jdk.net.MulticastSocket
The multicast datagram socket class is useful for sending and receiving IP multicast packets. A MulticastSocket is a (UDP) DatagramSocket, with additional capabilities for joining "groups" of other multicast hosts on the internet.
A multicast group is specified by a class D IP address and by a standard UDP port number. Class D IP addresses are in the range 224.0.0.0 to 239.255.255.255, inclusive. The address 224.0.0.0 is reserved and should not be used.
One would join a multicast group by first creating a MulticastSocket with the desired port, then invoking the joinGroup(InetAddress groupAddr) method:
// join a Multicast group and send the group salutations ... String msg = "Hello"; InetAddress group = InetAddress.getByName("228.5.6.7"); MulticastSocket s = new MulticastSocket(6789); s.joinGroup(group); DatagramPacket hi = new DatagramPacket(msg.getBytes(), msg.length(), group, 6789); s.send(hi); // get their responses! byte[] buf = new byte[1000]; DatagramPacket recv = new DatagramPacket(buf, buf.length); s.receive(recv); ... // OK, I'm done talking - leave the group... s.leaveGroup(group);
When one sends a message to a multicast group, all subscribing recipients to that host and port receive the message (within the time-to-live range of the packet, see below). The socket needn't be a member of the multicast group to send messages to it.
When a socket subscribes to a multicast group/port, it receives datagrams sent by other hosts to the group/port, as do all other members of the group and port. A socket relinquishes membership in a group by the leaveGroup(InetAddress addr) method. Multiple MulticastSocket's may subscribe to a multicast group and port concurrently, and they will all receive group datagrams.
Currently applets are not allowed to use multicast sockets.
The multicast datagram socket class is useful for sending
and receiving IP multicast packets. A MulticastSocket is
a (UDP) DatagramSocket, with additional capabilities for
joining "groups" of other multicast hosts on the internet.
A multicast group is specified by a class D IP address
and by a standard UDP port number. Class D IP addresses
are in the range 224.0.0.0 to 239.255.255.255,
inclusive. The address 224.0.0.0 is reserved and should not be used.
One would join a multicast group by first creating a MulticastSocket
with the desired port, then invoking the
joinGroup(InetAddress groupAddr)
method:
// join a Multicast group and send the group salutations
...
String msg = "Hello";
InetAddress group = InetAddress.getByName("228.5.6.7");
MulticastSocket s = new MulticastSocket(6789);
s.joinGroup(group);
DatagramPacket hi = new DatagramPacket(msg.getBytes(), msg.length(),
group, 6789);
s.send(hi);
// get their responses!
byte[] buf = new byte[1000];
DatagramPacket recv = new DatagramPacket(buf, buf.length);
s.receive(recv);
...
// OK, I'm done talking - leave the group...
s.leaveGroup(group);
When one sends a message to a multicast group, all subscribing
recipients to that host and port receive the message (within the
time-to-live range of the packet, see below). The socket needn't
be a member of the multicast group to send messages to it.
When a socket subscribes to a multicast group/port, it receives
datagrams sent by other hosts to the group/port, as do all other
members of the group and port. A socket relinquishes membership
in a group by the leaveGroup(InetAddress addr) method.
Multiple MulticastSocket's may subscribe to a multicast group
and port concurrently, and they will all receive group datagrams.
Currently applets are not allowed to use multicast sockets.->multicast-socketclj
(->multicast-socket)(->multicast-socket port)Constructor.
Create a multicast socket and bind it to a specific port.
If there is a security manager, its checkListen method is first called with the port argument as its argument to ensure the operation is allowed. This could result in a SecurityException.
When the socket is created the DatagramSocket.setReuseAddress(boolean) method is called to enable the SO_REUSEADDR socket option.
port - port to use - int
throws: java.io.IOException - if an I/O exception occurs while creating the MulticastSocket
Constructor. Create a multicast socket and bind it to a specific port. If there is a security manager, its checkListen method is first called with the port argument as its argument to ensure the operation is allowed. This could result in a SecurityException. When the socket is created the DatagramSocket.setReuseAddress(boolean) method is called to enable the SO_REUSEADDR socket option. port - port to use - `int` throws: java.io.IOException - if an I/O exception occurs while creating the MulticastSocket
get-interfaceclj
(get-interface this)Retrieve the address of the network interface used for multicast packets.
returns: An InetAddress representing
the address of the network interface used for
multicast packets. - java.net.InetAddress
throws: java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.
