Introduction

MicroPie is a fast, lightweight, modern Python web framework that supports asynchronous web applications. Designed with flexibility and simplicity in mind, MicroPie enables you to handle high-concurrency applications with ease while allowing natural integration with external tools like Socket.IO for real-time communication.

Key Features

• 🔄 Routing: Automatic mapping of URLs to functions with support for dynamic and query parameters.
• 🔒 Sessions: Simple, plugable, session management using cookies.
• 🎨 Templates: Jinja2, if installed, for rendering dynamic HTML pages.
• ⚙️ Middleware: Support for custom request middleware enabling functions like rate limiting, authentication, logging, and more.
• ✨ ASGI-Powered: Built w/ asynchronous support for modern web servers like Uvicorn and Daphne, enabling high concurrency.
• 🛠️ Lightweight Design: Only optional dependencies for flexibility and faster development/deployment.
• ⚡ Blazing Fast: Check out how MicroPie compares to other popular ASGI frameworks below!

Useful Links

• Homepage: patx.github.io/micropie
• API Reference: README.md#api-documentation
• PyPI Page: pypi.org/project/MicroPie
• GitHub Project: github.com/patx/micropie
• File Issue/Request: github.com/patx/micropie/issues
• Example Applications: github.com/patx/micropie/tree/main/examples

Installing MicroPie

Installation

Install MicroPie with all optional dependencies via pip:

pip install micropie[all]

This will install MicroPie along with jinja2 for template rendering and multipart/aiofiles for parsing multipart form data.

Minimal Setup

You can also install MicroPie without ANY dependencies via pip:

pip install micropie

For an ultra-minimalistic approach, download the standalone script:

MicroPie.py

Place it in your project directory, and you are good to go. Note that jinja2 must be installed separately to use the _render_template method and/or multipart & aiofiles for handling file uploads (the _parse_multipart method), but this is optional and you can use MicroPie without them. To install the optional dependencies use:

pip install jinja2 multipart aiofiles

Install an ASGI Web Server

In order to test and deploy your apps you will need a ASGI web server like Uvicorn, Hypercorn or Daphne. Install uvicorn with:

pip install uvicorn

Getting Started

Create Your First ASGI App

Save the following as app.py:

from MicroPie import App

class MyApp(App):
    async def index(self):
        return "Welcome to MicroPie ASGI."

app = MyApp()

Run the server with:

uvicorn app:app

Access your app at http://127.0.0.1:8000.

Core Features

1. Flexible HTTP Routing for GET Requests

MicroPie automatically maps URLs to methods within your App class. Routes can be defined as either synchronous or asynchronous functions, offering good flexibility.

For GET requests, pass data through query strings or URL path segments, automatically mapped to method arguments.

class MyApp(App):
    async def greet(self, name="Guest"):
        return f"Hello, {name}!"

    async def hello(self):
        name = self.request.query_params.get("name", None)[0]
        return f"Hello {name}!"

Access:

• http://127.0.0.1:8000/greet?name=Alice returns Hello, Alice!, same as http://127.0.0.1:8000/greet/Alice returns Hello, Alice!.
• http://127.0.0.1:8000/hello/Alice returns a 500 Internal Server Error because it is expecting http://127.0.0.1:8000/hello?name=Alice, which returns Hello Alice!

2. Flexible HTTP POST Request Handling

MicroPie also supports handling form data submitted via HTTP POST requests. Form data is automatically mapped to method arguments. It is able to handle default values and raw/JSON POST data:

class MyApp(App):
    async def submit_default_values(self, username="Anonymous"):
        return f"Form submitted by: {username}"

    async def submit_catch_all(self):
        username = self.request.body_params.get("username", ["Anonymous"])[0]
        return f"Submitted by: {username}"

By default, MicroPie's route handlers can accept any request method, it's up to you how to handle any incoming requests! You can check the request method (and an number of other things specific to the current request state) in the handler withself.request.method. You can see how to handle POST JSON data at examples/api.

3. Real-Time Communication with Socket.IO

Because of its designed simplicity, MicroPie does not handle WebSockets out of the box. While the underlying ASGI interface can theoretically handle WebSocket connections, MicroPie’s routing and request-handling logic is designed primarily for HTTP. While MicroPie does not natively support WebSockets, you can easily integrate dedicated Websockets libraries like Socket.IO alongside Uvicorn to handle real-time, bidirectional communication. Check out examples/socketio to see this in action.

