What protocols are used to create a chat application for iOS, Android and Microsoft? -

i have asp.net application talking sql db ios, android , microsoft mobile applications talking 1 db. individuals , chat on platform , receive message on one-to-one or one-to-group. im doing 2sec refresh. technology or best practice used chatting application ?

thanks

you can use websockets or can use long polling or comet. of them proven , latest 1 getting wide acceptance websockets javascript.