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.