5.2 Building Your Own API Layer

Once the engine returns structured opportunities, you can wrap it with an HTTP/WebSocket API and plug it anywhere.

5.2.1 Minimal FastAPI wrapper (REST + WebSocket)

# api_server.py
import asyncio
from fastapi import FastAPI, WebSocket
from capture_engine import CaptureEngine

app = FastAPI()
engine = CaptureEngine(min_profit_threshold=0.2, sleep_seconds=2)

latest_opportunities: list[dict] = []

async def engine_loop():
    global latest_opportunities
    while True:
        latest_opportunities = await engine.tick()
        await asyncio.sleep(engine.sleep_seconds)

@app.on_event("startup")
async def startup_event():
    asyncio.create_task(engine_loop())

@app.get("/opportunities")
async def get_opportunities():
    return latest_opportunities

@app.websocket("/ws")
async def ws_opportunities(ws: WebSocket):
    await ws.accept()
    try:
        while True:
            await ws.send_json(latest_opportunities)
            await asyncio.sleep(engine.sleep_seconds)
    except Exception:
        await ws.close()

Now you have:

• GET /opportunities → JSON snapshot (top N opportunities).

• WS /ws → periodic push of the same JSON.

You can swap FastAPI with any other framework; the pattern is the same.