Please note that this documentation is not final and is subject to change.

JavaTM SCTP API
DRAFT ea-b11

com.sun.nio.sctp
Class SctpChannel

java.lang.Object
  extended by java.nio.channels.spi.AbstractInterruptibleChannel
      extended by java.nio.channels.SelectableChannel
          extended by java.nio.channels.spi.AbstractSelectableChannel
              extended by com.sun.nio.sctp.SctpChannel
All Implemented Interfaces:
Closeable, Channel, InterruptibleChannel

public abstract class SctpChannel
extends AbstractSelectableChannel

A selectable channel for message-oriented connected SCTP sockets.

An SCTP channel can only control one SCTP association. An SCTPChannel is created by invoking one of the open methods of this class. A newly-created channel is open but not yet connected, that is, there is no association setup with a remote peer. An attempt to invoke an I/O operation upon an unconnected channel will cause a NotYetConnectedException to be thrown. An association can be setup by connecting the channel using one of its connect methods. Once connected, the channel remains connected until it is closed. Whether or not a channel is connected may be determined by invoking getRemoteAddresses.

SCTP channels support non-blocking connection: A channel may be created and the process of establishing the link to the remote socket may be initiated via the connect method for later completion by the finishConnect method. Whether or not a connection operation is in progress may be determined by invoking the isConnectionPending method.

Socket options are configured using the setOption method. An SCTP channel support the following 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 channels are safe for use by multiple concurrent threads. They support concurrent reading and writing, though at most one thread may be reading and at most one thread may be writing at any given time. The connect and finishConnect methods are mutually synchronized against each other, and an attempt to initiate a send or receive operation while an invocation of one of these methods is in progress will block until that invocation is complete.

Since:
1.7

Constructor Summary
protected SctpChannel(SelectorProvider provider)
          Initializes a new instance of this class.
 
Method Summary
abstract  Association association()
          Returns the association on this channel's socket.
abstract  SctpChannel bind(SocketAddress local)
          Binds the channel's socket to a local address.
abstract  SctpChannel bindAddress(InetAddress address)
          Adds the given address to the bound addresses for the channel's socket.
abstract  boolean connect(SocketAddress remote)
          Connects this channel's socket.
abstract  boolean connect(SocketAddress remote, int maxOutStreams, int maxInStreams)
          Connects this channel's socket.
abstract  boolean finishConnect()
          Finishes the process of connecting an SCTP channel.
abstract  Set<SocketAddress> getAllLocalAddresses()
          Returns all of the socket addresses to which this channel's socket is bound.
abstract
<T> T
getOption(SctpSocketOption<T> name)
          Returns the value of a socket option.
abstract  Set<SocketAddress> getRemoteAddresses()
          Returns all of the remote addresses to which this channel's socket is connected.
abstract  boolean isConnectionPending()
          Tells whether or not a connection operation is in progress on this channel.
static SctpChannel open()
          Opens an SCTP channel.
static SctpChannel open(SocketAddress remote, int maxOutStreams, int maxInStreams)
          Opens an SCTP channel and connects it to a remote address.
abstract
<T> MessageInfo
receive(ByteBuffer dst, T attachment, NotificationHandler<T> handler)
          Receives a message into the given buffer and/or handles a notification.
abstract  int send(ByteBuffer src, MessageInfo messageInfo)
          Sends a message via this channel.
abstract
<T> SctpChannel
setOption(SctpSocketOption<T> name, T value)
          Sets the value of a socket option.
abstract  SctpChannel shutdown()
          Shutdown a connection without closing the channel.
abstract  Set<SctpSocketOption<?>> supportedOptions()
          Returns a set of the socket options supported by this channel.
abstract  SctpChannel unbindAddress(InetAddress address)
          Removes the given address from the bound addresses for the channel's socket.
 int validOps()
          Returns an operation set identifying this channel's supported operations.
 
Methods inherited from class java.nio.channels.spi.AbstractSelectableChannel
blockingLock, configureBlocking, implCloseChannel, implCloseSelectableChannel, implConfigureBlocking, isBlocking, isRegistered, keyFor, provider, register
 
Methods inherited from class java.nio.channels.SelectableChannel
register
 
Methods inherited from class java.nio.channels.spi.AbstractInterruptibleChannel
begin, close, end, isOpen
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface java.nio.channels.Channel
close, isOpen
 

Constructor Detail

SctpChannel

protected SctpChannel(SelectorProvider provider)
Initializes a new instance of this class.

Parameters:
provider - The selector provider for this channel
Method Detail

open

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

The new channel is unbound and unconnected.

