@EnableFlowWarden

Overview

@EnableFlowWarden activates the FlowWarden framework. Place it on a @Configuration or @SpringBootApplication class. It is a marker annotation — it does not perform package scanning itself. @ChangeStream classes are discovered through Spring’s standard @ComponentScan (since @ChangeStream is meta-annotated with @Component), and ChangeStreamBeanPostProcessor inspects all beans in the context to find those annotated with @ChangeStream. At startup, FlowWarden will:

Discover all @ChangeStream beans from the Spring application context
Validate the configuration — execution mode, MongoDB template availability, handler signatures
Register discovered streams in the internal registry
Start streams with autoStart = true after the Spring context is ready

Minimal Setup

@SpringBootApplication
@EnableFlowWarden
public class MyApplication {
    public static void main(String[] args) {
        SpringApplication.run(MyApplication.class, args);
    }
}

Your @ChangeStream classes just need to be picked up by Spring’s @ComponentScan — which happens automatically when they are in the same package (or a sub-package) as your @SpringBootApplication class.

Attributes

Attribute	Type	Default	Description
`propertyPrefix`	`String`	`"flowwarden.stream"`	Prefix for FlowWarden configuration properties
`enabled`	`boolean`	`true`	Globally enable or disable all streams

@EnableFlowWarden does not have basePackages or basePackageClasses attributes. Handler discovery relies on Spring’s standard @ComponentScan. If you need to restrict which @ChangeStream classes are loaded (e.g., in tests), use Spring’s own @ComponentScan(basePackages = ...) or @SpringBootTest(classes = ...).

Configuration

The execution mode defaults to IMPERATIVE when not explicitly configured. For Spring WebFlux applications, set it to REACTIVE in application.yml:

flowwarden:
  default-mode: REACTIVE   # defaults to IMPERATIVE if omitted

If flowwarden.default-mode is not set, FlowWarden defaults to IMPERATIVE and logs:

INFO  FlowWardenConfigurationValidator - No 'flowwarden.default-mode' configured, defaulting to IMPERATIVE

Spring MVC applications can omit this property entirely. Spring WebFlux applications must set it to REACTIVE explicitly.

How Auto-Configuration Works

FlowWarden uses Spring Boot’s auto-configuration mechanism. When @EnableFlowWarden is present, three auto-configuration classes activate in order:

Class	Condition	Provides
`FlowWardenAutoConfiguration`	Always	`ChangeStreamBeanPostProcessor`, `FlowWardenConfigurationValidator`
`ImperativeFlowWardenAutoConfiguration`	`flowwarden.default-mode=IMPERATIVE` (or missing)	`ImperativeStreamManager`, `CheckpointStore` → `MongoCheckpointStore`
`ReactiveFlowWardenAutoConfiguration`	`flowwarden.default-mode=REACTIVE`	`ReactiveStreamManager`, `CheckpointStore` → `ReactiveMongoCheckpointStore`

Startup validation details

The FlowWardenConfigurationValidator runs after all singleton beans are created (SmartInitializingSingleton) and checks:

Mode is resolved — flowwarden.default-mode defaults to IMPERATIVE if not set
Template available — IMPERATIVE requires MongoTemplate, REACTIVE requires ReactiveMongoTemplate

All errors follow the Spring Boot error format with a Description and an Action section suggesting how to fix the issue.

Disabling FlowWarden

Set enabled = false to disable all stream processing without removing the annotation:

@SpringBootApplication
@EnableFlowWarden(enabled = false)
public class MyApplication { }

This is useful for running the application in a degraded mode (e.g., maintenance) or for profiles where streams should not start.

Full Example

@SpringBootApplication
@EnableFlowWarden
public class SampleSpringMvcApplication {
    public static void main(String[] args) {
        SpringApplication.run(SampleSpringMvcApplication.class, args);
    }
}

@SpringBootApplication
@EnableFlowWarden
public class SampleSpringReactiveApplication {
    public static void main(String[] args) {
        SpringApplication.run(SampleSpringReactiveApplication.class, args);
    }
}

application.yml

flowwarden:
  default-mode: IMPERATIVE   # or REACTIVE

spring:
  data:
    mongodb:
      uri: mongodb://localhost:27017/mydb   # Must be a Replica Set

Quickstart

Full getting-started guide with dependency setup

@ChangeStream

Declare a Change Stream handler class

Imperative vs Reactive

Choose the right execution mode

Configuration

All FlowWarden configuration properties

Annotations

Runtime

SPI

Overview

Minimal Setup

Attributes

Configuration

How Auto-Configuration Works

Disabling FlowWarden

Full Example

See Also

Quickstart

@ChangeStream

Imperative vs Reactive

Configuration

​Overview

​Minimal Setup

​Attributes

​Configuration

​How Auto-Configuration Works

​Disabling FlowWarden

​Full Example

​See Also

Quickstart

@ChangeStream

Imperative vs Reactive

Configuration

Overview

Minimal Setup

Attributes

Configuration

How Auto-Configuration Works

Disabling FlowWarden

Full Example

See Also