com.diffusiondata.gateway.framework

Interface SinkHandler<T>

Type Parameters:

T - the type of object that is expected by the update(java.lang.String, T) method. This should match the type that is output by the payload convertor in use for the service.

All Superinterfaces:

ServiceHandler

All Known Subinterfaces:

HybridHandler<T>

public interface SinkHandler<T>
extends ServiceHandler

The interface that a sink handler must implement.

A sink handler receives updates from the framework via its update method. A sink handler will only receive updates when the service is in an ACTIVE state.

A sink handler will not receive updates until the start method has been called. It will also not receive updates if the pause method has been called and updates will not resume until the resume method is called.

An object that implements this interface must be returned when the GatewayApplication.addSink method is called. A different object must be returned for each different service. The object must implement the update method to publish any update(s) received from the framework to the back end sink.

The handler may also optionally return service specific properties via its getSinkServiceProperties() method. If it does not then defaults will be assumed.

Author:

DiffusionData Limited

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	SinkHandler.SinkServiceProperties The service properties that apply to the sink service.

Nested classes/interfaces inherited from interface com.diffusiondata.gateway.framework.ServiceHandler

ServiceHandler.PauseReason, ServiceHandler.ResumeReason

Method Summary

Modifier and Type	Method and Description
default SinkHandler.SinkServiceProperties	getSinkServiceProperties() This is used to set topic-specific properties for topics consumed by this service.
CompletableFuture<?>	update(String path, T value) Called by the framework to publish a new value received from Diffusion to the sink.

Methods inherited from interface com.diffusiondata.gateway.framework.ServiceHandler

pause, resume, start, stop

Method Detail

getSinkServiceProperties

default SinkHandler.SinkServiceProperties getSinkServiceProperties()
                                                            throws InvalidConfigurationException

This is used to set topic-specific properties for topics consumed by this service.

Properties can be built using a builder which can be created using DiffusionGatewayFramework.newSinkServicePropertiesBuilder().

The default implementation returns null, which means that all defaults are assumed for service properties. See the methods of SinkHandler.SinkServiceProperties.Builder for details about defaults.

Returns:

service properties or null to indicate defaults

Throws:

InvalidConfigurationException - possibly thrown by SinkHandler.SinkServiceProperties.Builder

update

CompletableFuture<?> update(String path,
                            T value)

Called by the framework to publish a new value received from Diffusion to the sink.

The payload convertor defined by the service properties will have been applied to the Diffusion value received from the topic to produce the sink specific value.

Parameters:

path - the path of the Diffusion topic that the value has been been received from

value - the value to publish to the sink

Returns:

a completable future that completes successfully when the update has been performed.

If the update completes successfully, the CompletableFuture result should be null. The result type is any rather than Void to provide forward compatibility with future iterations of this API that may provide a non-null result with a more specific result type.

If the future completes exceptionally or the future fails to complete within the timeout specified in the configuration, the framework will pause the service. If the method throws an exception, it will be logged but the service will not be paused.