Module jdk.sctp
Package com.sun.nio.sctp

Class SctpMultiChannel

java.lang.Object
java.nio.channels.spi.AbstractInterruptibleChannel
java.nio.channels.SelectableChannel
java.nio.channels.spi.AbstractSelectableChannel
com.sun.nio.sctp.SctpMultiChannel
All Implemented Interfaces:
Closeable, AutoCloseable, Channel, InterruptibleChannel
public abstract class SctpMultiChannel extends AbstractSelectableChannel
A selectable channel for message-oriented SCTP sockets.

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:

Socket options
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)
Additional (implementation specific) options may also be supported. The list of options supported is obtained by invoking the 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.

Since:
1.7

  • Constructor Details

    • SctpMultiChannel

      protected SctpMultiChannel(SelectorProvider provider)
      Initializes a new instance of this class.
      Parameters:
      provider - The selector provider for this channel

  • Method Details

    • open

      public static SctpMultiChannel open() throws IOException
      Opens an SCTP multi channel.

      The new channel is unbound.

      Returns:
      A new SCTP multi channel
      Throws:
      UnsupportedOperationException - If the SCTP protocol is not supported
      IOException - If an I/O error occurs

    • associations

      public abstract Set<Association> associations() throws IOException
      Returns the open associations on this channel's socket.

      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.

      Returns:
      A Set containing the open associations, or an empty Set if there are none.
      Throws:
      ClosedChannelException - If this channel is closed
      IOException - If some other I/O error occurs

    • bind

      public abstract SctpMultiChannel bind(SocketAddress local, int backlog) throws IOException
      Binds the channel's socket to a local address and configures the socket to listen for connections.

      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.

      Parameters:
      local - The local address to bind the socket, or null to bind the socket to an automatically assigned socket address
      backlog - The maximum number of pending connections
      Returns:
      This channel
      Throws:
      ClosedChannelException - If this channel is closed
      AlreadyBoundException - If this channel is already bound
      UnsupportedAddressTypeException - If the type of the given address is not supported
      SecurityException - If a security manager has been installed and its checkListen method denies the operation
      IOException - If some other I/O error occurs

    • bind

      public final SctpMultiChannel bind(SocketAddress local) throws IOException
      Binds the channel's socket to a local address and configures the socket to listen for connections.

      This method works as if invoking it were equivalent to evaluating the expression: 

       bind(local, 0);
      Parameters:
      local - The local address to bind the socket, or null to bind the socket to an automatically assigned socket address
      Returns:
      This channel
      Throws:
      ClosedChannelException - If this channel is closed
      AlreadyBoundException - If this channel is already bound
      UnsupportedAddressTypeException - If the type of the given address is not supported
      SecurityException - If a security manager has been installed and its checkListen method denies the operation
      IOException - If some other I/O error occurs

    • bindAddress

      public abstract SctpMultiChannel bindAddress(InetAddress address) throws IOException
      Adds the given address to the bound addresses for the channel's socket.

      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.

      Parameters:
      address - The address to add to the bound addresses for the socket
      Returns:
      This channel
      Throws:
      ClosedChannelException - If this channel is closed
      NotYetBoundException - If this channel is not yet bound
      AlreadyBoundException - If this channel is already bound to the given address
      IllegalArgumentException - If address is null or the wildcard address
      IOException - If some other I/O error occurs

    • unbindAddress

      public abstract SctpMultiChannel unbindAddress(InetAddress address) throws IOException
      Removes the given address from the bound addresses for the channel's socket.

      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.

      Parameters:
      address - The address to remove from the bound addresses for the socket
      Returns:
      This channel
      Throws:
      ClosedChannelException - If this channel is closed
      NotYetBoundException - If this channel is not yet bound
      IllegalUnbindException - address is not bound to the channel's socket, or the channel has only one address bound to it
      IllegalArgumentException - If address is null or the wildcard address
      IOException - If some other I/O error occurs

    • getAllLocalAddresses

      public abstract Set<SocketAddress> getAllLocalAddresses() throws IOException
      Returns all of the socket addresses to which this channel's socket is bound.
      Returns:
      All the socket addresses that this channel's socket is bound to, or an empty Set if the channel's socket is not bound
      Throws:
      ClosedChannelException - If the channel is closed
      IOException - If an I/O error occurs

