1. Data To Go
Mobile API Design
Chuck Greb
Mobile Platform Architect
AWeber Communications
@ecgreb

2. Data To Go
Good Mobile API Design
Chuck Greb
Mobile Platform Architect
AWeber Communications
@ecgreb

3. A Brief Survey

4. What is an API?
An application programming interface (API)
is a specification of how software
components should interact with each other.
In most cases an API is a library that
includes specification for routines, data
structures, object classes, and variables.
http://en.wikipedia.org/wiki/Application_programming_interface

5. Remote Service API
● Remote (web-based) services
● Desktop, laptop, or mobile client
● Communication protocol and data model
(HTTP + REST + JSON)

6. Web API Request

7. Mobile API Request
Mobile API requests are
generally slower and more
prone to timeouts and other
failures!

8. 3 Principles of Good Mobile APIs
1. Reduce round trips to the server
2. Control verbosity
3. Restrict access
These 3 rules don't always get along!

9. Principle #1
Reduce round trips to the server
● Resources are limited (battery,
bandwidth, memory, CPU)
● Eliminate network overhead
● Brevity trumps discoverability
● Users are impatient

10. Batch Request (3 in 1)
POST https://www.example.com/api/v1/login
Input
{"username":"chuck@example.com", "password":"Kronos"}
Output
{
"user_id": 123
"access_token":"Y2h1Y2tAZXhhbXBsZS5jb20=",
"name":"Chuck Greb",
"email":"chuck@example.com",
"avatar":"http://www.example.com/images/dh3d67kfb.jpg",
"recent_messages": [
{"message_id":"101", "subject":"Hey!", "sender":{...}},
{"message_id":"102", "subject":"What's up?", "sender":{...}},
...
]
}

11. Principle #2
Control Verbosity
● Slow connection speed
● Limited data plans $$$
● Purge irrelevant and empty data
● Specify verbosity level per request
● Object expansion

12. Object Expansion
GET https://www.example.com/api/v1/user/123/recent_messages
{"recent_messages": [
{
"message_id":"101", "subject":"Hey bro!", "sender":{
"name":"Jeff Greb",
"avatar":"http://www.example.com/images/dh3d67kfb.jpg"}
},
...
]}
GET https://www.example.com/api/v1/message/101
{
"message_id":"101", "subject":"Hey bro!", "sender":{
"name":"Jeff Greb",
"avatar":"http://www.example.com/images/dh3d67kfb.jpg",
"interests":["English", "Japanese", "Music", "Comedy", ...]},
"timestamp":"2013-6-12T13:38:22",
"body":"Long time no see. What's new? I was thinking last..."
}

13. Principle #3
Restrict Access
● Identify the source of all requests
● Prevent unauthorized access
● Protect sensitive data
● Mobile-friendly security model

14. Authentication & Authorization
POST https://www.example.com/api/v1/login
Input
{"username":"chuck@example.com", "password":"Kronos"}
Output
{
"user_id": 123,
"auth_token":"Y2h1Y2tAZXhhbXBsZS5jb20="
...
}
Header
"Access-Token":"Y2h1Y2tAZXhhbXBsZS5jb20="

15. Thank You
Questions?
Chuck Greb
Mobile Platform Architect
AWeber Communications
@ecgreb