4. Jinja2 Template Rendering

Dynamic HTML generation is supported via Jinja2. This happens asynchronously using Pythons asyncio library, so make sure to use the async and await with this method.

app.py

class MyApp(App):
    async def index(self):
        return await self._render_template("index.html", title="Welcome", message="Hello from MicroPie!")

templates/index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>{{ title }}</title>
</head>
<body>
    <h1>{{ message }}</h1>
</body>
</html>

5. Static File Serving

Here again, like Websockets, MicroPie does not have a built in static file method. While MicroPie does not natively support static files, if you need them, you can easily integrate dedicated libraries like ServeStatic or Starlette’s StaticFiles alongside Uvicorn to handle async static file serving. Check out examples/static_content to see this in action.

6. Streaming Responses

Support for streaming responses makes it easy to send data in chunks.

class MyApp(App):
    async def stream(self):
        async def generator():
            for i in range(1, 6):
                yield f"Chunk {i}\n"
        return generator()

7. Sessions and Cookies

Built-in session handling simplifies state management:

class MyApp(App):
    async def index(self):
        if "visits" not in self.session:
            self.request.session["visits"] = 1
        else:
            self.request.session["visits"] += 1
        return f"You have visited {self.request.session['visits']} times."

You also can use the SessionBackend class to create your own session backend. You can see an example of this in examples/sessions.

8. Middleware

MicroPie allows you to create pluggable middleware to hook into the request lifecycle. Take a look a trivial example using HttpMiddleware to send the console messages before and after the request is processed.

from MicroPie import App, HttpMiddleware

class MiddlewareExample(HttpMiddleware):
    async def before_request(self, request):
        print("Hook before request")

    async def after_request(self, request, status_code, response_body, extra_headers):
        print("Hook after request")


class Root(App):
    async def index(self):
        return "Hello, World!"

app = Root()
app.middlewares.append(MiddlewareExample())

9. Deployment

MicroPie apps can be deployed using any ASGI server. For example, using Uvicorn if our application is saved as app.py and our App subclass is assigned to the app variable we can run it with:

uvicorn app:app --workers 4 --port 8000

Learn by Examples

The best way to get an idea of how MicroPie works is to see it in action! Check out the examples folder for more advanced usage, including:

• Template rendering
• Custom HTTP request handling
• File uploads
• Serving static content with ServeStatic
• Session usage
• JSON Requests and Responses
• Websockets with Socket.io
• Async Streaming
• Middleware
• Form handling and POST requests
• And more

Why ASGI?

ASGI is the future of Python web development, offering:

• Concurrency: Handle thousands of simultaneous connections efficiently.
• WebSockets: Use tools like Socket.IO for real-time communication.
• Scalability: Ideal for modern, high-traffic applications.

MicroPie allows you to take full advantage of these benefits while maintaining simplicity and ease of use you're used to with your WSGI apps and it lets you choose what libraries you want to work with instead of forcing our ideas onto you!

Comparisons

Features vs Other Popular Frameworks

Feature	MicroPie	Flask	CherryPy	Bottle	Django	FastAPI
Ease of Use	Very Easy	Easy	Easy	Easy	Moderate	Moderate
Routing	Automatic	Manual	Manual	Manual	Views	Manual
Template Engine	Jinja2 (Opt.)	Jinja2	None	SimpleTpl	Django	Jinja2
Middleware	Yes	Yes	Yes	Yes	Yes	Yes
Session Handling	Simple	Extension	Built-in	Plugin	Built-in	Extension
Async Support	Yes (ASGI)	No (Quart)	No	No	Limited	Yes (ASGI)
Built-in Server	No	No	Yes	Yes	Yes	No

Benchmark Results

Below is a performance comparison of various ASGI frameworks using their "Hello World" examples from each framework's website. Ran with uvicorn with 4 workers and wrk -t12 -c1000 -d30s http://127.0.0.1:8000/:

Framework	Requests/sec	Transfer/sec	Avg Latency	Stdev Latency	Max Latency	Socket Errors (timeouts)
Muffin	6508.80	0.90MB	132.62ms	69.71ms	2.00s	533
Starlette	6340.40	0.86MB	130.72ms	75.55ms	2.00s	621
BlackSheep	5928.99	0.98MB	142.48ms	73.61ms	1.99s	526
MicroPie	5447.04	0.85MB	157.04ms	71.55ms	2.00s	470
Litestar	5088.38	730.46KB	151.59ms	81.75ms	2.00s	662
Sanic	4236.29	682.61KB	196.80ms	80.56ms	2.00s	452
FastAPI	2352.53	326.23KB	396.95ms	112.41ms	2.00s	516

Suggestions or Feedback?

