Question

Which protocol is used to protect boundary of the message?

Answer 1

A "message boundary" is the separation between two messages being sent over a protocol.

UDP preserves message boundaries. If you send "FOO" and then "BAR" over UDP, the other end will receive two datagrams, one containing "FOO" and the other containing "BAR".

If you send "FOO" and then "BAR" over TCP, no message boundary is preserved. The other end might get "FOO" and then "BAR". Or it might get "FOOBAR". Or it might get "F" and then "OOB" and then "AR". TCP does not make any attempt to preserve application message boundaries -- it's just a stream of bytes in each direction.

example:

UDP: FOO+ BAR ====> BAR + FOO or FOO + BAR

TCP: FOO + BAR ====> F + OO + BA + R