# Class MessageInfo

java.lang.Object
com.sun.nio.sctp.MessageInfo

public abstract class MessageInfo extends Object
The `MessageInfo` class provides additional ancillary information about messages.

Received SCTP messages, returned by `SctpChannel.receive` and `SctpMultiChannel.receive`, return a `MessageInfo` instance that can be queried to determine ancillary information about the received message. Messages being sent should use one of the `createOutgoing` methods to provide ancillary data for the message being sent, and may use the appropriate setter methods to override the default values provided for `unordered`, `timeToLive`, `complete` and `payloadProtocolID`, before sending the message.

For out going messages the `timeToLive` parameter is a time period that the sending side SCTP stack may expire the message if it has not been sent. This time period is an indication to the stack that the message is no longer required to be sent after the time period expires. It is not a hard timeout and may be influenced by whether the association supports the partial reliability extension, RFC 3758 .

`MessageInfo` instances are not safe for use by multiple concurrent threads. If a MessageInfo is to be used by more than one thread then access to the MessageInfo should be controlled by appropriate synchronization.

Since:
  1.7

- ## Constructor Summary

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

- ## Method Summary

  Modifier and Type
  Method
  Description
  `abstract SocketAddress`
  `address()`
  Returns the source socket address if the message has been received, otherwise the preferred destination of the message to be sent.
  `abstract Association`
  `association()`
  Returns the association that the message was received on, if the message has been received, otherwise the association that the message is to be sent on.
  `abstract int`
  `bytes()`
  Returns the number of bytes read for the received message.
  `abstract MessageInfo`
  `complete(boolean complete)`
  Sets whether or not the message is complete.
  `static MessageInfo`
  `createOutgoing(Association association, SocketAddress address, int streamNumber)`
  Creates a `MessageInfo` instance suitable for use when sending a message to a given association.
  `static MessageInfo`
  `createOutgoing(SocketAddress address, int streamNumber)`
  Creates a `MessageInfo` instance suitable for use when sending a message.
  `abstract boolean`
  `isComplete()`
  Tells whether or not the message is complete.
  `abstract boolean`
  `isUnordered()`
  Tells whether or not the message is unordered.
  `abstract int`
  `payloadProtocolID()`
  Returns the payload protocol Identifier.
  `abstract MessageInfo`
  `payloadProtocolID(int ppid)`
  Sets the payload protocol Identifier.
  `abstract int`
  `streamNumber()`
  Returns the stream number that the message was received on, if the message has been received, otherwise the stream number that the message is to be sent on.
  `abstract MessageInfo`
  `streamNumber(int streamNumber)`
  Sets the stream number that the message is to be sent on.
  `abstract long`
  `timeToLive()`
  The time period that the sending side may expire the message if it has not been sent, or `0` to indicate that no timeout should occur.
  `abstract MessageInfo`
  `timeToLive(long millis)`
  Sets the time period that the sending side may expire the message if it has not been sent.
  `abstract MessageInfo`
  `unordered(boolean unordered)`
  Sets whether or not the message is unordered.

  ### Methods declared in class java.lang.Object

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

- ## Constructor Details

  - ### MessageInfo

    protected MessageInfo()
    Initializes a new instance of this class.

- ## Method Details

  - ### createOutgoing

    public static MessageInfo createOutgoing(SocketAddress address, int streamNumber)
    Creates a `MessageInfo` instance suitable for use when sending a message.

    The returned instance will have its `unordered` value set to `false`, its `timeToLive` value set to `0`, its `complete` value set to `true`, and its `payloadProtocolID` value set to `0`. These values, if required, can be set through the appropriate setter method before sending the message.

    Parameters:
      `address` - For a connected `SctpChannel` the address is the preferred peer address of the association to send the message to, or `null` to use the peer primary address. For an `SctpMultiChannel` the address is used to determine the association, or if no association exists with a peer of that address then one is setup.
      `streamNumber` - The stream number that the message will be sent on
    Returns:
      The outgoing message info
    Throws:
      `IllegalArgumentException` - If the streamNumber is negative or greater than `65536`

  - ### createOutgoing

    public static MessageInfo createOutgoing(Association association, SocketAddress address, int streamNumber)
    Creates a `MessageInfo` instance suitable for use when sending a message to a given association. Typically used for `SctpMultiChannel` when an association has already been setup.

    The returned instance will have its `unordered` value set to `false`, its `timeToLive` value set to `0`, its `complete` value set to `true`, and its `payloadProtocolID` value set to `0`. These values, if required, can be set through the appropriate setter method before sending the message.

