@auto-engineer/flowlang

@auto-engineer/flowlang

Domain-specific language for building event-driven applications with type-safe schemas and GraphQL API generation. Plugin for the Auto Engineer CLI that enables defining business flows, data transformations, and integrations using TypeScript-based syntax.

Installation

This is a plugin for the Auto Engineer CLI. Install both the CLI and this plugin:

npm install -g @auto-engineer/cli
npm install @auto-engineer/flowlang

Configuration

Add this plugin to your auto.config.ts:

export default {
  plugins: [
    '@auto-engineer/flowlang',
    // ... other plugins
  ],
};

Commands

This plugin provides the following commands:

• create:example - Create an example project with FlowLang
• export:schema - Export flow schema to JSON

What is FlowLang?

FlowLang is a declarative language for describing business processes, data flows, and system integrations. It combines:

• Type Safety: Full TypeScript integration with compile-time validation
• Event-Driven Architecture: Built on top of the Emmett event sourcing framework
• GraphQL Integration: Schema generation and resolver creation
• Message Bus Support: Support for inter-service communication
• Flow Orchestration: Define workflows with branching logic and error handling

Key Features

Fluent API Design

Define business flows using chainable API:

import { flow } from '@auto-engineer/flowlang';

const orderFlow = flow('place-order')
  .input<PlaceOrderCommand>()
  .validate(command => /* validation logic */)
  .process(async (command, ctx) => {
    // Business logic here
    return { orderId: generateId(), status: 'confirmed' };
  })
  .emit<OrderPlaced>()
  .build();

Schema Generation

Generate GraphQL schemas from flow definitions:

// Flows are converted to GraphQL mutations and queries
// Input types become GraphQL input types
// Output events become GraphQL object types

Integration Support

Support for external service integrations:

const flow = flow('payment-processing')
  .integration('stripe', StripePaymentGateway)
  .integration('email', EmailService)
  .process(async (command, ctx) => {
    const payment = await ctx.integrations.stripe.charge(command.amount);
    await ctx.integrations.email.sendReceipt(command.email, payment);
    return payment;
  });

Testing Support

Testing utilities for flow validation:

import { testFlow } from '@auto-engineer/flowlang/testing';

describe('order flow', () => {
  it('should process valid orders', async () => {
    const result = await testFlow(orderFlow)
      .withInput({ productId: '123', quantity: 2 })
      .expectEvent<OrderPlaced>()
      .run();

    expect(result.orderId).toBeDefined();
  });
});

Architecture

FlowLang builds on several core concepts:

• Flows: The main building blocks that define business processes
• Messages: Strongly-typed data structures for communication
• Integrations: External service connectors with retry and error handling
• Context: Runtime environment providing access to integrations and utilities
• Registry: Central repository for flow definitions and metadata

Getting Started

• Install the plugin (see Installation above)
• Create your first flow project:

  auto create:example
  

• Explore the generated example flows in the flows/ directory
• Define your own business flows using the FlowLang API
• Export your schema for GraphQL integration:

  auto export:schema
  

Integration with Auto Engineer

FlowLang works with other Auto Engineer plugins:

• @auto-engineer/emmett-generator: Generates backend infrastructure from FlowLang schemas
• @auto-engineer/react-graphql-generator: Creates React components from flow-generated GraphQL schemas
• @auto-engineer/server-implementer: Implements flow handlers with AI assistance
• @auto-engineer/information-architect: Generates information architecture from flow definitions

This plugin-based approach allows building applications from high-level flow definitions to production code.