C4: a device's `viewers` (superusers by default, or members) covers the
image and video messages its ports publish. Anyone else gets none of their
values on the socket, in the catalogue or a flow's state, 403 for their
history, for the frames they hold (the last 8 included) and for TURN
credentials, no bytes when asking for them, and `bye: forbidden` for a live
view. A device credential stays bounded by its dashboards. The device page
sets it in its Camera section, and a tile the viewer may not see says
"No access to this camera" and asks the camera for nothing.
C3:
- A volatile upload is held to MAX_FRAME_BYTES (4 MiB, 413 above it, read
without extra copies), and so is a frame on a device's socket.
- A frame the engine holds in memory is written to the ring directory
before a local worker is handed it, so load_artifact finds it.
- A socket the bus dropped events for catches up with a snapshot, demand
included, and a device's credential is checked again per frame, cached by
the flow store revision and its nonce, so a lost event never keeps an
unpaired device's frames coming.
- A report is at most 64 KB once its named config_schemas are put in place.
- A device away for 60 s has its true bool messages set to false.
- Refused frames are logged by fixed keys, a frame is named after its
message, `fluksio serve` waits 5 s for open connections, a tile with a
stream URL creates no demand, the 8-name cap keeps the newest names.
- Every container's log rotates (json-file, 3 x 10 MB).
- Volatile frames are held in memory with a byte-bounded queue instead of
the /dev/shm ring scanned on every put; workers keep writing to the
directory, which is trimmed on a timer. A volatile upload no longer spools
to disk. ARTIFACT_VOLATILE_BYTES=0 turns the ring off.
- A device sends camera frames as binary messages on its socket, held and
published in one step and credited to its device node; refused frames are
logged and dropped. Its snapshot carries demand and the uplink (binary, or
http through the portal).
- One demand registry for every socket's wanted media, the tunnel's
included, plus what running flows read, mapped onto on-demand ports and
published as device_demand; at most 8 media names per socket.
- Per-message deflate off in serve and dev; a device may fetch the last 8
digests of a message; published dashboards cached per store revision; a
revoked device socket is closed with 1008.
- Media tiles want bytes only while on screen; the Devices tab previews a
wired camera; the device node warns when a flow reads an on-demand port.
`wanted_names` never read its `previous` argument — the caller reassigns
`wanted` from the return value — so the parameter goes rather than gaining
an underscore; its one call site and four test calls follow. Sorts the
imports in test_artifacts.py. Both were failing `make lint-backend` at HEAD.
Regenerates the client, which 8c097d9 left behind when it corrected the
revoke_client docstring.
The rate the media dtypes could carry was one frame every second or two: each
was a file on the data volume, an event on the socket, and a request back for
the bytes. This closes both halves of that, and they are one feature.
`save_artifact(..., volatile=True)` writes to a `VolatileStore` — the same
content-addressed store, in `/dev/shm`, bounded by size with the oldest falling
out (`ARTIFACT_VOLATILE_BYTES`, 48 MB under the container's raised `shm_size`).
Nothing sweeps it: a frame nobody kept is not worth walking the store to find.
`ArtifactStore.path` falls through to it, which is what lets a volatile frame be
an ordinary reference everywhere else — the dtype check, a panel's digest scope,
`load_artifact` in a node, and the widget's own fetch all work on one unchanged.
`adopt` copies one into the store when a run records it, so "returned media is
kept, emitted media is not" stays true.
The bytes then go down the flows websocket as a length-prefixed binary frame,
sent just ahead of the `message_value` naming them, so a tile has the frame when
it hears the value moved. Nothing is pushed unasked: a client names the messages
it is drawing (`{"type":"media","names":[…]}`), a panel's list is intersected
with the scope it already had, and only the newest frame per name in a batch is
sent — a client that fell behind is not handed frames it would draw over. The
tunnel relays text only, so a screen reached through a portal falls back to
fetching, which is why the rate table now has two rows.
Around the edges: the remote worker's fetch cache is bounded at last
(`FLUKSIO_ARTIFACT_CACHE_BYTES`), since content addressing means nothing in it
ever expires and a media stream fills it with chunks nothing asks for twice; a
port carrying an image draws the frame in the node panel rather than only
saying `image/png · frame.png · 1.79kB`; and an edge chip says that much instead
of a line of hash. The media screenshot stops waiting for `networkidle` — a
camera is a socket that never goes quiet, which is the point of it.
A port may now declare `image`, `audio` or `video`. Each is the artifact
reference the engine already had, narrowed by the `media_type` on it, so a
speech recogniser declares what it eats rather than taking any bytes at all and
finding out. Bytes still never travel as a message and nothing on the wire
stops being JSON: a camera publishes one reference per frame, a microphone one
per chunk, and a reference may carry a `meta` dict nothing here interprets.
Streaming media is therefore an ordinary streaming port — with one change to
what that means. An emission used to journal an item with no payload, so
downstream read whatever was current when the item was claimed; a consumer
slower than its producer saw only the newest chunk and the ones between were
lost. That is right for a training curve and wrong for a second of speech, so
an emission now journals a `kind="emission"` item carrying its values, and the
executor hands them to the nodes reading that message instead of writing them
to state again. The value in state stays the latest, which is what everything
else reads, and the wave is filtered by what actually changed rather than
walking everything reachable. No queue serialization change — the existing
`outputs` field carries it.
Continuous media makes the store's missing GC a real problem, so this closes
it: `sweep_artifacts` runs hourly, keeps every digest a `run_artifact` row
records or a live message holds, spares anything written in the last hour, and
stands aside entirely while a run is in flight, since a node may store a
checkpoint long before it returns the reference to it. That also collects the
orphans a deleted flow has always left behind. `ARTIFACT_GC_INTERVAL_S=0` turns
it off.
Around the edges: `GET /artifacts/{digest}` serves the media type the caller
passes and answers ranged requests, so a browser plays a clip rather than
downloading it; `PUT` spools to disk instead of holding the whole body in
memory, as does `save_artifact` given a path; a Media widget draws whatever its
message points at, and a wall panel may fetch the bytes its own tiles are
showing and nothing else; and a connector gets `save_artifact`, for a device
whose readings are bytes.
What this cannot do is live video: a frame every second or two is a glance, and
the honest answer above that is the camera's own stream, which the widget takes
as a URL and the browser plays from source.
stroblme
Melvin Strobl