sdk-java/examples/spring-function

Spring Reactive + CloudEvents sample

Build

mvn package

Start HTTP Server

mvn spring-boot:run

You can try sending a request using curl, and it echos back a cloud event the same body and with new ce-* headers:

curl -v -d '{"value": "Foo"}' \
    -H'Content-type: application/json' \
    -H'ce-id: 1' \
    -H'ce-source: cloud-event-example' \
    -H'ce-type: my.application.Foo' \
    -H'ce-specversion: 1.0' \
    http://localhost:8080/event

It also accepts data in "structured" format:

curl -v -H'Content-type: application/cloudevents+json' \
    -d '{"data": {"value": "Foo"},
         "id": "1",
         "source": "cloud-event-example",
         "type": "my.application.Foo",
         "specversion": "1.0"}' \
    http://localhost:8080/event

The /event endpoint is implemented like this (the request and response are modelled directly as a CloudEvent`):

@PostMapping("/event")
public Mono<CloudEvent> event(@RequestBody Mono<CloudEvent> body) {
	return ...;
}

and to make that work we need to install the codecs:

@Configuration
public static class CloudEventHandlerConfiguration implements CodecCustomizer {

	@Override
	public void customize(CodecConfigurer configurer) {
		configurer.customCodecs().register(new CloudEventHttpMessageReader());
		configurer.customCodecs().register(new CloudEventHttpMessageWriter());
	}

}

The same feature in Spring MVC is provided by the CloudEventHttpMessageConverter.

The /foos endpoint does the same thing. It doesn't use the CloudEvent data type directly, but instead models the request and response body as a Foo (POJO type):

@PostMapping("/foos")
public ResponseEntity<Foo> echo(@RequestBody Foo foo, @RequestHeader HttpHeaders headers) {
	...
}

Note that this endpoint only accepts "binary" format cloud events (context in HTTP headers like in the first example above). It translates the HttpHeaders to CloudEventContext using a utility class provided by cloudevents-spring.