Категория: Программное обеспечение
Life-cycle phases from software project Мanagement by walker royce of IBM. (Chapter 5)
1. Chapter 5Life-Cycle Phases
Software Project Management
Walker Royce (of IBM)
And Slides on Spiral by Barry Boehm
2. IntroductionOn one hand,
Do we spend far too much time on analyses and paper
Do we delay actually doing the builds: the development
Very easy to do… Some feel in general that this is true…
On the other hand,
Do we jump into designs and coding, and hack the heck
out of an application in attempts to get it to work?
Lots of people think we do this too….
What do you do?
What do you think corporations think they do?
3. Introductory Statement:Walker Royce feels that we need BALANCE
between research and development (R&D) and
Need some kind of balance between:
Concentrating on capturing and modeling functionality
Building a robust product that has the performance,
reliability, and scalability customers desire….
We are after a development life-cycle BALANCE…
4. Finer GranularityFurther, we need a process that supports this
Need this stated more precisely:
Need a process to help balance:
Planning, capturing, and modeling requirements and
establishing a baseline architecture,
Continuous assessment, measuring risk, and
testing to ensure progress and quality
Evolution and verification of the application’s
functionality through series of customer
demonstrations and ultimate validation.
5. Engineering and Production StagesRoyce claims to achieve the ROI for software
development, we need to use a ‘manufacturing
process’ that is characterized by the
highest utilization of automated development tools and
use of component-based approaches to development.
He likens a desirable software process to a
6. Engineering and Production StagesHe breaks all activities down into
Engineering and Production
Engineering work: This centers on risk
reduction, prototyping, establishing architectural
baseline, assessment, analysis, design, and
Implies a smaller team up front.
Production work: programming and unit test,
system and integration testing, demonstrations,
assessment, base-lining (alpha, beta, …)
configuration, and releases; operations
Note that production includes operations…
7. Two Stages: Far Too AbstractBUT, he argues a life cycle of two stages is far too abstract to track the many
detailed activities – all with actors, activities, and artifacts….
So, he maps RUP Phases into these more comprehensive phases.
Enter: Engineering Phase = Inception and Elaboration
Enter: Production Phase = Construction and Transition
Engineering, i.e., Inception and Elaboration, focuses on the concept (idea)
of the application and its architectural components (analysis and
preliminary design – perhaps a wee bit of detailed design)
Artifacts are established and base-lined; (Configurations…)
Production, i.e., Construction and Transition, focuses on programming,
testing, releases and converting / establishing operational capabilities
Implies that artifacts from earlier stage (engineering) more difficult to
change as activities more ‘downstream activities’ occur
8. Royce Claims that:These phases can be mapped into the famous
Spiral Model for Software Development
developed by (Barry Boehm) (shall see ahead)
Conventional Software Development Model (as
represented by the Waterfall Model and its many
OOSE approach (as represented by the RUP);
Spiral Model…Let’s discuss this important model…
9. Spiral Model - OverviewSpiral Model is another incremental model.
Embraces (well known for these:)
iterative software development, and
Model is graphed like a spiral.
Development can be halted at the end of any
cycle…depending on evaluation of previous
IS ROI still looking good?
Are expended costs in line with anticipated costs –
Have risks been mitigated?
Functionality delivered evolving properly via high
priority requirements? And much more…..
10. Spiral ModelVery much a Risks-Driven Approach
Different idea of software development.
How does this project affect the developers
and the clients?
How does each step in the project affect
its overall development?
Not used in previous development models.
They were usually code-driven or document-driven.
11. Previous Software Process ModelsAn evolution of models
–Code & Fix
–Stagewise & Waterfall
Code & Fix
• Write code now; fix it later
• No planning involved
– Code is poorly structured.
– The software developed was usually a poor match for users’
12. Stagewise & WaterfallStagewise & Waterfall
Born out of the shortsightedness of the Code &
- need for a design phase, requirements phase,
and a testing phase.
First used to develop SAGE (Semi-Automated
Ground Environment), an early warning
system for the Cold War era.
