What transport service does an app need?

data integrity

$-$ some apps $($e$.$g$.,$ file transfer, web transactions$)$ require $100\backslash \%$ reliable data transfer

$-$ other apps $($e$.$g$.,$ audio$)$ can tolerate some loss

timing

$-$ some apps $($e$.$g$.,$ Internet telephony, interactive games$)$ require low delay to be "effective"

throughput

$-$ some apps $($e$.$g$.,$ multimedia$)$ require minimum amount of throughput to be "effective"

$-$ other apps $("$elastic apps"$)$ make use of whatever throughput they get

security

$\backslash (\backslash$cdot $\backslash )$ encryption, data integrity,