This document discusses the importance of user-agent strings for mobile apps and websites. It notes that the majority of web traffic now comes from mobile devices. It provides guidance on constructing meaningful user-agent strings for native mobile apps, hybrid apps, and mobile webviews. Specifically, it recommends prepending the app name and version for native apps and appending it for hybrid and webview apps. The document also discusses how user-agent strings can be used to gather device and platform statistics, optimize content delivery, and improve debugging and monitoring.

1. WHAT DEVOPS NEED TO
KNOW ABOUT MOBILE
…or really everyone…
Jon Arne Sæterås
twitter: @jonarnes

2. MOBILE MAJORITY
0
20
40
60
80
100
2009-01 2010-01 2011-01 2012-01 2013-01 2014-01 2015-01 2016-01 2017-01
Desktop Mobile Tablet Console
statcounter.com
Oct. 2016

3. 80% MOBILE
In India, and most of Asia, mobile is the main concern
0
25
50
75
100
2009-01 2010-01 2011-01 2012-01 2013-01 2014-01 2015-01 2016-01 2017-01
Desktop Mobile Tablet Console
statcounter.com
Aug. 2012

4. RUSSIA
?

5. Browsers Web sites
http

6. Native apps
Browsers
Hybrid apps
Web sites
APIs
Services
http
Logs
Analytics
Reporting
Debug
? ?

10. KNOW WHO
YOU’RE
COMMUNICATING
WITH
Who sent the message?

11. #devops
Inside Out (2015)

12. USER-AGENT
User Agent:“A software acting on behalf of a user”
h"ps://tools.ie-.org/html/rfc7231#sec8on-5.5.3

13. Native apps
Browsers
Hybrid apps
Web sites
APIs
Services
Host:www.example.com
User-Agent: ...
Logs
Analytics
Reporting
Debug
MEANINGFUL USER-AGENTS

14. The "User-Agent" header field contains information about the user
agent originating the request, which is often used by servers to help
identify the scope of reported interoperability problems, to work
around or tailor responses to avoid particular user agent
limitations, and for analytics regarding browser or operating system
use.
The User-Agent field-value consists of one or more product
identifiers, each followed by zero or more comments (Section 3.2 of
[RFC7230]), which together identify the user agent software and its
significant subproducts. By convention, the product identifiers are
listed in decreasing order of their significance for identifying the
user agent software. Each product identifier consists of a name and
optional version.
#devops
#BFF

15. Format:
User-Agent = product *( RWS ( product / comment ) )
MostSignificant/1.0 Significant/1.1 LessSignificant
significancehigh low
Name of the “thing” “Thing” version White space

16. IN THE BEGINNING…
NCSA_Mosaic/2.0
Mozilla/1.22 (compatible; MSIE 2.0; Windows 95)
History of the browser user-agent string:
https://webaim.org/blog/user-agent-string-history/
Mozilla/1.0 (Win3.1)
supported frames!

17. …AND NOW…
Mozilla/5.0 (Mobile; Windows Phone 8.1; Android 4.0; ARM; Trident/7.0; Touch;
rv:11.0; IEMobile/11.0; NOKIA; Lumia 630) like iPhone OS 7_0_3 Mac OS X
AppleWebKit/537 (KHTML, like Gecko) Mobile Safari/537
if(preg_match(‘/^Mozilla/‘, $userAgent)){
//frameset support!! :D
} WTF…
#mess…

18. OK, IT’S A MESS
…but what can we do with our apps?

19. THREE KINDS OF APPS
• (Progressive) Web Apps
• Hybrid Apps
• Native Apps
…for simplicity
Run in the browser.
We’re good.
An app, but loads web
content/pages
Native code using APIs
to communicate

20. ANDROID WEBVIEW
<Stock User-Agent> WebViewApp <AppName>/<Version>
Mozilla/5.0 (Linux; Android 5.1.1; Nexus 5 Build/LMY48B; wv) AppleWebKit/537.36 (KHTML,
like Gecko) Version/4.0 Chrome/43.0.2357.65 Mobile Safari/537.36 WebViewApp MyApp/1
Hybrid Apps
Mozilla/5.0 (Linux; Android 5.1.1; Nexus 5 Build/LMY48B; wv) AppleWebKit/537.36 (KHTML,
like Gecko) Version/4.0 Chrome/43.0.2357.65 Mobile Safari/537.36
More here: https://www.scientiamobile.com/page/correctly-form-user-agents-for-hybrid-apps/

21. ANDROID WEBVIEW
String ua = new WebView(this).getSettings().getUserAgentString();
webviewToUse.getSettings().setUserAgentString(ua + “ WebViewApp MyApp/1”);
Hybrid Apps
More here: https://www.scientiamobile.com/page/correctly-form-user-agents-for-hybrid-apps/

