EXTERNAL_SESSION.md

HTTP Session Management

Overview

The python-openevse-http library requires you to pass an external aiohttp.ClientSession to OpenEVSE. Session ownership stays with the caller, so the library no longer constructs temporary HTTP clients internally.

Benefits

• Session Reuse: Share a single session across multiple OpenEVSE instances or other aiohttp clients
• Custom Configuration: Configure timeouts, connectors, proxies, and SSL behavior yourself
• Resource Management: Keep connection pooling and cleanup in one place
• Predictable Lifecycle: Avoid hidden session creation inside request and websocket code paths

Usage

Basic Usage

import aiohttp
from openevsehttp import OpenEVSE


async def main():
    timeout = aiohttp.ClientTimeout(total=30)
    async with aiohttp.ClientSession(timeout=timeout) as session:
        charger = OpenEVSE("openevse.local", session=session)
        await charger.update()
        print(f"Status: {charger.status}")
        await charger.ws_disconnect()

Sharing a Session

import aiohttp
from openevsehttp import OpenEVSE


async def main():
    async with aiohttp.ClientSession() as session:
        charger1 = OpenEVSE("charger1.local", session=session)
        charger2 = OpenEVSE("charger2.local", session=session)

        await charger1.update()
        await charger2.update()

Websocket Startup

Start websocket listening from the same event loop that owns the aiohttp.ClientSession:

import aiohttp
from openevsehttp import OpenEVSE


async def main():
    async with aiohttp.ClientSession() as session:
        charger = OpenEVSE("openevse.local", session=session)
        await charger.ws_start()
        await charger.ws_disconnect()

ws_start() is async so websocket tasks are created on the event loop that owns the configured aiohttp.ClientSession. This prevents using a session from a private background loop it was not created on.

API Notes

• OpenEVSE(..., session=session) uses the provided session for HTTP requests.
• OpenEVSEWebsocket(..., session=session) uses the provided session for websocket connections.
• If no session is configured, HTTP requests and websocket startup raise RuntimeError.
• Call await charger.ws_start() from the event loop that owns the session.
• Externally provided sessions are never closed by the library.

Migration

Before:

charger = OpenEVSE("openevse.local")
await charger.update()

After:

import aiohttp

async with aiohttp.ClientSession() as session:
    charger = OpenEVSE("openevse.local", session=session)
    await charger.update()