What's in an mPulse Beacon (Web Apps)

The content of this page applies to mPulse web apps. Documentation for mobile apps is available here.

mPulse is built on top of the boomerang JavaScript library which collects web performance data from a user’s web browser and sends the data back to the mPulse servers via a beacon.

Beacons are invisible network requests that contain performance data and other page-load characteristics. All of this data is included on the beacon via HTTP headers or as part of the query string or form payload.

Within the web performance community, this data is commonly called RUM or Real User Measurement data because it involves measuring the experience of real users.

In this document, we will describe the various parameters collected via the boomerang beacon as well as how they are mapped to other parts of mPulse such as S3, Asgard and DSWB.

As of April 2020, all IP addresses are truncated. IPv4 IPs are truncated to /24 (e.g. 1.2.3.4 to 1.2.3.0) and IPv6 IPs are truncated to /64 (e.g. aaaa:bbbb:cccc:dddd:eeee:ffff:gggg:hhhh to aaaa:bbbb:cccc:dddd::).

Top Level Fields

Session

The following fields live under the session: {} object in S3.

User Agent Fields

The following fields come from the User-Agent HTTP Request Header. There are no query string parameters.

The following fields live under the user_agent: {} object in S3.

Geo Information

The following fields come from doing a MaxMind GeoIP lookup on the source IP address. There are no query string parameters.

The following fields live under the geo: {} object in S3.

Bandwidth

The following fields live under the bandwidth: {} object in S3.

Also see Bandwidth & Latency details in the Other Parameters section below.

Timers

All timers are in milliseconds unless otherwise specified.

The following fields live under the timers: {} object in S3 unless otherwise specified.

Standard Timers

Prerender States

These are only supported on Chrome at this time.

See Chromium Prerender docs & Prerendering in Chrome

Added by Server

The following are calculated on the server. There are no query string parameters.

Custom Timers

Custom Timers are configured via the mPulse App config dialog and may be based on a JavaScript variable, NavigationTiming, Resource Timing or User Timing.

On the beacon, these are part of t_other.

User Defined Timers

You may also add your own timers by calling BOOMR.plugins.RT.setTimer() from JavaScript.

Every custom timer also contains a corresponding *_st (eg: custom0_st) that specifies the timestamp (Unix epoch) when the timer started.

Custom Metrics

Custom metrics are defined in the mPulse App config dialog.

On the beacon, these metrics have the prefix cmet., followed by a sanitized version of the metric name.

In the S3 logs, these metrics are all numerically indexed. Example:

...
custom_metrics: {
    "0": 10,
    "5": 1
},
...

Metric values are always numeric.

Currency values are always in the lowest unit (eg, ¢ rather than $). If a decimal place is included, then the value is multiplied by 100 to get the actual currency value.

Custom Dimensions

Custom dimensions are defined in the mPulse App config dialog.

On the beacon, these dimensions have the prefix cdim., followed by a sanitized version of the dimension name.

In the S3 logs, these dimensions are in the custom_dimensions array indexed by their dimension number. Dimensions that aren't set may be null or missing (if no dimensions follow). Example:

...
custom_dimensions: [
    {
        "Region": "us",
        "alias": "United States"
    },
    null,
    {
        "Logged In": false,
        "alias": "False"
    }
],
...

Dimension values may be numeric, string or boolean.

HTTP Headers

The following fields live under the headers: {} object in S3.

All headers are lower-cased.

This is not an exhaustive list of all possible HTTP headers.

Other Parameters

Navigation Timing Data

See the NavigationTiming spec for more details, and browser support can be reviewed at caniuse.com.

All timestamps are in (Unix epoch) unless otherwise specified.

The following fields live under the params: {} object in S3.

Paint Timing Data

Data from the Boomerang PaintTiming plugin

See the PaintTiming spec for more details, and browser support can be reviewed at caniuse.com.

All timestamps are in DOMHighResTimeStamp rounded to the nearest millisecond.

The following fields live under the timers: {} object in S3:

The following fields live under the params: {} object in S3:

Single Page App

Information about Single Page App (SPA) navigations.

The following fields live under the params: {} object in S3.

Debugging Info and Timestamps

Other browser timestamps and related information taken in Boomerang, mainly used for debugging.

All timestamps are in (Unix epoch) unless otherwise specified.

The following fields live under the params: {} object in S3.

URLs

URLs related to the beacon.

The following fields live under the params: {} object in S3.

Page Structure

Details about the page structure like DOM nodes, SCRIPTs, etc.

The following fields live under the params: {} object in S3.

Screen and Device Details

Details about screen resolution, CPU, memory, battery, etc.

The following fields live under the params: {} object in S3.

Visibility State

Tells you when the user last had the page hidden or visible on screen.

All timestamps are in (Unix epoch) unless otherwise specified.

The following fields live under the params: {} object in S3.

User Agent Details

User Agent details.

The following fields live under the params: {} object in S3.

XHR Details

Details related to XHRs and Single Page Apps.

The following fields live under the params: {} object in S3.

Bandwidth and Latency Details

More details from the bandwidth test.

The following fields live under the params: {} object in S3.

Mobile Connection Details

Details about mobile connections via the Network Information API.

The following fields live under the params: {} object in S3.

Cross Domain Session Tracking

Details about cross-domain session tracking.

The following fields live under the params: {} object in S3.

Errors

Application (JavaScript and network) errors.

Data is compressed on the beacon, see the Boomerang Errors plugin for details.

