Martin Lucina wrote: > [email protected] said: >> Chris Wong wrote: >>> Actually i want support for unreliable multicast vs reliable multicast. >>> Zeromq is a nice framework to allow me to transparently switch the >>> underlying transport. There are applications that don't need the >>> ordering and lossless guarantee of PGM. >>> >>> The unreliable multicast transport may or may not work for all the >>> messaging pattern but should at least work for the multicast pattern. >> Now it makes sense. Paradoxically, unreliable multicast is easier to >> implement than unreliable unicast. > > How so? Isn't unreliable unicast just unicast UDP? And unreliable multicast > just multicast UDP? (But see below about datagram length)
Well. Yes. I thought of other issues that are actually pretty irrelevant. >> Just copy pgm_sender.cpp/.hpp and pgm_receiver.cpp/.hpp, name it >> udp_sender/udp_reciever. Rip off OpenPGM stuff, use UDP socket instead. > > This is starting to look the the 'udp' transport we don't have (yet) :-) This is starting to look messy: rename udp->epgm, then introduce brand new, incompatibel udp... > >> One additional thing that has to be done is to attach a sequence number >> to each UDP packet, so that you know when packet was lost. > > Why would you need to know when a packet was lost, it is after all just > unreliable multicast... > > What I see as more of a problem is that UDP datagrams are limited to 65,507 > bytes in length, so any 0MQ UDP transport (multicast or unicast) would have > to split and recombine messages. Bingo. See what packet numbers are good for? Martin _______________________________________________ zeromq-dev mailing list [email protected] http://lists.zeromq.org/mailman/listinfo/zeromq-dev
