111 lines
3.6 KiB
Markdown
111 lines
3.6 KiB
Markdown
# Python Binding for Node.js
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## Description
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This project enables seamless integration of a Python backend with a Node.js application by maintaining a persistent Python subprocess. It allows calling Python methods asynchronously from Node.js using a dynamic JavaScript class interface, supports setting and getting Python-side properties, and enables receiving streamed partial results from long-running Python operations.
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## How to Use
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### JavaScript Usage Example
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```js
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import ChatModel from "./python_bindings.js";
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async function runExample() {
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const chat = new ChatModel({ model: "something" });
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// Set properties dynamically
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await chat.setProperty("model", "something");
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await chat.setProperty("tokenizer", 123);
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// Get properties from Python backend
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const modelResponse = await chat.getModelPath();
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console.log(modelResponse); // { Model: "something" }
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const tokenizerResponse = await chat.getTokenizer();
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console.log(tokenizerResponse); // { Tokenizer: 123 }
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// Call Python methods asynchronously
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let response = await chat.increment({ by: 5 });
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console.log("Incremented counter:", response.counter);
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response = await chat.increment({ by: 2 });
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console.log("Incremented counter:", response.counter);
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response = await chat.increment({ by: 2 });
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console.log("Incremented counter:", response.counter);
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// Listen for streamed partial results
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chat.onMessage(function(data) {
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console.log("Streamed data:", data);
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});
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// Call method that streams partial results
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await chat.testStream();
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// Cleanly terminate Python subprocess
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chat.end();
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}
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runExample();
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```
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## How to Write the Python Controller
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The Python controller defines the backend logic and exposes methods callable from Node.js. It should extend the provided `BaseController` class and implement any methods you want to call from Node.js.
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### Controller Structure Example
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```python
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# python/controller.py
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import time
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from baseController import BaseController
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class Controller(BaseController):
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model = None
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tokenizer = None
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counter = 0
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def getModelPath(self, params):
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return {"Model": self.model}
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def getTokenizer(self, params):
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return {"Tokenizer": self.tokenizer}
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def increment(self, params):
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self.counter += params.get("by", 1)
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return {"counter": self.counter}
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def reset(self, params):
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self.counter = 0
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return {"counter": self.counter}
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def testStream(self, params):
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for i in range(5):
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time.sleep(0.5)
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self.send({"partial": f"step {i+1} complete"})
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return {"counter": self.counter}
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```
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### Important Details
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- **Inheritance:** Your controller must inherit from `BaseController`.
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- **Methods:** Each method takes a single `params` dictionary argument containing parameters passed from Node.js.
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- **Return Value:** Methods return a JSON-serializable dictionary as a response.
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- **Streaming:** Use `self.send(data)` within methods to send partial streaming data back to Node.js. The JavaScript side will receive these via the registered stream callback.
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- **Properties:** Define class properties to maintain state accessible from both Python and Node.js via dynamic `setProperty` and `getProperty` calls.
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## Summary
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- Extend the Python `Controller` class to implement your backend logic.
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- Methods receive parameters and return JSON-serializable results.
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- Use `self.send()` to stream intermediate results when needed.
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- From Node.js, call these methods via the binding class, passing parameters as objects and receiving results asynchronously.
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- The binding handles JSON serialization, communication, and a persistent Python process lifecycle.
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This design allows flexible and efficient integration between Node.js and Python for complex applications.
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