Workflow Engine

A configurable workflow engine built on GoCodeAlone's Modular library v1.3.9, allowing applications to be built entirely from YAML configuration files.

Overview

This workflow engine lets you create applications by chaining together modular components based on YAML configuration files. You can configure the same codebase to operate as:

• An API server with authentication middleware
• An event processing system
• A bidirectional chat system with triage capabilities

All without changing code - just by modifying configuration files.

Requirements

• Go 1.23 or later
• GoCodeAlone/modular v1.3.9

Architecture

The workflow engine is built on these core concepts:

• Modules: Self-contained components that provide specific functionality
• Workflows: Configurations that chain modules together to create application behavior
• Handlers: Components that understand how to interpret and configure specific workflow types

Module Types

The engine supports several types of modules:

• HTTP Server: Handles HTTP requests
• HTTP Router: Routes HTTP requests to handlers
• HTTP Handlers: Processes HTTP requests and generates responses
• Authentication Middleware: Validates requests before they reach handlers
• Message Broker: Facilitates message-based communication
• Message Handlers: Processes messages from specific topics

Configuration

Applications are defined via YAML configuration files. Here's a basic example:

modules:
  - name: http-server
    type: http.server
    config:
      address: ":8080"
  - name: router
    type: http.router
  - name: hello-handler
    type: http.handler

workflows:
  http:
    routes:
      - method: GET
        path: /hello
        handler: hello-handler

Advanced Configuration

You can create more complex applications with authentication and messaging:

modules:
  - name: api-http-server
    type: http.server
    config:
      address: ":8080"
  - name: api-router
    type: http.router
  - name: auth-middleware
    type: http.middleware.auth
  - name: users-api
    type: api.handler
    config:
      resourceName: "users"
  - name: message-broker
    type: messaging.broker

workflows:
  http:
    routes:
      - method: GET
        path: /api/users
        handler: users-api
        middlewares:
          - auth-middleware
  messaging:
    subscriptions:
      - topic: user-events
        handler: user-event-handler

Example Applications

The repository includes several example applications:

1. API Server: A RESTful API with protected endpoints
2. Event Processor: A message-based event processing system
3. SMS Chat: A bidirectional chat system with triage workflow

Usage

Run any example by specifying the configuration file:

go run example/main.go -config example/api-server-config.yaml

Extending

To extend the workflow engine with custom modules:

1. Implement the appropriate interfaces in the module package
2. Register your module type in the BuildFromConfig method of the engine
3. Create a configuration file that uses your new module type

Testing

Run the tests to verify the workflow engine functionality:

go test ./...