JVM - topic.subscribe()

Subscribe a handler to a topic and receive new events for processing.

import io.nitric.Nitric;

public class Application {
  public static void main(String[] args) {
    var topic = Nitric.INSTANCE.topic("new-user");

    topic.subscribe(ctx -> {
      // process event
      return ctx;
    });

    Nitric.INSTANCE.run();
  }
}

Parameters

Name
middleware
Required
Required
Type
Middleware<EventContext> or List<Middleware<EventContext>>
Description
The middleware (code) to be triggered by the topic.

Examples

import io.nitric.Nitric;

public class Application {
  public static void main(String[] args) {
    var topic = Nitric.INSTANCE.topic("new-user");

    topic.subscribe(ctx -> {
      // process event
      return ctx;
    });

    Nitric.INSTANCE.run();
  }
}

Subscibe to a topic with chained middleware

import io.nitric.Nitric;

public class Application {
  public static void main(String[] args) {
    var topic = Nitric.INSTANCE.topic("topic");

    topic.subscribe(List.of((ctx, next) -> {
      // process event
      return next.invoke(ctx);
    }, (ctx, next) -> {
      // process event
      return next.invoke(ctx);
    }));

    Nitric.INSTANCE.run();
  }
}

Notes

A function may only subscribe to a topic once, if multiple subscribers are required, create them in different functions.
A function may subscribe to OR publish to a topic but not both

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Last updated on Oct 22, 2024