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Execution Modes

FlowDrop supports multiple execution modes (called orchestrators) that control how your workflow runs. Choosing the right orchestrator depends on how fast your workflow needs to complete, how many nodes it has, and whether it requires user interaction.

Executing a Workflow

To manually execute a workflow:

  1. Navigate to Administration > FlowDrop > Execute (/admin/flowdrop/execute).
  2. Click Execute Workflow.
  3. Select the workflow from the dropdown.
  4. Choose an orchestrator (see below).
  5. Click Execute.

Note

You can also execute workflows automatically using Triggers — no manual action required.

Choosing an Orchestrator

Orchestrator Speed Best For Requires Queue?
Synchronous Instant Simple workflows (< 10 nodes), testing, form processing No
Synchronous Pipeline Instant Same as synchronous, but with per-node tracking in the admin UI No
Asynchronous Background Long-running workflows, many nodes, external API calls Yes
StateGraph Background Loops, human-in-the-loop, chat workflows, approval gates Yes

Synchronous

Runs all nodes in a single HTTP request. The page waits until execution finishes and then shows results immediately.

Use when:

  • Testing a new workflow
  • The workflow has a small number of nodes
  • You need an immediate result (e.g., processing a form submission)

Limitations:

  • Bound by PHP execution time limits
  • The browser waits until the workflow finishes
  • Not suitable for workflows that call slow external APIs

Synchronous Pipeline

Same as synchronous, but creates a Pipeline entity with individual Job records for each node. This gives you per-node tracking and status visibility in the admin UI.

Use when:

  • You want synchronous execution but also want to inspect per-node results afterward
  • Debugging workflows to see exactly what each node produced

Asynchronous

Queues the workflow for background processing. The page returns immediately while the workflow runs in the background via Drupal's queue system.

Use when:

  • The workflow takes more than a few seconds to complete
  • The workflow calls external APIs or services
  • You are processing large amounts of data
  • The workflow is triggered automatically (triggers default to async)

Queue Processing Required

Asynchronous workflows depend on Drupal's queue system. You must ensure queues are being processed, otherwise workflows will remain stuck in "pending" status. See Setting Up Queue Processing below.

StateGraph

A stateful orchestrator that maintains execution state across steps. Supports loops, conditional routing, human-in-the-loop pauses, and checkpoint-based resumption.

Use when:

  • The workflow contains loops (ForEach, iterator nodes)
  • The workflow pauses for user input (confirmation, choice, text input nodes)
  • You are building chat-based interactive workflows
  • The workflow needs approval gates

Tip

The Playground always uses the StateGraph orchestrator. If your workflow works in the playground, it will work with StateGraph.

Requires: Enable the flowdrop_stategraph module: 

drush en flowdrop_stategraph

Setting Up Queue Processing

Asynchronous and StateGraph orchestrators require Drupal's queues to be processed. FlowDrop uses two queues:

Queue Purpose
flowdrop_runtime_pipeline_execution Processes pipeline-level execution requests
flowdrop_runtime_job_execution Processes individual node execution requests

Option 1: Drupal Cron (Simplest)

Drupal's built-in cron processes queues automatically. Ensure cron is configured and running at a reasonable frequency (every 1-5 minutes for responsive workflows).

Verify cron is running: 

drush cron

For faster, more reliable processing, run dedicated queue workers:

# Process pipeline execution queue
drush queue:run flowdrop_runtime_pipeline_execution

# Process job execution queue
drush queue:run flowdrop_runtime_job_execution

You can run these commands via a process manager (e.g., Supervisor) or as periodic cron jobs running every minute.

Verifying Queue Status

Check if there are items waiting in the queue:

drush queue:list

If you see items accumulating in the FlowDrop queues but they are not being processed, verify that cron is running or start the queue workers manually.

Monitoring Execution

After executing a workflow, you can monitor its progress:

  1. Navigate to Administration > FlowDrop > Pipelines (/admin/flowdrop/pipelines).
  2. Find your pipeline in the list (most recent first).
  3. Click on the pipeline to see per-node job statuses.
  4. Click on individual jobs to see their input/output data and any error messages.

For more details, see the Monitoring Workflows guide.

Next Steps