WOML: Workflow Orchestration Markup Language

Build durable workflow automation with readable markup and JavaScript.

WOML (Workflow Orchestration Markup Language) is a markup language for building and running workflow automation. A workflow written in WOML is a document you can read top to bottom — its triggers, steps, control flow, approvals, and lifecycle all expressed as clear, HTML-inspired structure rather than tangled code or an unreadable diagram.

Key Features

• Structured workflow markup — define workflows through semantic elements such as <triggers>, <steps>, <step>, <script>, and <lifecycle>.
• Flexible automation triggers — start workflows manually or through webhooks, Slack, Telegram, Discord, WhatsApp, schedules, intervals, and internal events.
• Embedded JavaScript — use the familiar context binding to read the trigger payload, previous step results, and run information.
• Durable execution — runs are supervised by the Rust core and represented through versioned events instead of an authoritative mutable context object.
• Workflow control flow — compose sequential steps, parallel work, conditional choices, switches, and forked branches with explicit joins.
• Retries and idempotency — declare retry behavior with the retry attribute while WOML preserves durable attempt history and safe execution boundaries.
• Human-in-the-loop automation — pause a workflow for approval, notify reviewers, and continue through approved or rejected routes.
• Built-in capabilities — access HTTP, SQL databases, storage, cache, events, durable state, and other workflows through services.
• Reusable building blocks — import JavaScript or TypeScript modules and define reusable WOML steps and notification providers.
• Production operation — apply concurrency, rate-limit, timeout, queue, and durable-state policies; run automations in the background and inspect their durable logs.
• Native VS Code experience — get HTML-style WOML markup, embedded JavaScript highlighting, visible runtime bindings, reference-expression highlighting, snippets, and a dedicated .woml file icon.

Quick Start

Create a file named hello.woml:

<woml>
  <workflow
    id="hello-workflow"
    name="Hello workflow"
    description="Build a personalized greeting"
    version="1.0.0"
  >
    <triggers>
      <manual id="start" />
    </triggers>

    <steps>
      <step
        id="person"
        name="Prepare person"
        description="Create the person used by the next step."
      >
        <script>
          return {
            name: "World"
          };
        </script>
      </step>

      <step
        id="greeting"
        name="Build greeting"
        description="Build the final message from the previous result."
      >
        <script>
          return {
            message: `Hello ${context.steps.person.name}`
          };
        </script>
      </step>
    </steps>
  </workflow>
</woml>

Run it with:

woml run hello.woml

The manual trigger keeps the automation active. Press Enter to start a run, and WOML executes both steps in order. The second step reads the first step's result through context.steps.person and returns:

{
  "message": "Hello World"
}

WOML Runtime Bindings

WOML provides a small set of explicit bindings inside scripts and reference expressions:

Reference expressions use the same roots inside WOML attributes:

message="Order total: {{context.steps.calculateTotal.total}}"

Visual Studio Code Experience

WOML follows the active editor theme rather than introducing a separate color theme:

• WOML elements use the same scopes as HTML elements.
• Code inside <script> uses native JavaScript highlighting.
• Runtime bindings remain visually distinct from ordinary variables.
• {{...}} expressions are highlighted inside attribute values.
• .woml files receive a dedicated file icon.

Provider and workflow snippets are available:

Documentation

For WOML syntax, workflow execution, triggers, control flow, approvals, services, modules, runtime policies, durable state, and production operations, visit the WOML documentation.

License

WOML is available under the Apache License 2.0.