io.simplesource.saga.action.app

Class ActionApp<A>

java.lang.Object

io.simplesource.saga.action.app.ActionApp<A>

Type Parameters:

A - The action command type (shared across all actions)

public class ActionApp<A>
extends Object

An ActionApp is the main component in an KStream action processor application.

An action processor application consists of one or more action processors.

The following action processors are provided out-the-box in Simple Sagas:

• Event Sourcing Action processor
• Async Action processor
• Http Action processor

To create a custom action processor, you can provide an implementation of the functional interface ActionProcessorBuildStep. In this implementation you define both the instructions for building the stream topology, and the details about the topics that are required for this action processor (Note that each action processor uses its own set of topics)

It is recommended, though note essential to use this pattern to create action processors.

ActionProcessorBuildStep implementations can also be used to provide implementations of other sub-topologies that are not directly related to action processors. ActionProcessorBuildStep can be added to extend the action app topology in arbitrary ways.

This can be useful for transforming stream data that might be used by an action processor, and making this transformation part of the stream topology.

Method Summary

Modifier and Type	Method and Description
StreamBuildResult	build(PropertiesBuilder.BuildSteps properties) Builds the stream.
static <A> ActionApp<A>	of(ActionSerdes<A> serdes)
void	run(PropertiesBuilder.BuildSteps properties) Builds and runs the stream.
ActionApp<A>	withActionProcessor(ActionProcessorBuildStep<A> processorBuildStep) Adds an action processor build step to the application.

Methods inherited from class java.lang.Object

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

Method Detail

of

public static <A> ActionApp<A> of(ActionSerdes<A> serdes)

Type Parameters:

A - The action command type (shared across all actions)

Parameters:

serdes - - the Serdes for the action request and response topics. Note that all action types share the same serdes

Returns:

the ActionApp

withActionProcessor

public ActionApp<A> withActionProcessor(ActionProcessorBuildStep<A> processorBuildStep)

Adds an action processor build step to the application.

Note that it is only possible to add one action processor per action type to a given action app instance, and this is enforced by the framework.

It is up to the user to ensure that there is only one action processor per action type running on the cluster (to ensure single processing of an action).

Parameters:

processorBuildStep - - the action processor build step

Returns:

this

build

public StreamBuildResult build(PropertiesBuilder.BuildSteps properties)

Builds the stream. This creates the stream topology and the topic definitions, but doesn't create the topics or run the application.

Parameters:

properties - a functional interface for setting or overriding the Kafka properties

Returns:

a structure with the result of the build

run

public void run(PropertiesBuilder.BuildSteps properties)

Builds and runs the stream. This creates the stream topology and the topic definitions, then create the topics and run the application

Parameters:

properties - a functional interface for setting or overriding the Kafka properties