session

Module nuspace.system.devices.web.session.

One browser connection, and how a worker reaches it.

A cell never runs in the host, so a cell that draws is always across a process boundary. The two ends talk over a frame pipe: one TCP stream per worker process, length-prefixed msgpack messages, every live connection multiplexed over it by sid.

• worker side: piped_session binds a PipeSession for connection sid, a local Session whose every call is a message on the worker's one pipe. This module imports no web server at module scope: a worker unpickling a body would otherwise load uvicorn and starlette for a server it never runs.
• host side: served_sessions puts SessionPipe on one socket, a router on the host's loop between the pipe and the ws server's book of connections.

Why a pipe and not a proxy. Both ends are asyncio loops, and the host's is the one every browser socket lives on. A proxy is a blocking call: a browser edit firing a reverse proxy into the worker blocked the host loop, and the worker drawing in answer needed that same loop, so the host hung. Here nothing blocks and nothing calls back: the host only reads and writes messages, the worker owns its subscriptions, and a notify is one message.

Messages, each a msgpack array whose first item is the kind:

• worker -> host: open(rid, sid), send(sid, frame), read(rid, sid, path), sub(id, sid, path), unsub(id)
• host -> worker: reply(rid, ok, value), notify(id, payload)

frame is a frame already encoded the way the browser reads it.

ConnectedSession

Bind connection sid as the session, over the pipe at address.

ConnectedSession(address, sid)

Path nuspace.system.devices.web.ConnectedSession. Kind Bracket, sort bracket, cardinality transparent. Arity 2 (2 required).

Opening asks the host whether the connection is live, so a run for a tab that closed between dispatch and now fails here rather than drawing into nothing.

Arguments

Undocumented: yields, example.

piped_session

body with connection sid bound as the session it draws on.

web.piped_session(address, sid, body)

Path nuspace.system.devices.web.piped_session. Defined on nuspace.system.devices.web.session, bound as a function. Builds nu.With.

Arguments

Undocumented: example.

served_sessions

Every live connection on one socket, so a worker can draw on one.

web.served_sessions(address)

Path nuspace.system.devices.web.served_sessions. Defined on nuspace.system.devices.web.session, bound as a function. Builds nu.With.

Goes inside the server bracket: the book it reads is the server's.

Arguments

Undocumented: example.