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

open

public static SctpChannel open(SocketAddress remote,
                               int maxOutStreams,
                               int maxInStreams)
                        throws IOException
Opens an SCTP channel and connects it to a remote address.

This is a convenience method and is equivalent to evaluating the following expression:

 open().connect(remote, maxOutStreams, maxInStreams);
 

Parameters:
remote - The remote address to which the new channel is to be connected
maxOutStreams - The number of streams that the application wishes to be able to send to. Must be non negative and no larger than 65536. 0 to use the endpoints default value.
maxInStreams - The maximum number of inbound streams the application is prepared to support. Must be non negative and no larger than 65536. 0 to use the endpoints default value.
Returns:
A new SCTP channel connected to the given address
Throws:
AsynchronousCloseException - If another thread closes this channel while the connect operation is in progress
ClosedByInterruptException - If another thread interrupts the current thread while the connect operation is in progress, thereby closing the channel and setting the current thread's interrupt status
UnresolvedAddressException - If the given remote address is not fully resolved
UnsupportedAddressTypeException - If the type of the given remote address is not supported
SecurityException - If a security manager has been installed and it does not permit access to the given remote peer
UnsupportedOperationException - If the SCTP protocol is not supported
IOException - If some other I/O error occurs

association

public abstract Association association()
                                 throws IOException
Returns the association on this channel's socket.

Returns:
the association, or null if the channel's socket is not connected.
Throws:
ClosedChannelException - If the channel is closed
IOException - If some other I/O error occurs

bind

public abstract SctpChannel bind(SocketAddress local)
                          throws IOException
Binds the channel's socket to a local address.

This method is used to establish a relationship between the socket and the local addresses. 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.

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:
AlreadyConnectedException - If this channel is already connected
ClosedChannelException - If this channel is closed
ConnectionPendingException - If a non-blocking connection operation is already in progress on this channel
AlreadyBoundException - If this channel is already bound
UnsupportedAddressTypeException - If the type of the given address is not supported
IOException - If some other I/O error occurs

bindAddress

public abstract SctpChannel 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.

Adding addresses to a connected association 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
ConnectionPendingException - If a non-blocking connection operation is already in progress on this channel
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 SctpChannel 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.

Removing addresses from a connected association 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
ConnectionPendingException - If a non-blocking connection operation is already in progress on this channel
NotYetBoundException - If this channel is not yet bound
IllegalArgumentException - If address is null or the wildcard address
IllegalUnbindException - If address is not bound to the channel's socket. or the channel has only one address bound to it
IOException - If some other I/O error occurs

connect

public abstract boolean connect(SocketAddress remote)
                         throws IOException
Connects this channel's socket.

If this channel is in non-blocking mode then an invocation of this method initiates a non-blocking connection operation. If the connection is established immediately, as can happen with a local connection, then this method returns true. Otherwise this method returns false and the connection operation must later be completed by invoking the finishConnect method.

If this channel is in blocking mode then an invocation of this method will block until the connection is established or an I/O error occurs.

If a security manager has been installed then this method verifies that its checkConnect method permits connecting to the address and port number of the given remote peer.

This method may be invoked at any time. If a send or receive operation upon this channel is invoked while an invocation of this method is in progress then that operation will first block until this invocation is complete. If a connection attempt is initiated but fails, that is, if an invocation of this method throws a checked exception, then the channel will be closed.

Parameters:
remote - The remote peer to which this channel is to be connected
Returns:
true if a connection was established, false if this channel is in non-blocking mode and the connection operation is in progress
Throws:
AlreadyConnectedException - If this channel is already connected
ConnectionPendingException - If a non-blocking connection operation is already in progress on this channel
ClosedChannelException - If this channel is closed
AsynchronousCloseException - If another thread closes this channel while the connect operation is in progress
ClosedByInterruptException - If another thread interrupts the current thread while the connect operation is in progress, thereby closing the channel and setting the current thread's interrupt status
UnresolvedAddressException - If the given remote address is not fully resolved
UnsupportedAddressTypeException - If the type of the given remote address is not supported
SecurityException - If a security manager has been installed and it does not permit access to the given remote peer
IOException - If some other I/O error occurs

connect

public abstract boolean connect(SocketAddress remote,
                                int maxOutStreams,
                                int maxInStreams)
                         throws IOException
Connects this channel's socket.

This is a convience method and is equivalent to evaluating the following expression:

 setOption(SctpStandardSocketOption.SCTP_INIT_MAXSTREAMS, SctpStandardSocketOption.InitMaxStreams.create(maxInStreams, maxOutStreams))
  .connect(remote);
 

The maxOutStreams and maxInStreams parameters represent the maximum number of streams that the application wishes to be able to send to and receive from. They are negotiated with the remote peer and may be limited by the operating system.

