dispytch 0.9.0

Lightweight Python framework for writing clean and testable event-driven services

⚡ Dispytch

Dispytch is a lightweight, async-first Python framework for event-handling. It’s designed to streamline the development of clean and testable event-driven services.

🚀 Features

• 🧠 Async-first core – built for modern Python I/O
• 🔌 FastAPI-style dependency injection – clean, decoupled handlers
• 🔁 Built-in retry logic – configurable, resilient, no boilerplate
• 📬 Backend-flexible – Kafka and RabbitMQ out-of-the-box
• 🧱 Composable architecture – extend, override, or inject anything

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📦 Installation

pip install dispytch

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✨ Handler example

from typing import Annotated

from pydantic import BaseModel
from dispytch import Event, Dependency, HandlerGroup

from service import UserService, get_user_service


class User(BaseModel):
    id: str
    email: str
    name: str


class UserCreatedEvent(BaseModel):
    user: User
    timestamp: int


user_events = HandlerGroup()


@user_events.handler(topic='user_events', event='user_registered')
async def handle_user_registered(
        event: Event[UserCreatedEvent],
        user_service: Annotated[UserService, Dependency(get_user_service)]
):
    user = event.body.user
    timestamp = event.body.timestamp

    print(f"[User Registered] {user.id} - {user.email} at {timestamp}")

    await user_service.do_smth_with_the_user(event.body.user)

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✨ Emitter example

import uuid
from datetime import datetime

from pydantic import BaseModel
from dispytch import EventBase


class User(BaseModel):
    id: str
    email: str
    name: str


class UserEvent(EventBase):
    __topic__ = "user_events"


class UserRegistered(UserEvent):
    __event_type__ = "user_registered"

    user: User
    timestamp: int


async def example_emit(emitter):
    await emitter.emit(
        UserRegistered(
            user=User(
                id=str(uuid.uuid4()),
                email="[e-mail]",
                name="John Doe",
            ),
            timestamp=int(datetime.now().timestamp()),
        )
    )

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✅ Why Dispytch?

• 🧼 Minimal boilerplate – Just annotate and go
• 🧪 Testable logic – Handlers are first-class coroutines
• 🔄 Flexible backends – Kafka, RabbitMQ, or bring your own
• 🧩 Clean separation of concerns – business logic ≠ plumbing

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⚠️ Limitations

While dispytch is a great choice for most usecases there are some limitations to be aware of:

🧾 No schema-on-write support Dispytch uses a schema-on-read model. Formats like Avro, Protobuf, or Thrift aren’t supported yet.

🕵️ No dead-letter queue (DLQ) Failed messages are retried using built-in logic, but there’s no DLQ or fallback mechanism after final retries yet.

🧩 No topic pattern matching Wildcard or templated subscriptions (e.g. user.*, order:{id}:events) aren’t supported in handler declarations yet. Though the backend of you choice may route events to the appropriate queues/topics/channels there is no way for a dispytch handler to know it yet

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💡 See something missing? Some features aren’t here yet—but with your help, they could be. Contributions welcome via PRs or discussions.