Closeable
, AutoCloseable
, Channel
, InterruptibleChannel
public abstract class SctpMultiChannel extends AbstractSelectableChannel
An SCTP multi channel supports many associations on a single socket. An SctpMultiChannel
is created by invoking the open
method of this class. A newly-created channel is open but not yet bound. An attempt to invoke the receive
method of an unbound channel will cause the NotYetBoundException
to be thrown. An attempt to invoke the send
method of an unbound channel will cause it to first invoke the bind
method. The address(es) that the channel's socket is bound to can be retrieved by calling getAllLocalAddresses
.
Messages may be sent and received without explicitly setting up an association with the remote peer. The channel will implicitly setup a new association whenever it sends or receives a message from a remote peer if there is not already an association with that peer. Upon successful association setup, an association changed
notification will be put to the SCTP stack with its event
parameter set to COMM_UP
. This notification can be received by invoking receive
.
Socket options are configured using the setOption
method. An SctpMultiChannel
supports the following options:
Additional (implementation specific) options may also be supported. The list of options supported is obtained by invoking the
Option Name Description SCTP_DISABLE_FRAGMENTS
Enables or disables message fragmentation SCTP_EXPLICIT_COMPLETE
Enables or disables explicit message completion SCTP_FRAGMENT_INTERLEAVE
Controls how the presentation of messages occur for the message receiver SCTP_INIT_MAXSTREAMS
The maximum number of streams requested by the local endpoint during association initialization SCTP_NODELAY
Enables or disable a Nagle-like algorithm SCTP_PRIMARY_ADDR
Requests that the local SCTP stack use the given peer address as the association primary SCTP_SET_PEER_PRIMARY_ADDR
Requests that the peer mark the enclosed address as the association primary SO_SNDBUF
The size of the socket send buffer SO_RCVBUF
The size of the socket receive buffer SO_LINGER
Linger on close if data is present (when configured in blocking mode only)
supportedOptions
method. SCTP multi channels are safe for use by multiple concurrent threads. They support concurrent sending and receiving, though at most one thread may be sending and at most one thread may be receiving at any given time.
Modifier | Constructor | Description |
---|---|---|
protected |
Initializes a new instance of this class. |
Modifier and Type | Method | Description |
---|---|---|
abstract Set |
associations() |
Returns the open associations on this channel's socket. |
final SctpMultiChannel |
bind |
Binds the channel's socket to a local address and configures the socket to listen for connections. |
abstract SctpMultiChannel |
bind |
Binds the channel's socket to a local address and configures the socket to listen for connections. |
abstract SctpMultiChannel |
bindAddress |
Adds the given address to the bound addresses for the channel's socket. |
abstract SctpChannel |
branch |
Branches off an association. |
abstract Set |
getAllLocalAddresses() |
Returns all of the socket addresses to which this channel's socket is bound. |
abstract <T> T |
getOption |
Returns the value of a socket option. |
abstract Set |
getRemoteAddresses |
Returns all of the remote addresses to which the given association on this channel's socket is connected. |
static SctpMultiChannel |
open() |
Opens an SCTP multi channel. |
abstract <T> MessageInfo |
receive |
Receives a message and/or handles a notification via this channel. |
abstract int |
send |
Sends a message via this channel. |
abstract <T> SctpMultiChannel |
setOption |
Sets the value of a socket option. |
abstract SctpMultiChannel |
shutdown |
Shutdown an association without closing the channel. |
abstract Set |
supportedOptions() |
Returns a set of the socket options supported by this channel. |
abstract SctpMultiChannel |
unbindAddress |
Removes the given address from the bound addresses for the channel's socket. |
final int |
validOps() |
Returns an operation set identifying this channel's supported operations. |
blockingLock, configureBlocking, implCloseChannel, implCloseSelectableChannel, implConfigureBlocking, isBlocking, isRegistered, keyFor, provider, register
register
begin, close, end, isOpen
protected SctpMultiChannel(SelectorProvider provider)
provider
- The selector provider for this channelpublic static SctpMultiChannel open() throws IOException
The new channel is unbound.
UnsupportedOperationException
- If the SCTP protocol is not supportedIOException
- If an I/O error occurspublic abstract Set<Association> associations() throws IOException
Only associations whose COMM_UP
association change event has been received are included in the returned set of associations. Associations for which a COMM_LOST
or SHUTDOWN
association change event have been receive are removed from the set of associations.
The returned set of associations is a snapshot of the open associations at the time that this method is invoked.
Set
containing the open associations, or an empty Set
if there are none.ClosedChannelException
- If this channel is closedIOException
- If some other I/O error occurspublic abstract SctpMultiChannel bind(SocketAddress local, int backlog) throws IOException
This method is used to establish a relationship between the socket and the local address. Once a relationship is established then the socket remains bound until the channel is closed. This relationship may not necesssarily be with the address local
as it may be removed by unbindAddress
, but there will always be at least one local address bound to the channel's socket once an invocation of this method successfully completes.
Once the channel's socket has been successfully bound to a specific address, that is not automatically assigned, more addresses may be bound to it using bindAddress
, or removed using unbindAddress
.
