com.vaadin.collaborationengine

Interface CollaborationMap

public interface CollaborationMap

A map that is shared between multiple users. Map instances can be retrieved through a TopicConnection. Changes performed by one user will be delivered as events to subscribers defined by other users.

Author:

Vaadin Ltd

Method Summary

Modifier and Type	Method and Description
<T> T	get(String key, Class<T> type) Gets the map value for the given key as an instance of the given class.
<T> T	get(String key, com.fasterxml.jackson.core.type.TypeReference<T> type) Gets the map value for the given key as an instance corresponding to the given type reference.
TopicConnection	getConnection() Gets the topic connection which is used to propagate changes to this map.
Stream<String>	getKeys() Gets a stream of the currently available keys.
CompletableFuture<Void>	put(String key, Object value) Associates the given value with the given key.
CompletableFuture<Boolean>	replace(String key, Object expectedValue, Object newValue) Atomically replaces the value for a key if and only if the current value is as expected.
Registration	subscribe(MapSubscriber subscriber) Subscribes to changes to this map.

Method Detail

get

<T> T get(String key,
          Class<T> type)

Gets the map value for the given key as an instance of the given class.

Parameters:

key - the string key for which to get a value, not null

type - the expected type

Returns:

the value associated with the key, or null if no value is present

Throws:

JsonConversionException - if the value in the map cannot be converted to an instance of the given class

get

<T> T get(String key,
          com.fasterxml.jackson.core.type.TypeReference<T> type)

Gets the map value for the given key as an instance corresponding to the given type reference.

Parameters:

key - the string key for which to get a value, not null

type - the type reference of the expected type to get

Returns:

the value associated with the key, or null if no value is present

Throws:

JsonConversionException - if the value in the map cannot be converted to an instance of the given type reference

put

CompletableFuture<Void> put(String key,
                            Object value)

Associates the given value with the given key. This method can also be used to remove an association by passing null as the value. Subscribers are notified if the new value isn't equals() with the old value.

The given value must be JSON-serializable so it can be sent over the network when Collaboration Engine is hosted in a standalone server.

Parameters:

key - the string key for which to make an association, not null

value - the value to set, or null to remove the association

Returns:

a completable future that is resolved when the data update is completed.

Throws:

JsonConversionException - if the given value isn't serializable as JSON string

replace

CompletableFuture<Boolean> replace(String key,
                                   Object expectedValue,
                                   Object newValue)

Atomically replaces the value for a key if and only if the current value is as expected. Subscribers are notified if the new value isn't equals() with the old value. equals() is also used to compare the current value with the expected value.

The given value must be JSON-serializable so it can be sent over the network when Collaboration Engine is hosted in a standalone server.

Parameters:

key - the string key for which to make an association, not null

expectedValue - the value to compare with the current value to determine whether to make an update, or null to expect that no value is present

newValue - the new value to set, or null to remove the association

Returns:

a boolean completable future that is resolved when the data update is completed. The resolved value is true if the expected value was present so that the operation could proceed; false if the expected value was not present

Throws:

JsonConversionException - if the given value isn't serializable as JSON string

getKeys

Stream<String> getKeys()

Gets a stream of the currently available keys. The stream is backed by a current snapshot of the available keys and will thus not update even if keys are added or removed before the stream is processed.

Returns:

the stream of keys, not null

subscribe

Registration subscribe(MapSubscriber subscriber)

Subscribes to changes to this map. When subscribing, the subscriber will receive an event for each current value association.

Parameters:

subscriber - the subscriber to use, not null

Returns:

a handle that can be used for removing the subscription, not null

getConnection

TopicConnection getConnection()

Gets the topic connection which is used to propagate changes to this map.

Returns:

the topic connection used by this map, not null