Chapter 6. Multicast Protocol

Abstract

Multicast is an unreliable protocol that allows clients to connect to brokers using IP multicast.

URI syntax

Example 6.1, “Multicast URI” shows the syntax for a Multicast connection.

Example 6.1. Multicast URI

multicast://Host:[Port]?transportOptions

The Multicast protocol supports the following transport options:

Table 6.1. Transport Options Supported by Multicast Protocol
Property	Default	Description
`group`	`default`	Specifies a unique group name that can segregate multicast traffic.
`minmumWireFormatVersion`	`0`	Specifies the minimum wire format version that is allowed.
`trace`	`false`	Causes all commands sent over the transport to be logged.
`useLocalHost`	`true`	When `true`, causes the local machine's name to resolve to `localhost`.
`datagramSize`	`4 * 1024`	Specifies the size of a datagram.
`timeToLive`	`-1`	Specifies the time to live of datagrams. Set greater than 1 to send packets beyond the local network. ^[a]
`loopBackMode`	`false`	Specifies whether loopback mode is used.
`wireFormat`		The name of the wire format to use.
`wireFormat.*`		All the properties with this prefix are used to configure the wireFormat. See Table A.1, “Wire Format Options Supported by OpenWire Protocol” for more information.
`jms.*`		All the properties with this prefix are used to configure client connections to a broker. See Appendix B, Client Connection Options for more information.
^[a] This won't work for IPv4 addresses without setting the property `java.net.preferIPv4Stack=true`.