Mobile Friendly APIsConsiderations for Connected Mobile Apps

Torey LomendaChief Technologist, Object Partners (OPI)

Mobile Friendly APIs

About OPI• Founded in 1996

• Java, Groovy, Mobile, Web, Open Source

• ~ 100 Employees

–Twin Cities, Omaha

–Chicago, Denver

–Average Tenure over 5 Years

Mobile Friendly APIs

Living in a Mobile World

Mobile Friendly APIs

What Users Expect

Responsive, connected apps

...All The Time

Reality

Mobile Constraints

•Network Latency

•Runs on Battery

•CPU

Mobile Friendly APIs

Mobile Apps Need

Access to Online Data & Services

Remembering Constraints

Mobile Friendly APIs

From Web Apps to Mobile AppsEvolution of Connected Apps

Mobile Friendly APIs

Focus on Web

Mobile Friendly APIs

Focus on Interoperability

Mobile Friendly APIs

Focus on Mobile (Web)

Mobile Friendly APIs

Another Challenge

The move to Micro-services

Mobile Friendly APIs

Martin Fowler Article (http://martinfowler.com/articles/microservices.html)

Mobile Friendly APIs

A Friendly API

User Perspective

Doesn't get in the way of a great UX

Developer Perspective

Is intuitive, a pleasure to integrate into codebase

Mobile Friendly APIs

The Rise of the “Friendly” Interface

Mobile Friendly APIs

Connecting Apps Shouldn't Be Painful

Mobile Friendly APIs

Mobile API Standards Simple & Fast Completeness Best Practices Extras

Mobile API Considerations

Mobile Friendly APIs: Standards

Whatever Happened to SOA?

HTTP Request (Headers/Body)

SOAP Envelope (WS-Basic)

WS-Security

WS-* Stack

XML Payload

Interoperability

XML for data exchange

HTTP for network protocol

What could be better?

Mobile Friendly APIs: Standards

DATA

From SOAP to REST<?xml version="1.0"?>

<soap:Envelope

xmlns:soap="http://www.w3.org/2001/12/soap-envelope"

soap:encodingStyle="http://www.w3.org/2001/12/soap-

encoding">

<soap:Body xmlns:m="http://www.example.org/stock">

<m:GetStockPrice>

<m:Ticker>GOOG</m:Ticker>

</m:GetStockPrice>

</soap:Body>

</soap:Envelope>

<?xml version="1.0"?>

<soap:Envelope

xmlns:soap="http://www.w3.org/2001/12/soap-envelope"

soap:encodingStyle="http://www.w3.org/2001/12/soap-

encoding">

<soap:Body xmlns:m="http://www.example.org/stock">

<m:GetStockPriceResponse>

<m:Price>534.5</m:Price>

</m:GetStockPriceResponse>

</soap:Body>

</soap:Envelope>

ticker=GOOG

{"price":534.5}

Mobile Friendly APIs: Standards

RESTlike NOT RESTful

The “Essential” Parts

JSON

POST/GET Requests

Action & Parameters

The “Other” Parts

PUT/DELETE

HATEOS & HAL

engine of application state

relational links

Mobile Friendly APIs: Simple & Fast

RESTlike is Just Fine

POST player/create

POST player/delete/$id

POST player/update/$id

Mobile Friendly APIs: Simple & Fast

JSON is your FriendStay Consistent

Completeness

Only What is Needed

Mobile Friendly APIs: Simple & Fast

"player": {

"name": "Torey Lomenda",

"number": "14",

"position": "center",

"funFacts": [...],

"seasonStats": [...]

}

"team": {

"name": "Lakeville Panthers"

"roster": [{

"player_name": "Torey Lomenda",

"player_number": "14",

"player_position": "center",

}]

}

NOT CONSISTENT

Mobile Friendly APIs: Completeness

API Granularity

Design APIs by Screen

Consider an API Gateway for Mobile

Mobile Friendly APIs: Completeness

API GranularityLazy APIs put the burden on the mobile app

Minimize use of Network

– Completeness (avoid roundtrips)

Minimizing Use of NetworkHTTP Latency ~1 second for each request over

3G

Battery drain as each network request requires power

Mobile Friendly APIs: Completeness

API: Pure REST Approach

2

1

3

API: “Friendlier” Approach

Mobile Friendly APIs: Completeness

12 3

Mobile Friendly APIs: Best Practice

Don't Forget

Slim It Down (gzip compression)

Heavy Lifting on the server

aggregation

server-side caching strategies

Mobile Friendly APIs: Best Practice

API Errors

Manage errors on server-side

Human-readable (ie: friendly) messages

Caching and Offline AccessHTTP Headers (Cache Control)

Cache-Control: specify how to cache the data

max-age: <seconds>

ETag: "15f0fff99ed5aae4edffdd6496d7131f" ← Entity Tag

If-None-Match: "15f0fff99ed5aae4edffdd6496d7131f"

Last-modified: <GMT Date>

If-Modified: <GMT Date>

Mobile Friendly APIs: Best Practice

Intermittent Connectivity: Maintain State

Picking up where you left off.

Keeping APIs stateless

Mobile-side: send “current state” from device through API

API-side: Merging & Conflict Resolution

Mobile Friendly APIs: Best Practice

Mobile Friendly APIs: Best Practice

Securing Your APIs Basic Auth/SSL

Token-based approaches like OATH

SSL Pinning (client checks server's certificate against a known copy of the certificate)

Batching Requests[{"method":"POST",

"relative_url":"me/feed",

"body":"message=Test status update&link="

},

{"method":"GET","relative_url":"me/feed?limit=

1"}]

[{ "code": 200,

"headers": [...],

"body":"{...}"

},

{ "code": 200,

"headers": [...],

"body": "{...}

}]

Mobile Friendly APIs: Best Practice

Return batch responses

Mobile Friendly APIs: Best Practice

Background/Async Processing

Making multiple requests for a screen → Don't hold up the UI

HAL JSON (http://stateless.co/hal_specification.html) → Fetch linked data asynchronously

Neutral Testing of API

Useful Tools to Test APIs:

RESTClient

Runscope

Mobile Friendly APIs: Best Practice

Mobile Friendly APIs: Best Practice

API Versioning

Indicate Version to Client

Version via URL

(major version only)

HTTP accepts-header

Version in JSON Document

JSON Format

blank-out fields no longer used

deprecated fields

backward compatible on minor version, breaking changes on major version

API Documentation

Swagger

https://helloreverb.com/developers/swagger

Mashery I/O Docs

http://www.mashery.com/product/io-docs

Mobile Friendly APIs: Best Practice

Mobile Friendly APIs: Extras

What's In a Protocol?

(TCP/IP is Fabric of Internet Not HTTP)

Mobile Friendly APIs: Extras

Custom Key/Value Pair (KVP)

Taking message-passing efficiency to the next level

Not as “friendly” but fast. Consumption of messages

Serializing/Deserializing

Mobile Friendly APIs: Extras

MQTT (Message Queue Telemetry Transport)

What is It

Low overhead protocol with bandwidth and CPU limitations in mind

publish/subscribe message passing

Can use JSON over MQTT

Use Cases

In-app push notification

Internet of Things (device to device)

Facebook Messenger App (Chat)

Mobile Friendly APIs

ReferencesFred Brunel- CTO WhereCloudhttps://speakerdeck.com/fbrunel/mobile-api-design-techniques

Article

http://natashatherobot.com/best-practices-mobile-friendly-apis/