Documenting REST APIs

DOCUMENTING REST APIS

BY TOM JOHNSON

IDRATHERBEWRITING.COM

STC Summit 2015 Columbus, Ohio @tomjohnson

CONVENTIONS

• Access the course module at http://idratherberwriting.com/restapicourse

• 1.1 Numbers in slide headings refers to the place in the course module.

• This icon indicates an activity you’re supposed to do.

• If you get lost, read the course page.

http://idratherberwriting.com/restapicourse

1.0 OVERVIEW

• Focus of the course is REST APIs

• Time to completion

• Learn with a real example and context

• No programming skills required

1.0 OVERVIEW

What you’ll need:

• Text editor• Chrome browser• Postman REST Client• cURL• Network connection

Follow along online: idratherbewriting.com/restapicourse

1.1 INTRODUCTION TO REST API DOCUMENTATION

Complete and accurate docs are most important factor in APIs


REST APIs are taking off in a huge way


Job market is hot for API technical writers


API doc is a new world for most tech writers


Increasing learning materials about API documentation

1.2 USING A REST API LIKE A DEVELOPER

An API is an interface between systems.


Our course scenario: Weather forecast API


Get an idea of the end goal

http://idratherbewriting.com/files/restapicourse/windcalls.html


Browse the available APIs on Mashape


Find the "Weather" API by fyhao


Answer some questions about the API

• What does the API do?

• How many endpoints does the API have?

• What does each endpoint do?

• What kind of parameters does each endpoint take?

• What kind of response does the endpoint provide?

✔ Terminology tip: API == Endpoint

1.3 GET THE AUTHORIZATION KEYS

• Authorization for making API calls

• License access to the API

• Rate limit the number of requests

• Control availability of certain features within the API


Get the Mashape authorization keys


To get the keys:

1. Click Sign Up Free and create an account.

2. Click Applications on the top nav bar.

3. Click Get the Key.

4. In the dialog box, click Copy. (Choose the Testing

keys.)

5. Open up a text editor and paste the key.


Text editors:

• Sublime Text (Mac or PC)

• TextWrangler (Mac)

• WebStorm (Mac or PC)

• Notepad++ (PC)

1.4 MAKE A CURL CALL

Prepare the cURL call:

1. Go into Weather API.

2. Copy the cURL request example for the aqi endpoint into your text editor.

3. Important: If you're on Windows, change the single quotes to double, and add -k as well to work around security certificate issues.

4. Swap in your own API key.

5. Use Google Maps to find the latitude and longtitude of your current location.


Make the call in cURL (Mac)

1. Open a terminal.

2. Paste the call you have in your text editor into the command line.

3. Press your Enter key.


Make the call in cURL (Windows)

1. Copy the cURL call from your text editor.

2. Go to Start and type cmd to open up the command line.

3. Right-click and then select Paste to insert the call.


If it didn’t work, try the Advanced REST Client

• cURL is a cross-platform way to show requests and responses

• REST APIs follow the same request/return model of the web

• Try using cURL to GET a web page:

curl http://example.com

1.5 UNDERSTANDING CURL

Requests and responses include headers too

Use –i or -I include the response header:

curl http://example.com -i

curl http://example.com -I


Other methods you can use besides GET:

• POST: Create a resource

• GET: Read a resource

• PUT: Update a resource

• DELETE: Delete a resource



Specifying the method with a cURL call

--get

-X GET

-x PUT

curl –X GET http://example.com


Passing headers into the request:

-H

curl --get --include 'https://simple-weather.p.mashape.com/aqi?lat=37.354108&lng=-121.955236’ \-H 'X-Mashape-Key: WOyzMuE8c9mshcofZaBke3kw7lMtp1HjVGAjsndqIPbU9n2eET' \-H 'Accept: text/plain'


Passing data into the request:

-d

curl -i -H "Accept: application/json" -X POST -d "{status:MIA}" http://personsreport.com?status


Make cURL more readable:

curl -i \ -H "Accept: application/json" \ -X POST \ -d "{status:MIA}" \ http://personsreport.com?status \


Query strings:

?lat=37.354108&lng=-121.955236

Listening multiple parameters:

&parameter1&parameter2&parameter3

1.6 SUBMIT REST CALLS THROUGH POSTMAN

GUI clients make REST calls a little easier

Common GUI clients:

• Postman• Advanced REST Client• Paw


Insert the cURL call into Postman following the sample screenshot


View the format of the weatherdata response in pretty JSON

1.7 ANALYZE THE JSON RESPONSE

Prettify the JSON response: http://jsonformatter.curiousconcept.com/

JSON is how most REST APIs structure the response

http://jsonformatter.curiousconcept.com/

http://jsonformatter.curiousconcept.com/


JSON objects are key-value pairs:

{"key1":"value1","key2":"value2"}

JSON objects start and end with curly braces { }.


