io.pravega.client

Interface ClientFactory

All Superinterfaces:

java.lang.AutoCloseable

public interface ClientFactory
extends java.lang.AutoCloseable

Used to create Writers, Readers, and Synchronizers operating on a stream.

Events that are written to a stream can be read by a reader. All events can be processed with exactly once semantics provided the reader has the ability to restore to the correct position upon failure. See EventRead.getPosition()

A note on ordering: Events inside of a stream have a strict order, but may need to be divided between multiple readers for scaling. In order to process events in parallel on different hosts and still have some ordering guarantees; events written to a stream have a routingKey see EventStreamWriter.writeEvent(String, Object). Events within a routing key are strictly ordered (i.e. They must go the the same reader or its replacement). However because ReaderGroups process events in parallel there is no ordering between different readers.

A note on scaling: Because a stream can grow in its event rate, streams are divided into Segments. For the most part this is an implementation detail. However its worth understanding that the way a stream is divided between multiple readers in a group that wish to split the messages between them is by giving different segments to different readers.

Method Summary

Modifier and Type	Method and Description
void	close() Closes the client factory.
BatchClient	createBatchClient() Create a new batch client.
<T> EventStreamWriter<T>	createEventWriter(java.lang.String streamName, Serializer<T> s, EventWriterConfig config) Creates a new writer that can write to the specified stream.
<T> EventStreamReader<T>	createReader(java.lang.String readerId, java.lang.String readerGroup, Serializer<T> s, ReaderConfig config) Creates (or recreates) a new reader that is part of a ReaderGroup.
<T> RevisionedStreamClient<T>	createRevisionedStreamClient(java.lang.String streamName, Serializer<T> serializer, SynchronizerConfig config) Creates a new RevisionedStreamClient that will work with the specified stream.
<StateT extends Revisioned,UpdateT extends Update<StateT>,InitT extends InitialUpdate<StateT>> StateSynchronizer<StateT>	createStateSynchronizer(java.lang.String streamName, Serializer<UpdateT> updateSerializer, Serializer<InitT> initSerializer, SynchronizerConfig config) Creates a new StateSynchronizer that will work on the specified stream.
static ClientFactory	withScope(java.lang.String scope, java.net.URI controllerUri) Creates a new instance of Client Factory.

Method Detail

withScope

static ClientFactory withScope(java.lang.String scope,
                               java.net.URI controllerUri)

Creates a new instance of Client Factory.

Parameters:

scope - The scope string.

controllerUri - The URI for controller.

Returns:

Instance of ClientFactory implementation.

createEventWriter

<T> EventStreamWriter<T> createEventWriter(java.lang.String streamName,
                                           Serializer<T> s,
                                           EventWriterConfig config)

Creates a new writer that can write to the specified stream.

Type Parameters:

T - The type of events.

Parameters:

streamName - The name of the stream to write to.

config - The writer configuration.

s - The Serializer.

Returns:

Newly created writer object

createReader

<T> EventStreamReader<T> createReader(java.lang.String readerId,
                                      java.lang.String readerGroup,
                                      Serializer<T> s,
                                      ReaderConfig config)

Creates (or recreates) a new reader that is part of a ReaderGroup. The reader will join the group and the members of the group will automatically rebalance among themselves.

In the event that the reader dies, the method ReaderGroup.readerOffline(String, Position) should be called, passing the last position of the reader. (Usually done by storing the position along with the output when it is processed.) Which will trigger redistribute the events among the remaining readers.

Note that calling reader offline while the reader is still online may result in multiple reader within the group receiving the same events.

Type Parameters:

T - The type of events.

Parameters:

readerId - A unique name (within the group) for this readers.

readerGroup - The name of the group to join.

s - The serializer for events.

config - The readers configuration.

Returns:

Newly created reader object that is a part of reader group

createRevisionedStreamClient

<T> RevisionedStreamClient<T> createRevisionedStreamClient(java.lang.String streamName,
                                                           Serializer<T> serializer,
                                                           SynchronizerConfig config)

Creates a new RevisionedStreamClient that will work with the specified stream.

Type Parameters:

T - The type of events

Parameters:

streamName - The name of the stream for the synchronizer

serializer - The serializer for updates.

config - The client configuration

Returns:

Revisioned stream client

createStateSynchronizer

<StateT extends Revisioned,UpdateT extends Update<StateT>,InitT extends InitialUpdate<StateT>> StateSynchronizer<StateT> createStateSynchronizer(java.lang.String streamName,
                                                                                                                                                 Serializer<UpdateT> updateSerializer,
                                                                                                                                                 Serializer<InitT> initSerializer,
                                                                                                                                                 SynchronizerConfig config)

Creates a new StateSynchronizer that will work on the specified stream.

Type Parameters:

StateT - The type of the state being synchronized.

UpdateT - The type of the updates being written.

InitT - The type of the initial update used.

Parameters:

streamName - The name of the stream for the synchronizer

updateSerializer - The serializer for updates.

initSerializer - The serializer for the initial update.

config - The synchronizer configuration

Returns:

Newly created StateSynchronizer that will work on the given stream

createBatchClient

@Beta
BatchClient createBatchClient()

Create a new batch client. A batch client can be used to perform bulk unordered reads without the need to create a reader group. Please note this is an experimental API.

Returns:

A batch client

close

void close()

Closes the client factory. This will close any connections created through it.

Specified by:

close in interface java.lang.AutoCloseable

See Also:

AutoCloseable.close()