Turning the app up to 11: Optimizing API Performance for Mobile

Transcript

1. Confidential ©2008-15 New Relic, Inc. All rights reserved.
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   ©2008-15 New Relic, Inc. All rights reserved.
   What this talk is about
   Mobile is
   everywhere!
   Network-related
   performance problems
   affect customer
   experience.
   Nobody wants 

   to get 1-star 

   app reviews.
   Covers network 

   request best 

   practices in 

   mobile.
   

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3. ©2008-15 New Relic, Inc. All rights reserved. 3
   App Network Backend
   Web Server
   The Three Pillars of App Blame
   

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4. ©2008-15 New Relic, Inc. All rights reserved.
   Blame the app.
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5. ©2008-15 New Relic, Inc. All rights reserved. 5
   "App is unresponsive." ★ ★ ★ ★ ★
   "Pages are slow to reload.” ★★★★★
   "It takes forever when I tap login." ★★★★★
   "The app freezes all the time." ★ ★ ★ ★ ★
   Reviews you might read...
   

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6. Confidential ©2008-15 New Relic, Inc. All rights reserved. 6
   ▪
   Don't block the main thread
   Lesson #1:
   CC A ND https://www.flickr.com/photos/buechertiger/6499330057
   

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7. ©2008-15 New Relic, Inc. All rights reserved. 7
   Introducing... the world's slowest viewDidLoad:
   - (void) viewDidLoad {
   // Sync Example #1
   NSHTTPURLResponse *response = nil;
   NSURLRequest *request = [NSURLRequest
   requestWithURL:[NSURL URLWithString:@"https://nr/api/v1/data"];
   cachePolicy:NSURLRequestReloadIgnoringCacheData
   timeoutInterval:5.0];
   NSData *conn = [NSURLConnection
   sendSynchronousRequest:request returningResponse:&response error:&error];
   // Sync Example #2
   NSData *data = [NSData dataWithContentsOfURL:@"http://nr/api/data"];
   // Sync Example #3
   cell.photo.image = [UIImage imageWithData:
   [NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://nr/bar.png"]]];
   }
   

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8. ©2008-15 New Relic, Inc. All rights reserved.
   Main Thread Blocking Checklist
   No synchronous network calls happen on the main thread.
   
   Use a decent open-source networking library that does the
   threading for you.
   
   If the UI stutters or scrolling performance seems degraded, start
   looking for code that's blocking the main (UI) thread.
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9. Confidential ©2008-15 New Relic, Inc. All rights reserved. 9
   ▪
   Do go chasing waterfalls
   Lesson #2:
   CC A ND https://www.flickr.com/photos/salford_ian/3053537527
   

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10. ©2008-15 New Relic, Inc. All rights reserved.
    Waterfalls are for mobile, too!
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11. ©2008-15 New Relic, Inc. All rights reserved.
    How many parallel requests are too many?
    • Per-host limit on iOS and Android. Fuzzy documentation.
    
    • Generally you'll get limited to 4-5 depending on OS version,
    library or SDK (NSURLSession vs NSURLConnection).
    
    • Rule: just bundle requests and don't flood hosts.
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12. ©2008-15 New Relic, Inc. All rights reserved.
    API Client Request Best Practices
    Issue network requests in parallel (with limits).
    
    Have a single API request per screen.
    
    HTTP cache headers are your friend and API clients 

    can use them intelligently.
    
    Pay attention to request size (and gzip compression).
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13. ©2008-15 New Relic, Inc. All rights reserved.
    Blame the network.
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14. ©2008-15 New Relic, Inc. All rights reserved.
    Reviews you might read...
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    "Bonjour. Your app is slow on Orange 3G." ★ ★ ★ ★ ★
    "Takes 15 seconds to login in Singapore." ★ ★ ★ ★ ★
    "App is slow when not on WiFi." ★★ ★ ★ ★
    "不正なアプリケーション" ★ ★ ★ ★ ★
    

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15. Confidential ©2008-15 New Relic, Inc. All rights reserved.
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    Never trust the network
    Lesson #3:
    CC A ND https://www.flickr.com/photos/ian1231/33443537527
    

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16. ©2008-15 New Relic, Inc. All rights reserved.
    Information can't travel faster than the speed of light
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    CC0
    Problem: 

    your datacenter is in
    Virginia and customers
    are in Singapore.
    Advanced: 

    Consider implementing CDN
    caching of API requests 

    as well.
    Content-delivery networks
    (CDNs) can move your static
    content physically closer to
    customers.
    

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17. ©2008-15 New Relic, Inc. All rights reserved.
    Unreliable Network Best Practices
    Always test your app in airplane mode.
    
    Pay attention to user experience differences across 

    different regions, countries, and providers.
    
    Re-create bad networks locally using open-source tools 

    (i.e. augmented-traffic-control, Network Link Conditioner)
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18. ©2008-15 New Relic, Inc. All rights reserved.
    Blame the backend.
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19. ©2008-15 New Relic, Inc. All rights reserved.
    Reviews you might read...
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    "Search takes foooooorever." ★ ★ ★ ★ ★
    "The progress indicator keeps spinning." ★ ★ ★ ★ ★
    "Keeps saying operation can't be completed." ★★ ★ ★ ★
    "I get weird error messages about parsing JSON." ★ ★ ★ ★ ★
    

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20. Confidential ©2008-15 New Relic, Inc. All rights reserved. 20
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    "Mobile APIs are forever"
    (credit: @alperkomen)
    Lesson #4:
    CC A ND https://www.flickr.com/photos/torkildr/3462607995
    

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21. ©2008-15 New Relic, Inc. All rights reserved.
    "This is clear to anyone who uses this API"
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    curl -H "a_token=aea22f80344147c4" http://
    api.bad-api.horse/mobile/create/user?name=Bob
    {"status": "fail"}
    200 OK
    Request
    

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22. ©2008-15 New Relic, Inc. All rights reserved. 22
    API Design for Mobile Best Practices
    Have clear, consistent documentation.
    
    Make mobile clients uniquely identifiable by the 

    User-Agent HTTP header.
    
    Return standard error codes (200s, 400s, and 500s).
    
    Consider versioned APIs ("mobile is forever").
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23. ©2008-15 New Relic, Inc. All rights reserved. 23
    Good idea
    Pay attention to the network
    

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