JSON arrays are lists of items:

["first", "second", "third"]

Arrays start and end with square brackets [ ].


An array can contain a list of objects:

[ { "name":"Tom", "age":39 }, { "name":"Shannon", "age":37 }]


An object can contain arrays:

children: ["Avery","Callie","lucy","Molly"],hobbies: ["swimming","biking","drawing","horseplaying"]


Identify the objects and arrays in the weatherdata API response.

• Where are the objects?

• Where are the arrays?

1.8 LOG THE JSON RESPONSE TO THE CONSOLE

Making use of the JSON response

Use the sample code from Mashape to parse and display the REST response: http://docs.mashape.com/javascript

http://docs.mashape.com/javascript



Customize the Mashape code with the weatherdata endpoint:

1. Open text editor. Insert Mashape code.

2. Customize the url to the useweatherdata endpoint.

3. Enter your API key.

4. Uncomment out the \\ next to console.log(data).

5. Save and view the file in Chrome.

6. Open the Developer Console: View > Developer > JavaScript Console. Refresh page.


You can customize your Console log messages

Inspect the payload

Replace "undefined”:

document.getElementById("output").innerHTML = data.query.results.channel.item.description;

1.9 ACCESS THE VALUES FROM JSON

Dot notation allows you to access specific values from the JSON response

data.query.results.channel.item.description


How dot notation works

"data": {"name": "Tom"}

To access Tom, I would use data.name.


Use square brackets to access the values in an array:

"data" : {"items": ["ball", "bat", "glove"]}

To access glove, you would use data.items[2]


Download the dotnotationexercise.html file from the workshop files.

Change john.children[0].child1 to display the following:

• green

• nike

• goldenrod

• Sarah


Get the wind speed from the weather API weatherdata endpoint.

Download the windcalls.html file from the workshop files. Look at the different values accessed from the JSON response.

2.0 YOU HAVE A NEW API TO DOCUMENT

Shift perspectives: Now you're the technical writer

You have a new endpoint to document

Review the wiki page: http://idratherbewriting.com/restapicourse2-0/

http://idratherbewriting.com/restapicourse2-0/



Essential sections in REST API documentation:

• Resource description

• Endpoint

• Methods

• Parameters

• Request submission example

• Request response example

• Status and error codes

• Code samples


Create the basic structure for the endpoint documentation

Use a text editor to create the sections.

Bonus: Use Markdown syntax.

2.1 DOCUMENTING THE RESOURCE DESCRIPTION

The terminology to describe a "resource" varies: • API calls• Endpoints• API methods• Calls• Resources• Objects• Services• Requests


Look at some examples:

• Mailchimp• Twitter• Instagram

http://kb.mailchimp.com/api/resources/automations/emails/automations-emails-instance

https://dev.twitter.com/rest/reference/get/statuses/retweets/:id

https://instagram.com/developer/endpoints/relationships


Referring to resources by the endpoint name can get problematic:api_site.com/{apikey}/users// gets all users

api_site.com/{apikey}/users/{userId}// gets a specific user

api_site.com/{apikey}/rewards// gets all rewards

api_site.com/{apikey}/rewards/{rewardId}// gets a specific reward

api_site.com/{apikey}/users/{userId}/rewards// gets all rewards for a specific user

api_site.com/{apikey}/users/{userId}/rewards/{rewardId}// gets a specific reward for a specific user

api_site.com/{apikey}/users/{userId}/rewards/{missionId}// gets the rewards for a specfic mission related to a specific user

api_site.com/{apikey}/missions/{missionid}/rewards// gets the rewards available for a specific mission


One resource can have multiple endpoints


When describing the resource, start with a verb.

Review some examples:

• Delicious API• Foursquare API• Box API

https://github.com/SciDevs/delicious-api/blob/master/api/posts.md%23v1postsupdate

https://developer.foursquare.com/docs/venues/menu

https://box-content.readme.io/%23add-a-comment-to-an-item


Review the surf report wiki page (2.0) containing the information about the endpoint, and try to describe the endpoint in the length of one or two sentences.