13. StagewiseA development process of successive phases.
– Phases included operational plan, operational
specs, coding specs, coding, parameter
testing, assembly testing, shakedown, system
Underwent two refinements in 1970.
Now referred to as the Waterfall Model.
14. Waterfall ModelIntroduced:
– Feedback loops across multiple stages:
Validation and verification steps.
– Prototyping via a “build it twice” step alongside of
requirements and design.
• Difficulties exposed even as revisions were made to
– Required elaborated documents. (Documentdriven; lengthy development cycles, etc.
– Led to pursuing stages of development in the
16. Evolutionary DevelopmentEvolution of the system in directions based on
Provides rapid initial operational capability.
“I can’t tell you what I want, but I’ll know it when I see it.”
Flexible, yet uncertain approach.
Evolutionary Development Problems:
No formal design phase (same problem as Code & Fix).
One bad assumption – the unplanned paths “will” be
Hard-to-change code resulted.
Many problems when new software was incrementally
replacing old software
19. Spiral Model - OverviewIn the Spiral Model, prototyping, evaluation, planning, and all engineering
and production activities are executed in different quadrants. (Different
variations of the model…)
But the basic notion of iteration is very firmly established.
For each ‘cycle’:
risk is assessed,
more design and development is undertaken,
the work products and evaluated, and
planning for the next cycle in the spiral is undertaken;
Please note that in reality, the Spiral Model curve is actually
skewed to the right, as the spirals do not ‘carve’ out equal
Area in each cycle is a determinant of effort and cost….
20. Spiral Model - OverviewQuadrants in a cycle:
Creation of a prototype as a means to gather and lock
in requirements; gain customer buy-in.
Risk is assessed and if acceptable,
Development activities then follow using the waterfall
Specifications are created from the prototyping
effort, Then Requirements, Analysis, Design,
Implementation, … ensue
Review and release are undertaken…
Restart and iterate as above…
Planning for next iteration is undertaken – or not…
Iterate until application is developed fully and totally
released to the clients.
21. Spiral Model - moreMay be several cycles of prototyping…but as prototypes
evolve, these may become official releases of the product
(internal or external).
Before a cycle ends, the review discusses experiences,
assesses risk, and decision made whether or not to proceed.
Note: for each cycle, FIRST thing before embarking is to
decide what are the major requirements to be handled.
Adjust the architecture and requirements and/or project
plan as needed.
The Spiral forms the basis for entire life cycle of the product.
Thus, the Spiral Model continues the spiral process for
Maintenance, and the model continues until the application is
ultimately retired or replaced…
R & D Stage
Major risk items
Change managed baselines
Low Risk Items
23. Back to our Process Model (RUP)Let’s look more closely at the phases for our process
Each phase has
essential activities, and
primary evaluation criteria
to judge its success at milestone time.
Since the process that is underpinning our management
of software processes and personnel course is the RUP,
it is imperative that we understand this management
process, the RUP, as much as possible
24. Inception Phase (1 of 3)Overriding Goal: achieve concurrence among
stakeholders on life-cycle objectives for the project
Primary Objectives: (by end of phase…)
Establish project software scope and boundary conditions
Includes operational concept, acceptance criteria, and a clear
understanding of what is and what is not intended in the product
Identify critical use cases (core functionalities) of system
and the primary scenarios that will drive the activities
Demonstrate at least one candidate architecture against
some of the primary scenarios (walk through it…)
Estimate the cost and schedule for the entire project
(including detailed estimates for the elaboration phase)
Estimate potential risks (sources of unpredictability)
25. Inception Phase (2 of 3)Essential Activities
Develop Project Scope
Capture requirements and concept of operations repository
Describes users’ view of the requirements
Repository contains information used to define problem space
Repository must contain information to capture acceptance criteria
Develop a Candidate Architecture and Demonstrate it
Repository contains enough information to demonstrate at least a
single candidate architecture
This might be at a very high level, such as deployment level;
A general layered architecture may also be demonstrated.
But considerable Requirements have not yet been done and almost NO
Analysis and Design have been undertaken.
Repository must include enough data to support make/buy
decisions so that cost, schedule, resources can be ‘costed out.’