The following fields live under the errors: {} object in S3.

Akamai

The following fields live under the params: {} object in S3 unless otherwise specified.

The following metrics are only available if Akamai Edge-Injected mPulse is enabled. These fields live under the params: {} object in S3 unless otherwise specified.

The following metrics are only available if Akamai Adaptive Acceleration and Edge Injection are both enabled. These fields live under the params: {} object in S3 unless otherwise specified.

Resource Timing Data

Resource Timing Data is compressed and sent via a single beacon parameter restiming. The compression is described at http://nicj.net/compressing-resourcetiming/.

The full Resource Timing documentation can be found at https://www.w3.org/TR/resource-timing-2/, and browser support can be reviewed at caniuse.com.

All timestamps are in (Unix epoch) unless otherwise specified.

This field is expanded into a separate table in Asgard, which includes the following fields:

Resource Timing Summary Data

Resource Timing Summary Data is a summary of the Resource Timing Data by Asset Type.

Asset Types include:

• total: Total (all resources)
• page: The page load itself
• css: CSS files
• js: JavaScript files
• img: Images
• html: HTMLs (IFRAMEs, .htms, plus the page itself)
• font: Fonts
• bcn: navigator.sendBeacon()
• xhr: XMLHttpRequests
• other: Other

The format is as follows:

restiming.[type] = "[requestCount],[transferSize],[decodedSize],[browserCacheHitRate],[compressionRate]_[byteCompressionRate],[cdnCacheHitRate],[cdnEdgeTime],[originTime]"

For each Asset Type:

• requestCount: Number of requests for this Asset Type.
• transferSize: The sum of the size of the fetched resources including the response header fields plus the response payload body (transferSize) for this Asset Type.
• decodedSize: The sum of the size received from the fetch (HTTP or cache) of the message body, after removing any applied content-codings (decodedBodySize) for this Asset Type.
• browserCacheHitRate: The ratio (0-10000, where 5000 = 50% and 10000 = 100%) of the number of browser cache hits to browser cache misses for this Asset Type.
• compressionRate: The ratio (0-10000, where 5000 = 50% and 10000 = 100%) of the number of requests where compression was applied to the total number of requests for this Asset Type.
• byteCompressionRate: The percent reduction (0-10000, where 5000 = 50% and 10000 = 100%) in total number of bytes as a result of compression for this Asset Type.
• cdnCacheHitRate: The ratio (0-10000, where 5000 = 50% and 10000 = 100%) of the number of requests that were CDN cache hits (that is the request did not go to the origin) to the total number of requests made to the Akamai network for this Asset Type.
• cdnEdgeTime: The sum of the times between when the first bytes of the requests are received by the Akamai edge server from the client browser, and just before the first bytes of the responses are written back, for this Asset Type. This does not include the times that may or may not have been spent forwarding the requests to the origin.
• originTime: The sum of the round-trip times between the Akamai edge server (nearest to the origin), and the origin, for this Asset Type. This includes the time the origin spends handling the requests.

User Timing Data

User Timing data comes from the Boomerang UserTiming Plugin.

User Timing data is compressed and sent via a single beacon parameter usertiming. The compression is described at http://nicj.net/compressing-usertiming/.

The full User Timing documentation can be found at https://www.w3.org/TR/user-timing/, and browser support can be reviewed at caniuse.com.

The following fields live under the params: {} object in S3.

Server Timing Data

Server Timing Data is compressed and sent via a single beacon parameter servertiming. The compression is described at https://github.com/nicjansma/resourcetiming-compression.js#server-timing.

The full Server Timing documentation can be found at https://www.w3.org/TR/server-timing/, and browser support can be reviewed at caniuse.com.

In the DSWB RT table, the column is a JSON array of decompressed ServerTiming headers:

[{
    "name": "<entry name>",
    "duration": <numeric value>,
    "description": "<entry description>"
}, {...}, ...]

The following fields live under the params: {} object in S3.

Event Timing Data

Event Timing data comes from the Boomerang EventTiming Plugin.

The full Event Timing documentation can be found at https://github.com/WICG/event-timing/, and browser support can be reviewed at caniuse.com.

The following fields live under the params: {} object in S3.

Continuity Metrics

Continuity metrics come from the Boomerang Continuity Plugin.

All of the compressed data formats are described in the Boomerang API documentation.

The following fields live under the params: {} object in S3 unless otherwise noted (e.g. via timers.*).

Visitor Consent

The following parameters are sent only on the first beacon when a visitor opts-in for first time. The
parameters come from the Consent Inlined Plugin.

The following fields live under the params: {} object in S3.

IFRAME Delay Data

Data from the Boomerang IFrameDelay plugin which delays page load until all <iframe>s have loaded.

All timestamps are in (Unix epoch) unless otherwise specified.

The following fields live under the params: {} object in S3.

Third Party Analytics

Data from the Boomerang TPAnalytics plugin.

See Data Collection from Third Party Analytics for more details.

The following fields live under the params: {} object in S3.

Google Analytics

Adobe Analytics

IBM Digital Analytics

Early Beacon

Data from the Boomerang Early plugin.

The following fields live under the params: {} object in S3.

Soft Navigation Heuristics

Data from the Soft Navigation Heuristics API.

The following fields live under the params: {} object in S3.

Back-Forward Cache

Data from the Boomerang BFCache plugin for Back-Forward Cache Navigations.

The following fields live under the params: {} object in S3.