learning/prompts/code-generation/java/02_io_pubsub.md

Prompt:
Write a sample Java code snippet that writes data to a Google Pub/Sub topic using Apache Beam.

Response:
Your Apache Beam pipeline can write data to a Google Pub/Sub topic using the Apache Beam PubSubIO connector.

Here is an example of how to use the PubSubIO connector to accomplish this:

```java
 package pubsub;
 import org.apache.beam.sdk.Pipeline;
 import org.apache.beam.sdk.io.gcp.pubsub.PubsubIO;
 import org.apache.beam.sdk.options.Description;
 import org.apache.beam.sdk.options.PipelineOptions;
 import org.apache.beam.sdk.options.PipelineOptionsFactory;
 import org.apache.beam.sdk.transforms.Create;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

 import java.util.Arrays;
 import java.util.List;

 // Pipeline to write data to a Google Pub/Sub topic
 public class WritePubSubTopic {

     private static final Logger LOG = LoggerFactory.getLogger(WritePubSubTopic.class);

    // Pipeline options to configure the pipeline
     public interface WritePubSubTopicOptions extends PipelineOptions {
         @Description("PubSub topic name to write to")
         String getTopicName();

         void setTopicName(String value);
     }

     public static void main(String[] args) {

        // Parse the pipeline options from the command line
        WritePubSubTopicOptions options = PipelineOptionsFactory.fromArgs(args).withValidation().as(WritePubSubTopicOptions.class);

        // Create a pipeline
         Pipeline p = Pipeline.create(options);

        // Sample messages to write to the Pub/Sub topic
         final List<String> messages = Arrays.asList(
                "PubSub message 1",
                "PubSub message 2",
                "PubSub message 3"
         );

         p
                // Create a list of messages to write to the Pub/Sub topic
                 .apply(Create.of(messages))
                 // Write the messages to the Pub/Sub topic
                 .apply(PubsubIO.writeStrings().to(options.getTopicName()));

        // Execute the pipeline
         p.run();
     }

 }
```

This code snippet utilizes the pipeline options pattern to parse command-line arguments.