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Executing WfSpecs


Now that you've created your first WfSpec, let's explore the different ways to run it. LittleHorse provides multiple methods to execute WfSpecs, each suited for different use cases.

warning

This tutorial assumes you have completed the Your First WfSpec guide.

Executing with lhctl​

The simplest way to execute a WfSpec is using the command-line interface. The lhctl command provides a quick way to execute and monitor WfRuns:

# Execute the `WfSpec` with a name parameter
lhctl run quickstart name Obi-Wan

You'll see output like:

{
  "id":  {
    "id":  "69881bf9aaf84c2f84bdde7ceb2dd105"
  },
  "wfSpecId":  {
    "name":  "quickstart",
    "majorVersion":  0,
    "revision":  0
  },
  "oldWfSpecVersions":  [],
  "status":  "RUNNING",
  "greatestThreadrunNumber":  0,
  "startTime":  "2025-01-07T01:53:47.212Z",
  "threadRuns":  [
    {
      "wfSpecId":  {
        "name":  "quickstart",
        "majorVersion":  0,
        "revision":  0
      },
      "number":  0,
      "status":  "RUNNING",
      "threadSpecName":  "entrypoint",
      "startTime":  "2025-01-07T01:53:47.296Z",
      "childThreadIds":  [],
      "haltReasons":  [],
      "currentNodePosition":  1,
      "handledFailedChildren":  [],
      "type":  "ENTRYPOINT"
    }
  ],
  "pendingInterrupts":  [],
  "pendingFailures":  []
}
info

The lhctl command is perfect for development and testing scenarios. It's also commonly used in CI/CD pipelines for automation.

Executing from the Dashboard​

LittleHorse provides a visual interface for running and monitoring WfSpec and WfRuns:

  1. Navigate to http://localhost:8080 in your browser
  2. Click on the "quickstart" WfSpec
  3. Click "Execute"
  4. Enter "Obi-Wan" in the name field
  5. Click "Execute Workflow"

The 'Execute WfRun' modal in LH Dashboard

The dashboard will show you the WfRun's execution status in real-time, making it ideal for debugging.

Executing with the Java SDK​

For production applications, you'll typically want to execute WfSpecs programmatically. Create a new file called RunWorkflow.java:

src/main/java/io/littlehorse/quickstart/Main.java
package io.littlehorse.quickstart;

import io.littlehorse.sdk.common.config.LHConfig;
import io.littlehorse.sdk.client.LHClient;

public class Main {
    public static void main(String[] args) throws Exception {
        // Initialize the client
        LHConfig config = new LHConfig();
        LHClient client = new LHClient(config);

        // Run the workflow
        String wfRunId = client.runWorkflow(
            "quickstart",
            java.util.Map.of("name", "anakin"),
            null
        ).getId();

        System.out.println("Started workflow with ID: " + wfRunId);
    }
}
note

The Java SDK provides the most flexibility for executing WfSpecs. You can integrate it into your existing applications and handle WfSpec execution programmatically.

Choosing the Right Method​

Each method has its ideal use case:

MethodBest For
lhctlDevelopment, testing, and CI/CD pipelines
DashboardDebugging, monitoring, and team collaboration
Java SDKProduction applications and system integration

Remember, all methods interact with the same LittleHorse server, so you can mix and match them based on your needs.

Wrapping Up​

You've learned how to execute WfSpecs using different methods and monitor their execution. In the next lesson, we'll dive deeper into debugging WfRuns and handling errors.

If you haven't already: