Back-End Time and Front-End Time

Document created by DPM Admin Employee on Jul 13, 2017
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Back-End Time and Front-End Time


A key component of the user’s page load experience includes how fast the server can dynamically generate or fetch the base document after a new page request.  In SOASTA mPulse, that timer value is called Back-End Time.  If the median value for Back-End Time is high, then you definitely know that you have a problem that impacts the customer experience.  However, if the Back-End Time is good, there could still be other issues on the page, including server-side performance issues that are happening at other parts in the page load.  The portion of the page load time that follows the Back-End Time is what SOASTA mPulse calls Front-End Time. That timer includes all the remaining time to load the page, including fetching both static and dynamic assets on the page, delays processing Javascript or CSS, time to initialize plug-ins like Flash, and other browser-side delays until the onLoad event has fired.


How to Calculate Back-End Time


The value assigned to Back-End Time for a given beacon (page view) depends on whether the browser being used supports the W3C Navigation Timing standard.  For browsers that support Navigation Timing, the value reported for Back-End Time is the time from navigationStart to responseStart.  For legacy browsers that do not support the Navigation Timing standard, the value is the time from the onBeforeUnload event or the onClick event (whichever is later) to the OnUnload to OnPageHide event (whichever fires).  If the page view is the first page in a session, and there are no onBeforeUnload or onUnload events to base a timing from, SOASTA mPulse will calculate an estimated value based on a statistical sample of all Back-End Times observed so far and the time it takes Boomerang to load on the page.  For more information on the browsers that support Navigation Timing, see:


How to Calculate Front-End Time

Front-End Time for a beacon is the time from the calculated Back-End Time to the end of the page load (when the onLoad event fires on the page.)

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