CloudEvents Protocol Buffers

This module provides the Protocol Buffer (protobuf) EventFormat implementation using the Java Protobuf runtime and classes generated from the CloudEvents proto spec.

Setup

For Maven-based projects, use the following dependency:

<dependency>
    <groupId>io.cloudevents</groupId>
    <artifactId>cloudevents-protobuf</artifactId>
    <version>4.1.1</version>
</dependency>

No further configuration is required is use the module.

Using the Protobuf Event Format

Event serialization

import io.cloudevents.CloudEvent;
import io.cloudevents.core.format.ContentType;
import io.cloudevents.core.provider.EventFormatProvider;
import io.cloudevents.core.builder.CloudEventBuilder;

CloudEvent event = CloudEventBuilder.v1()
    .withId("hello")
    .withType("example.vertx")
    .withSource(URI.create("http://localhost"))
    .build();

byte[]serialized = EventFormatProvider
    .getInstance()
    .resolveFormat(ContentType.PROTO)
    .serialize(event);

The EventFormatProvider will automatically resolve the ProtobufFormat using the ServiceLoader APIs.

Passing Protobuf messages as CloudEvent data.

The ProtoCloudEventData capability provides a convenience mechanism to handle Protobuf message object data.

Building

// Build my business event message.
com.google.protobuf.Message myMessage = ..... ;

// Wrap the protobuf message as CloudEventData.
CloudEventData ceData = ProtoCloudEventData.wrap(myMessage);

// Build the CloudEvent
CloudEvent event = CloudEventBuilder.v1()
    .withId("hello")
    .withType("example.protodata")
    .withSource(URI.create("http://localhost"))
    .withData(ceData)
    .build();

Reading

If the ProtobufFormat is used to deserialize a CloudEvent that contains a protobuf message object as data you can use the ProtoCloudEventData to access it as an ‘Any’ directly.

// Deserialize the event.
CloudEvent myEvent = eventFormat.deserialize(raw);

// Get the Data
CloudEventData eventData = myEvent.getData();

if (ceData instanceOf ProtoCloudEventData) {

    // Obtain the protobuf 'any'
    Any anAny = ((ProtoCloudEventData) eventData).getAny();

    ...
}