org.wso2.mb.integration.common.clients

Enum QualityOfService

java.lang.Object

java.lang.Enum<QualityOfService>

org.wso2.mb.integration.common.clients.QualityOfService

All Implemented Interfaces:

Serializable, Comparable<QualityOfService>

public enum QualityOfService
extends Enum<QualityOfService>

The quality of service levels in MQTT.

Enum Constant Summary

Enum Constants

Enum Constant and Description
EXACTLY_ONCE The message is always delivered exactly once.
LEAST_ONCE The message is always delivered at least once.
MOST_ONCE The message is delivered at most once, or it may not be delivered at all.

Method Summary

Modifier and Type	Method and Description
int	getValue() Get the corresponding value for the given quality of service.
static QualityOfService	valueOf(String name) Returns the enum constant of this type with the specified name.
static QualityOfService[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

MOST_ONCE

public static final QualityOfService MOST_ONCE

The message is delivered at most once, or it may not be delivered at all. Its delivery across the network is not acknowledged. The message is not stored. The message could be lost if the client is disconnected, or if the server fails. QoS0 is the fastest mode of transfer. It is sometimes called "fire and forget".

LEAST_ONCE

public static final QualityOfService LEAST_ONCE

The message is always delivered at least once. It might be delivered multiple times if there is a failure before an acknowledgment is received by the sender. The message must be stored locally at the sender, until the sender receives confirmation that the message has been published by the receiver. The message is stored in case the message must be sent again.

EXACTLY_ONCE

public static final QualityOfService EXACTLY_ONCE

The message is always delivered exactly once. The message must be stored locally at the sender, until the sender receives confirmation that the message has been published by the receiver. The message is stored in case the message must be sent again. QoS2 is the safest, but slowest mode of transfer. A more sophisticated handshaking and acknowledgement sequence is used than for QoS1 to ensure no duplication of messages occurs.

Method Detail

values

public static QualityOfService[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (QualityOfService c : QualityOfService.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static QualityOfService valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

getValue

public int getValue()

Get the corresponding value for the given quality of service. Retrieve this value whenever quality of service level needs to feed into external libraries.

Returns:

The integer representation of this quality of service