22. IOS WEBVIEW
Mozilla/5.0 (iPhone; CPU iPhone OS 11_1 like Mac OS X) AppleWebKit/604.3.5 (KHTML, like
Gecko) Mobile/15B93 WebViewApp MyApp/1 iPhone4,1
Hybrid Apps
Mozilla/5.0 (iPhone; CPU iPhone OS 11_1 like Mac OS X) AppleWebKit/604.3.5 (KHTML, like
Gecko) Mobile/15B93
<Stock User-Agent> WebViewApp <AppName>/<Version> <iOS HW ID>
Code at https://github.com/WURFL/User-Agent-Native-apps
More here: https://www.scientiamobile.com/page/correctly-form-user-agents-for-hybrid-apps/

23. IOS WEBVIEW
UIWebView* webView = [[UIWebView alloc] initWithFrame:CGRectZero];
NSString* ua = [webView stringByEvaluatingJavaScriptFromString:@“navigator.userAgent"];
Then modify the extracted User-Agent via the AppDelegate file:
NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys: ua + @" WebViewApp Foo/1 “ + [self deviceName],
@"UserAgent", nil];
[[NSUserDefaults standardUserDefaults] registerDefaults:dictionary];
Swift
let userAgent = UIWebView().stringByEvaluatingJavaScript(from: "navigator.userAgent")! + "WebViewApp Foo/1 “ + getName();
UserDefaults.standard.register(defaults: ["UserAgent" : userAgent])
Hybrid Apps
Swift:
Objective C:
Code at https://github.com/WURFL/User-Agent-Native-apps
More here: https://www.scientiamobile.com/page/correctly-form-user-agents-for-hybrid-apps/

24. ANDROID
<AppName>/<version> <Default User-Agent>
Myapp/1 Dalvik/2.1.0 (Linux; U; Android 6.0.1; vivo 1610 Build/MMB29M)
Code here: https://github.com/WURFL/ImageEngine-DemoApp
Native Apps
Dalvik/2.1.0 (Linux; U; Android 6.0.1; vivo 1610 Build/MMB29M)
More here: https://www.scientiamobile.com/page/correctly-form-user-agent-strings-in-mobile-apps/

25. ANDROID
URLConnection cn = new URL("http://....").openConnection();
cn.setRequestProperty("User-agent", “Myapp/1 ” + System.getProperty("http.agent"));
cn.connect();
Code at https://github.com/WURFL/ImageEngine-DemoApp
Native Apps
More here: https://www.scientiamobile.com/page/correctly-form-user-agent-strings-in-mobile-apps/

26. IOS
MyApp/1 CFNetwork/808.3 Darwin/16.3.0
<AppName/<version> <iDevice platform><Apple model identifier>
iOS/<OS version> CFNetwork/<version> Darwin/<version>
MyApp/1 iPhone5,2 iOS/10_1 CFNetwork/808.3 Darwin/16.3.0
Native Apps
More here: https://www.scientiamobile.com/page/correctly-form-user-agent-strings-in-mobile-apps/

27. IOS
Code at: https://github.com/WURFL/User-Agent-Native-apps
NSString* userAgent = getUAString();
NSURL* url = [NSURL URLWithString:@""];
NSMutableURLRequest* request = [[NSMutableURLRequest alloc] initWithURL:url];
[request setValue:userAgent forHTTPHeaderField:@"User-Agent"];
let userAgent = UAString()
if let url = NSURL(string: "") {
let request = NSMutableURLRequest(url: url as URL)
request.setValue(userAgent, forHTTPHeaderField: "User-Agent")
//...
}
Native Apps
Swift:
Objective C:
More here: https://www.scientiamobile.com/page/correctly-form-user-agent-strings-in-mobile-apps/

28. PITFALLS
• Fingerprinting/privacy
• Truncation
• Pretending to be something you’re not
• Don’t ever trust regular expressions to parse a
User-Agent

29. NOW THAT WE HAVE THE
USER-AGENT…
how to use it?

30. RUSSIA
Form factors
Q3 2017
4 %
40 %
56 %
Desktop Smartphone
Tablet Feature Phone
Smart-TV
Source: MOVR by ScientiaMobile

31. RUSSIA
Popular Devices
Q3 2017
Samsung Galaxy J5 (2016)
Samsung Galaxy J5
Samsung Galaxy J3 Duos
Apple iPhone 6S
Apple iPhone 6
Samsung Galaxy J7 (2016)
Samsung Galaxy Grand Prime
Apple iPhone 7
Apple iPhone 5S
HuaweiY5II
0 0,013 0,025 0,038 0,05
1,95 %
2,05 %
2,16 %
2,17 %
2,39 %
2,61 %
2,84 %
2,84 %
3,59 %
4,15 %Samsung Galaxy J5 (2016)
Samsung Galaxy J5
Samsung Galaxy J3 Duos
Apple iPhone 6S
Apple iPhone 6
Samsung Galaxy J7 (2016)
Samsung Galaxy Grand Prime
Apple iPhone 7
Apple iPhone 5S
HuaweiY5II
Other
0 0,2 0,4 0,6 0,8
73,25 %
1,95 %
2,05 %
2,16 %
2,17 %
2,39 %
2,61 %
2,84 %
2,84 %
3,59 %
4,15 %
Source: MOVR by ScientiaMobile