Planning and Preparing the Business Case
Risk management strategies, staffing, general iteration plans,
cost/schedule/profitability tradeoffs are all evaluated.
Environmental (Infrastructure) support is defined.
ROI, market share, etc.
26. Inception Phase (3 of 3)Primary Evaluation Criteria
Stakeholder concurrence on scope definition and
Do critical use cases demonstrate that the
requirements are understood?
Do we have credible estimates for
Does the architectural prototype support previous
items? (Does the prototype indicate that the scope of
project is understood, and does the development
group indicate prevalent understanding?)
Are actual expenditures verses planned expenditures
acceptable? <<end inception>>
27. Elaboration Phase (1 of 5)Clearly the most important phase! Overriding
goals are several, varied, and critical!
At end of phase:
engineering is complete,
almost all use cases are designed (certainly all critical use cases and
a prototype for gathering requirements and to demonstrate proof of
concept is accommodated, and
an analysis model is constructed, and
a baseline executable architecture is established and demonstrated.
Risks have to have been addressed and strategies understood;
Business Rules have been subscribed to closely;
Cost and schedule are acceptable and predictable and updated, if
Stakeholder acceptance is achieved (the vision is realized in the
artifacts), etc. and
We have stability…
We want to graduate from a low-cost effort into a full-blown
production process, where costs are maxed and personnel are on staff.
28. Elaboration Phase (2 of 5)Primary Objectives (at end of phase…)
Base-lining the architecture asap (establishing
configuration management procedures…for
tracking all artifacts!
Base-lining the Vision. It is now ‘solid’ and
accommodated in the artifacts so far.
Base-lining a detailed plan for Construction
Demonstrating the baseline architecture such
that it clearly supports the vision – at, of course,
reasonable cost in reasonably time.
29. Elaboration Phase (3 of 5)Essential Activities
Detail the Vision.
Ensure all have this shared functional vision and that this is
reflected in the Use Cases that will drive the architecture and
Discuss: What does this mean to you??? Explain!
Detail the process (to come) and the infrastructure
Must be spelled out; the plans for each iteration in
Construction (project management supporting discipline) and
the anticipated assessment at the end of each iteration, the
functionality accommodated by each iteration must be
spelled out in general.
Detailed iteration planning (after first iteration or two) will
come later. But overview planning is now!
Discuss: What does this mean? Explain!
30. Elaboration Phase (4 of 5)Essential Activities – continued
Build the Architecture…
Group classes into packages; subsystems; consider
existing executable components that may be reusable – e.g.
GUI Components (commonly available); can you reverse
engineer existing components? (Should you seek to buy
components? Contract for them? Develop them?)
But you MUST integrate these into architectural units (layers,
packages, subsystems, all with dependencies, well-defined
Bounce your candidate architecture against your primary
scenarios to trace that all functionality is accommodated by
May result in a number of design choices and changes in
model elements (e.g. classes, responsibilities…)
May point out some requirements missing…
Remember, requirements are singular; but there is not a
single, perfect design.
31. Elaboration Phase (5 of 5)Primary Evaluation Criteria
Remember, at the end of Elaboration Phase we have
the LCA – Life Cycle Architecture Milestone. So, …
Is the Vision solid? Stable?
Is the architecture stable? Demonstratable?
Execute example of addressing a high risk scenario?
Does the architecture indicated that all risk elements have
Have we looked carefully into Construction and established
sufficient planning detail to project credibility in our estimates?
(initial iteration – one or two – carefully planned?)
Do we have stakeholder buy-in that their vision can be
accommodated if we proceed as plans indicate?
Are actual resource expenditures verses planned resource
expenditures acceptable so far?
Achieve this Milestone! Press on – with concurrence.31
32. Construction Phase (1 of 5)Great mindset change: now interested in
producing a deployable product!
iterate, iterate…, integrate/assess/plan as we go.
No longer ‘engineering;’ rather, production!!!
Need to manage resources, control operations to
optimize costs, schedules, and quality.
Emphasis on the development of intellectual
property shifts to the reality of usable products.
