Notes from AT&T ARO Session at Oredev 2013
By Geertjan on Nov 08, 2013
The mobile internet is 12 times bigger than internet was 12 years ago. Explosive growth, faster networks, and more powerful devices. 85% of users prefer mobile apps, while 56% have problems. Almost 60% want less than 2 second mobile app startup.
App with poor mobile experience results in not buying stuff, going to competitor, not liking your company. Battery life. Bad mobile app is worse than no app at all because it turns people away from brand, etc. Apps didn't exist 10 years ago, 72 billion dollars a year in 2013, 151 billion in 2017.Testing performance. Mobile is different than regular app. Need to fix issues before customers discover them. ARO is free and open source AT&T tool for identifying mobile app performance problems. Mobile data is different -- radio resource control state machine. Radio resource control -- radio from idle to continuous reception -- drains battery, sends data, packets coming through, after packets come through radio is still on which is tail time, after 10 seconds of no data coming through radio goes off. For example, YouTube, e.g., 10 to 15 seconds after every connection, can be huge drain on battery, app traffic triggers RRC state.
Goal. Balance fast network connectivity against battery usage. ARO is free and open source and test any platform and won awards. How do I test my app? pcap or tcdump network. Native collector: Android and iOS. Android rooted device is needed. Test app on phone, background data, idle for ads and analytics. Graded against 25 best practices. See all the processes, all network traffic mapped to processes, stats about trace, can look just at your app, exlude Facebook, etc. Many tests conducted, e.g., file download, HTML (wrapped applications, e.g., cordova).
- Make stuff smaller. GZIP, smaller files, download faster, best for files larger than 800 bytes, minification -- remove tabs and commenting -- browser doesn't need that, just give processor what it needs remove wheat from chaff. Images -- make images smaller, 1024x1024 image for a checkmark, swish it, make it 33% smaller, ARO records the screen, probably could be 9 times smaller.
- Download less stuff. 17% of HTTP content on mobile is duplicate data because of caching, reloading from cache is 75% to 99% faster than downloading again, 75% possible savings which means app will start up faster because using cache -- everyone wants app starting up 2 seconds.
- Make fewer HTTP requests. Inline and combine CSS and JS when possible reduces the number of requests, spread images used often.
- Fewer connections. Faster and use less battery, for example, download an image every 60 secs, download an add every 60 seconds, send analytics every 60 seconds -- instead of that, use transaction manager, download everything at once, reduce amount of time connected to network by 40% also -- 80% of applications do NOT close connections when they are finished, e.g., download picture, 10 seconds later the radio turns off, if you do not explicitly close, eventually server closes, 38% more tail time, 40% less energy if you close connection right away, background data traffic is 27% of data and 55% of network time, this kills the battery.
- Look at redirection. Adds 200 to 600 ms on each connection, waterfall diagram to all the requests -- e.g., xyz.com redirect to www.xyz.com redirect to xyz.mobi to www.xyz.com, waterfall visualization of packets, minimize redirects but redirects are fine.
- HTML best practices. Order matters and hiding code (JS downloading blocks rendering, always do CSS before JS or JS asynchronously, CSS 'display:none' hides images from user but the browser downloads them which adds latency to application.
- Some apps turn on GPS for no reason. Tell network when down, but maybe some other app is using the radio at the same time.
It's all about knowing best practices: everyone wins with ARO (carriers, e.g., AT&T, developers, customers). Faster apps, better battery usage, network traffic better, better app reviews, happier customers. MBTA app, referenced as an example.
ARO is free, open source, can test all platforms.