py-micro-plumberd 0.1.8

A lightweight Python library for writing events to EventStore, compatible with .NET micro-plumberd

py-micro-plumberd

A lightweight Python library for writing events to EventStore, designed for seamless interoperability with the .NET micro-plumberd framework. This library ensures that events written from Python can be read and processed by C# applications using micro-plumberd.

Features

• Simple event definition with automatic ID generation (lowercase UUID with dashes)
• Stream naming convention: {Category}-{StreamId}
• Automatic metadata enrichment (Created timestamp, ClientHostName)
• EventStore client for appending events
• Full compatibility with C# micro-plumberd event format

Installation

pip install py-micro-plumberd

Quick Start

Define an Event

from py_micro_plumberd import Event
from datetime import datetime
import uuid

class RecordingFinished(Event):
    def __init__(self, recording_id: str, duration: float, file_path: str):
        super().__init__()
        self.recording_id = recording_id
        self.duration = duration
        self.file_path = file_path

Append Events to EventStore

from py_micro_plumberd import EventStoreClient, StreamName

# Create client
client = EventStoreClient("esdb://localhost:2113?tls=false")

# Create an event
event = RecordingFinished(
    recording_id="rec-123",
    duration=120.5,
    file_path="/recordings/rec-123.mp4"
)

# Define stream
stream = StreamName(category="Recording", stream_id="b27f9322-7d73-4d98-a605-a731a2c373c6")

# Append event
client.append_to_stream(stream, event)

Core Concepts

Events

All events must inherit from the Event base class, which automatically:

• Generates a unique ID (UUID) for each event instance
• Provides serialization support
• Enables metadata enrichment

Stream Naming

Streams follow the pattern {Category}-{StreamId}:

• Category: Logical grouping of events (e.g., "Recording", "User", "Order")
• StreamId: Unique identifier for the stream instance (typically a UUID)

Example: Recording-b27f9322-7d73-4d98-a605-a731a2c373c6

Metadata

Each event is automatically enriched with metadata:

• Created: ISO 8601 timestamp of when the event was created
• ClientHostName: Hostname of the machine creating the event
• $correlationId: Same as TEvent.Id
• $causationId: Same as TEvent.Id

Advanced Usage

Custom Metadata

from py_micro_plumberd import Event, Metadata

class UserRegistered(Event):
    def __init__(self, email: str, username: str):
        super().__init__()
        self.email = email
        self.username = username


client.append_to_stream(stream, event)

Reading Events in C#

Events written by py-micro-plumberd can be read using the .NET micro-plumberd framework:

using MicroPlumberd;

// Define matching event class
public record RecordingFinished(string RecordingId, double Duration, string FilePath);

// Read events using micro-plumberd
var plumber = serviceProvider.GetRequiredService<IPlumber>();
var events = await plumber.ReadStream("Recording-b27f9322-7d73-4d98-a605-a731a2c373c6");

foreach (var evt in events)
{
    if (evt.Event is RecordingFinished recording)
    {
        Console.WriteLine($"Recording {recording.RecordingId} finished");
        Console.WriteLine($"Duration: {recording.Duration} seconds");
        Console.WriteLine($"Created: {evt.Metadata.Created}");
    }
}

Configuration

Connection String

The EventStore connection string supports various formats:

# Insecure connection
client = EventStoreClient("esdb://localhost:2113?tls=false")

# Secure connection
client = EventStoreClient("esdb://localhost:2113")

# With credentials
client = EventStoreClient("esdb://admin:changeit@localhost:2113")

Client Options

client = EventStoreClient(
    connection_string="esdb://localhost:2113",
    default_deadline=30,  # seconds
    keep_alive_interval=10,  # seconds
    keep_alive_timeout=10  # seconds
)

Examples

Complete Example: Task Management System

from py_micro_plumberd import Event, EventStoreClient, StreamName
from datetime import datetime

# Define events
class TaskCreated(Event):
    def __init__(self, title: str, description: str):
        super().__init__()
        self.title = title
        self.description = description

class TaskCompleted(Event):
    def __init__(self, completed_by: str, completion_notes: str = None):
        super().__init__()
        self.completed_by = completed_by
        self.completion_notes = completion_notes

def main():
    # Setup client
    client = EventStoreClient("esdb://localhost:2113?tls=false")
    
    # Create task stream
    task_id = "7d73-4d98-a605-a731a2c373c6"
    stream = StreamName(category="Task", stream_id=task_id)
    
    # Create task
    created_event = TaskCreated(
        title="Implement py-micro-plumberd",
        description="Create Python version of micro-plumberd"
    )
    client.append_to_stream(stream, created_event)
    
    # Complete task
    completed_event = TaskCompleted(
        completed_by="[e-mail]",
        completion_notes="Successfully implemented core functionality"
    )
    client.append_to_stream(stream, completed_event)
    
    print(f"Events written to stream: {stream}")
    print("These events can now be read using C# micro-plumberd")

if __name__ == "__main__":
    main()

Requirements

• Python 3.8+
• EventStore 20.6+
• esdbclient

License

MIT License - see LICENSE file for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Integration Testing

The library includes integration tests to ensure compatibility between Python and C#:

# Run Python tests
pytest tests/

# Run C# integration tests (requires .NET SDK)
cd tests/csharp
dotnet test

Event Format Compatibility

To ensure C# compatibility, events written by py-micro-plumberd follow these conventions:

1. Event ID: Lowercase UUID with dashes (e.g., "3fa85f64-5717-4562-b3fc-2c963f66afa6")
2. Metadata Format: JSON object with:
   • Created: ISO 8601 timestamp (e.g., "2025-07-13T18:22:19.2192669+02:00")
   • ClientHostName: Machine hostname (e.g., "MARS")
3. Event Data: JSON serialized with property names in PascalCase to match C# conventions

Links

• EventStore Documentation
• Original micro-plumberd (.NET)