Typed proxy support

Requirements

In order to create a type-safe experience for working with orchestrations and activities, the Java SDK for the Durable Task Framework should support type-safe invocation of orchestration and activities.

For example, when calling an activity, instead of the following:

Object activityInput = "World";
String result = context.callActivity("SayHello", activityInput, String.class).get();

...we should be able to instead write:

MyActivities activities = // get a pointer to an activity proxy
String result = activities.sayHello("World");

We'd want the same experience also for orchestrations (created by a client) and sub-orchestrations.

Ideally this support will also allow developers to easily unit test their code.

Design considerations

Java's Proxy support could be a good starting point for such a feature.

Comienza con los requisitos y la documentación de Java Proxy enlazada. Define el alcance de la invocación de actividades tipadas, orquestaciones y suborquestaciones, incluida la experiencia propuesta para las pruebas unitarias. Se considera terminado cuando el Java SDK proporciona un enfoque de proxy con seguridad de tipos documentado que cubre los tres casos de invocación.