Usable Software Design

A Talk by Alex Bolboacahttp://www.nasa.gov/sites/default/files/thumbnails/image/iss043e124426.jpg

My belief:

YOU Deserve Better!

Naomi WeastActress, not a programmerhttps://plus.google.com/110657773112027365790/posts

It reminds me of something else

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

It reminds me of something I read in a book ...

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?

Example: Namespaces

Example: Modules

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?

Example: Consistency

Example: Modules APIs

This is just the beginning

What is Usable Software Design?

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?

How to Improve The Usability of Software 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.

Specific practices for Usable Software Design?

(Incomplete list)

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.

2. Efficiency

Once users have learned the design, how quickly can they perform tasks?

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?

Memorability ≈ Efficiency + Learnability

+ The style is internalized

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

Example: TicTacToeMistake-prone Design

Mistake-proof Design

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?

4. Satisfaction

How pleasant is it to use the design?

Hints: Design For Satisfaction

Strictly personal, but relevant

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)

My belief:

YOU Deserve Better!

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

Q&A

“The important thing is

not to stop questioning”