Usable Software Design
A Talk by Alex Bolboacahttp://www.nasa.gov/sites/default/files/thumbnails/image/iss043e124426.jpg
Jacques CarelmanArtist, creator of “The Catalogue of Impossible Objects” in the 60shttp://www.patakosmos.com/wp-content/uploads/2013/09/RDA00147250.jpg
Coffee pot for masochistsCatalogue of Impossible Objects by Jacques Carelmanhttp://impossibleobjects.com/catalogue/coffeepot-for-masochists.html
Absorbent BottleCatalogue of Impossible Objects by Jacques Carelmanhttp://impossibleobjects.com/catalogue/absorbent-bottle.html
Siamese HammersCatalogue of Impossible Objects by Jacques Carelmanhttp://impossibleobjects.com/catalogue/siamese-hammers.html
Donald A. NormanAuthor of “The Design of Everyday Things”http://www.jnd.org/NNg-Photographs/Photo1.jpg
“It is the duty of
machines and those
who design them to
understand people.
It is not our duty to
understand the
arbitrary,
meaningless dictates
of machines.”
User Centric Design Process by UXPARevolution started by Donald A. Norman's bookhttp://uxmastery.com/what-does-a-user-centred-design-process-look-like/
All designs have an user.
Who is the user of software design?
Can't be the end user.
Only one answer: the developer is the user of software design.
So, then, developer-centric software design is a thing?
How about “Usable Software Design”?
You Are The User: Changing Code
● Figure out what you need to change● Navigate there● Read the code, tests, documentation, comments● Write/change code, write/change tests● Refactor● Build● Validate● Integrate
Figure Out What To Change
● How easy can you reason about the runtime behavior based on the static structure of the code?
Is Your Design Easy to Navigate?
● What module / namespace to look in? – See previous examples
● How is that thing named?– Should be Consistent, Memorable, Precise
● How deep is the inheritance tree?
What is Usable Software Design?
Usable Software Design is any code structure that exhibits design qualities similar to usability
5 Design Qualities of Usability
1. Learnability
2. Efficiency
3. Memorability
4. Errors
5. Satisfaction
http://www.nngroup.com/articles/usability-101-introduction-to-usability/
How easy it is to accomplish basic tasks the first time you're using the design?
How quickly can you perform a task once you've learned the design?
When you go back to the design after a period of not using it, how easy is to become efficient again?
How many errors do you make, how severe are they and how can you recover from them?
How pleasant it is to use the design?
Developer Persona For Your Team
● Kernel Developer● Java Enterprise Developer● Rails Developer● C/C++ Embedded Developer● Android Developer● Front-end Javascript + html + CSS developer● Etc.
Each persona has different needs.
Usability depends on the user!
Example of Team Agreement
Usable Software Design means to us that:
1. It is written for developers to read
2. It is easy to find where to modify the code
3. Any modification has a minimal ripple-effect
4. It is easy AND fast to validate that we did the right thing
5. We don’t have to do similar modifications in several places
Usable Software Design – A Federating Conceptby Johan Martinsson
Next Step: Practices
“It is written for developers to read”
=> coding guidelines, clean code etc.
“It is easy to find where to modify the code”
=> navigability, consistency etc.
“Any modification has a minimal ripple effect”
=> follow Open Closed Principle, Single Responsibility Principle etc.
1. Learnability
How easy is it for users to accomplish basic tasks the first time they encounter the design?
Hints: Design For Learnability
Code structure that shows what the application doesConsistency
Minimal SurpriseUse Clearly Defined Modules With Clear APIs
Readability / Clean CodeNavigability
Add Usage examples – tests / comments etc
Test Learnability
Measure how long it takes for developers outside your team to understand the purpose of a
class with as little help as possible.
Hints: Design For Efficiency
Use code constructs the whole team understandsConsistency
Fast Validation
Test Efficiency
Retro question: “what slowed you down in the past two weeks?”
Measure how long it takes for developers to finish typical tasks (not simple, but typical)
3. Memorability
When you go back to the design after a period of not using it, how easy is to become efficient again?
4. Errors
How many errors do you make?How severe are these errors?
How easily can they recover from the errors?
Hints: Design For Mistake Proofing
It's the system's faultWrite automated testsEliminate exceptions
Pass mandatory arguments to constructor(more difficult when using Dependency Injection libraries)
Avoid Primitive ObsessionPrinciple of Minimum Surprise
Test Mistake-Proofing
How many bugs do we have?What is the main cause of the bugs?
(remember, it's typically in the design)How can we change the design to avoid it?
Test Satisfaction
What parts of the system are unpleasant to use?
How can we change them to be more pleasant?
What To Tell Managers
Usable Software Design has the potential to bring four economical benefits:● Faster integration of new developers in the team
(learnability)● Faster time to implement typical (not simple) tasks
(efficiency)● Making less mistakes (mistake-proofing)● Feeling more motivated (satisfaction)
Recap
● The developer is the user of software design● Usable software design means code structure that
exhibits the qualities of usability: Learnability, Efficiency, Memorability, Error Treatment and Satisfaction
● Define the personas of your team● Create a team agreement● Start applying practices that help the agreement● This is just the beginning