Astrix Plugins - AvanzaBank/astrix GitHub Wiki

This is a very early draft

Astrix provides a number of extension points, where some of the more important are:

• ServiceComponent
• ServiceDiscoveryFactoryPlugin
• BeanPublisherPlugin

This part describes how you plug-in your custom extensions into Astrix at runtime.

Plugins vs Strategies

Astrix allows for two different types of extensions, plugins and strategy. Put simply, there might be an arbritrary number of a given plugin type (for instance ServiceComponent plugins), as opposed to a strategy where Astrix assumes exactly one instance at runtime.

Implementing a plugin

A plugin is created by implementing the AstrixContextPlugin interface. It contains one non-default method:

public interface AstrixContextPluign {
	void prepare(ModuleContext moduleContext);
}

@MetaInfServices(AstrixContextPlugin.class)
public class CustomRemotingModule implements AstrixContextPlugin {

	@Override
	public void prepare(ModuleContext moduleContext) {
		// 1.
		moduleContext.bind(ServiceComponent.class, MyCustomRemotingComponent.class);
		
		// 2.
		moduleContext.importType(AstrixServiceActivator.class);
		moduleContext.importType(ObjectSerializerFactory.class);
		moduleContext.importType(RemotingProxyFactory.class);
		moduleContext.importType(AstrixConfig.class);
		
		// 3.
		moduleContext.export(ServiceComponent.class);
	}
}

1. Setup internal bindings used for dependency injection within the component, see astrix-modules
2. Import components from the AstrixContext
3. Export the ServcieComponent type from this module

Loading the plugin

Astrix uses the java ServiceLoader mechanism to load plugins at runtime.

Content of META-INF/services/com.avanza.astrix.context.AstrixContextPlugin

com.mycorp.astrix.ext.CustomRemotingModule

Implementing a Stratgey

@MetaInfServices(AstrixContextPlugin.class)
public class MyCustomHystrixCommandNamingStrategy implements AstrixContextPlugin {
	
	@Override
	public void registerStrategies(AstrixStrategiesConfig strategiesConfig) {
		strategiesConfig.registerStrategy(HystrixCommandNamingStrategy.class, MyCustomHystrixCommandNamingStrategy.class);
	}
	
	@Override
	public void prepare(ModuleContext moduleContext) {
	}
}

Loading a Strategy

Strategies are loaded in the same way as a plugin.