Using the WebPagetest APIWebPagetest:

The Good, The Bad & The Ugly

1 First … some basic tips

Understand the test environmentWindows version? DNS resolver?

Hardware specs (RAM, processor)?

Run a large number of tests

Collect RUM data too !

Summary statistics hide insight

Mean: ~1400 msMedian: ~1100 ms

Look at individual tests

Normal

Ouch!

New stuff in the WPT ui2

Homepage > Advanced tab

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 :-)”

Minimum test durationIt works, kindof ...

Example (minTestDur=45)

WPT API introduction3

Getting started

Get an API key from Pat (required)

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, ...)

Know your requests will have low prio /getLocations.php

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

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 !

Documentation

Official API documentation

Python lib for ad-hoc batch processing

Batch processing command line tool

Scripting4

Lots of possibilities!

Navigation/DOM interaction (submitForm)

End Conditions (setDOMelement)

Request Manipulation (setDNS)

Misc (combineSteps)

Great for simulating user-page interaction, multi-page testing and different 'conditions'

https://sites.google.com/a/webpagetest.org/docs/using-webpagetest/scripting

Example scripts

logData 0navigate http://www.gamesgames.com/logData 1navigate http://www.gamesgames.com/search.html?

search=bloons+4

SetDNSName cdn.domain.com www.domain.comoverrideHost cdn.domain.com www.domain.comnavigate www.domain.com

Commands you'll likely useCommand Descriptionnavigate Navigate to next page, wait for it to completelogData 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 loadingcombineSteps Causes multiple script steps to be combined into a single

"step" in the resultssetViewportSize Changes size of visible browser windowfirefoxPref 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.

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

5 WPT – hidden gems

&notify=theboss@whitehouse.org

e-mail address to notify with the test results

&iq=90

Specify a jpeg compression level (30-10095) for the screen shots and video capture

iq=default

iq=90

Video!

&pngss=1

Set to 1 to save a full-resolution version of the fully loaded screen shot as a png

Normal JPG

Big PNG24

&f=json

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

&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?

console.log() outputCan be found on the screen shots page ...

Example

Time to TitleNot in UI, but ís in results from API: <titleTime>

Example

Can also be found in “Raw Page data” CSV

Closing remarks6

WPT can act … surprising

The documentation may not help out

It may drive you mad

Don't give up easily

Put some effort in!

Be the Success Kid!