I am trying to get topic of mqtt client, i searched in google, i couldn't find right one.
for example, from mqtt client, publish one message,consider server topic is 'topicOfServer' and client topic is 'topicOfClient'.
client.publish('topicOfServer','hi server');
server will get 'hi server' message. but how do server knows that message came from which client ex: 'topicOfClient'
You seam to be confusing a couple of things here