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Overview

The Comfy server runs on top of the aiohttp framework, which in turn uses asyncio. Messages from the server to the client are sent by socket messages through the send_sync method of the server, which is an instance of PromptServer (defined in server.py). They are processed by a socket event listener registered in api.js. See messages. Messages from the client to the server are sent by the api.fetchApi() method defined in api.js, and are handled by http routes defined by the server. See routes.
The client submits the whole workflow (widget values and all) when you queue a request. The server does not receive any changes you make after you send a request to the queue. If you want to modify server behavior during execution, you’ll need routes.