順序指定キーを使用してメッセージをパブリッシュします。 順序指定キーは、ハッシュされてパーティションにマッピングされます。同じ順序指定キーのメッセージは、同じパーティションにパブリッシュされます。パーティションがいっぱいになると、最も古いメッセージから上書きされます。
もっと見る
このコードサンプルを含む詳細なドキュメントについては、以下をご覧ください。
コードサンプル
Go
Pub/Sub Lite に対する認証を行うには、アプリケーションのデフォルト認証情報を設定します。詳細については、ローカル開発環境の認証の設定をご覧ください。
import (
"context"
"fmt"
"io"
"cloud.google.com/go/pubsub"
"cloud.google.com/go/pubsublite/pscompat"
)
func publishWithOrderingKey(w io.Writer, projectID, zone, topicID string, messageCount int) error {
// projectID := "my-project-id"
// zone := "us-central1-a"
// topicID := "my-topic"
// messageCount := 10
ctx := context.Background()
topicPath := fmt.Sprintf("projects/%s/locations/%s/topics/%s", projectID, zone, topicID)
// Create the publisher client.
publisher, err := pscompat.NewPublisherClient(ctx, topicPath)
if err != nil {
return fmt.Errorf("pscompat.NewPublisherClient error: %w", err)
}
// Ensure the publisher will be shut down.
defer publisher.Stop()
// Messages of the same ordering key will always get published to the same
// partition. When OrderingKey is unset, messages can get published to
// different partitions if more than one partition exists for the topic.
var results []*pubsub.PublishResult
for i := 0; i < messageCount; i++ {
r := publisher.Publish(ctx, &pubsub.Message{
OrderingKey: "test_ordering_key",
Data: []byte(fmt.Sprintf("message-%d", i)),
})
results = append(results, r)
}
// Print publish results.
var publishedCount int
for _, r := range results {
// Get blocks until the result is ready.
id, err := r.Get(ctx)
if err != nil {
// NOTE: A failed PublishResult indicates that the publisher client
// encountered a fatal error and has permanently terminated. After the
// fatal error has been resolved, a new publisher client instance must be
// created to republish failed messages.
fmt.Fprintf(w, "Publish error: %v\n", err)
continue
}
// Metadata decoded from the id contains the partition and offset.
metadata, err := pscompat.ParseMessageMetadata(id)
if err != nil {
return fmt.Errorf("failed to parse message metadata %q: %w", id, err)
}
fmt.Fprintf(w, "Published: partition=%d, offset=%d\n", metadata.Partition, metadata.Offset)
publishedCount++
}
fmt.Fprintf(w, "Published %d messages with ordering key\n", publishedCount)
return publisher.Error()
}
Java
Pub/Sub Lite に対する認証を行うには、アプリケーションのデフォルト認証情報を設定します。詳細については、ローカル開発環境の認証の設定をご覧ください。
import com.google.api.core.ApiFuture;
import com.google.api.gax.rpc.ApiException;
import com.google.cloud.pubsublite.CloudRegion;
import com.google.cloud.pubsublite.CloudRegionOrZone;
import com.google.cloud.pubsublite.CloudZone;
import com.google.cloud.pubsublite.MessageMetadata;
import com.google.cloud.pubsublite.ProjectNumber;
import com.google.cloud.pubsublite.TopicName;
import com.google.cloud.pubsublite.TopicPath;
import com.google.cloud.pubsublite.cloudpubsub.Publisher;
import com.google.cloud.pubsublite.cloudpubsub.PublisherSettings;
import com.google.protobuf.ByteString;
import com.google.pubsub.v1.PubsubMessage;
import java.util.concurrent.ExecutionException;
public class PublishWithOrderingKeyExample {
public static void main(String... args) throws Exception {
// TODO(developer): Replace these variables before running the sample.
String cloudRegion = "your-cloud-region";
char zoneId = 'b';
// Choose an existing topic for the publish example to work.
String topicId = "your-topic-id";
long projectNumber = Long.parseLong("123456789");
// True if using a regional location. False if using a zonal location.
// https://cloud.google.com/pubsub/lite/docs/topics
boolean regional = false;
publishWithOrderingKeyExample(cloudRegion, zoneId, projectNumber, topicId, regional);
}
// Publish a message to a topic with an ordering key.
public static void publishWithOrderingKeyExample(
String cloudRegion, char zoneId, long projectNumber, String topicId, boolean regional)
throws ApiException, ExecutionException, InterruptedException {
CloudRegionOrZone location;
if (regional) {
location = CloudRegionOrZone.of(CloudRegion.of(cloudRegion));
} else {
location = CloudRegionOrZone.of(CloudZone.of(CloudRegion.of(cloudRegion), zoneId));
}
TopicPath topicPath =
TopicPath.newBuilder()
.setProject(ProjectNumber.of(projectNumber))
.setLocation(location)
.setName(TopicName.of(topicId))
.build();
PublisherSettings publisherSettings =
PublisherSettings.newBuilder().setTopicPath(topicPath).build();
Publisher publisher = Publisher.create(publisherSettings);
// Start the publisher. Upon successful starting, its state will become RUNNING.
publisher.startAsync().awaitRunning();
String message = "message-with-ordering-key";
// Convert the message to a byte string.
ByteString data = ByteString.copyFromUtf8(message);
PubsubMessage pubsubMessage =
PubsubMessage.newBuilder()
.setData(data)
// Messages of the same ordering key will always get published to the
// same partition. When OrderingKey is unset, messages can get published
// to different partitions if more than one partition exists for the topic.
.setOrderingKey("testing")
.build();
// Publish a message.
ApiFuture<String> future = publisher.publish(pubsubMessage);
// Shut down the publisher.
publisher.stopAsync().awaitTerminated();
String ackId = future.get();
MessageMetadata metadata = MessageMetadata.decode(ackId);
System.out.println("Published a message with ordering key:\n" + metadata);
}
}
Python
Pub/Sub Lite に対する認証を行うには、アプリケーションのデフォルト認証情報を設定します。詳細については、ローカル開発環境の認証の設定をご覧ください。
from google.cloud.pubsublite.cloudpubsub import PublisherClient
from google.cloud.pubsublite.types import (
CloudRegion,
CloudZone,
MessageMetadata,
TopicPath,
)
# TODO(developer):
# project_number = 1122334455
# cloud_region = "us-central1"
# zone_id = "a"
# topic_id = "your-topic-id"
# num_messages = 100
# regional = True
if regional:
location = CloudRegion(cloud_region)
else:
location = CloudZone(CloudRegion(cloud_region), zone_id)
topic_path = TopicPath(project_number, location, topic_id)
# PublisherClient() must be used in a `with` block or have __enter__() called before use.
with PublisherClient() as publisher_client:
for message in range(num_messages):
data = f"{message}"
# Messages of the same ordering key will always get published to the same partition.
# When ordering_key is unset, messsages can get published ot different partitions if
# more than one partition exists for the topic.
api_future = publisher_client.publish(
topic_path, data.encode("utf-8"), ordering_key="testing"
)
# result() blocks. To resolve api futures asynchronously, use add_done_callback().
message_id = api_future.result()
message_metadata = MessageMetadata.decode(message_id)
print(
f"Published {data} to partition {message_metadata.partition.value} and offset {message_metadata.cursor.offset}."
)
print(
f"Finished publishing {num_messages} messages with an ordering key to {str(topic_path)}."
)
次のステップ
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