org.axonframework.axonserver.connector.query

Class AxonServerQueryBus

java.lang.Object

org.axonframework.axonserver.connector.query.AxonServerQueryBus

All Implemented Interfaces:

Lifecycle, Distributed<QueryBus>, MessageDispatchInterceptorSupport<QueryMessage<?,?>>, MessageHandlerInterceptorSupport<QueryMessage<?,?>>, QueryBus

public class AxonServerQueryBus
extends Object
implements QueryBus, Distributed<QueryBus>, Lifecycle

Axon QueryBus implementation that connects to Axon Server to submit and receive queries and query responses. Delegates incoming queries to the provided localSegment.

Since:

4.0

Author:

Marc Gathier

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AxonServerQueryBus.Builder Builder class to instantiate an AxonServerQueryBus.

Nested classes/interfaces inherited from interface org.axonframework.lifecycle.Lifecycle

Lifecycle.LifecycleHandler, Lifecycle.LifecycleRegistry

Constructor Summary

Constructors

Constructor and Description
AxonServerQueryBus(AxonServerQueryBus.Builder builder) Instantiate a AxonServerQueryBus based on the fields contained in the AxonServerQueryBus.Builder.

Method Summary

Modifier and Type	Method and Description
static AxonServerQueryBus.Builder	builder() Instantiate a Builder to be able to create an AxonServerQueryBus.
void	disconnect() Disconnect the query bus from Axon Server, by unsubscribing all known query handlers.
QueryBus	localSegment() Return the message bus of type MessageBus which is regarded as the local segment for this implementation.
<Q,R> CompletableFuture<QueryResponseMessage<R>>	query(QueryMessage<Q,R> queryMessage) Dispatch the given query to a single QueryHandler subscribed to the given query's queryName and responseType.
QueryUpdateEmitter	queryUpdateEmitter() Gets the QueryUpdateEmitter associated with this QueryBus.
Registration	registerDispatchInterceptor(MessageDispatchInterceptor<? super QueryMessage<?,?>> dispatchInterceptor) Register the given DispatchInterceptor.
Registration	registerHandlerInterceptor(MessageHandlerInterceptor<? super QueryMessage<?,?>> interceptor) Register the given handlerInterceptor.
void	registerLifecycleHandlers(Lifecycle.LifecycleRegistry lifecycle) Registers the activities to be executed in the various phases of an application's lifecycle.
<Q,R> Stream<QueryResponseMessage<R>>	scatterGather(QueryMessage<Q,R> queryMessage, long timeout, TimeUnit timeUnit) Dispatch the given query to all QueryHandlers subscribed to the given query's queryName/responseType.
CompletableFuture<Void>	shutdownDispatching() Shutdown the query bus asynchronously for dispatching queries to Axon Server.
void	start() Start the Axon Server QueryBus implementation.
<Q,R> org.reactivestreams.Publisher<QueryResponseMessage<R>>	streamingQuery(StreamingQueryMessage<Q,R> query) Builds a Publisher of responses to the given query.
<R> Registration	subscribe(String queryName, Type responseType, MessageHandler<? super QueryMessage<?,R>> handler) Subscribe the given handler to queries with the given queryName and responseType.
<Q,I,U> SubscriptionQueryResult<QueryResponseMessage<I>,SubscriptionQueryUpdateMessage<U>>	subscriptionQuery(SubscriptionQueryMessage<Q,I,U> query, int updateBufferSize) Dispatch the given query to a single QueryHandler subscribed to the given query's queryName/initialResponseType/updateResponseType.
<Q,I,U> SubscriptionQueryResult<QueryResponseMessage<I>,SubscriptionQueryUpdateMessage<U>>	subscriptionQuery(SubscriptionQueryMessage<Q,I,U> query, SubscriptionQueryBackpressure backPressure, int updateBufferSize) Deprecated. in favor of using the {subscriptionQuery(SubscriptionQueryMessage, int)}

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.axonframework.queryhandling.QueryBus

subscriptionQuery

Constructor Detail

AxonServerQueryBus

public AxonServerQueryBus(AxonServerQueryBus.Builder builder)

Instantiate a AxonServerQueryBus based on the fields contained in the AxonServerQueryBus.Builder.

Parameters:

builder - the AxonServerQueryBus.Builder used to instantiate a AxonServerQueryBus instance

Method Detail

streamingQuery

public <Q,R> org.reactivestreams.Publisher<QueryResponseMessage<R>> streamingQuery(StreamingQueryMessage<Q,R> query)

Description copied from interface: QueryBus

Builds a Publisher of responses to the given query. The actual query is not dispatched until there is a subscription to the result. The query is dispatched to a single query handler. Implementations may opt for invoking several query handlers and then choosing a response from single one for performance or resilience reasons.

