How CEM total transaction time being calculated for a Business Transaction?
Answer is good for versions of APM 9.1, 9.5, 9.6, 9.7, 10.0, 10.1 and 10.2.
CEM Business Transaction time is the time from the first packet of the identifying transaction's request to the last packet of the response of the last transaction that is observed as part of the Business Transaction, regardless of whether it is cacheable.
CEM monitors transactions time on the switch (monitored network interface; where CEM TIM/MTP appliance is installed). We have to remember that switch level packets indirectly captures the end user/client time (like user idle time, browser response time etc) if Business Transaction has more than one transaction. Below CEM component screenshot explains.
Use case explained above shows that CEM includes most of the end user/client activity time in the total Business Transaction time.
TEC603709 -- An Explanation of APM CE (CEM) Transaction Time Breakdown as shown in the Component Timing Diagram
TEC596052 -- Why are there gaps in my component timing graphs?
TEC596047 -- What does the Component Timings Area of a CEM Report show?