
to the user community
It includes manufacturing, shipping, installation, training,
technical support and maintenance
Development team begins to shrink
Control is moved to maintenance team
Alpha, Beta, and final releases
Integration with existing systems (legacy, existing
Elaboration Phase in Detail
Use Case Analysis
– Find and understand 80% of architecturally significant
use cases and actors
– Prototype User Interfaces
– Prioritize Use Cases within the Use Case Model
– Detail the architecturally significant Use Cases (write
and review them)
Prepare Domain Model of architecturally significant
classes, and identify their responsibilities and central
interfaces (View of Participating Classes)
Introduction to XP
“When the tests all run, you’re done”
XP is designed around the concept of
– Option to abandon
– Option to switch
– Option to defer
– Option to grow and learn
The Four Variables
Management or the Customer chooses 3 of the four variables, the
development team defines the fourth.
– Cost is the amount of capital available, which defines resources.
More resources don’t necessarily mean better quality or shorter
time (remember Brooks?)
– The amount of time available for the project through delivery
– Quality is the degree to which and aplomb with which functionality meets
– Scope is the amount of work to be done, the totality of the set of
requirements. As requirements come and go, scope vacillates.
The Paradigm Shift
XP is based on the rejection of a fundamental and long-
standing principle, that it costs less to make changes earlier
in the development cycle rather than later. That the graph
of cost to change is exponential across time. This
fundamental principle has led to several strategies:
– Better safe than sorry
– Functional extravagance
– Design extravagance
– Proliferation of activities that may never provide a
return on the investment
The Paradigm Shift Continued
The fundamental technical premise of XP is that the graph of cost to
change is not exponential but digressive, and as time goes by, the
cost to change is asymptotic. “You make the big decisions as late in
the process as possible.” This has several strategies:
– You implement only what you have to, and add functionality
later only if necessary
– Design is parsimonious
– Thoreau’s principle: Simplify, Simplify, Simplify.
– Automated tests
– Learning to drive analogy
The Four Values
– Communication is bipartite. Developers need to communicate
with customers as well as between themselves
– “What’s the simplest thing that could possibly work?” Let’s do that.
– Continuous and instant feedback to all artifacts
– Continuous and instant feedback to the project progression
– Continuous and instant feedback to code
– The courage to change (alter design, throw away code)
– The courage to decide
– The courage to do
– The courage to be
The Basic Principles of XP
– instant evaluation of all work and deliverables
– 98% of problems can be solved with “ridiculous simplicity”
– What happened to complexity?
• Complexity != complex solutions
– Avoid big changes, make smaller changes more often (driving analogy)
– Might as well. Heraclitus was right, Parmenides was wrong. You simply
will not be stepping into the same river twice.
– Work ethic
– Is Beck a little too hopeful on the human condition?
Small initial investment
Play to win
Open, honest communication
Work with people’s instincts, not against them
Accepted not foisted responsibility
Local adaptation (of process)
Travel light (the nomadic team)
Honest measurement (no lying)
The Four Basic Activities
Dominance of Coding and Testing
Code is unambiguous and constant. It offers no opinions.
Code is a another language for communication (as in pair
Tests allow for a secondary view into the code, from another angle
Tests verify that “what was meant” was actually implemented
Tests can validate performance as well as functionality
You are responsible for writing multiple unit tests, you write a simple
test for every possible way to “break” your code.
Automated tests can prolong the longevity of the code, and provide
A testing mentality promotes more self-assured programming style, as
successful tests yield confidence in the code.
Planning – quickly determine the scope of the next iteration.
Customers do the planning based on feedback from the developers.
– “Software development is always an evolving dialog between the possible
and the desirable.”
Small Releases – take baby steps in each iteration. Rank iterations
according to those which deliver the most valuable business
Metaphor – define a simple story of how the system will work. It
should be enlightening.
Simple design – few classes and methods, no duplicated logic
Testing – Developers write unit tests, Customers write functional tests
Refactoring – revisiting code with rules that simplify the code. “When
the system requires that you duplicate code, it’s asking for
Collective Ownership – anyone can change any code at any time.
The Practices, cont.
Continuous Integration – code is integrated every half or full day at
most. Integration is putting new code with the current system.
Sane work week
On-site customer – customer needs to be around
Coding standards that all coders follow
One programmer writes the code, at the low level. He/she “has the
ball”, or at least the keyboard.
The other programmer looks at the code being written from a higher
– What additional tests could break this?
– Can this be done more simply? (designing)
– Have I seen this before? (Refactoring)
– Did the guy with the ball just introduce a bug?
– Is this the best approach to this problem?
– Did the guy with the ball forget something?
– Does a question need to be answered by the Customer?
Coding standards help reduce the need for reformatting code and
bickering about style.
Pairs write tests together too, following the same principles.
“Problems” With Pair Programming
What happens on a geographically
distributed development team?
Management will object to “waste”, you
only get half as much done, or we’ll need
twice as many programmers.
Pairs will naturally “self-select” in a
Darwinian sense, militating against teaching
Write a story (think “simplified” Use Case)
Estimate a story: how long will it take to
Split a story: if a part of a story is more
important than another, split it into two
Business chooses the scope and delivery date of
the next iteration
– Sort by value (must have, should have, nice to have)
– Sort by (estimation) risk
– Set velocity – how quickly do we expect to move on
– Choose Scope – Ok, given the above, what are we to
deliver and when is it due?
