Secrets of the Usable REST API
Teowaki founder Javier Ramirez kicked off his Future of Web Apps presentation with a striking headline from a local town newspaper:
“I’ve been posting my letters in the dog poo box for two years.”
In an effort to class up the North Yorkshire town (or perhaps to save on supplies), the town had painted dog waste bins the same elegant red of the public mailboxes.
“Everybody agrees web usability is a good investment.” Ramirez said, but “When I use an API, usability is not that cool,” he said, then running through the tedious process to get information via the Amazon API. “Ten simple steps,” he said, tongue in cheek.
How can we compare this poo faux pas to Amazon, you ask?
First and foremost, developer experience matters. And as your developer customer evolves, so must the way you develop an API for them. That, and when your API evolves, make it clear to everyone involved — by proper municipal signage or documentation — whichever the situation calls for.
And thus began Ramirez’s talk on “Writing Usable REST APIs.”
I would argue that his advice could be applied to all forms of the application programming interface or perhaps all apps and websites in general. After all, usability is in the eye of the developer.
Remember, “If a developer doesn’t use your API, they won’t tell you what they don’t like.”
What is API usability?
Let’s first start with the more common definition. Gary B. Shelly wrote:
“Web usability is an approach to make websites easy to use for an end user, without the requirement that any special training be undertaken.”
Jakob Nielsen in his Usability 101 elaborated the five quality components of usability:
- Learnability: In order for people to use your product, it has to be easy to learn how to use it.
- Efficient: Once I learn it, I want to use it efficiency. I don’t want to go through the tutorial every time.
- Memorability: It has to be easy to remember how it was, you don’t have to learn every time.
- Errors: Give sensible error messages.
- Satisfaction: Always a priority in usability.
Ramirez argues that, by applying these five principles, you can also bring about API usability.
How do you know if your API is usable?
Some might say usability testing has no place in the API world. I’m inclined to disagree, but until that’s a trend, certainly dogfooding your API should be a no-brainer — if you don’t want to use it, who will?
We like to cite Amazon Web Services as the original dogfooder, but we really should give kudos to Mike Scott, then president of Apple who banned the Macintosh’s main competitor — the typewriter — from the premise back in 1980.
Within two years, typewriters were essentially obsolete as a company was built upon dogfooding.
Different nerds; different needs
This is Ramirez’s way of saying my dad’s favorite: “You know what happens when you assume...” You can’t just stop at dogfooding because you can never assume anyone is going to use your API in the same way.
“As my girlfriend tells me time and again: ‘Javi, you are not an example of anything’.”
Similarly, don’t assume that everyone knows the same as you, the developers that built this API. Ramirez suggests that when you are making a REST API available to the masses, the easiest thing is to put everything you can into the query stream, which he says is quite good when people are learning, but afterwards, they can hide it in the headers.
And don’t be an over-sharer. He reminded us not to expose your implementations details, focusing on resources not whole database tables.
Don’t reinvent the API
“As of today, you don’t need to implement your own authentication.” In fact, Ramirez said, “don’t implement something new, don’t try to be too smart” at all. “If something is already available, someone has already been thinking about it for a long time.”
Similarly, he argues, whenever possible, just use the standards that are available. “If you don’t like a standard too much, that’s too bad.”
Your API is your best way of communicating with developers
Perhaps even more important than Nielsen’s five, is the Ramirez one: Consistency.
“If your API behaves consistently all the time,” he says you have nothing to worry about. Follow common API call patterns and, likewise, follow common fail patterns. You have to return the same error every time in order to fail consistently too.
“Just choose the code that makes sense for your application and keep it consistent,” he continued.
Ramirez later offered the example of a Twitter quota where it’s clear in the metadata of how many API calls you have made and can make but, for many APIs, it’s not that clear at all.
But communication isn’t just about writing clear code. It’s about proper API documentation. In Zappos’ case, they’ve written right into their API’s error message that “If you’re reading this, maybe you should be working at Zappos instead. Check out jobs.zappos.com.”
Go as fast as you can... when you can
“If your API is slow and someone has to call your API and wait 30 seconds to get a response, they aren’t going to use you.”
Ramirez went on to admit that sometimes you just can’t be fast, but then you can at least be asynchronous, “But don’t make developers wait for your API.”
Sometimes, speed comes by not having a clunky API. Netflix started out with what Ramirez calls its OSFA or One Size Fits All API, but they found they could be more agile by providing a series of REST APIs.
“What they did is that they move away from that system to what they call an experience[-based] API” Depending on device, different experience, “and I’m going to give you a different API adapted for that experience.”
When you’re having two billion requests to your API per day, it really helps to do different requests for different devices. This led to a better developer experience, a better user experience, and it cut a huge amount of expenses by saving bandwidth.
Is Hypermedia the secret to the Usable REST API?
Ramirez doesn’t offer any secret formula but he offers certain ways he believes you can more easily deliver a better developer experience.
First and foremost, he believes hypermedia makes for more navigable APIs through the Hypermedia Application Language Standard or HAL, allowing you to embed several resources in a single request.
To some extent, “if there is an alignment of the planet and the sun, you can do versioning without versions,” and you can create a link to give me information for a new object. “By doing those things and also using hypermedia, you can do great things,” Ramirez assured.
And fitting nicely with hypermedia APIs, he also recommended you just go and build your API with JSON, as he is among many that believe this will eventually be the standard.
Of course, a good developer experience comes with great API documentation, which he said should include:
- code examples
- where you do
Ramirez went on to suggest you use Swagger to write your API documentation, as well as allowing you to “play with your API without writing any code.”
Ramirez said two things that are most important in order to balance your business with your developer experience:
- Model your API around your business not around your internal architecture, which comes with benefits like moving to another version without breaking your API.
- And always remind your team: “I don’t care about companies; I care about people doing things.”
When you are looking to build a usable REST API or any amazing developer experience, you need to ask yourself these questions and more:
- Should my API allow asynchronous creation, update, and deletion?
- Should my API ignore unrecognized parameters silently, even when it is getting a valid request, or should it return and error?
- Should it allow bulk operations?
- Does API need real-time?
“There are not good or bad answers. Every API is different. Every user base is different. The only wrong answer is copying and pasting from the last project,” Ramirez said.
Most importantly, you must always ask yourself: Would I want to use it?
Learn more about API usability.
Watch my full interview with Javier Ramirez at Future of Web Apps.
How do you make sure your APIs are usable? Tell us below!