# Class SctpServerChannel

java.lang.Object
java.nio.channels.spi.AbstractInterruptibleChannel
java.nio.channels.SelectableChannel
java.nio.channels.spi.AbstractSelectableChannel
com.sun.nio.sctp.SctpServerChannel

All Implemented Interfaces:
  `Closeable, AutoCloseable, Channel, InterruptibleChannel`

public abstract class SctpServerChannel extends AbstractSelectableChannel
A selectable channel for message-oriented listening SCTP sockets.

An `SCTPServerChannel` is created by invoking the `open` method of this class. A newly-created SCTP server channel is open but not yet bound. An attempt to invoke the `accept` method of an unbound channel will cause the `NotYetBoundException` to be thrown. An SCTP server channel can be bound by invoking one of the `bind` methods defined by this class.

Socket options are configured using the `setOption` method. SCTP server socket channels support the following options:

> Socket options
> Option Name | Description
> --- | ---
> `SCTP_INIT_MAXSTREAMS` | The maximum number of streams requested by the local endpoint during association initialization

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

SCTP server channels are safe for use by multiple concurrent threads.

Since:
  1.7

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  `protected`
  `SctpServerChannel(SelectorProvider provider)`
  Initializes a new instance of this class.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `abstract SctpChannel`
  `accept()`
  Accepts an association on this channel's socket.
  `final SctpServerChannel`
  `bind(SocketAddress local)`
  Binds the channel's socket to a local address and configures the socket to listen for associations.
  `abstract SctpServerChannel`
  `bind(SocketAddress local, int backlog)`
  Binds the channel's socket to a local address and configures the socket to listen for associations.
  `abstract SctpServerChannel`
  `bindAddress(InetAddress address)`
  Adds the given address to the bound addresses for the channel's socket.
  `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.
  `static SctpServerChannel`
  `open()`
  Opens an SCTP server channel.
  `abstract <T> SctpServerChannel`
  `setOption(SctpSocketOption<T> name, T value)`
  Sets the value of a socket option.
  `abstract Set<SctpSocketOption<?>>`
  `supportedOptions()`
  Returns a set of the socket options supported by this channel.
  `abstract SctpServerChannel`
  `unbindAddress(InetAddress address)`
  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.

  ### Methods declared in class AbstractSelectableChannel

  `blockingLock, configureBlocking, implCloseChannel, implCloseSelectableChannel, implConfigureBlocking, isBlocking, isRegistered, keyFor, provider, register`

  ### Methods declared in class SelectableChannel

  `register`

  ### Methods declared in class AbstractInterruptibleChannel

  `begin, close, end, isOpen`

  ### Methods declared in class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

  ### Methods declared in interface Channel

  `isOpen`

- ## Constructor Details

  - ### SctpServerChannel

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

- ## Method Details

  - ### open

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

    The new channel's socket is initially unbound; it must be bound to a specific address via one of its socket's `bind` methods before associations can be accepted.

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

  - ### accept

    public abstract SctpChannel accept() throws IOException
    Accepts an association on this channel's socket.

    If this channel is in non-blocking mode then this method will immediately return `null` if there are no pending associations. Otherwise it will block indefinitely until a new association is available or an I/O error occurs.

    The `SCTPChannel` returned by this method, if any, will be in blocking mode regardless of the blocking mode of this channel.

    Returns:
      The SCTP channel for the new association, or `null` if this channel is in non-blocking mode and no association is available to be accepted
    Throws:
      `ClosedChannelException` - If this channel is closed
      `AsynchronousCloseException` - If another thread closes this channel while the accept operation is in progress
      `ClosedByInterruptException` - If another thread interrupts the current thread while the accept operation is in progress, thereby closing the channel and setting the current thread's interrupt status
      `NotYetBoundException` - If this channel's socket has not yet been bound
      `IOException` - If some other I/O error occurs

  - ### bind

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

    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
      `IOException` - If some other I/O error occurs

  - ### bind

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

    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 associations 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 associations
    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
      `IOException` - If some other I/O error occurs

  - ### bindAddress

    public abstract SctpServerChannel 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 accepted after this method successfully completes will be associated with the given address.

    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 SctpServerChannel 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 accepted after this method successfully completes will not be associated with the given address.

    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
      `IllegalArgumentException` - If address is `null` or the `wildcard` address
      `IllegalUnbindException` - If the implementation does not support removing addresses from a listening socket, `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

  - ### 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

  - ### getOption

    public abstract <T> T getOption(SctpSocketOption<T> name) throws IOException
    Returns the value of a socket option.
    Type Parameters:
      `T` - The type of the socket option value
    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:
      - `SctpStandardSocketOptions`

  - ### setOption

    public abstract <T> SctpServerChannel setOption(SctpSocketOption<T> name, T value) throws IOException
    Sets the value of a socket option.
    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.
    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:
      - `SctpStandardSocketOptions`

  - ### 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 server channels only support the accepting of new associations, so this method returns `SelectionKey.OP_ACCEPT`.

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