io.spine.server.stand

Class Stand

java.lang.Object

io.spine.server.stand.Stand

All Implemented Interfaces:

java.lang.AutoCloseable

public class Stand
extends java.lang.Object
implements java.lang.AutoCloseable

A bridge which connects QueryService and SubscriptionService with a Read-side of a Bounded Context.

Each BoundedContext contains only one instance of Stand.

The Stand is responsible for obtaining results of queries sent by the QueryService.

The Stand also manages creation of subscriptions, their activation, and delivering updates to the subscribers when requested by the SubscriptionService.

See Also:

Spine Architecture Diagram

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Stand.Builder

Method Summary

Modifier and Type	Method and Description
void	activate(io.spine.client.Subscription subscription, SubscriptionCallback callback, io.grpc.stub.StreamObserver<io.spine.core.Response> responseObserver) Activates the subscription created via subscribe() method.
void	cancel(io.spine.client.Subscription subscription, io.grpc.stub.StreamObserver<io.spine.core.Response> responseObserver) Cancels the Subscription.
void	close() Closes the Stand performing necessary cleanups.
Listener<EventEnvelope>	eventListener() Obtains the bus listener which propagates all events and state updates to subscriptions.
void	execute(io.spine.client.Query query, io.grpc.stub.StreamObserver<io.spine.client.QueryResponse> responseObserver) Reads a particular set of items from the read-side of the application and feed the result into an instance.
com.google.common.collect.ImmutableSet<io.spine.type.TypeUrl>	exposedAggregateTypes() Reads all Aggregate entity types exposed for reading by this instance of Stand.
com.google.common.collect.ImmutableSet<io.spine.type.TypeUrl>	exposedEventTypes() Reads all event types produced by the repositories associated with this Stand.
com.google.common.collect.ImmutableSet<io.spine.type.TypeUrl>	exposedTypes() Reads all Entity types exposed for reading by this instance of Stand.
static Stand.Builder	newBuilder()
void	registerTypeSupplier(EventProducer producer) Registers the passed EventProducer as the event type supplier.
void	registerTypeSupplier(Repository<?,?> repository) Registers the passed Repository as an entity/event type supplier.
void	subscribe(io.spine.client.Subscription subscription) Registers this inactive subscription is this Stand.
void	subscribe(io.spine.client.Topic topic, io.grpc.stub.StreamObserver<io.spine.client.Subscription> responseObserver) Creates a subscription for the passed topic.

Methods inherited from class java.lang.Object

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

Method Detail

newBuilder

public static Stand.Builder newBuilder()

subscribe

public void subscribe(io.spine.client.Topic topic,
                      io.grpc.stub.StreamObserver<io.spine.client.Subscription> responseObserver)
               throws InvalidRequestException

Creates a subscription for the passed topic.

Parameters:

topic - defines the subscription target

responseObserver - the observer for obtaining created subscription

Throws:

InvalidRequestException

subscribe

public void subscribe(io.spine.client.Subscription subscription)
               throws InvalidRequestException

Registers this inactive subscription is this Stand.

The given subscription is shared between different Bounded Contexts.

Parameters:

subscription - an existing subscription

Throws:

InvalidRequestException

activate

public void activate(io.spine.client.Subscription subscription,
                     SubscriptionCallback callback,
                     io.grpc.stub.StreamObserver<io.spine.core.Response> responseObserver)
              throws InvalidRequestException

Activates the subscription created via subscribe() method.

After the activation, the clients will start receiving the updates via the passed SubscriptionCallback.

Parameters:

subscription - the subscription to activate

callback - the action which notifies the subscribers about an update

responseObserver - an observer to notify of a successful acknowledgement of the subscription activation

Throws:

InvalidRequestException

See Also:

Stand.subscribe(Topic, StreamObserver)

cancel

public void cancel(io.spine.client.Subscription subscription,
                   io.grpc.stub.StreamObserver<io.spine.core.Response> responseObserver)
            throws InvalidRequestException

Cancels the Subscription.

Typically invoked to cancel the previous activate() call.

After this method is called, the subscribers stop receiving the updates, related to the given Subscription.

Parameters:

subscription - the subscription to cancel

responseObserver - an observer to notify of a successful acknowledgement of the subscription cancellation.

Throws:

InvalidRequestException

eventListener

public Listener<EventEnvelope> eventListener()

Obtains the bus listener which propagates all events and state updates to subscriptions.

exposedTypes

public com.google.common.collect.ImmutableSet<io.spine.type.TypeUrl> exposedTypes()

Reads all Entity types exposed for reading by this instance of Stand.

In order to expose the type, use Stand.registerTypeSupplier(Repository).

The result includes all values from Stand.exposedAggregateTypes() as well.

Returns:

the set of types as TypeUrl instances

exposedEventTypes

public com.google.common.collect.ImmutableSet<io.spine.type.TypeUrl> exposedEventTypes()

Reads all event types produced by the repositories associated with this Stand.

Returns:

the set of types as TypeUrl instances

exposedAggregateTypes

public com.google.common.collect.ImmutableSet<io.spine.type.TypeUrl> exposedAggregateTypes()

Reads all Aggregate entity types exposed for reading by this instance of Stand.

Use Stand.registerTypeSupplier(Repository) to expose an Aggregate type.

Returns:

the set of types as TypeUrl instances

execute

public void execute(io.spine.client.Query query,
                    io.grpc.stub.StreamObserver<io.spine.client.QueryResponse> responseObserver)
             throws InvalidRequestException

Reads a particular set of items from the read-side of the application and feed the result into an instance.

Query defines the query target and the expected detail level for response.

The query results are fed to an instance of StreamObserver<QueryResponse>.

Parameters:

query - the instance of query

responseObserver - the observer to feed the query results to

Throws:

InvalidRequestException

registerTypeSupplier

public void registerTypeSupplier(Repository<?,?> repository)

Registers the passed Repository as an entity/event type supplier.

registerTypeSupplier

public void registerTypeSupplier(EventProducer producer)

Registers the passed EventProducer as the event type supplier.

close

public void close()
           throws java.lang.Exception

Closes the Stand performing necessary cleanups.

Specified by:

close in interface java.lang.AutoCloseable

Throws:

java.lang.Exception