32. RUSSIA
Top manufacturers
Q3 2017
2 %
2 %
3 %
4 %
4 %
6 %
7 %
15 %
15 %
41 %
Samsung Huawei Apple
LG Lenovo Sony
Alcatel Nokia HTC
Microsoft
Source: MOVR by ScientiaMobile

33. RUSSIA
Popular Apps Q3 2017
6 %
9 %
9 %
12 %
13 %
50 %
Facebook Flipboard Google Search
UCBrowser Opera browser Instagram
Pinterest Twitter Facebook Messenger
Source: MOVR by ScientiaMobile

34. CHIPSETS
Huuuge difference in
performance
Other; 2,8%
Exynos
5410; 2,4%
Exynos
7420; 19,5%
Exynos 7420
Octa; 9,5%
Exynos 7580
Octa; 2,1%
Exynos
8890; 37,9%
Exynos
8895; 1,5%
Snapdragon
400; 3,4%
Snapdragon
801; 17,0%
Snapdragon
820; 1,1%
Snapdragon
835; 2,8%
SamsungChipsets
Apple A10
Fusion; 25,8%
Apple A4;0,2%
Apple A5;0,4%
Apple A6; 4,4%
Apple A7;8,4%
Apple A8;24,6%
Apple A9; 36,1%
Apple Chipsets
https://www.scientiamobile.com/page/most-used-chipsets

35. See device capabilities in Splunk

36. WHAT ELSE…
OK, we got some stats,
but is there more?

37. THE WEB
• 55% of the web is images
1 %
2 %
3 %
3 %
14 %
24 %
55 %
images video scripts
css fonts html
other

38. SCREEN
RESOLUTIONS
“Other” is the biggest!
22 %
1 %1 %
1 %
1 % 2 % 2 %
2 % 2 % 2 %
2 %
3 %
3 %
3 %
3 %
3 %
4 %
5 %
7 %
13 %
19 %
360x640
1366x768
1920x1080
375x667
720x1280
768x1024
320x568
1440x900
1280x800
1600x900
1024x768
320x534
1280x1024
480x800
414x736
320x570
540x960
1536x864
1080x1920
1280x720
Other

39. IMAGE CDN
optimize
detect
distribute
User-Agent
Native apps
Browsers
Hybrid apps
origin cache
detect
Screen size
Resolution
Formats
Network
etc.
Cache key

40. 0 Mbps
35 000 000 Mbps
70 000 000 Mbps
105 000 000 Mbps
140 000 000 Mbps
Time
Actual Bandwidth Usage For Optimized Objects Original Bandwidth Usage For Non-Optimized Objects
IS IT WORKING?

41. IS IT WORKING?
• 75%-ish less data
transmitted
• No visual quality loss
• >50% of images converted
to different formats
• In apps, most images resized
• Faster loading UI
traffic
Original Optimized

42. MEANINGFUL USER-AGENTS
• Would have been too romantic sticking with the
standard
• The real world is a mess with historical “mistakes”
that stick with us.
MostSignificant/1.0 Significant/1.1 LessSignificant
significancehigh low
Name of the “thing” “Thing” version White space

43. MEANINGFUL USER-AGENTS
• Rule of thumb:
• Native apps: Prepend app name/version
• Hybrid apps: Append app name/version
• Special rule for iOS
• Include hardware info

44. MEANINGFUL USER-AGENTS
Default Recommended
iOS MyApp/1 CFNetwork/808.3 Darwin/16.3.0 MyApp/1 iPhone5,2 iOS/10_1 CFNetwork/808.3 Darwin/16.3.0
Android
Dalvik/2.1.0 (Linux; U; Android 6.0.1;
vivo 1610 Build/MMB29M)
Myapp/1 Dalvik/2.1.0 (Linux; U; Android 6.0.1; vivo 1610
Build/MMB29M)
Default Recommended
iOS
Mozilla/5.0 (iPhone; CPU iPhone OS 11_1
like Mac OS X) AppleWebKit/604.3.5
(KHTML, like Gecko) Mobile/15B93
Mozilla/5.0 (iPhone; CPU iPhone OS 11_1 like Mac OS X)
AppleWebKit/604.3.5 (KHTML, like Gecko) Mobile/15B93
WebViewApp MyApp/1 iPhone4,1
Android
Mozilla/5.0 (Linux; Android 5.1.1; Nexus
5 Build/LMY48B; wv) AppleWebKit/537.36
(KHTML, like Gecko) Version/4.0 Chrome/
43.0.2357.65 Mobile Safari/537.36
Mozilla/5.0 (Linux; Android 5.1.1; Nexus 5 Build/LMY48B)
AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0
Chrome/43.0.2357.65 Mobile Safari/537.36 WebViewApp
MyApp/1
Native apps
Hybrid apps

45. BENEFITS OF MEANINGFUL
USER-AGENTS
• “Know who you’re communicating with”
• Easier debug
• Richer statistics
• Better monitoring
• Safely apply Device Detection (WURFL)

46. –The pretty girl
“I know where you live.”