@message-in-the-middle/cli

⚠️ Work in Progress Is this library production-ready? No. Is this library safe? No. When will it be ready? Soon™ (maybe tomorrow, maybe never). Why is it public? Experiment

message-in-the-middle is to Express.js what your message queue processing is to HTTP request processing. Just as Express provides a middleware pattern for HTTP requests, this library provides a middleware pattern for processing queue messages.

Why This Exists

Processing queue messages usually means copy-pasting the same boilerplate: parse JSON, validate, log, retry, deduplicate, route to handlers. This library lets you compose that logic as middlewares.

A powerful code generator and scaffolding tool for Queue-Centric Design applications.

Installation

# Global installation
npm install -g @message-in-the-middle/cli

# Or use with npx (no installation required)
npx @message-in-the-middle/cli --help

Quick Start

# Create a new project
mitm init my-queue-app --template express-sqs-mysql

# Generate a new queue
cd my-queue-app
mitm generate queue payments --preset critical

# Add a handler
mitm generate handler refund --queue payments

# Validate structure
mitm validate all

Commands

mitm init <project-name>

Create a new message-in-the-middle project with Queue-Centric Design structure.

Options:

• -t, --template <name> - Project template (default: express-sqs)
• -pm, --package-manager <pm> - Package manager: npm, pnpm, yarn (default: pnpm)
• --skip-install - Skip dependency installation
• --git - Initialize git repository
• --no-examples - Don't generate example queues

Available Templates:

• minimal - Core library only
• express-sqs - Express + SQS (no persistence)
• express-sqs-mysql - Express + SQS + MySQL (full stack)
• nestjs-sqs - NestJS integration
• standalone-sqs - Queue processing only
• multi-queue - Complex example with 5 queues

Example:

mitm init payment-processor --template express-sqs-mysql
cd payment-processor
pnpm install
pnpm dev

mitm generate queue <name>

Generate a new queue with handlers, pipeline, events, and types.

Aliases: mitm g queue, mitm g q

Options:

• -h, --handlers <list> - Comma-separated handler names
• -e, --events - Generate events.ts file
• -p, --preset <name> - Use preset (critical, standard, best-effort, high-throughput)
• -i, --interactive - Interactive mode with prompts
• --skip-app-update - Don't update app.ts

Presets:

• critical - 5 retries, circuit breaker, full audit trail
• standard - 3 retries, error logging (default)
• best-effort - 1 retry, minimal overhead
• high-throughput - Batching, optimized for speed

Examples:

# Quick generation
mitm generate queue payments

# With handlers
mitm generate queue orders --handlers create,update,cancel,ship

# With preset
mitm generate queue payments --preset critical --events

# Interactive mode
mitm generate queue --interactive

mitm generate handler <name>

Add a new handler to an existing queue.

Aliases: mitm g handler, mitm g h

Options:

• -q, --queue <name> - Target queue (required)
• -a, --action <name> - Action name (defaults to uppercase handler name)
• -i, --interactive - Interactive mode

Examples:

# Add handler to queue
mitm generate handler refund --queue payments

# Interactive mode
mitm generate handler --interactive

mitm list <target>

List queues, handlers, or templates.

Aliases: mitm ls

Targets:

• queues - List all queues in project
• handlers <queue> - List handlers for specific queue
• templates - List available project templates

Examples:

mitm list queues
mitm list handlers orders
mitm list templates

mitm validate <target>

Validate Queue-Centric Design structure.

Targets:

• all - Validate entire project
• queue <name> - Validate specific queue
• structure - Same as all (default)

Options:

• --fix - Auto-fix issues where possible
• --strict - Strict validation mode
• --json - Output as JSON

Examples:

# Validate all
mitm validate all

# Validate and fix
mitm validate all --fix

# Validate specific queue
mitm validate queue orders

Development Status

Current Version: 0.1.0 (Phase 1 - MVP)

Implemented:

• ✅ CLI framework and command structure
• ✅ Type definitions
• ✅ Utility functions
• ✅ Handlebars templates
• ✅ Basic commands (init, generate, list, validate)

In Progress:

• 🚧 Template rendering engine
• 🚧 File generation logic
• 🚧 AST manipulation for code updates
• 🚧 Interactive prompts

Coming Soon (Phase 2):

• Middleware generation
• Advanced validation with auto-fix
• More templates
• Better error handling

Project Structure

packages/cli/
├── src/
│   ├── commands/          # Command implementations
│   ├── generators/        # Code generators
│   ├── templates/         # Handlebars templates
│   ├── validators/        # Structure validators
│   ├── utils/            # Utility functions
│   └── types/            # Type definitions
├── templates/            # Handlebars template files
├── bin/                  # CLI executable
└── tests/               # Tests

Contributing

See CLI_PROPOSAL.md for the complete roadmap and feature specifications.

License

MIT

Links

• Documentation
• Main Repository
• CLI Proposal