Parameters:
remote - The remote peer to which this channel is to be connected
maxOutStreams - Must be non negative and no larger than 65536. 0 to use the endpoints default value.
maxInStreams - Must be non negative and no larger than 65536. 0 to use the endpoints default value.
Returns:
true if a connection was established, false if this channel is in non-blocking mode and the connection operation is in progress
Throws:
AlreadyConnectedException - If this channel is already connected
ConnectionPendingException - If a non-blocking connection operation is already in progress on this channel
ClosedChannelException - If this channel is closed
AsynchronousCloseException - If another thread closes this channel while the connect operation is in progress
ClosedByInterruptException - If another thread interrupts the current thread while the connect operation is in progress, thereby closing the channel and setting the current thread's interrupt status
UnresolvedAddressException - If the given remote address is not fully resolved
UnsupportedAddressTypeException - If the type of the given remote address is not supported
SecurityException - If a security manager has been installed and it does not permit access to the given remote peer
IOException - If some other I/O error occurs

isConnectionPending

public abstract boolean isConnectionPending()
Tells whether or not a connection operation is in progress on this channel.

Returns:
true if, and only if, a connection operation has been initiated on this channel but not yet completed by invoking the finishConnect() method

finishConnect

public abstract boolean finishConnect()
                               throws IOException
Finishes the process of connecting an SCTP channel.

A non-blocking connection operation is initiated by placing a socket channel in non-blocking mode and then invoking one of its connect methods. Once the connection is established, or the attempt has failed, the channel will become connectable and this method may be invoked to complete the connection sequence. If the connection operation failed then invoking this method will cause an appropriate IOException to be thrown.

If this channel is already connected then this method will not block and will immediately return true. If this channel is in non-blocking mode then this method will return false if the connection process is not yet complete. If this channel is in blocking mode then this method will block until the connection either completes or fails, and will always either return true or throw a checked exception describing the failure.

This method may be invoked at any time. If a send or receive operation upon this channel is invoked while an invocation of this method is in progress then that operation will first block until this invocation is complete. If a connection attempt fails, that is, if an invocation of this method throws a checked exception, then the channel will be closed.

Returns:
true if, and only if, this channel's socket is now connected
Throws:
NoConnectionPendingException - If this channel is not connected and a connection operation has not been initiated
ClosedChannelException - If this channel is closed
AsynchronousCloseException - If another thread closes this channel while the connect operation is in progress
ClosedByInterruptException - If another thread interrupts the current thread while the connect operation is in progress, thereby closing the channel and setting the current thread's interrupt status
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()
                                               throws IOException
Returns all of the remote addresses to which this channel's socket is connected.

If the channel is connected to a remote peer that is bound to multiple addresses then it is these addresses that the channel's socket is connected.

Returns:
All of the remote addresses to which this channel's socket is connected, or an empty Set if the channel's socket is not connected
Throws:
ClosedChannelException - If the channel is closed
IOException - If an I/O error occurs

shutdown

public abstract SctpChannel shutdown()
                              throws IOException
Shutdown a connection without closing the channel.

Sends a shutdown command to the remote peer, effectively preventing any new data from being written to the socket by either peer. Further sends will throw ClosedChannelException. The channel remains open to allow the for any data (and notifications) to be received that may have been sent by the peer before it received the shutdown command. If the channel is already shutdown then invoking this method has no effect.

Returns:
This channel
Throws:
NotYetConnectedException - If this channel is not yet connected
ClosedChannelException - If this channel is closed
IOException - If some other I/O error occurs

getOption

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

Parameters:
name - The socket option
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:
SctpStandardSocketOption

setOption

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

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.
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:
SctpStandardSocketOption

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

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

receive

public abstract <T> MessageInfo receive(ByteBuffer dst,
                                        T attachment,
                                        NotificationHandler<T> handler)
                             throws IOException
Receives a message into the given buffer and/or handles a notification.

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. 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.

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.

Parameters:
dst - The buffer into which message 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
NotYetConnectedException - If this channel is not yet connected
IllegalReceiveException - If the given handler invokes the receive method of this channel
IOException - If some other I/O error occurs

send

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

If this channel is in non-blocking mode and there is sufficient room in the underlying output buffer, or if this channel is in blocking mode and sufficient room becomes available, 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.

The message is transferred from the byte buffer as if by a regular write operation.

The bytes will be written to the stream number that is specified by streamNumber in the given messageInfo.

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:
src - 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:
InvalidStreamExcepton - If streamNumner is negative or greater than or equal to 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
NotYetConnectedException - If this channel is not yet connected
IOException - If some other I/O error occurs

JavaTM SCTP API
DRAFT ea-b11