Overview

Key Insight

Signals provide lightweight message dispatch between workflows, enabling sophisticated coordination patterns without tight coupling.

Signals are lightweight messages that enable workflows to communicate asynchronously. Unlike direct task dependencies, signals provide a decoupled coordination mechanism where publishers and subscribers operate independently.

Event-Driven Architecture

Build reactive systems that respond to business events as they occur

Loose Coupling

Workflows coordinate without direct dependencies or knowledge of each other

Asynchronous Communication

Non-blocking message passing enables parallel workflow execution

Data Propagation

Share structured payloads between workflows with type safety

Signal Components

How Signals Work

Loading diagram...

Signal Flow Architecture

Signal Publication

Signals are published via signal tasks, Event API, or external systems with structured payloads

Temporal Routing

Temporal signal dispatcher routes signals through a dedicated Dispatcher Workflow that manages signal distribution to matching wait tasks and signal triggers based on signal IDs

Signal Processing

Processors transform and validate signal data using agents or tools

Workflow Orchestration

Target workflows continue execution or start automatically with signal data accessible via template variables

Response & Cascading

Processing results can trigger additional signals, creating sophisticated event chains and coordination patterns

Basic Usage

# Send a signal when task completes
- id: notify-completion
  type: signal
  signal:
    id: "order-processed"
    payload:
      order_id: "{{ .workflow.input.order_id }}"
      status: "{{ .task.output.status }}"
      total: "{{ .task.output.total }}"

Learn more in Signal Tasks.

Signal Architecture Patterns

Core Usage Scenarios

Human-in-the-Loop

Approval workflows with escalation and timeout handling

Service Orchestration

Coordinate microservices and distributed systems

Event-Driven Pipelines

Reactive data processing and ETL workflows

External Integrations

Webhook handling and API response coordination

Request approval

- id: request-approval
  type: signal
  signal:
    id: "approval-request"
    payload:
      request_id: "{{ .workflow.id }}"
      type: "budget-increase"
      amount: "{{ .workflow.input.amount }}"
      requestor: "{{ .workflow.input.user }}"

Wait for manager approval

- id: await-approval
  type: wait
  wait_for: "manager-approval"
  on_timeout: escalate-request

Advanced Features

Signal Processing

Wait tasks can process signals using optional processors:

- id: priority-handler
  type: wait
  wait_for: "task-update"
  processor:
    type: basic
    tool:
      id: task-processor
    with:
      task_data: "{{ .signal.payload }}"

Signal Timeouts

Handle scenarios where signals might not arrive:

- id: wait-with-fallback
  type: wait
  wait_for: "external-webhook"
  on_timeout: use-default-values

Multi-Signal Coordination

Use composite tasks to coordinate multiple signals:

- id: wait-all-approvals
  type: composite
  mode: parallel
  wait_all: true
  tasks:
    - type: wait
      wait_for: "manager-approval"
      on_timeout: handle-manager-timeout
    - type: wait
      wait_for: "compliance-approval"
      on_timeout: handle-compliance-timeout
    - type: wait
      wait_for: "finance-approval"
      on_timeout: handle-finance-timeout