Retrieve the address of the network interface used for multicast packets. returns: An InetAddress representing the address of the network interface used for multicast packets. - `java.net.InetAddress` throws: java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.
get-loopback-mode?clj
(get-loopback-mode? this)Get the setting for local loopback of multicast datagrams.
returns: true if the LoopbackMode has been disabled - boolean
throws: java.net.SocketException - if an error occurs while getting the value
Get the setting for local loopback of multicast datagrams. returns: true if the LoopbackMode has been disabled - `boolean` throws: java.net.SocketException - if an error occurs while getting the value
get-network-interfaceclj
(get-network-interface this)Get the multicast network interface set.
returns: the multicast NetworkInterface currently set - java.net.NetworkInterface
throws: java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.
Get the multicast network interface set. returns: the multicast NetworkInterface currently set - `java.net.NetworkInterface` throws: java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.
get-time-to-liveclj
(get-time-to-live this)Get the default time-to-live for multicast packets sent out on the socket.
returns: the default time-to-live value - int
throws: java.io.IOException - if an I/O exception occurs while getting the default time-to-live value
Get the default time-to-live for multicast packets sent out on the socket. returns: the default time-to-live value - `int` throws: java.io.IOException - if an I/O exception occurs while getting the default time-to-live value
get-ttlclj
(get-ttl this)Deprecated. use the getTimeToLive method instead, which returns an int instead of a byte.
returns: the default time-to-live value - byte
throws: java.io.IOException - if an I/O exception occurs while getting the default time-to-live value
Deprecated. use the getTimeToLive method instead, which returns an int instead of a byte. returns: the default time-to-live value - `byte` throws: java.io.IOException - if an I/O exception occurs while getting the default time-to-live value
join-groupclj
(join-group this mcastaddr)(join-group this mcastaddr net-if)Joins the specified multicast group at the specified interface.
If there is a security manager, this method first calls its checkMulticast method with the mcastaddr argument as its argument.
mcastaddr - is the multicast address to join - java.net.SocketAddress
net-if - specifies the local interface to receive multicast datagram packets, or null to defer to the interface set by setInterface(InetAddress) or setNetworkInterface(NetworkInterface) - java.net.NetworkInterface
throws: java.io.IOException - if there is an error joining or when the address is not a multicast address.
Joins the specified multicast group at the specified interface. If there is a security manager, this method first calls its checkMulticast method with the mcastaddr argument as its argument. mcastaddr - is the multicast address to join - `java.net.SocketAddress` net-if - specifies the local interface to receive multicast datagram packets, or null to defer to the interface set by setInterface(InetAddress) or setNetworkInterface(NetworkInterface) - `java.net.NetworkInterface` throws: java.io.IOException - if there is an error joining or when the address is not a multicast address.
leave-groupclj
(leave-group this mcastaddr)(leave-group this mcastaddr net-if)Leave a multicast group on a specified local interface.
If there is a security manager, this method first calls its checkMulticast method with the mcastaddr argument as its argument.
mcastaddr - is the multicast address to leave - java.net.SocketAddress
net-if - specifies the local interface or null to defer to the interface set by setInterface(InetAddress) or setNetworkInterface(NetworkInterface) - java.net.NetworkInterface
throws: java.io.IOException - if there is an error leaving or when the address is not a multicast address.