33. Construction Phase (2 of 5)One very nice attribute in Construction:
Based on architecture…do homework up front!!!!
Accelerates delivery of deployable releases
Downside: complicates project management and
synchronization of teams, integration, and workflow.
Architecture will drive this
A good architecture will support parallel development
Emphasized during Elaboration – planning for
34. Construction Phase (3 of 5)Primary Objectives
Develop the system rapidly but with high
quality – that is, construction (programming
and unit testing) ‘implements’ the design;
‘realize’ the design…
Take advantage of the process, versioning,
reviews, assessment, etc. to minimize costs
due to needless rework and scrap.
Develop alpha, beta, ‘or what have you’
releases for Transition phase.
35. Construction Phase (4 of 5)Essential Activities
Manage resources; control development (via
plans, configuration management, change
Perform unit testing (component testing)
against requirements (verification)
Assess releases against acceptance criteria
cited in vision. (validation)
36. Construction Phase (5 of 5)Primary Evaluation Criteria (at end)
Milestone is ‘Initial Operational Capability’ (IOC)
Is the product reliable enough for deployment?
Does not mean everything must be perfect…Showstoppers?
Does it fail frequently??
Is product ‘stable’ enough for deployment?
Pending changes are okay
But are we getting change requests a-plenty?
Are defects being identified rapidly ‘as we speak?’
How significant are the changes??
Is the stakeholder community ready to transition?
Are actual expenditures reasonably close to planned
37. Transition PhaseRecall end of phase milestone: product release to
Implies product is stable, has high quality, has
accompanying user documentation (on-site or web-based
training…), customer support is ‘ready’, etc...
Phase ‘could’ include any of these…
Beta testing to validate new system against expectations
Beta testing in parallel with legacy system to be replaced
Conversion of operational data bases
Training users, maintenance team, customer support…
38. Transition PhasePhase concludes when the baseline realizes the
original vision and we are ready to put it in the
Might be end of project development or starting
point for next cycle, or starting point for next
version of deployable version...
Might be forwarding ‘whole shooting match’ over
the maintenance group or
third party for future work…
39. Transition PhaseTransition is not uncomplicated
May involve several iterations including
Beta1, beta2, … testing and ‘levels’ of releases (all
releases may not be equal…)
Development of user documentation,
User training, especially in initial use of product
Web-X; on developer’s site; on client’s site.
Who pays for what? How does this work? Millions!!!
Usability problems and tuning,
(Un)solicited feedback, and more….
40. Transition PhaseEssential Activities
“Synchronization and integration of concurrent
construction increments into consistent deployable
baselines” – ensure all flows…
Installation / Conversion
Cut over (complete switch to new application)
Run in parallel, or
Assessment against vision and acceptance criteria.
Is user satisfied?
Are actual expenditures reasonably close to planned
41. Summary - Know TheseRecognize each phase has one or more
Phases end with major milestones; (Know
Iterations within phases have minor milestones.
Each have deliverable(s) and undergoes assessment
Each iteration entails a sequence of activities that
culminate in a minor milestones or major milestones
(if iteration ends phase)
Scope and results of iterations are captured via
42. Summary (continued) – Know!Major Milestones (phase end):
Approved by stakeholders
Map to significant management/business decisions rather than
to completion of a specific software development activity.
Minor milestones (iteration end):
Approved internally and
Realized by artifacts / new versions of artifacts in repository;
Additional planning take place…
‘Executable’ releases (not necessary deployable…)
43. Lessons Learned – Organizational ChangeMiddle management is where the war is won
Championed by respected leaders who own the plan and
Project Management: Can be immense pressures from
above (Sr. Management) and different sets of
problems/issues from below (actual developers)
ROI on first implementation
Disruption costs must be absorbable in the benefit
Implemented on business critical project
This is where the A-players are
Success breeds success – (like the NFL)
First increment needs to be ambitious, but realistic
Results drive incentives
Such as: milestone demonstrations, release timeliness,
release content, etc
Not: processes, methods, expended energy, reuse, audits,
meetings, subjective assessments, document production,…