When no handlers are available that can answer the given query, the return Publisher will be completed with a NoHandlerForQueryException.

Specified by:

streamingQuery in interface QueryBus

Type Parameters:

Q - the payload type of the streaming query

R - the response type of the streaming query

Parameters:

query - the streaming query message

Returns:

a Publisher of responses

builder

public static AxonServerQueryBus.Builder builder()

Instantiate a Builder to be able to create an AxonServerQueryBus.

The QueryPriorityCalculator is defaulted to QueryPriorityCalculator.defaultQueryPriorityCalculator(), the TargetContextResolver defaults to a lambda returning the AxonServerConfiguration.getContext() as the context, the ExecutorServiceBuilder defaults to ExecutorServiceBuilder.defaultQueryExecutorServiceBuilder(). The AxonServerConnectionManager and the SpanFactory defaults to a NoOpSpanFactory. The AxonServerConfiguration, the local QueryBus, the QueryUpdateEmitter, and the message and generic Serializers are hard requirements and as such should be provided.

Returns:

a Builder to be able to create a AxonServerQueryBus

registerLifecycleHandlers

public void registerLifecycleHandlers(@Nonnull
                                      Lifecycle.LifecycleRegistry lifecycle)

Description copied from interface: Lifecycle

Registers the activities to be executed in the various phases of an application's lifecycle. This could either be at startup, shutdown, or both.

Specified by:

registerLifecycleHandlers in interface Lifecycle

Parameters:

lifecycle - the lifecycle instance to register the handlers with

See Also:

Lifecycle.LifecycleRegistry.onShutdown(int, Runnable), LifecycleRegistry#onShutdown(int, LifecycleHandler), Lifecycle.LifecycleRegistry.onStart(int, Runnable), LifecycleRegistry#onStart(int, LifecycleHandler)

start

public void start()

Start the Axon Server QueryBus implementation.

subscribe

public <R> Registration subscribe(@Nonnull
                                  String queryName,
                                  @Nonnull
                                  Type responseType,
                                  @Nonnull
                                  MessageHandler<? super QueryMessage<?,R>> handler)

Description copied from interface: QueryBus

Subscribe the given handler to queries with the given queryName and responseType. Multiple handlers may subscribe to the same combination of queryName/responseType.

Specified by:

subscribe in interface QueryBus

Parameters:

queryName - the name of the query request to subscribe

responseType - the type of response the subscribed component answers with

handler - a handler that implements the query

Returns:

a handle to un-subscribe the query handler

query

public <Q,R> CompletableFuture<QueryResponseMessage<R>> query(@Nonnull
                                                              QueryMessage<Q,R> queryMessage)

Description copied from interface: QueryBus

Dispatch the given query to a single QueryHandler subscribed to the given query's queryName and responseType. This method returns all values returned by the Query Handler as a Collection. This may or may not be the exact collection as defined in the Query Handler.

If the Query Handler defines a single return object (i.e. not a collection or array), that object is returned as the sole entry in a singleton collection.

When no handlers are available that can answer the given query, the returned CompletableFuture will be completed with a NoHandlerForQueryException.

Specified by:

query in interface QueryBus

Type Parameters:

Q - the payload type of the query

R - the response type of the query

Parameters:

queryMessage - the query

Returns:

a CompletableFuture that resolves when the response is available

scatterGather

public <Q,R> Stream<QueryResponseMessage<R>> scatterGather(@Nonnull
                                                           QueryMessage<Q,R> queryMessage,
                                                           long timeout,
                                                           @Nonnull
                                                           TimeUnit timeUnit)

Description copied from interface: QueryBus

Dispatch the given query to all QueryHandlers subscribed to the given query's queryName/responseType. Returns a stream of results which blocks until all handlers have processed the request or when the timeout occurs.

If no handlers are available to provide a result, or when all available handlers throw an exception while attempting to do so, the returned Stream is empty.

Note that any terminal operation (such as Stream.forEach(Consumer)) on the Stream may cause it to block until the timeout has expired, awaiting additional data to include in the stream.

Specified by:

scatterGather in interface QueryBus

Type Parameters:

Q - the payload type of the query

R - the response type of the query

Parameters:

queryMessage - the query

timeout - time to wait for results

timeUnit - unit for the timeout

Returns:

stream of query results

subscriptionQuery

@Deprecated
public <Q,I,U> SubscriptionQueryResult<QueryResponseMessage<I>,SubscriptionQueryUpdateMessage<U>> subscriptionQuery(@Nonnull
                                                                                                                                SubscriptionQueryMessage<Q,I,U> query,
                                                                                                                                SubscriptionQueryBackpressure backPressure,
                                                                                                                                int updateBufferSize)

Deprecated. in favor of using the {subscriptionQuery(SubscriptionQueryMessage, int)}

Dispatch the given query to a single QueryHandler subscribed to the given query's queryName/initialResponseType/updateResponseType. The result is lazily created and there will be no execution of the query handler before there is a subscription to the initial result. In order not to miss updates, the query bus will queue all updates which happen after the subscription query is done and once the subscription to the flux is made, these updates will be emitted.

