Workflow Service

Overview

Workflow service enables you to build and execute complex, multi-step background jobs with automatic state management and resume capabilities on Tailor Platform.

If a workflow fails at any step, you can resume it from where it stopped without re-executing successful steps, making it ideal for long-running operations that need reliability.

With Workflow service, you can:

• Chain multiple JavaScript functions into durable workflows
• Automatically preserve execution state at each step
• Resume failed workflows from the point of failure
• Access TailorDB and other platform services with proper authentication
• Monitor execution progress through Tailor Console and tailor-sdk CLI

Workflow vs Function

Both Workflow and Function services execute JavaScript code, but serve different purposes:

Feature	Function	Workflow
Execution model	Synchronous, single execution	Multi-step, stateful execution
Duration	Short-lived (seconds)	Long-running (minutes to hours)
State management	None	Automatic state preservation
Resume capability	No	Yes, from point of failure
Use case	Data transformation, API calls	Complex background jobs, multi-step processes
Called from	Pipeline resolvers, Executors	Executors, Functions

When to use Workflow:

• You need to chain multiple operations with state preservation
• The job may fail and needs to be resumed without repeating successful steps
• You're orchestrating complex business processes across multiple services

When to use Function:

• You need quick, synchronous data processing
• The operation is a single, atomic task
• You're transforming data within Pipeline resolvers

How Workflow Execution Works

Durable Execution Model

Workflow service uses a durable execution model where the execution state is automatically saved after each successful step.

Example execution flow:

Step 1: Fetch data from API    → Success ✓ (result cached)
Step 2: Transform data          → Success ✓ (result cached)
Step 3: Save to database        → Failed ✗

When you resume the workflow:

Step 1: Fetch data from API    → Skipped (use cached result)
Step 2: Transform data          → Skipped (use cached result)
Step 3: Save to database        → Retry from here

Benefits:

• No duplicate work: Successful steps are never re-executed
• Safe retries: You can retry as many times as needed
• Cost efficient: Only failed steps consume resources on retry
• Data consistency: Results from successful steps remain available

Stack-Based Execution

Workflows support nested function calls, similar to regular programming:

export function main(args) {
  // Call functions sequentially
  const data = tailor.workflow.triggerJobFunction("fetchData", {});
  const processed = tailor.workflow.triggerJobFunction("processData", data);
  return processed;
}

The execution stack:

[] → [main] → [main, fetchData] → [main] → [main, processData] → [main] → []

Each function's result is cached and passed to the next function in the chain.

Job functions within a single workflow execute sequentially, not in parallel. Each function completes before the next one starts. For concurrent execution, you can start multiple workflows asynchronously using tailor.workflow.triggerWorkflow().