Package com.vaadin.collaborationengine

Interface CollaborationMessagePersister

All Superinterfaces:

Serializable

public interface CollaborationMessagePersister
extends Serializable

Persister of CollaborationMessage items, which enables to read and write messages from/to a backend, for example a database.

It can be used with a CollaborationMessageList to have the component read messages from the backend when attached and write new messages to it when appended to the list with a submitter component, e.g. CollaborationMessageInput.

Since:

3.1

Author:

Vaadin Ltd

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	CollaborationMessagePersister.FetchQuery	A query to fetch messages from a backend.
static class	CollaborationMessagePersister.PersistRequest	A request to persist messages to a backend.

Method Summary

Modifier and Type	Method	Description
Stream<CollaborationMessage>	fetchMessages(CollaborationMessagePersister.FetchQuery query)	Reads a stream of CollaborationMessage items from a persistence backend.
static CollaborationMessagePersister	fromCallbacks(SerializableFunction<CollaborationMessagePersister.FetchQuery,Stream<CollaborationMessage>> fetchCallback, SerializableConsumer<CollaborationMessagePersister.PersistRequest> persistCallback)	Creates an instance of CollaborationMessagePersister from the provided callbacks.
void	persistMessage(CollaborationMessagePersister.PersistRequest request)	Writes a CollaborationMessage to the persistence backend.

Method Detail

fromCallbacks

static CollaborationMessagePersister fromCallbacks(SerializableFunction<CollaborationMessagePersister.FetchQuery,Stream<CollaborationMessage>> fetchCallback,
                                                   SerializableConsumer<CollaborationMessagePersister.PersistRequest> persistCallback)

Creates an instance of CollaborationMessagePersister from the provided callbacks.

Parameters:

fetchCallback - the callback to fetch messages, not null

persistCallback - the callback to persist messages, not null

Returns:

the persister instance

fetchMessages

Stream<CollaborationMessage> fetchMessages(CollaborationMessagePersister.FetchQuery query)

Reads a stream of CollaborationMessage items from a persistence backend. The query parameter contains the topic identifier and the timestamp from which messages should be read.

Note: You must include the messages sent during or after the timestamp returned from CollaborationMessagePersister.FetchQuery.getSince(), including the messages sent at that exact time. More formally, you should return all such messages, for which the following condition is true:

 message.getTime() >= fetchQuery.getSince()
 

Parameters:

query - the fetch query

Returns:

a stream of messages

persistMessage

void persistMessage(CollaborationMessagePersister.PersistRequest request)

Writes a CollaborationMessage to the persistence backend.

It is recommended to let the backend set the message timestamp and only use CollaborationMessage.getTime() as a fallback.

Parameters:

request - the request to persist the message