Ordinary TCP/IP connections are one-on-one exchanges of information, with one side establishing the connection that the other side is prepared to accept.
Multicasting, on the other hand, is a type of "free-for-all" communications channel to which clients connect but where no specific receiver exists; anyone subscribed to the channel hears what others "shout" into it (including their own transmissions). This is often used for efficient delivery of content (audio or video) to anyone who shows an interest in the data by subscribing to the channel, even if that's thousands of subscribers at the same time.
We have used multicasting technology in Java to build a high-speed master-slave mechanism that allowed potentially hundreds of nodes to negotiate an authoritative master; if the master ever went down, the remaining nodes would negotiate a new master among themselves to replace the deceased master. This formed the core of a highly reliable fail-over mechanism in which many dozen nodes could negotiate a master within merely a handful of seconds.
Many commercial systems designed to handle fail-over situations aren't that fast or reliable. And we offer you insights into using this technology in Java so you, too, can write ever cooler and more astounding software!
|Description:||Multicasting network communications could be described as the neworking equivalent of a chat room: You subscribe to a group (consisting of a network address in the multicasting range 184.108.40.206 through 220.127.116.11 and and 16-bit number, like a port). This can be used for anonymous peer-to-peer communications, among other uses.|
|Documentation:||Coming soon: multicasting-in-java.odt|
Coming soon: multicasting-in-java.pdf
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