Bandwidth/latency plugin API

The bandwidth plugin measures the bandwidth and latency of the user's network connection to your server. The bandwidth API is encapsulated within the BOOMR.plugins.BW namespace.

Configuration

All bandwidth plugin configuration items are under the BW namespace. The full configuration object is described in Howto #6 — Configuring boomerang.

base_url

[recommended] By default, the bandwidth plugin looks for its bandwidth measurement images in the images/ subdirectory of the current directory. This may not be true for all pages on your site. You can set the base_url parameter to the HTTP path of the directory that contains the bandwidth images. This can be an absolute or a relative URL. If it's relative, remember that it's relative to the page that boomerang is included in and not to the javascript file.

cookie

[optional] The name of the cookie in which to store the measured bandwidth and latency of the user's network connection. The default name is BA. See Howto #3 for more details on the bandwidth cookie.

cookie_exp

[optional] The lifetime in seconds of the bandwidth cookie. The default is set to 7 days. This specifies how long it will be before we run the bandwidth test again for a user, assuming their IP address doesn't change within this time. You probably do not need to change this setting at all since the bandwidth of a given network connection typically does not change by an order of magnitude on a regular basis.
Note that if you're doing some kind of real-time streaming, then chances are that this bandwidth test isn't right for you, so setting this cookie to a shorter value isn't the right solution.

timeout

[optional] The timeout in seconds for the entire bandwidth test. The default is set to 15 seconds. The bandwidth test can run for a long time, and sometimes, due to network errors, it might never complete. The timeout forces the test to complete at that time. This is a hard limit. If the timeout fires, we stop further iterations of the test and attempt to calculate bandwidth with the data that we've collected at that point. Increasing the timeout can get you more data and increase the accuracy of the test, but at the same time increases the risk of the test not completing before the user leaves the page.

nruns

[optional] The number of times the bandwidth test should run. The default is set to 5. The first test is always a pilot to figure out the best way to proceed with the remaining tests. Increasing this number will increase the tests accuracy, but at the same time increases the risk that the test will timeout. It should take about 2-4 seconds per run, so consider this value along with the timeout value above.

Methods

init(oConfig)

Called by the BOOMR.init() method to configure the bandwidth plugin.

Parameters

oConfig

The configuration object passed in via BOOMR.init(). See the Configuration section for details.

Returns

a reference to the BOOMR.plugins.BW object, so you can chain methods.

run()

Starts the bandwidth test. This method is called automatically when boomerang's page_ready event fires, so you won't need to call it yourself.

Returns

a reference to the BOOMR.plugins.BW object, so you can chain methods.

abort()

Stops the bandwidth test immediately and attempts to calculate bandwidth and latency from values that it has already gathered. This method is called automatically if the bandwidth test times out. It is better to set the timeout value appropriately when calling the BOOMR.init() method.

Returns

a reference to the BOOMR.plugins.BW object, so you can chain methods.

is_complete()

Called by BOOMR.sendBeacon() to determine if the bandwidth plugin has finished what it's doing or not.

Returns

• true if the plugin has completed.
• false if the plugin has not completed.

Beacon Parameters

This plugin adds the following parameters to the beacon:

bw

User's measured bandwidth in bytes per second

bw_err

95% confidence interval margin of error in measuring user's bandwidth

lat

User's measured HTTP latency in milliseconds

lat_err

95% confidence interval margin of error in measuring user's latency

bw_time

Timestamp (seconds since the epoch) on the user's browser when the bandwidth and latency was measured

The latest code and docs is available on github.com/lognormal/boomerang