The backlog parameter is the maximum number of pending connections on the socket. Its exact semantics are implementation specific. An implementation may impose an implementation specific maximum length or may choose to ignore the parameter. If the backlog parameter has the value 0
, or a negative value, then an implementation specific default is used.
local
- The local address to bind the socket, or null
to bind the socket to an automatically assigned socket addressbacklog
- The maximum number of pending connectionsClosedChannelException
- If this channel is closedAlreadyBoundException
- If this channel is already boundUnsupportedAddressTypeException
- If the type of the given address is not supportedSecurityException
- If a security manager has been installed and its checkListen
method denies the operationIOException
- If some other I/O error occurspublic final SctpMultiChannel bind(SocketAddress local) throws IOException
This method works as if invoking it were equivalent to evaluating the expression:
bind(local, 0);
local
- The local address to bind the socket, or null
to bind the socket to an automatically assigned socket addressClosedChannelException
- If this channel is closedAlreadyBoundException
- If this channel is already boundUnsupportedAddressTypeException
- If the type of the given address is not supportedSecurityException
- If a security manager has been installed and its checkListen
method denies the operationIOException
- If some other I/O error occurspublic abstract SctpMultiChannel bindAddress(InetAddress address) throws IOException
The given address must not be the wildcard
address. The channel must be first bound using bind
before invoking this method, otherwise NotYetBoundException
is thrown. The bind
method takes a SocketAddress
as its argument which typically contains a port number as well as an address. Addresses subquently bound using this method are simply addresses as the SCTP port number remains the same for the lifetime of the channel.
New associations setup after this method successfully completes will be associated with the given address. Adding addresses to existing associations is optional functionality. If the endpoint supports dynamic address reconfiguration then it may send the appropriate message to the peer to change the peers address lists.
address
- The address to add to the bound addresses for the socketClosedChannelException
- If this channel is closedNotYetBoundException
- If this channel is not yet boundAlreadyBoundException
- If this channel is already bound to the given addressIllegalArgumentException
- If address is null
or the wildcard
addressIOException
- If some other I/O error occurspublic abstract SctpMultiChannel unbindAddress(InetAddress address) throws IOException
The given address must not be the wildcard
address. The channel must be first bound using bind
before invoking this method, otherwise NotYetBoundException
is thrown.
If this method is invoked on a channel that does not have address
as one of its bound addresses, or that has only one local address bound to it, then this method throws IllegalUnbindException
.
The initial address that the channel's socket is bound to using bind
may be removed from the bound addresses for the channel's socket.
New associations setup after this method successfully completes will not be associated with the given address. Removing addresses from existing associations is optional functionality. If the endpoint supports dynamic address reconfiguration then it may send the appropriate message to the peer to change the peers address lists.
address
- The address to remove from the bound addresses for the socketClosedChannelException
- If this channel is closedNotYetBoundException
- If this channel is not yet boundIllegalUnbindException
- address
is not bound to the channel's socket, or the channel has only one address bound to itIllegalArgumentException
- If address is null
or the wildcard
addressIOException
- If some other I/O error occurspublic abstract Set<SocketAddress> getAllLocalAddresses() throws IOException
Set
if the channel's socket is not boundClosedChannelException
- If the channel is closedIOException
- If an I/O error occurspublic abstract Set<SocketAddress> getRemoteAddresses(Association association) throws IOException
association
- The associationSet
if the association has been shutdownClosedChannelException
- If the channel is closedIOException
- If an I/O error occurspublic abstract SctpMultiChannel shutdown(Association association) throws IOException
association
- The association to shutdownClosedChannelException
- If this channel is closedIOException
- If some other I/O error occurspublic abstract <T> T getOption(SctpSocketOption<T> name, Association association) throws IOException
Note that some options are retrieved on the channel's socket, therefore the association
parameter is not applicable and will be ignored if given. However, if the option is association specific then the association must be given.
T
- The type of the socket option valuename
- The socket optionassociation
- The association whose option should be retrieved, or null
if this option should be retrieved at the channel's socket level.null
may be a valid value for some socket options.UnsupportedOperationException
- If the socket option is not supported by this channelClosedChannelException
- If this channel is closedIOException
- If an I/O error occurspublic abstract <T> SctpMultiChannel setOption(SctpSocketOption<T> name, T value, Association association) throws IOException
Note that some options are retrieved on the channel's socket, therefore the association
parameter is not applicable and will be ignored if given. However, if the option is association specific then the association must be given.
T
- The type of the socket option valuename
- The socket optionvalue
- The value of the socket option. A value of null
may be a valid value for some socket options.association
- The association whose option should be set, or null
if this option should be set at the channel's socket level.UnsupportedOperationException
- If the socket option is not supported by this channelIllegalArgumentException
- If the value is not a valid value for this socket optionClosedChannelException
- If this channel is closedIOException
- If an I/O error occurspublic abstract Set<SctpSocketOption<?>> supportedOptions()
This method will continue to return the set of options even after the channel has been closed.
public final int validOps()
SCTP multi channels support reading, and writing, so this method returns (
SelectionKey.OP_READ
|
SelectionKey.OP_WRITE
)
.
validOps
in class SelectableChannel
public abstract <T> MessageInfo receive(ByteBuffer buffer, T attachment, NotificationHandler<T> handler) throws IOException
If a message or notification is immediately available, or if this channel is in blocking mode and one eventually becomes available, then the message or notification is returned or handled, respectively. If this channel is in non-blocking mode and a message or notification is not immediately available then this method immediately returns null
.