    Parameters:
      `association` - The association to send the message on
      `address` - The preferred peer address of the association to send the message to, or `null` to use the peer primary address
      `streamNumber` - The stream number that the message will be sent on.
    Returns:
      The outgoing message info
    Throws:
      `IllegalArgumentException` - If `association` is `null`, or the streamNumber is negative or greater than `65536`

  - ### address

    public abstract SocketAddress address()
    Returns the source socket address if the message has been received, otherwise the preferred destination of the message to be sent.
    Returns:
      The socket address, or `null` if this instance is to be used for sending a message and has been construced without specifying a preferred destination address

  - ### association

    public abstract Association association()
    Returns the association that the message was received on, if the message has been received, otherwise the association that the message is to be sent on.
    Returns:
      The association, or `null` if this instance is to be used for sending a message and has been construced using the the `createOutgoing(SocketAddress,int)` static factory method

  - ### bytes

    public abstract int bytes()
    Returns the number of bytes read for the received message.

    This method is only appicable for received messages, it has no meaning for messages being sent.

    Returns:
      The number of bytes read, `-1` if the channel is an `SctpChannel` that has reached end-of-stream, otherwise `0`

  - ### isComplete

    public abstract boolean isComplete()
    Tells whether or not the message is complete.

    For received messages `true` indicates that the message was completely received. For messages being sent `true` indicates that the message is complete, `false` indicates that the message is not complete. How the send channel interprets this value depends on the value of its `SCTP_EXPLICIT_COMPLETE` socket option.

    Returns:
      `true` if, and only if, the message is complete

  - ### complete

    public abstract MessageInfo complete(boolean complete)
    Sets whether or not the message is complete.

    For messages being sent `true` indicates that the message is complete, `false` indicates that the message is not complete. How the send channel interprets this value depends on the value of its `SCTP_EXPLICIT_COMPLETE` socket option.

    Parameters:
      `complete` - `true` if, and only if, the message is complete
    Returns:
      This MessageInfo
    See Also:
      - `isComplete()`

  - ### isUnordered

    public abstract boolean isUnordered()
    Tells whether or not the message is unordered. For received messages `true` indicates that the message was sent non-ordered. For messages being sent `true` requests the un-ordered delivery of the message, `false` indicates that the message is ordered.
    Returns:
      `true` if the message is unordered, otherwise `false`

  - ### unordered

    public abstract MessageInfo unordered(boolean unordered)
    Sets whether or not the message is unordered.
    Parameters:
      `unordered` - `true` requests the un-ordered delivery of the message, `false` indicates that the message is ordered.
    Returns:
      This MessageInfo
    See Also:
      - `isUnordered()`

  - ### payloadProtocolID

    public abstract int payloadProtocolID()
    Returns the payload protocol Identifier.

    A value indicating the type of payload protocol data being transmitted/received. This value is passed as opaque data by SCTP. `0` indicates an unspecified payload protocol identifier.

    Returns:
      The Payload Protocol Identifier

  - ### payloadProtocolID

    public abstract MessageInfo payloadProtocolID(int ppid)
    Sets the payload protocol Identifier.

    A value indicating the type of payload protocol data being transmitted. This value is passed as opaque data by SCTP.

    Parameters:
      `ppid` - The Payload Protocol Identifier, or `0` indicate an unspecified payload protocol identifier.
    Returns:
      This MessageInfo
    See Also:
      - `payloadProtocolID()`

  - ### streamNumber

    public abstract int streamNumber()
    Returns the stream number that the message was received on, if the message has been received, otherwise the stream number that the message is to be sent on.
    Returns:
      The stream number

  - ### streamNumber

    public abstract MessageInfo streamNumber(int streamNumber)
    Sets the stream number that the message is to be sent on.
    Parameters:
      `streamNumber` - The stream number
    Returns:
      This MessageInfo
    Throws:
      `IllegalArgumentException` - If the streamNumber is negative or greater than `65536`

  - ### timeToLive

    public abstract long timeToLive()
    The time period that the sending side may expire the message if it has not been sent, or `0` to indicate that no timeout should occur. This value is only applicable for messages being sent, it has no meaning for received messages.
    Returns:
      The time period in milliseconds, or `0`

  - ### timeToLive

    public abstract MessageInfo timeToLive(long millis)
    Sets the time period that the sending side may expire the message if it has not been sent.
    Parameters:
      `millis` - The time period in milliseconds, or `0` to indicate that no timeout should occur
    Returns:
      This MessageInfo
    See Also:
      - `timeToLive()`