WebPagetest - Good, Bad & Ugly

1. Paget e s t:
W eWebPagetest APIly
Using the b he Ug
he Ba d&T
The Good, T

2. 1 First … some basic tips

3. Understand the test environment
Windows version? DNS resolver?
Hardware specs (RAM, processor)?

4. Run a large number of tests

5. Collect RUM data too !

6. Summary statistics hide insight
Mean: ~1400 ms
Median: ~1100 ms

7. Look at individual tests
Normal
Ouch!

8. 2 New stuff in the WPT ui

9. Homepage > Advanced tab

10. Capture Network Log (Chrome)
Returns big TXT file with JSON … then what?
Pat: “You probably don't want to use the
network log - it was added for the Chrome
team themselves to debug the browser :-)”

11. Minimum test duration
It works, kindof ...
Example (minTestDur=45)

12. 3 WPT API introduction

13. Getting started
Get an API key from Pat (required)
Know your requests will have low prio /getLocations.php
Basic process:
1. Submit request via POST or GET
2. Poll for the test status (or use pingback)
3. Fetch test results
4. Fetch objects (charts, screen shots, ...)

14. Submitting requests
Send a POST or GET to
http://www.webpagetest.org/runtest.php
url is only required parameter
Defaults: Dulles DSL, 1 run, first & repeat
view, public, no video
Overview of parameters

15. Results
Example XML
It has it all, incl.
1. PageSpeed version & results
2. Page <title>
3. Links to pages/files for everything in UI
4. Video frame URLs & Speed Index score !

16. Documentation
Official API documentation
Python lib for ad-hoc batch processing
Batch processing command line tool

17. 4 Scripting

18. Lots of possibilities!
https://sites.google.com/a/webpagetest.org/docs/using-webpagetest/scripting
Navigation/DOM interaction (submitForm)
End Conditions (setDOMelement)
Request Manipulation (setDNS)
Misc (combineSteps)
Great for simulating user-page interaction,
multi-page testing and different 'conditions'

19. Example scripts
logData 0
navigate http://www.gamesgames.com/
logData 1
navigate http://www.gamesgames.com/search.html?
search=bloons+4
SetDNSName cdn.domain.com www.domain.com
overrideHost cdn.domain.com www.domain.com
navigate www.domain.com

20. Commands you'll likely use
Command Description
navigate Navigate to next page, wait for it to complete
logData Set to 0 to not record anything; 1 = record!
setValue Sets the value attribute of the given DOM element to the
provided value.
submitForm Triggers a submit event for the identified form.
setDOMElement Sets the attribute of a DOM element that is required for
the next event to complete successfully.
block Blocks individual requests from loading
combineSteps Causes multiple script steps to be combined into a single
"step" in the results
setViewportSize Changes size of visible browser window
firefoxPref Allows you to specify arbitrary preferences that will be
configured before launching the browser. Eg.
firefoxPref network.http.pipelining false
setDNS Allows for overriding the IP address for a host name.

21. Why did the test fail?
Can be very hard to troubleshoot, esp. on
large scripts

22. 5 WPT – hidden gems

23. &notify=theboss@whitehouse.org
e-mail address to notify with the test results

24. &iq=90
Specify a jpeg compression level (30-10095)
for the screen shots and video capture
iq=default
iq=90
Video!

25. &pngss=1
Set to 1 to save a full-resolution version of
the fully loaded screen shot as a png
Normal JPG
Big PNG24

26. &f=json
Format. Set to "xml" to request an XML
response instead of a redirect ("json" is also
provisionally supported)

27. &plr=50
Packet loss rate - percent of packets to drop
(used when specifying a custom connectivity
profile)
plr=0
plr=50
No diff !
Location
specific
issue?

28. console.log() output
Can be found on the screen shots page ...
Example

29. Time to Title
Not in UI, but ís in results from API: <titleTime>
Can also be found in “Raw Page data” CSV
Example

30. 6 Closing remarks

31. WPT can act … surprising

32. The documentation may not help out

33. It may drive you mad

34. Don't give up easily

35. Put some effort in!

36. Be the Success Kid!