pylecular 0.1.8

Python Moleculer Library

Pylecular

Pylecular is a Python library that implements the Moleculer protocol, enabling microservices communication and orchestration.

Status

🚧 Early Development: Pylecular is in alpha stage and under active development. Currently, it supports basic Moleculer protocol features and only includes NATS transport integration. The API is not stable, and breaking changes are expected. Use with caution in production environments.

Features

• Basic implementation of the Moleculer protocol.
• Support for service-to-service communication.
• Extensible and modular design.

Installation

You can install Pylecular using pip:

pip install pylecular

For development installation, you can clone the repository and install in editable mode:

git clone https://github.com/alvaroinckot/pylecular.git
cd pylecular
pip install -e .

Usage

Basic Usage - Python API

import asyncio
from pylecular.broker import Broker
from pylecular.service import Service
from pylecular.decorators import action
from pylecular.context import Context

# Define a service
class GreeterService(Service):
    name = "greeter"
    
    def __init__(self):
        super().__init__(self.name)
    
    @action(params=["name"])
    async def hello(self, ctx: Context):
        name = ctx.params.get("name", "World")
        return f"Hello, {name}!"

async def main():
    # Create a broker
    broker = Broker("my-node")
    
    # Register the service
    broker.register(GreeterService())
    
    # Start the broker
    await broker.start()
    
    # Make a call
    result = await broker.call("greeter.hello", {"name": "John"})
    print(result)  # Outputs: Hello, John!
    
    # Wait for termination
    await broker.wait_for_shutdown()

# Run the main function
asyncio.run(main())

Command Line Interface

Pylecular includes a command line interface (CLI) that allows you to easily start a broker and load services from a directory:

pylecular <service_directory> [options]

CLI Options

• service_directory: Path to the directory containing service files
• --broker-id, -b: Broker ID (default: node-<current_dir_name>)
• --transporter, -t: Transporter URL (default: nats://localhost:4222)
• --log-level, -l: Log level (default: INFO)
• --log-format, -f: Log format (options: PLAIN, JSON) (default: PLAIN)
• --namespace, -n: Service namespace (default: default)

Example:

# Start a broker with services from the 'services' directory
pylecular services

# Start with a custom broker ID and transporter
pylecular services -b my-broker -t nats://nats-server:4222

# Use verbose logging
pylecular services -l DEBUG

The CLI will:

1. Start a broker
2. Import and register all services found in the specified directory
3. Wait for requests
4. Gracefully shut down on SIGINT or SIGTERM signals (Ctrl+C)

Here is a basic example of how to use Pylecular:

For more complete examples, check the /examples folder in the repository:

from pylecular.context import Context
from pylecular.service import Service
from pylecular.decorators import action, event
from pylecular.broker import Broker

broker = ServiceBroker("broker-sample")

class MathService(Service):
    name = "math"

    def __init__(self):
        super().__init__(self.name)

    @action()
     def add(self, ctx):
          # Regular action
          result = ctx.params.get("a") + ctx.params.get("b")
          
          # Emit event to local listeners
          ctx.emit("calculation.done", {"operation": "add", "result": result})
          
          # Broadcast event to all nodes
          ctx.broadcast("calculation.completed", {"operation": "add", "result": result})
          
          return result

     @event(name="calculation.done")
     def calculation_done_handler(self, ctx):
          print(f"Calculation done: {ctx.params}")

broker.register(MathService())

await broker.start()

await broker.call("math.add", { "a": 5, "b": 20 })

Roadmap

• Add support for more Moleculer features.
• Improve documentation and examples.
• Enhance performance and stability.

Contributing

Contributions are welcome! Feel free to open issues or submit pull requests to help improve Pylecular.

License

This project is licensed under the MIT License. See the LICENSE file for details.