Flowable — Open-Source Business Process and Workflow Engine

Introduction

Flowable is a compact, high-performance process engine written in Java that supports BPMN 2.0, CMMN, and DMN standards. It provides everything needed to model, deploy, and execute business processes and decision tables, from a graphical modeler to a REST API and task management UI.

What Flowable Does

• Executes BPMN 2.0 process definitions with support for user tasks, service tasks, gateways, and events
• Handles case management workflows using the CMMN standard
• Evaluates business rules and decision tables via the DMN engine
• Provides a web-based modeler for designing processes visually
• Exposes a REST API for deploying definitions and managing process instances programmatically

Architecture Overview

Flowable consists of separate engines for BPMN, CMMN, and DMN that share a common persistence layer backed by a relational database. Each engine manages its own lifecycle and state machine. The Spring Boot starter auto-configures all engines with sensible defaults, and the REST application wraps them in a single deployable service.

Self-Hosting & Configuration

• Embed the engine as a Maven dependency in any Java or Kotlin application
• Use the Spring Boot starter for zero-configuration setup with auto-database-migration
• Supports PostgreSQL, MySQL, Oracle, SQL Server, and H2 as backing stores
• Configure async job executors and history levels in flowable.cfg.xml or application.properties
• Deploy the Flowable UI apps (modeler, admin, task) as separate Spring Boot services

Key Features

• Standards-compliant BPMN 2.0, CMMN 1.1, and DMN 1.1 execution in a single engine
• Hot-deploy process definitions at runtime without restarting the application
• Built-in async job executor for timer events and asynchronous service tasks
• Comprehensive history and audit logging for compliance and debugging
• Lightweight footprint suitable for embedding in microservices

Comparison with Similar Tools

• Camunda — similar BPMN engine with a larger enterprise ecosystem; Flowable is more lightweight and permissively licensed
• Activiti — Flowable forked from Activiti and has since added CMMN, DMN, and significant performance improvements
• Temporal — code-first workflow orchestration; Flowable uses visual BPMN diagrams as the primary authoring format
• Zeebe — cloud-native workflow engine by Camunda; Flowable offers a more traditional embedded engine model

FAQ

Q: How does Flowable relate to Activiti? A: Flowable was created by the original Activiti founders and has evolved independently with new engines and features since 2016.

Q: Can I use it without Spring Boot? A: Yes. The core engine is standalone Java and can be configured programmatically without any Spring dependency.

Q: Is it production-ready? A: Yes. Flowable is used in production by banks, insurance companies, and government organizations for mission-critical process automation.

Q: What license does it use? A: The open-source edition is Apache 2.0. A commercial edition with additional features and support is also available.

Sources

• https://github.com/flowable/flowable-engine
• https://www.flowable.com/open-source