• Critique the Mashape Weather API descriptions

• There’s a difference between reference docs versus user guides

• Re-using the resource description

2.2 DOCUMENTING THE ENDPOINT DEF. AND METHOD

Terminology for the endpoint definition varies:• Requests• Endpoints• API methods• Resource URIs• Resource URLs• URLs• URL syntax


The endpoint definition usually contains the end path only

/surfreport/{beachId}

Represent parameter values with curly braces


You can list the method beside the endpoint


• Write the endpoint definition for surfreport

• Aim for 1-3 sentences

2.3 DOCUMENTING PARAMETERS

Parameters are ways to configure the endpoint


Data types indicate the format for the values:

• String

• Integer

• boolean


• Parameter order doesn’t matter

/surfreport/{beachID}?days=3&units=metric&time=1400

• Note any max and min values

• Note whether parameters are optional or required


• You can also pass parameters in the JSON body

{"days": 2,"units": "imperial","time": 1433524597}

• Time values usually follow ISO or Unix format


Construct a table to list the surfreport parameters

2.4 DOCUMENTING SAMPLE REQUESTS

The sample request clarifies how to use the endpoint

http://api.nytimes.com/svc/search/v2/articlesearch.response-format?[q=search term&fq=filter-field:(filter-term)&additional-params=values]&api-key=####


API Explorers provide interactivity with your own data


API Explorers can be dangerous in the hands of a newbie


• If different requests return different responses, show multiple responses

Document the sample request with the surfreport/{beachId} endpoint

2.5 DOCUMENTING SAMPLE RESPONSES• Provide a sample response for the endpoint

• Example from Flattr API

• Define what the values mean in the endpoint response

http://developers.flattr.net/api/resources/activities/

2.5 DOCUMENTING SAMPLE RESPONSES

Strategies for documenting nested objects

Check out the following approaches:

• Dropbox• Bit.ly• eBay

https://www.dropbox.com/developers/core/docs%23disable-token

http://dev.bitly.com/user_info.html

http://developer.ebay.com/Devzone/shopping/docs/CallRef/FindPopularItems.html


Information design choice: Where to include the response

https://stripe.com/docs/api%23charge_object


• Use realistic values in the response

• Format the JSON in a readable way

• Add syntax highlighting

• Some APIs embed dynamic responses


Create a section for a sample request in your surfreport/{beachId} endpoint

2.6 DOCUMENTING RESPONSE AND ERROR CODES

• Response codes let you know the status of the request

• Common status codes follow standard protocols: http://www.restapitutorial.com/httpstatuscodes.html

http://www.restapitutorial.com/httpstatuscodes.html

http://www.restapitutorial.com/httpstatuscodes.html


• List the HTTP response and error codes

• Main page and also on each endpoint where relevant

https://dev.twitter.com/overview/api/response-codes


Run your request and look at your header code

List three status codes for surfreport/{beachId}

2.7 DOCUMENTING CODE SAMPLES IN REST APIS

• Code samples bridge the gap between reference and user guides

• Look at the code sample on Mashape: http://docs.mashape.com/javascript

• Code samples are like candy for developers




• You are not the audience

• Focus on the why, not the what

• Focus on the why, not the what

• Focus your explanation on your company's code only


• Keep code samples simple

• Add both code comments and before-and-after explanations

• Make code samples copy-and-pastable


Provide a code sample in your target language

https://www.twilio.com/docs/api/rest/making-calls


• From code samples to real tasks in user guides

• Your turn to practice: Create a code sample and documentation for the surfreport endpoint

2.8 PUTTING IT ALL TOGETHER

• View my sample here: http://idratherbewriting.com/restapicourse2-8/

• Share and comment on each other’s samples?






2.9 CREATING THE USER GUIDE

User guides versus reference documentation

Essential sections in a user guide:

• Overview• Getting started• Authorization keys• Core concepts• Rate limits• Code samples• Hello world tutorial• Quick reference• Glossary


Overview section


Getting started section


Authorization keys


Rate limits


Quick reference guide

3.0 COMPLETION

Learning summary

• How to make calls to an API using cURL and Postman

• How to pass parameters to API calls

• How to inspect the objects in the JSON payload

• How to use dot notation to access the JSON values you want

• How to display the integrate the information into your site

3.0 COMPLETION

Learning summary

• Documenting the resource description

• Documenting the endpoint definition and method

• Documenting parameters

• Documenting the request example

• Documenting the response example

• Providing a code example

• Listing status codes

THANKS!

Tom Johnson

idratherbewriting.com

[email protected]

IMAGE CREDITSMost images are screenshots linked to a webpage, but some are from Flickr. Required attribution is as follows:

• Structure, https://flic.kr/p/oFD6MM Rafal Zych

• Earth patterns. https://flic.kr/p/ssQqiL Evriel Venefice

• Dave’s Bike Tools, https://flic.kr/p/QMVMw Bri Pettis

https://flic.kr/p/oFD6MM



https://flic.kr/p/ssQqiL

https://flic.kr/p/ssQqiL

https://flic.kr/p/QMVMw



Technology

Documenting REST APIs