org.apache.samza.operators

Interface StreamGraph

@InterfaceStability.Unstable
public interface StreamGraph

Provides access to MessageStreams and OutputStreams used to describe the processing logic.

Method Summary

Modifier and Type	Method and Description
<K,V,M> MessageStream<M>	getInputStream(java.lang.String streamId, java.util.function.BiFunction<? super K,? super V,? extends M> msgBuilder) Gets the input MessageStream corresponding to the streamId.
<K,V,M> OutputStream<K,V,M>	getOutputStream(java.lang.String streamId, java.util.function.Function<? super M,? extends K> keyExtractor, java.util.function.Function<? super M,? extends V> msgExtractor) Gets the OutputStream corresponding to the streamId.
StreamGraph	withContextManager(ContextManager contextManager) Sets the ContextManager for this StreamGraph.

Method Detail

getInputStream

<K,V,M> MessageStream<M> getInputStream(java.lang.String streamId,
                                        java.util.function.BiFunction<? super K,? super V,? extends M> msgBuilder)

Gets the input MessageStream corresponding to the streamId.

Multiple invocations of this method with the same streamId will throw an IllegalStateException.

Type Parameters:

K - the type of key in the incoming message

V - the type of message in the incoming message

M - the type of message in the input MessageStream

Parameters:

streamId - the unique ID for the stream

msgBuilder - the BiFunction to convert the incoming key and message to a message in the input MessageStream

Returns:

the input MessageStream

Throws:

java.lang.IllegalStateException - when invoked multiple times with the same streamId

getOutputStream

<K,V,M> OutputStream<K,V,M> getOutputStream(java.lang.String streamId,
                                            java.util.function.Function<? super M,? extends K> keyExtractor,
                                            java.util.function.Function<? super M,? extends V> msgExtractor)

Gets the OutputStream corresponding to the streamId.

Multiple invocations of this method with the same streamId will throw an IllegalStateException.

Type Parameters:

K - the type of key in the outgoing message

V - the type of message in the outgoing message

M - the type of message in the OutputStream

Parameters:

streamId - the unique ID for the stream

keyExtractor - the Function to extract the outgoing key from the output message

msgExtractor - the Function to extract the outgoing message from the output message

Returns:

the output MessageStream

Throws:

java.lang.IllegalStateException - when invoked multiple times with the same streamId

withContextManager

StreamGraph withContextManager(ContextManager contextManager)

Sets the ContextManager for this StreamGraph.

The provided ContextManager can be used to setup shared context between the operator functions within a task instance

Parameters:

contextManager - the ContextManager to use for the StreamGraph

Returns:

the StreamGraph with contextManager set as its ContextManager