We welcome suggestions, bug reports, and pull requests!

• File issues or feature requests here.
• Security issues that should not be public, email harrisonerd [at] gmail.com.

API Documentation

Session Backend Abstraction

MicroPie provides an abstraction for session backends, allowing you to define custom session storage mechanisms.

SessionBackend Class

Methods

• load(session_id: str) -> Dict[str, Any]

  • Abstract method to load session data given a session ID.

• save(session_id: str, data: Dict[str, Any], timeout: int) -> None

  • Abstract method to save session data.

InMemorySessionBackend Class

An in-memory implementation of the SessionBackend.

Methods

• __init__()

  • Initializes the in-memory session backend.

• load(session_id: str) -> Dict[str, Any]

  • Loads session data for the given session ID.

• save(session_id: str, data: Dict[str, Any], timeout: int) -> None

  • Saves session data for the given session ID.

Middleware Abstraction

MicroPie allows you to create pluggable middleware to hook into the request lifecycle.

HttpMiddleware Class

Methods

• before_request(request: Request) -> None

  • Abstract method called before the request is processed.

• after_request(request: Request, status_code: int, response_body: Any, extra_headers: List[Tuple[str, str]]) -> None

  • Abstract method called after the request is processed but before the final response is sent to the client.

Request Object

Request Class

Represents an HTTP request in the MicroPie framework.

Attributes

• scope: The ASGI scope dictionary for the request.
• method: The HTTP method of the request.
• path_params: List of path parameters.
• query_params: Dictionary of query parameters.
• body_params: Dictionary of body parameters.
• get_json: JSON request body object.
• session: Dictionary of session data.
• files: Dictionary of uploaded files.
• headers: Dictionary of headers.

Application Base

App Class

The main ASGI application class for handling HTTP requests in MicroPie.

Methods

• __init__(session_backend: Optional[SessionBackend] = None) -> None

  • Initializes the application with an optional session backend.

• request -> Request

  • Retrieves the current request from the context variable.

• __call__(scope: Dict[str, Any], receive: Callable[[], Awaitable[Dict[str, Any]]], send: Callable[[Dict[str, Any]], Awaitable[None]]) -> None

  • ASGI callable interface for the server. Checks scope type.

• _asgi_app_http(scope: Dict[str, Any], receive: Callable[[], Awaitable[Dict[str, Any]]], send: Callable[[Dict[str, Any]], Awaitable[None]]) -> None

  • ASGI application entry point for handling HTTP requests.

• request(self) -> Request

  • Accessor for the current request object. - Returns the current request from the context variable.

• _parse_cookies(cookie_header: str) -> Dict[str, str]

  • Parses the Cookie header and returns a dictionary of cookie names and values.

• _parse_multipart(reader: asyncio.StreamReader, boundary: bytes)

  • Parses multipart/form-data from the given reader using the specified boundary.
  • Requires: multipart and aiofiles

• _send_response(send: Callable[[Dict[str, Any]], Awaitable[None]], status_code: int, body: Any, extra_headers: Optional[List[Tuple[str, str]]] = None) -> None

  • Sends an HTTP response using the ASGI send callable.

• _redirect(location: str) -> Tuple[int, str]

  • Generates an HTTP redirect response.

• _render_template(name: str, **kwargs: Any) -> str

  • Renders a template asynchronously using Jinja2.
  • Requires: jinja2

The App class is the main entry point for creating MicroPie applications. It implements the ASGI interface and handles HTTP requests.

Response Formats

Handlers can return responses in the following formats:

1. String or bytes or JSON
2. Tuple of (status_code, body)
3. Tuple of (status_code, body, headers)
4. Async or sync generator for streaming responses

Error Handling

MicroPie provides built-in error handling for common HTTP status codes:

• 404 Not Found: Automatically returned for non-existent routes
• 400 Bad Request: Returned for missing required parameters
• 500 Internal Server Error: Returned for unhandled exceptions

Custom error handling can be implemented through middleware.

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© 2025 Harrison Erd