If this method receives a message it is copied into the given byte buffer and an MessageInfo
is returned. The message is transferred into the given byte buffer starting at its current position and the buffers position is incremented by the number of bytes read. If there are fewer bytes remaining in the buffer than are required to hold the message, or the underlying input buffer does not contain the complete message, then an invocation of isComplete
on the returned
MessageInfo
will return false
, and more invocations of this method will be necessary to completely consume the messgae. Only one message at a time will be partially delivered in any stream. The socket option SCTP_FRAGMENT_INTERLEAVE
controls various aspects of what interlacing of messages occurs.
If this method receives a notification then the appropriate method of the given handler, if there is one, is invoked. If the handler returns CONTINUE
then this method will try to receive another message/notification, otherwise, if RETURN
is returned this method will return null
. If an uncaught exception is thrown by the handler it will be propagated up the stack through this method.
If a security manager has been installed then for each new association setup this method verifies that the associations source address and port number are permitted by the security manager's checkAccept
method.
This method may be invoked at any time. If another thread has already initiated a receive operation upon this channel, then an invocation of this method will block until the first operation is complete. The given handler is invoked without holding any locks used to enforce the above synchronization policy, that way handlers will not stall other threads from receiving. A handler should not invoke the receive
method of this channel, if it does an IllegalReceiveException
will be thrown.
T
- The type of the attachmentbuffer
- The buffer into which bytes are to be transferredattachment
- The object to attach to the receive operation; can be null
handler
- A handler to handle notifications from the SCTP stack, or null
to ignore any notifications.MessageInfo
, null
if this channel is in non-blocking mode and no messages are immediately available or the notification handler returns RETURN
after handling a notificationClosedChannelException
- If this channel is closedAsynchronousCloseException
- If another thread closes this channel while the read operation is in progressClosedByInterruptException
- If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt statusNotYetBoundException
- If this channel is not yet boundIllegalReceiveException
- If the given handler invokes the receive
method of this channelSecurityException
- If a security manager has been installed and it does not permit new associations to be accepted from the message's senderIOException
- If some other I/O error occurspublic abstract int send(ByteBuffer buffer, MessageInfo messageInfo) throws IOException
If this channel is unbound then this method will invoke bind(null, 0)
before sending any data.
If there is no association existing between this channel's socket and the intended receiver, identified by the address in the given messageInfo, then one will be automatically setup to the intended receiver. This is considered to be Implicit Association Setup. Upon successful association setup, an association changed
notification will be put to the SCTP stack with its event
parameter set to COMM_UP
. This notification can be received by invoking receive
.
If this channel is in blocking mode, there is sufficient room in the underlying output buffer, then the remaining bytes in the given byte buffer are transmitted as a single message. Sending a message is atomic unless explicit message completion SCTP_EXPLICIT_COMPLETE
socket option is enabled on this channel's socket.
If this channel is in non-blocking mode, there is sufficient room in the underlying output buffer, and an implicit association setup is required, then the remaining bytes in the given byte buffer are transmitted as a single message, subject to SCTP_EXPLICIT_COMPLETE
. If for any reason the message cannot be delivered an association
changed
notification is put on the SCTP stack with its event
parameter set to CANT_START
.
The message is transferred from the byte buffer as if by a regular write
operation.
If a security manager has been installed then for each new association setup this method verifies that the given remote peers address and port number are permitted by the security manager's checkConnect
method.
This method may be invoked at any time. If another thread has already initiated a send operation upon this channel, then an invocation of this method will block until the first operation is complete.
buffer
- The buffer containing the message to be sentmessageInfo
- Ancillary data about the message to be sentInvalidStreamException
- If streamNumber
is negative, or if an association already exists and streamNumber
is greater than the maximum number of outgoing streamsClosedChannelException
- If this channel is closedAsynchronousCloseException
- If another thread closes this channel while the read operation is in progressClosedByInterruptException
- If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt statusSecurityException
- If a security manager has been installed and it does not permit new associations to be setup with the messages's addressIOException
- If some other I/O error occurspublic abstract SctpChannel branch(Association association) throws IOException
An application can invoke this method to branch off an association into a separate channel. The new bound and connected SctpChannel
will be created for the association. The branched off association will no longer be part of this channel.
This is particularly useful when, for instance, the application wishes to have a number of sporadic message senders/receivers remain under the original SCTP multi channel but branch off those associations carrying high volume data traffic into their own separate SCTP channels.
association
- The association to branch offSctpChannel
ClosedChannelException
- If this channel is closedIOException
- If some other I/O error occurs
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/21/docs/api/jdk.sctp/com/sun/nio/sctp/SctpMultiChannel.html