• Iterations run 1 to 3 weeks generally.
• Each iteration selects one or more stories to
implement. Each iteration must yield a system that
runs end-to-end, however embryonically.
– Recovery: if development has overstated velocity, re-
evaluate the set of stories (deliverables)
– New story: If business realizes it’s got a new story, the
new story is estimated, ranked, and added.
– Reestimate: If development feels the plan is
inadequate, it can reestimate the remaining stories and
reset the estimated velocity.
– Exploration Phase
• Write a task by breaking down the stories into tasks
• Split a task if necessary
– Commitment Phase
• Accept a task
• Estimate a task
– Steering Phase
• Implement a task
• Record Progress
• Recovery – what to do if overworked: manage scope
• Verify story with functional tests
What about Design Strategy?
Start with a test. A simple test.
Design and implement just enough to get
that test running, and make sure you don’t
break another test.
Add functionality and repeat
“The definition of the best design is the
simplest design that runs all the test cases.”
Use Case Analysis
What is a Use Case?
– A sequence of actions a system performs that yields a
valuable result for a particular actor.
What is an Actor?
– A user or outside system that interacts with the system
being designed in order to obtain some value from that
Use Cases describe scenarios that describe the interaction
between users of the system and the system itself.
Use Cases describe WHAT the system will do, but never
HOW it will be done.
What’s in a Use Case?
Define the start state and any preconditions that accompany it
Define when the Use Case starts
Define the order of activity in the Main Flow of Events
Define any Alternative Flows of Events
Define any Exceptional Flows of Events
Define any Post Conditions and the end state
Mention any design issues as an appendix
Accompanying diagrams: State, Activity, Sequence Diagrams
View of Participating Objects (relevant Analysis Model Classes)
Logical View: A View of the Actors involved with this Use Case, and
any Use Cases used or extended by this Use Case
Use Cases Describe Function not Form
Use Cases describe WHAT the system will do, but never HOW it will be done.
Use Cases are Analysis Products, not Design Products.
Use Cases Describe Function not Form
Use Cases describe WHAT the system
should do, but never HOW it will be done
Use cases are Analysis products, not design
Benefits of Use Cases
Use cases are the primary vehicle for requirements capture
Use cases are described using the language of the customer
(language of the domain which is defined in the glossary)
Use cases provide a contractual delivery process (RUP is
Use Case Driven)
Use cases provide an easily-understood communication
When requirements are traced, they make it difficult for
requirements to fall through the cracks
Use cases provide a concise summary of what the system
should do at an abstract (low modification cost) level.
Difficulties with Use Cases
As functional decompositions, it is often difficult to make
the transition from functional description to object
description to class design
Reuse at the class level can be hindered by each developer
“taking a Use Case and running with it”. Since Ucs do not
talk about classes, developers often wind up in a vacuum
during object analysis, and can often wind up doing things
their own way, making reuse difficult
Use Cases make stating non-functional requirements
difficult (where do you say that X must execute at Y/sec?)
Testing functionality is straightforward, but unit testing the
particular implementations and non-functional
requirements is not obvious
Use Case Model Survey
The Use Case Model Survey is to illustrate, in
graphical form, the universe of Use Cases that the
system is contracted to deliver.
Each Use Case in the system appears in the
Survey with a short description of its main
• Domain Expert
• Analyst/Designer (Use Case author)
• Testing Engineer
Sample Use Case Model Survey
In Analysis, we analyze and refine the requirements described in the
Use Cases in order to achieve a more precise view of the requirements,
without being overwhelmed with the details
Again, the Analysis Model is still focusing on WHAT we’re going to
do, not HOW we’re going to do it (Design Model). But what we’re
going to do is drawn from the point of view of the developer, not from
the point of view of the customer
Whereas Use Cases are described in the language of the customer, the
Analysis Model is described in the language of the developer:
– Boundary Classes
– Entity Classes
– Control Classes
Why spend time on the Analysis Model, why
not just “face the cliff”?
By performing analysis, designers can inexpensively come to a better
understanding of the requirements of the system
By providing such an abstract overview, newcomers can understand
the overall architecture of the system efficiently, from a ‘bird’s eye
view’, without having to get bogged down with implementation
The Analysis Model is a simple abstraction of what the system is going
to do from the point of view of the developers. By “speaking the
developer’s language”, comprehension is improved and by abstracting,
simplicity is achieved
Nevertheless, the cost of maintaining the AM through construction is
weighed against the value of having it all along.
Boundary classes are used in the Analysis Model to model interactions
between the system and its actors (users or external systems)
Boundary classes are often implemented in some GUI format (dialogs,
widgets, beans, etc.)
Boundary classes can often be abstractions of external APIs (in the
case of an external system actor)
Every boundary class must be associated with at least one actor:
Entity classes are used within the Analysis
Model to model persistent information
Often, entity classes are created from
objects within the business object model or
The Great Et Cetera
Control classes model abstractions that coordinate, sequence, transact,
and otherwise control other objects
In Smalltalk MVC mechanism, these are controllers
Control classes are often encapsulated interactions between other
objects, as they handle and coordinate actions and control flows.