Mobile APIs in Practice

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A high-level talk on developing APIs for mobile devices in enterprise, partner, and internal modes, with notes on our experience at Klout. Some big concepts are glossed over, and lots of details may be simplified for brevity.

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  • A Note On My Perspective:Klout builds consumer experiences. We measure influence on social networks.I manage all partner relations in regards to data in and out, as well as managed the development of our new API and how it was divided for Mobile.My experience is primarily in this context.
  • We broke one cardinal rule for easily getting to data on Mobile: we made it require two calls. Our data model shifted from being keyed off of Twitter to being keyed off of internal Ids.Internal IDs are translated from social services, like Twitter, Google+, etc.Data is then accessed via those IDsPeople are influential about TopicsTopics are named entities, but also have unique identifiers referenced by RESTful routes and IDs.
  • Here’s where I get super opinionated.This applies to web as well.
  • In our mobile API protocol: interstitial can return a URL to a webview in case of a change to invaldiate or redirect a client.Deal with versioning clients to gracefully escape users to the newest versions
  • Cancel/Retry modals on Failure – usual.Write autoretry or store the POST for future use (always let the user know)Timers on state
  • Be able to specify a “critical read” -> indicating acceptance of longer latency or bypassing cache responses
  • If something like a “notif” object exists, include shortened versions of Actor and Subject objects in the payload, rather than reference them for future lookup.
  • Require server to return a handshake at the end of Writes: in addition to positive status codes, return a positive ACK that a server handled the write.Envelope the error messages – present user-readable error messages in the error response (in addition to developer responses)API endpoint that is a config file : apps local config file to manange features :
  • A Note On My Perspective:Klout builds consumer experiences. We measure influence on social networks.I manage all partner relations in regards to data in and out, as well as managed the development of our new API and how it was divided for Mobile.My experience is primarily in this context.
  • Mobile APIs in Practice

