1. Informatics 121 Software Design I
Lecture 4
Duplication of course material for any commercial purpose without the explicit written permission of the professor is prohibited.

2. Intermezzo: what experts do
Experts prefer to work with others
Experts prefer simple solutions
Experts look around
Experts focus on the essence

3. Discussion There will be discussion next Monday and Wednesday
Please join your designated discussion
Note: location of Wednesday 10:00-10:50 discussion has been changed to MTSB 118

4. Grace Hopper

5. Today
Design cycle
Design practice
Design studio 1 continued

6. Four types of software design
what is it to accomplish?
how does one interact with it?
what is its conceptual core?
what are its implementation details?
application design
interaction design
architecture design
implementation design
satisfactory experience
plan for realization
change in the world

7. Design cycle
synthesize
analyze
evaluate

8. Design cycle goals constraints assumptions decisions ideas analyze
evaluate
synthesize
goals
constraints
assumptions
decisions
ideas

9. Design cycle at the macro level: design process
synthesize
goals
constraints
assumptions
decisions
ideas
analyze
evaluate

10. Design process
A design process represents a planned course of action as to how to tackle a design problem to arrive at a design solution
where to focus effort
what methods to use
whom to involve
A design process may be defined up-front in its entirety, or defined in increments as the design project unfolds

11. Waterfall requirements phase design phase implementation phase
testing phase

12. Waterfall as a design process
satisfactory experience
plan for realization
change in the world
what is it to accomplish?
how does one interact with it?
what is its conceptual core?
what are its implementation details?

13. Agile
Our highest priority is to satisfy the customer through early and continuous delivery of valuable software.
Welcome changing requirements, even late in development. Agile processes harness change for the customer's competitive advantage.
Deliver working software frequently, from a couple of weeks to a couple of months, with a preference to the shorter timescale.
Business people and developers must work together daily throughout the project.
Build projects around motivated individuals. Give them the environment and support they need, and trust them to get the job done.
The most efficient and effective method of conveying information to and within a development team is face-to-face conversation.
Working software is the primary measure of progress.
Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely.
Continuous attention to technical excellence and good design enhances agility.
Simplicity—the art of maximizing the amount of work not done—is essential.
The best architectures, requirements, and designs emerge from self-organizing teams.
At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly.

14. Agile as a design process
satisfactory experience
plan for realization
change in the world
what is it to accomplish?
how does one interact with it?
what is its conceptual core?
what are its implementation details?

15. Other life cycle models
Extreme programming
Rapid prototyping
Spiral model
Iterative development
Rational unified process
Synchronize-and-stabilize …

16. Choosing a software life cycle
Choosing a software life cycle is choosing a design process
One has to make sure the design process matches the nature of the design problem
One has to make sure to remain flexible in adjusting the design process when the project so warrants

17. Realistic design process
satisfactory experience
plan for realization
change in the world
what is it to accomplish?
how does one interact with it?
what is its conceptual core?
what are its implementation details?

18. Backtracking is inevitable
satisfactory experience
plan for realization
change in the world
what is it to accomplish?
how does one interact with it?
what is its conceptual core?
what are its implementation details?

19. Minimize backtracking
satisfactory experience
plan for realization
change in the world
what is it to accomplish?
how does one interact with it?
what is its conceptual core?
what are its implementation details?
Strive to minimize backtracking more than absolutely necessary
Strive to minimize backtracking later than absolutely necessary

20. Routine, adaptive, and original design projects
high
original
complexity
adaptive
routine
low
high
low
familiarity

21. French fries and mayonnaise

22. Design at the micro level: design work
Design work represents the individual or collaborative activity of engaging with a design project at a detailed level
thinking
articulating context
analyzing alternative ideas
identifying constraints
making decisions
setting goals …

23. Opportunistic versus rationalistic design work
unexplored idea
explored idea
current decision

24. Mixed opportunistic and rationalistic design work
unexplored idea
explored idea
current decision

25. Backtracking unexplored idea previous decision explored idea
current decision

26. Backtracking unexplored idea previous decision explored idea
current decision

27. Simultaneous exploration
unexplored idea
explored idea
current decision

28. Putting it all together
what is it to accomplish?
how does one interact with it?
what is its conceptual core?
what are its implementation details?
application design
interaction design
architecture design
implementation design
analyze
evaluate
synthesize
goals
constraints
assumptions
decisions
ideas

29. French fries and mayonaise

30. Design studio 1
Your client is massbroadcast.com, a new company that seeks to enable organizations to reach out to a broad audience with a pre-determined message – via phone, text, instant message, Hangouts, Skype, and other media. The company plans to make money from clients who seek to advertise their products. Being altruistic, however, the company also wants to offer support for emergency alerts. The company has sought you out, because you are an excellent designer. All of the software design is in your hands.

31. Design studio 1
As a team, provide a design document that addresses the massbroadcast.com design task
You should primarily focus on application design and provide a well-motivated set of decisions regarding what the application is to accomplish
generically
specifically
In addition, please highlight three goals and three ideas each for interaction design and architecture design

32. Design studio 1 Due October 15 at the beginning of class
bring one printed copy of your document
Your group will remain the same as announced in your discussion

33. Design studio 1 Due October 15 at the beginning of class
bring one printed copy of your document
Your group will remain the same as announced in your discussion
If you are attending Grace Hopper, come talk to me after class for one minute

34. Design studio 1 Feasibility Desirability Understandability
Innovativeness
Completeness