org.apache.flink.statefun.sdk.spi

Interface StatefulFunctionModule

public interface StatefulFunctionModule

A StatefulFunctionModule is the entry point for adding to a Stateful Functions application the core building block primitives, i.e. IngressSpecs, EgressSpecs, Routers, and StatefulFunctions.

Extensibility of a Stateful Functions application

A Stateful Functions application is built up of ingresses, egresses, routers, and stateful functions that are added to the application by multiple different StatefulFunctionModules. This allows different parts of the application to be contributed by different modules; for example, one module may provide ingresses and egresses, while other modules may individually contribute specific parts of the application as stateful functions.

The extensibility is achieved by leveraging the Java Service Loader. In this context, each module is essentially a service provider.

Registering a StatefulFunctionModule

In order for an application to discover a given module, likewise to how the Java Service Loader works, a UTF-8 encoded provider configuration file needs to be stored in the META-INF/services directory of the module's containing JAR file. The name of the file should be org.apache.flink.statefun.sdk.spi.StatefulFunctionModule, i.e. the fully qualified name of the StatefulFunctionModule class. Each line in the file should be the fully qualified class name of a module in that JAR that you want to register for the Stateful Functions application. The configuration file may also be automatically generated using Google's AutoService tool.

Finally, to allow the Stateful Functions runtime to discover the registered modules, the JAR files containing the modules and provider configuration files should be added to a system-specific class path directory, /opt/statefun/modules/.

For a simple demonstration, you can consult the statefun-greeter-example example.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	StatefulFunctionModule.Binder A StatefulFunctionModule.Binder binds ingresses, egresses, routers, and functions to a Stateful Functions application.

Method Summary

Modifier and Type	Method and Description
void	configure(java.util.Map<java.lang.String,java.lang.String> globalConfiguration, StatefulFunctionModule.Binder binder) This method is the entry point for extending a Stateful Functions application by binding ingresses, egresses, routers, and functions.

Method Detail

configure

void configure(java.util.Map<java.lang.String,java.lang.String> globalConfiguration,
               StatefulFunctionModule.Binder binder)

This method is the entry point for extending a Stateful Functions application by binding ingresses, egresses, routers, and functions.

Parameters:

globalConfiguration - global configuration of the Stateful Functions application.

binder - the binder to be used to bind ingresses, egresses, routers, and functions.