Leave a multicast group on a specified local interface. If there is a security manager, this method first calls its checkMulticast method with the mcastaddr argument as its argument. mcastaddr - is the multicast address to leave - `java.net.SocketAddress` net-if - specifies the local interface or null to defer to the interface set by setInterface(InetAddress) or setNetworkInterface(NetworkInterface) - `java.net.NetworkInterface` throws: java.io.IOException - if there is an error leaving or when the address is not a multicast address.
sendclj
(send this p ttl)Deprecated. Use the following code or its equivalent instead: ...... int ttl = mcastSocket.getTimeToLive(); mcastSocket.setTimeToLive(newttl); mcastSocket.send(p); mcastSocket.setTimeToLive(ttl); ......
p - is the packet to be sent. The packet should contain the destination multicast ip address and the data to be sent. One does not need to be the member of the group to send packets to a destination multicast address. - java.net.DatagramPacket
ttl - optional time to live for multicast packet. default ttl is 1. - byte
throws: java.io.IOException - is raised if an error occurs i.e error while setting ttl.
Deprecated. Use the following code or its equivalent instead: ...... int ttl = mcastSocket.getTimeToLive(); mcastSocket.setTimeToLive(newttl); mcastSocket.send(p); mcastSocket.setTimeToLive(ttl); ...... p - is the packet to be sent. The packet should contain the destination multicast ip address and the data to be sent. One does not need to be the member of the group to send packets to a destination multicast address. - `java.net.DatagramPacket` ttl - optional time to live for multicast packet. default ttl is 1. - `byte` throws: java.io.IOException - is raised if an error occurs i.e error while setting ttl.
set-interfaceclj
(set-interface this inf)Set the multicast network interface used by methods whose behavior would be affected by the value of the network interface. Useful for multihomed hosts.
inf - the InetAddress - java.net.InetAddress
throws: java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.
Set the multicast network interface used by methods whose behavior would be affected by the value of the network interface. Useful for multihomed hosts. inf - the InetAddress - `java.net.InetAddress` throws: java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.
set-loopback-modeclj
(set-loopback-mode this disable)Disable/Enable local loopback of multicast datagrams The option is used by the platform's networking code as a hint for setting whether multicast data will be looped back to the local socket.
Because this option is a hint, applications that want to verify what loopback mode is set to should call getLoopbackMode()
disable - true to disable the LoopbackMode - boolean
throws: java.net.SocketException - if an error occurs while setting the value
Disable/Enable local loopback of multicast datagrams The option is used by the platform's networking code as a hint for setting whether multicast data will be looped back to the local socket. Because this option is a hint, applications that want to verify what loopback mode is set to should call getLoopbackMode() disable - true to disable the LoopbackMode - `boolean` throws: java.net.SocketException - if an error occurs while setting the value
set-network-interfaceclj
(set-network-interface this net-if)Specify the network interface for outgoing multicast datagrams sent on this socket.
net-if - the interface - java.net.NetworkInterface
throws: java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.
Specify the network interface for outgoing multicast datagrams sent on this socket. net-if - the interface - `java.net.NetworkInterface` throws: java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.
set-time-to-liveclj
(set-time-to-live this ttl)Set the default time-to-live for multicast packets sent out on this MulticastSocket in order to control the scope of the multicasts.
The ttl must be in the range 0 <= ttl <= 255 or an IllegalArgumentException will be thrown. Multicast packets sent with a TTL of 0 are not transmitted on the network but may be delivered locally.
ttl - the time-to-live - int
throws: java.io.IOException - if an I/O exception occurs while setting the default time-to-live value
Set the default time-to-live for multicast packets sent out on this MulticastSocket in order to control the scope of the multicasts. The ttl must be in the range 0 <= ttl <= 255 or an IllegalArgumentException will be thrown. Multicast packets sent with a TTL of 0 are not transmitted on the network but may be delivered locally. ttl - the time-to-live - `int` throws: java.io.IOException - if an I/O exception occurs while setting the default time-to-live value
set-ttlclj
(set-ttl this ttl)Deprecated. use the setTimeToLive method instead, which uses int instead of byte as the type for ttl.
ttl - the time-to-live - byte
throws: java.io.IOException - if an I/O exception occurs while setting the default time-to-live value
Deprecated. use the setTimeToLive method instead, which uses int instead of byte as the type for ttl. ttl - the time-to-live - `byte` throws: java.io.IOException - if an I/O exception occurs while setting the default time-to-live value
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