    • getRemoteAddresses

      public abstract Set<SocketAddress> getRemoteAddresses(Association association) throws IOException
      Returns all of the remote addresses to which the given association on this channel's socket is connected.
      Parameters:
      association - The association
      Returns:
      All of the remote addresses for the given association, or an empty Set if the association has been shutdown
      Throws:
      ClosedChannelException - If the channel is closed
      IOException - If an I/O error occurs

    • shutdown

      public abstract SctpMultiChannel shutdown(Association association) throws IOException
      Shutdown an association without closing the channel.
      Parameters:
      association - The association to shutdown
      Returns:
      This channel
      Throws:
      ClosedChannelException - If this channel is closed
      IOException - If some other I/O error occurs

    • getOption

      public abstract <T> T getOption(SctpSocketOption<T> name, Association association) throws IOException
      Returns the value of a socket option.

      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.

      Type Parameters:
      T - The type of the socket option value
      Parameters:
      name - The socket option
      association - The association whose option should be retrieved, or null if this option should be retrieved at the channel's socket level.
      Returns:
      The value of the socket option. A value of null may be a valid value for some socket options.
      Throws:
      UnsupportedOperationException - If the socket option is not supported by this channel
      ClosedChannelException - If this channel is closed
      IOException - If an I/O error occurs
      See Also:

    • setOption

      public abstract <T> SctpMultiChannel setOption(SctpSocketOption<T> name, T value, Association association) throws IOException
      Sets the value of a socket option.

      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.

      Type Parameters:
      T - The type of the socket option value
      Parameters:
      name - The socket option
      value - 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.
      Returns:
      This channel
      Throws:
      UnsupportedOperationException - If the socket option is not supported by this channel
      IllegalArgumentException - If the value is not a valid value for this socket option
      ClosedChannelException - If this channel is closed
      IOException - If an I/O error occurs
      See Also:

    • supportedOptions

      public abstract Set<SctpSocketOption<?>> supportedOptions()
      Returns a set of the socket options supported by this channel.

      This method will continue to return the set of options even after the channel has been closed.

      Returns:
      A set of the socket options supported by this channel

    • validOps

      public final int validOps()
      Returns an operation set identifying this channel's supported operations.

      SCTP multi channels support reading, and writing, so this method returns (SelectionKey.OP_READ | SelectionKey.OP_WRITE).

      Specified by:
      validOps in class SelectableChannel
      Returns:
      The valid-operation set

    • receive

      public abstract <T> MessageInfo receive(ByteBuffer buffer, T attachment, NotificationHandler<T> handler) throws IOException
      Receives a message and/or handles a notification via this channel.

      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.

      Type Parameters:
      T - The type of the attachment
      Parameters:
      buffer - The buffer into which bytes are to be transferred
      attachment - 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.
      Returns:
      The 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 notification
      Throws:
      ClosedChannelException - If this channel is closed
      AsynchronousCloseException - If another thread closes this channel while the read operation is in progress
      ClosedByInterruptException - 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 status
      NotYetBoundException - If this channel is not yet bound
      IllegalReceiveException - If the given handler invokes the receive method of this channel
      SecurityException - If a security manager has been installed and it does not permit new associations to be accepted from the message's sender
      IOException - If some other I/O error occurs

    • send

      public abstract int send(ByteBuffer buffer, MessageInfo messageInfo) throws IOException
      Sends a message via this channel.

      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.

      Parameters:
      buffer - The buffer containing the message to be sent
      messageInfo - Ancillary data about the message to be sent
      Returns:
      The number of bytes sent, which will be either the number of bytes that were remaining in the messages buffer when this method was invoked or, if this channel is non-blocking, may be zero if there was insufficient room for the message in the underlying output buffer
      Throws:
      InvalidStreamException - If streamNumber is negative, or if an association already exists and streamNumber is greater than the maximum number of outgoing streams
      ClosedChannelException - If this channel is closed
      AsynchronousCloseException - If another thread closes this channel while the read operation is in progress
      ClosedByInterruptException - 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 status
      SecurityException - If a security manager has been installed and it does not permit new associations to be setup with the messages's address
      IOException - If some other I/O error occurs

    • branch

      public abstract SctpChannel branch(Association association) throws IOException
      Branches off an association.

      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.

      Parameters:
      association - The association to branch off
      Returns:
      The SctpChannel
      Throws:
      ClosedChannelException - If this channel is closed
      IOException - If some other I/O error occurs