    1. 1. Mobile APIs In Practice November 2013 Tyler Singletary, Director of Platform tyler@klout.com ; @harmophone
    2. 2. When Klout Started Thinking Mobile Klout’s Partner API in 2010-2011: Klout’s API Strategy in 2012+: • Not Mobile Optimized • Not Used on Klout.com • Not Extensible. • XML and JSON response • No Mobile Web Experience • Easy Data in 1 Call • Acquired Blockboard • Redesigned Central API • Entitlement System for Klout.com, Mobile, Partners • Mobile Web • JSON Only • Easy Data in 2 Calls for Partners 2
    3. 3. Tradeoffs at Klout • • • We redesigned APIs for Klout.com and our 1stparty mobile App first. The Partner API drove some of the requirements, but always would be based on the Master API (with hidden data) The Mobile API payloads are optimized for mobile and its specific functions. Partner API • Crowdsourced Mobile Apps • CRM, Enterprise • Consumer Master API Mobile API • Official Klout App • Cinch Klout.com • Mobile Klout.com 3
    4. 4. Klout Mobile All data in one payload. { response: { user: { kloutId: "478569", nick: "harmophone", name: { firstName: "devty", lastName: "T" }, image: { network: { identifier: "tw", number: 1 }, urlTiny: "http://a0.twimg.com/profile_images/23083 33289/7s7abq8j02kuxf84g7ig_normal.jpeg", urlSmall: "http://a0.twimg.com/profile_images/23083 33289/7s7abq8j02kuxf84g7ig_reasonably_s mall.jpeg", urlMedium: "http://a0.twimg.com/profile_images/23083 33289/7s7abq8j02kuxf84g7ig_reasonably_s mall.jpeg", urlLarge: "http://a0.twimg.com/profile_images/23083 33289/7s7abq8j02kuxf84g7ig.jpeg", networkImage: "http://a0.twimg.com/profile_images/23083 33289/7s7abq8j02kuxf84g7ig_normal.jpeg" }, bio: "Adagio assai. Klout Devangelist.", bioSource: "tw", score: { score: 47.620975824983596, trueReach: 537 }, scoreDeltas: { dayChange: -0.16153993062354743, weekChange: -0.5384216786696854, monthChange: -1.8510836286192287 }, connectedNetworks: [ { id: “", network: "tw" } ], hasMobile: true }, topics: […], sourceOfInfluence: { myInfluencers: […], myInfluencees: […], }, preferences: {}, scoreHistory: {}, stats: { }, networkContributions: { } }, responseTime: 44 } 4
    5. 5. Klout’s Cinch APIs View-oriented payloads 5
    6. 6. What We Should Have Done • • We should have branched another “Mobile Partner API” to ease in partner development of mobile apps utilizing our API. November 2013 Update: – We still haven’t done this. :( Partner API • CRM, Enterprise • Consumer Klout.com Master API Mobile API • Official Klout App • Cinch Mobile Partner API • Appboy 6
    7. 7. Division of Labor Server Client/App • Talks to all external APIs • Proxy and repackage content exactly how the app needs it • Truth • Talks only to Server, except for auth (but even then…) • Temporary storage for UX and rendering • Maybe Truth 7
    8. 8. Problems With Any API in Mobile Data transfer rate is typically slower Delivering data to a device costs the consumer money Any one or more requests can fail. And will. Apps collecting from multiple sources will be slow. Latency. Device diversity, processing power, multitasking, storage Mobile development has a slower cycle due to App Publishing APIs Change. Apps change. Not always in sync. 8
    9. 9. The Main Conflict Larger Data Payload • Quick bursts of dense information • Just the facts • But extensible Less Requests 9
    10. 10. How Do You Protect Against These? Remove extraneous data Deliver large payloads, fewe r requests Try, try, again. But not too much. Real work should be done on the server Graceful Degregation 10
    11. 11. Failure is Routine. Plan for it. Requests User Detail Twitter Stream Server User Detail Twitter Stream App – 3G User Deta--------------tream It’s a race against time! 11
    12. 12. The Problem With SOAP • • • • Tons of Extraneous Data. Big payload. Processing response holds UI latency. Out of fashion for big data, social, web at large. The Good: • Type safety! • Fast Infoset standard. “The GZIP for XML!” 12
    13. 13. The Problem With REST and JSON • • • • • Resource collections and objects aren’t always best Non-optimized APIs require tons of individual requests Various interpretations of what REST is and isn’t Error Handling gets weird with arrays/collections and mobile nuance While not strictly part of REST, typically JSON. 13
    14. 14. Best Practices • Envelopes are an essential way to control and react to change, impress an update. • Default to POST and PUT with arrays, even for single record updates. • Reference both URLs to resources as well as content_ids • GZIP or compress responses whenever possible • OAuth/xAuth for authentication. Don’t roll your own. • Return collections with reasonable limits. Employ params or headers. • Version on a per-endpoint basis. Adopt easy, programmatic versioning. • Clients should identify themselves thoroughly. Version, platform, etc. It’s shipped software. The API needs to know who it’s talking to. • Be able to specify a “critical read” -> indicating acceptance of longer latency or bypassing cache responses 14
    15. 15. Just one more thing… (about errors) • Use HTTP status when appropriate • Server-side errors need clarity and extensibility, like exceptions. – Utilize custom schemes (-10, -11, etc.) – Use 500-504, but provide codified directive error messages inside. • Require server to return a handshake at the end of Writes: in addition to positive status codes, return a positive ACK that a server handled the write. • Potential Standards: vnd.error : https://github.com/blongden/vnd.error 15
    16. 16. Summary Master API -> Partner API Mobile API, Mobile Partner API Design for Mobile APIs: • both internal and external Mobile payloads: • data rich, extensible, lean on the DDL and extras. Low # of calls. { Mobile Envelope: • should become a standard way of change management "response":{}, "responseTime":26, "interstitial":{ "url": "http://m.klout.com/upgrade", } } 16
    17. 17. Mobile APIs In Practice November 2013 Tyler Singletary, Director of Platform tyler@klout.com ; @harmophone

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