Whether you're creating a complex web application or a simple library, everything you create has a user. Why, then, do we concentrate on our users when developing a user interface, but so often forget them when developing APIs? In this talk, Christopher presents a whirlwind overview of a variety of different User Experience considerations when designing your APIs.
5. Your API is a UI @choult
What is a UI?
A “space where interactions between humans and
machines occur. The goal of this interaction is effective
operation and control of the machine on the user’s end,
and feedback from the machine, which aids the operator
in making operational decisions.”
Wikipedia
6. Your API is a UI @choult
What is an API?
“An application programming interface (API) specifies
a software component in terms of its operations, their
inputs and outputs and underlying types. Its main
purpose is to define a set of functionalities that are
independent of their respective implementation, allowing
both definition and implementation to vary without
compromising each other.”
Wikipedia
8. Your API is a UI @choult
Who are your users?
• Developers
• Colleagues
• Customers
• Their Customers
• Applications
9. Your API is a UI @choult
What does your API do?
• Real use cases
• User stories
• Document usage/flow
• Sell your API
10. Your API is a UI @choult
What can users do?
• Why are you exposing an API?
• It’s very rare to expose everything
• Too much complexity -> confusion
• Define restrictions
• Validate user stories against goals
11. Your API is a UI @choult
API Hierarchy of Needs
APIUX.com: http://bit.ly/Zl8Exo
13. Your API is a UI @choult
Consistency
• Improves comfort for user
• Style guide (PSR-1/2; REST etc.)
• Common attributes/functions
• Naming
• Error codes
14. Your API is a UI @choult
Patterns
• Users understand Patterns
• Patterns aid understanding
• Webservices: RPC, REST
• Code: Gang of Four etc.
15. Your API is a UI @choult
Information Hierarchy
• Define ERM
• Arrange entry points from user POV
• Nesting entities can be problematic
• Get it right: classes and objects intuitive
16. Your API is a UI @choult
Abstraction
• User stories guide API design
• Hide complexity
• Avoid adhering to underlying model
• Do the hard work so users don’t have to
17. Your API is a UI @choult
Simplicity
• Best result of abstraction
• More straightforward, more use
• Smaller footprint = fewer failure paths
• Easy fault detection
18. Your API is a UI @choult
Extensibility
• Flipside to abstraction
• How will users extend codebase?
• Restrict as required - public/protected/private
• Take care - hard to retract public
• Patterns help here!
20. Your API is a UI @choult
Testing
• Use appropriate testing methodology
• Make part of build/release process
• Monitor production with live testing
• Consider record/replay testing
• Regression testing
21. Your API is a UI @choult
Metrics
• Metrics tell you what is happening
• Record status codes
• Calibrate with normal running
• Insight into running code
• Graphite/statsd
22.
23. Your API is a UI @choult
Logging
• Tells you what happened
• Helps debug production faults
• Reference in error messages
• Insight into running applications
• Information for users of code
24. Your API is a UI @choult
Versioning
• Plan versioning upfront
• Define upgrade/deprecation strategy
• What is a breaking change?
• How long will API be supported?
• Communicate with users
25. Your API is a UI @choult
Feedback
• Clear feedback
• Reasons for failure
• Appropriate language
• Error codes
• Normalized; human readable
• Provide glossary
27. Your API is a UI @choult
Documentation
• No such thing as “self-documenting code”
• Write fulsome documentation
• Include working examples
• Cross-link from code
• Manuals, Quick Start Guides, Cookbooks
28. Your API is a UI @choult
Living Documentation
• Docblocks (Javadoc/PHPdoc) are a good start
• Cross-language (eg Doxygen)
• Use standards like PSR 5
• Annotations
• Interactive documentation - eg. IODocs
29. Your API is a UI @choult
Support / Community
• Define channels of communication
• Define location for participation
• Invite feedback
• Invite contribution - define guidelines
• Respond gracefully and attentively
• Learn from your users
33. Your API is a UI @choult
On Pragmatism
• Pragmatism is good!
• Can promote technical debt
• Find a balance - RESTlike, RPCish
• Be realistic
• Iterate - versioning and deprecation
35. Your API is a UI @choult
Your API is You!
• Like your UI, your API is your public face
• It is your avatar
• Take pride in your work
• Impress your users with its awesomeness!
37. Your API is a UI @choult
Thank you!
@choult
christopherhoult
chris@choult.com@
This presentation was typeset in HandTIMES and Open Sans, using Adobe InDesign CS6
(because I’m a lunatic)
Feedback please! https://joind.in/13392
38. Your API is a UI @choult
Resources / Inspiration
10 User Interface Design Fundamentals - Kyle Sollenberger
http://blog.teamtreehouse.com/10-user-interface-design-fundamentals
APIUX: API Hierarchy of Needs
http://apiux.com/2013/05/29/api-hierarchy-needs/
5 Golden Rules for Great Web API Design - Jordan Ambra
http://www.toptal.com/api-developers/5-golden-rules-for-designing-a-great-web-api