In modern applications, event processing plays a crucial role in real-time data analysis and decision-making. Hazelcast Jet is a distributed computing platform that helps process large volumes of data in a scalable and fault-tolerant manner. In this blog post, we’ll explore how to leverage Hazelcast Jet’s event processing guarantees in Java applications.

Understanding Event Processing Guarantees

Hazelcast Jet provides two main types of event processing guarantees:

1. At-Least-Once - This guarantee ensures that every event is processed at least once, even in the presence of failures. Hazelcast Jet achieves this by storing the state of processing during failures and resuming from the last known state after recovery.

2. Exactly-Once - This guarantee ensures that every event is processed exactly once, even in the presence of failures and network inconsistencies. Hazelcast Jet achieves this by employing a combination of distributed snapshots, event deduplication, and transactional processing.

Enabling Event Processing Guarantees

To enable event processing guarantees in Hazelcast Jet, you need to configure your pipeline with the appropriate settings. Let’s see how we can achieve this in a Java application.

import com.hazelcast.jet.config.JobConfig;
import com.hazelcast.jet.config.ProcessingGuarantee;
import com.hazelcast.jet.pipeline.Pipeline;

public class EventProcessingExample {

    public static void main(String[] args) {
        Pipeline pipeline = createPipeline();

        JobConfig jobConfig = new JobConfig();
        jobConfig.setName("event-processing-job");
        jobConfig.setProcessingGuarantee(ProcessingGuarantee.EXACTLY_ONCE);

        HazelcastJetInstance jet = HazelcastJet.newJetInstance();
        jet.newJob(pipeline, jobConfig).join();
    }

    private static Pipeline createPipeline() {
        // Build and return your event processing pipeline using Hazelcast Jet APIs
    }
}

In the above code snippet, we first create a Pipeline using Hazelcast Jet’s API. Next, we create a JobConfig and set the processing guarantee to EXACTLY_ONCE. Finally, we start a new Jet job with the created pipeline and configuration.

Handling Event Processing Failures

One advantage of using Hazelcast Jet is its ability to handle event processing failures gracefully. In case of failures, Hazelcast Jet automatically retries the failed events transparently, ensuring that every event gets processed according to the specified guarantee.

Additionally, Hazelcast Jet provides mechanisms for handling and recovering from failures manually. You can leverage the APIs to monitor job progress, track job state, and interact with the failed events to implement custom recovery strategies tailored to your application requirements.

Conclusion

Hazelcast Jet offers powerful event processing guarantees to ensure reliable and fault-tolerant event processing in Java applications. By understanding and leveraging these guarantees, developers can build robust and scalable applications that process large volumes of data in real-time.

#HazelcastJet #EventProcessing #Java