Are Transactions supported?

[AlessandroMinoccheri]

Hi, are transaction supported? I have tried to make a simple transaction in php like this:

$data = [
            'id' => Uuid::uuid4()->toString(),
            'uuid' => $domainMessage->getId(),
            'playhead' => $domainMessage->getPlayhead(),
            'metadata' => json_encode($this->metadataSerializer->serialize($domainMessage->getMetadata())),
            'payload' => json_encode($this->payloadSerializer->serialize($domainMessage->getPayload())),
            'recorded_on' => $domainMessage->getRecordedOn()->toString(),
            'type' => $domainMessage->getType(),
        ];

        $marshal = new Marshaler();
        $data = $marshal->marshalJson(json_encode($data));

$this->client->transactWriteItems([
                'TransactItems' => [
                    [
                        'Put' => [
                            'TableName' => $this->table,
                            'Item' => $data
                        ]
                    ]
                ]
            ]
        );

It returns me this error:

GuzzleHttp\Exception\ClientException: Client error: `POST http://localhost:8000` resulted in a `400 Bad Request` response:
{"__type":"com.amazonaws.dynamodb.v20120810#UnknownOperationException","message":"An unknown operation was requested."}

If I make a simple putItem it works fine.

Let me know please
Thanks