Voltdb-procedure

The emitter voltdb-procedure invokes VoltDB stored procedure. It employs at-least-once delivery guarantees.

For each event it will synchronously or asynchronously invoke stored procedure passing event data as arguments. When using the Java API the argument to the sink is a VoltRequest object that contains: - parameters: an array of Object-s that correspond to stored procedure arguments. For example, to invoke a stored procedure that has public long run(long id, int anotherId, String someString) the Object[] should contain Long, Integer and String or compatible types as defined in the VoltDB documentation. - procedureName: name of the stored procedure to run for this specific event.

In case of downstream system error this processor will retry procedure execution with exponential backoff. The details of this behaviour are configurable using retry configuration that is nested within client configuration.

The voltdb-procedure operator requires VoltDBResource to be configured either in yaml or in java, see examples.

JAVAYAML

// if resource is configured in yaml
voltStreamBuilder.configureResource("primary-cluster", VoltDBResourceConfigBuilder.class);
// or
voltStreamBuilder.configureResource("primary-cluster",
         VoltDBResourceConfigBuilder.class,
         new Consumer<VoltDBResourceConfigBuilder>() {
             @Override
             public void consume(VoltDBResourceConfigBuilder configurator) {
                 configurator
                   .addToServers("localhost", 12122)
                   .withClientBuilder(vcb -> builder -> {
                       builder.withMaxOutstandingTransactions(42000);
                       builder.withMaxTransactionsPerSecond(23);
                       builder.withRequestTimeout(Duration.ofSeconds(5));
                       builder.withAuthBuilder(authBuilder -> authBuilder
                          .withUsername("admin")
                          .withPassword("admin123"));
                       builder.withSslBuilder(sslBuilder -> sslBuilder
                          .withTrustStoreFile("c:/Users32/trust.me")
                          .withTrustStorePassword("got2have"));
                       builder.withRetryBuilder(retryBuilder -> retryBuilder
                          .withRetries(4)
                          .withBackoffDelay(Duration.ofSeconds(2))
                          .withMaxBackoffDelay(Duration.ofSeconds(11)));
                   })
             }
         });
voltStreamBuilder
        .consumeFromSource(...)
        .terminateWithEmitter(VoltProcedureEmitterConfig.<Event, EnhancedEvent>builder()
            .withClientReferenceName("primary-cluster")
            .withExceptionHandler(exceptionHandler)
            .withRequestMapper(event -> new Object[] { event.id() })
            .withComputeFunction((event, result) -> {
                if (result != null && result.advanceRow()) {
                    return new EnhancedEvent(event.id(), result.getString("name"));
                }
                return null;
            })
        )
        .emit(VoltProcedureTrigger.onEachResponse)
        ...

public record EnhancedEvent(int id, String name) {}

resources:
- name: primary-cluster
  voltdb-client:
    servers: localhost:12122
    client:
        maxOutstandingTransactions: 42000
        maxTransactionsPerSecond: 23
        requestTimeout: PT5S
        auth:
            username: admin
            password: admin123
        ssl:
            trustStoreFile: c:/Users32/trust.me
            trustStorePassword: got2have
        retry:
            retries: 4
            backoffDelay: 2s
            maxBackoffDelay: 11s
emitter:
    voltdb-procedure:
      voltClientResource: primary-cluster
      requestMapper: "com.example.Event::toRequest"
      computeFunction: "com.example.Event::toResult"
      triggers:
        - trigger: onEachResponse
          ...

Java dependency management

Add this declaration to your dependency management system to access the configuration DSL for this plugin in Java.

MavenGradle

<dependency>
    <groupId>org.voltdb</groupId>
    <artifactId>volt-stream-plugin-volt-api</artifactId>
    <version>1.7.0</version>
</dependency>

implementation group: 'org.voltdb', name: 'volt-stream-plugin-volt-api', version: '1.7.0'

Properties

requestMapper

Given the input event this mapper returns request to VoltDB Type: object

computeFunction

The function computes result event for next operator in pipeline Required.

Type: object

asyncCall

Synchronously/asynchronously call to VoltDB. By default procedures are executed asynchronously. Type: boolean

Default value: true

voltClientResource

Client resource reference to be used when connecting to VoltDb cluster Required.

Type: object

exceptionHandler

A custom exception handler enabling interception of all errors related to this processor. Type: object

JSON Schema

You can validate or explore the configuration using its JSON Schema.