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

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2 ©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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©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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©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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©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. 8 ▪ ▪ ▪

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©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. 11

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©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). 12 ▪ ▪ ▪ ▪

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©2008-15 New Relic, Inc. All rights reserved. Reviews you might read... 14 "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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©2008-15 New Relic, Inc. All rights reserved. Information can't travel faster than the speed of light 16 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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©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) 17 ▪ ▪ ▪

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©2008-15 New Relic, Inc. All rights reserved. Reviews you might read... 19 "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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©2008-15 New Relic, Inc. All rights reserved. "This is clear to anyone who uses this API" 21 curl -H "a_token=aea22f80344147c4" http:// api.bad-api.horse/mobile/create/user?name=Bob {"status": "fail"} 200 OK Request

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©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"). ▪ ▪ ▪ ▪