If there is an error during retrieving or consuming initial result, stream for incremental updates is NOT interrupted.

If there is an error during emitting an update, subscription is cancelled causing further emits not reaching the destination.

Provided backpressure mechanism will be used to deal with fast emitters.

Specified by:

subscriptionQuery in interface QueryBus

Type Parameters:

Q - the payload type of the query

I - the response type of the query

U - the incremental response types of the query

Parameters:

query - the query

backPressure - the backpressure mechanism to be used for emitting updates

updateBufferSize - the size of buffer which accumulates updates before subscription to the flux is made

Returns:

query result containing initial result and incremental updates

subscriptionQuery

public <Q,I,U> SubscriptionQueryResult<QueryResponseMessage<I>,SubscriptionQueryUpdateMessage<U>> subscriptionQuery(@Nonnull
                                                                                                                    SubscriptionQueryMessage<Q,I,U> query,
                                                                                                                    int updateBufferSize)

Description copied from interface: QueryBus

Dispatch the given query to a single QueryHandler subscribed to the given query's queryName/initialResponseType/updateResponseType. The result is lazily created and there will be no execution of the query handler before there is a subscription to the initial result. In order not to miss updates, the query bus will queue all updates which happen after the subscription query is done and once the subscription to the flux is made, these updates will be emitted.

If there is an error during retrieving or consuming initial result, stream for incremental updates is NOT interrupted.

If there is an error during emitting an update, subscription is cancelled causing further emits not reaching the destination.

Specified by:

subscriptionQuery in interface QueryBus

Type Parameters:

Q - the payload type of the query

I - the response type of the query

U - the incremental response types of the query

Parameters:

query - the query

updateBufferSize - the size of buffer which accumulates updates before subscription to the flux is made

Returns:

query result containing initial result and incremental updates

queryUpdateEmitter

public QueryUpdateEmitter queryUpdateEmitter()

Description copied from interface: QueryBus

Gets the QueryUpdateEmitter associated with this QueryBus.

Specified by:

queryUpdateEmitter in interface QueryBus

Returns:

the associated QueryUpdateEmitter

localSegment

public QueryBus localSegment()

Description copied from interface: Distributed

Return the message bus of type MessageBus which is regarded as the local segment for this implementation. Would return the message bus used to dispatch and handle messages in a local environment to bridge the gap in a distributed set up.

Specified by:

localSegment in interface Distributed<QueryBus>

Returns:

a MessageBus which is the local segment for this distributed message bus implementation

registerHandlerInterceptor

public Registration registerHandlerInterceptor(@Nonnull
                                               MessageHandlerInterceptor<? super QueryMessage<?,?>> interceptor)

Description copied from interface: MessageHandlerInterceptorSupport

Register the given handlerInterceptor. After registration, the interceptor will be invoked for each handled Message on the messaging component that it was registered to, prior to invoking the message's handler.

Specified by:

registerHandlerInterceptor in interface MessageHandlerInterceptorSupport<QueryMessage<?,?>>

Parameters:

interceptor - The interceptor to register

Returns:

A Registration, which may be used to deregister the interceptor.

registerDispatchInterceptor

@Nonnull
public Registration registerDispatchInterceptor(@Nonnull
                                                         MessageDispatchInterceptor<? super QueryMessage<?,?>> dispatchInterceptor)

Description copied from interface: MessageDispatchInterceptorSupport

Register the given DispatchInterceptor. After registration, the interceptor will be invoked for each Message dispatched on the messaging component that it was registered to.

Specified by:

registerDispatchInterceptor in interface MessageDispatchInterceptorSupport<QueryMessage<?,?>>

Parameters:

dispatchInterceptor - The interceptor to register

Returns:

A Registration, which may be used to deregister the interceptor.

disconnect

public void disconnect()

Disconnect the query bus from Axon Server, by unsubscribing all known query handlers. This shutdown operation is performed in the Phase.INBOUND_QUERY_CONNECTOR phase.

shutdownDispatching

public CompletableFuture<Void> shutdownDispatching()

Shutdown the query bus asynchronously for dispatching queries to Axon Server. This process will wait for dispatched queries which have not received a response yet and will close off running subscription queries. This shutdown operation is performed in the Phase.OUTBOUND_QUERY_CONNECTORS phase.

Returns:

a completable future which is resolved once all query dispatching activities are completed