Creating a trigger for Data Streams that sends messages to WebSocket connections
Create a trigger for Data Streams to send messages to WebSocket connections when data is sent to a stream.
Getting started
To create a trigger, you need:
-
API gateway. Messages will be sent to WebSocket connections connected to the API gateway. If you do not have an API gateway, create one.
-
Service account with the
api-gateway.websocketBroadcaster
role. If you do not have a service account, create one.
- A stream that will activate the trigger as soon as it receives data. If you do not have a stream, create one.
Creating a trigger
Note
The trigger is initiated within 5 minutes of being created.
-
In the management console
, select the folder where you want to create a trigger. -
Open API Gateway.
-
In the left-hand panel, select
Triggers. -
Click Create trigger.
-
Under Basic settings:
- Enter a name and description for the trigger.
- In the Type field, select
Data Streams
. - In the Launched resource field, select
API gateway
.
-
Under Data Streams settings, select a data stream and a service account with permissions to read data from the stream and write data to it.
-
(Optional) Under Batch message settings, specify:
- Message batch size in bytes. The values may range from 1 B to 64 KB. The default value is 1 B.
- Maximum wait time. The values may range from 1 to 60 seconds. The default value is 1 second.
The trigger groups messages for a period not exceeding the specified wait time and sends them to WebSocket connections. The total amount of data transmitted to connections may exceed the specified batch size if the data is transmitted as a single message. In all other cases, the amount of data does not exceed the batch size.
-
Under API gateway settings:
- In the API gateway field, select the API gateway.
- In the Path field, specify the path in the OpenAPI specification. Messages will be sent through WebSocket connections established using this path.
- In the Service account field, select the service account to send messages to WebSocket connections.
-
Click Create trigger.
If you do not have the Yandex Cloud command line interface yet, install and initialize it.
The folder specified in the CLI profile is used by default. You can specify a different folder using the --folder-name
or --folder-id
parameter.
To create a trigger that sends messages to WebSocket connections, run this command:
yc serverless trigger create yds \
--name <trigger_name> \
--database <database_location> \
--stream <stream_name> \
--batch-size 1b \
--batch-cutoff 1s \
--stream-service-account-id <service_account_ID> \
--gateway-id <API_gateway_ID> \
--gateway-websocket-broadcast-path <path> \
--gateway-websocket-broadcast-service-account-id <service_account_ID>
Where:
-
--name
: Trigger name. -
--database
: Location of the YDB DB the Data Streams stream is linked to.To find out where the DB is located, run the
yc ydb database list
command. The DB location is specified in theENDPOINT
column, in thedatabase
parameter, e.g.,/ru-central1/b1gia87mbah2********/etn7hehf6gh3********
. -
--stream
: Stream name. -
--batch-size
: Message batch size. This is an optional parameter. The values may range from 1 B to 64 KB. The default value is 1 B. -
--batch-cutoff
: Maximum wait time. This is an optional parameter. The values may range from 1 to 60 seconds. The default value is 1 second. The trigger groups messages for a period not exceedingbatch-cutoff
and sends them to WebSocket connections. The total amount of data transmitted to connections may exceedbatch-size
if the data is transmitted as a single message. In all other cases, the amount of data does not exceedbatch-size
. -
--stream-service-account-id
: ID of the service account with permissions to read from the stream and write to it.
--gateway-id
: API gateway ID.--gateway-websocket-broadcast-path
: Path in the OpenAPI specification. Messages will be sent through WebSocket connections established using this path.--gateway-websocket-broadcast-account-id
: Service account ID with permissions to send messages to WebSocket connections.
Result:
id: a1s5msktijh2********
folder_id: b1gmit33hgh2********
created_at: "2022-10-24T14:07:04.693126923Z"
name: data-streams-trigger
rule:
data_stream:
database: /ru-central1/b1gia87mbah2********/etn7hehh2********
stream: streams-name
service_account_id: ajep8qm0kh2********
batch_settings:
size: "1"
cutoff: 1s
gateway_websocket_broadcast:
gateway_id: d4eofc7n0mh2********
path: /
service_account_id: aje3932acdh2********
status: ACTIVE
To create a trigger for Data Streams, use the create REST API method for the Trigger resource or the TriggerService/Create gRPC API call.
Checking the result
Check that the trigger operates correctly. Do it by viewing the API gateway logs that present information about its incoming requests.