CS 5150
Software Engineering
Lecture 2
Software Processes 1
Project Teams
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It’s okay if you don’t have a team yet
Piazza activated
Send email to Ben & Yue when you have (most of) a
team
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Team name
Names of team members
Client info
Project topic
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Projects
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Project suggestions continuing to come in
If you have your own project idea send email to Ben &
Yue
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What is a Software Process?
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More or less formal rules for organizing work
on software
Trivial example:
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Meeting with client
Meeting with team
Code code code
Test
Email finished program to client
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Software Processes Matter
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Cost
Risks
People
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Software is Different
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Best practices are still changing (relatively)
rapidly
Non-specialists (e.g. most clients) have
relatively poor insight into how software works
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Risks
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Most software projects have major problems
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Over budget (cost)
Late delivery (time)
Lots of code is wasted (perhaps 50% never
used)
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Does not work as expected (functionality)
Does the wrong thing
Poor interface
No one cares
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The Three-way Trade-off
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The terrible triangle
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Functionality (scope of project)
Cost (developer time & other resources)
Time (delivery date)
Force clients to make choices
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(without being a jerk)
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Client’s Risks
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Understand risks from the client’s perspective
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Late (cancelation of some related project?)
Over budget (middle manager gets fired?)
Insufficient functionality (competitor
dominates market?)
Full of bugs (plane crashes?)
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First Major Hurdle: Communication
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Most failed software projects fail because the
leaders didn’t plan the right software
Listen to the client!
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The client is not always right
The client must be satisfied at the end of the
day
Tight communication feedback loops
Expertise and a nose for exceptions
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Minimizing Risks
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Feasibility study
Stakeholder requirements and priorities versus
design decisions
Milestones and releases
Acceptance and testing
Handover
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A Popular Strategy: Short Cycles
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Minimize risk with short development cycles
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New pieces of working software every week
or two (not months)
Many opportunities to change course
This is one of the fundamental pieces of the
Agile development method
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Visibility and Accountability
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Managers and clients want to know the status
of in-progress software
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Must rely on reporting by developers
Developers
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Often have trouble reporting progress
Are usually optimistic
Dislike reporting
Frequent releases and accepted processes
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Teams
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Most software is built by teams
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Effectively all software is built on other
software
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Overall team efficiency is the critical metric
Indirect collaboration with other
programmers
Practical limit on team size is fairly small
Collaboration between teams requires more
planning
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Observations about Big Projects
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Big software represents thousands to millions
of person-years of effort
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Every project that is sufficiently successful
will have significant developer turnover
... and changes in requirements and
priorities
No large project is every complete
Our projects
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About 0.3 person-years (a single sprint)
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Fundamental Assumptions
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Good processes reduce risk
Good processes enhance visibility
Good processes increase probability of project
success
Systematic testing is the key to all processes
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Different Strokes for Different Folks
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Safety critical systems => more reliability
testing
Shrink-wrap software => more usability testing
Systems/frameworks => more robustness
testing
Contract software => more emphasis on core
requirements
No standard process
BUT there are common principles
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Basic Components of All Processes
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Feasibility and planning
Requirements and priorities
System and program design
Construction
Acceptance and release
Operation and maintenance
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Testing is Part of Every Phase
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Stakeholder review of plans
Usability prototyping
Design review
Automated testing
Code review
Manual testing
Acceptance testing
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Heavy vs Light: the Main Process Axis
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Heavy: Methodically (and slowly) work through
the complete development cycle
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Example: Modified Waterfall Model
Light: Incrementally work through (parts of) the
development cycle quickly
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Might have 100s of pages of design
documents before the first line of code is
written
Many web applications are run this way
Example: Agile Software Development
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Heavy or Light?
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Team size
Risk tolerance
Application space maturity
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