rocks.xmpp.core.session

Interface ReconnectionStrategy

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface ReconnectionStrategy

A strategy for reconnection logic, i.e. when and in which interval reconnection attempts will happen. You can provide your own strategy by implementing this interface.

Alternatively you can use some of the predefined strategies which you can retrieve by one of the static methods.

E.g. after(long, TimeUnit) always tries to reconnect after a fix amount of time.

See Also:

ReconnectionManager.setReconnectionStrategy(ReconnectionStrategy)

Method Summary

Modifier and Type	Method and Description
static ReconnectionStrategy	after(long duration, TimeUnit timeUnit) Reconnects always after a fix amount of time, e.g. after 10 seconds.
long	getNextReconnectionAttempt(int attempt, Throwable cause) Gets the time (in seconds) until the next reconnection is attempted.
default boolean	mayReconnect(Throwable e)
static ReconnectionStrategy	truncatedBinaryExponentialBackoffStrategy(int slotTime, int ceiling) This is the default reconnection strategy used by the ReconnectionManager.

Method Detail

mayReconnect

default boolean mayReconnect(Throwable e)

getNextReconnectionAttempt

long getNextReconnectionAttempt(int attempt,
                                Throwable cause)

Gets the time (in seconds) until the next reconnection is attempted.

Parameters:

attempt - The current reconnection attempt. The first attempt is 0, the second attempt is 1, etc...

cause - The cause for the disconnection.

Returns:

The number of seconds before the next reconnection is attempted.

truncatedBinaryExponentialBackoffStrategy

static ReconnectionStrategy truncatedBinaryExponentialBackoffStrategy(int slotTime,
                                                                      int ceiling)

This is the default reconnection strategy used by the ReconnectionManager.

It exponentially increases the time span from which a random value for the next reconnection attempt is chosen. The formula for doing this, is: (2n - 1) * s, where n is the number of reconnection attempt and s is the slot time, which is 60 seconds by default.

In practice this means, the first reconnection attempt occurs after a random period of time between 0 and 60 seconds.
The second attempt chooses a random number between 0 and 180 seconds.
The third attempt chooses a random number between 0 and 420 seconds.
The fourth attempt chooses a random number between 0 and 900 seconds.
The fifth attempt chooses a random number between 0 and 1860 seconds (= 31 minutes)

The strategy is called "truncated", because it won't increase the time span after the nth iteration, which means in the example above, the sixth and any further attempt behaves equally to the fifth attempt.

This "truncated binary exponential backoff" is the recommended reconnection strategy by the XMPP specification.

Parameters:

slotTime - The slot time (in seconds), usually 60.

ceiling - The ceiling, i.e. when the time is truncated. E.g. if the ceiling is 4, the back off is truncated at the 5th reconnection attempt (it starts at zero).

Returns:

The truncated binary exponential backoff strategy.

after

static ReconnectionStrategy after(long duration,
                                  TimeUnit timeUnit)

Reconnects always after a fix amount of time, e.g. after 10 seconds.

Parameters:

duration - The fix duration after which a reconnection is attempted.

timeUnit - The time unit.

Returns:

The reconnection strategy.