juniper-cascor-protocol

Cross-process WebSocket frame schemas for the juniper-cascor ecosystem.

This package is the canonical, single-sourced wire-protocol surface for the three Juniper WebSocket endpoints:

Why two subpackages?

The envelope subpackage uses Pydantic v2 for declarative validation of JSON-only frames. The worker subpackage stays Pydantic-free so juniper-cascor-worker can adopt the canonical type enum and binary codec without pulling Pydantic into its slim image — preserving the METRICS-MON R2 exit-gate decision. Importing juniper_cascor_protocol.worker does not load Pydantic (verified by the test suite).

Install

pip install juniper-cascor-protocol

Pinned by the cascor server, juniper-cascor-client, juniper-canopy, and juniper-cascor-worker — each consumer imports only the subpackage it needs.

Quick start

Validating an inbound /ws/training frame

import json
from juniper_cascor_protocol.envelope import (
    UnknownEnvelope,
    MetricsEnvelope,
    validate_envelope,
)

raw = ws.recv()                         # ``websockets`` text frame
frame = json.loads(raw)
envelope = validate_envelope(frame)     # never raises on bad input

if isinstance(envelope, MetricsEnvelope):
    handle_metrics(envelope.data)
elif isinstance(envelope, UnknownEnvelope):
    # ``envelope.type`` is the cardinality-bounded label
    # (collapses to ``"_unmatched"`` after N distinct unknowns).
    log_unrecognized_frame(envelope.type)

validate_envelope never raises on schema mismatch — chaos-testing of malformed frames is part of the package's contract so a misbehaving server cannot crash a consumer.

Worker-side BinaryFrame codec

import numpy as np
from juniper_cascor_protocol.worker import BinaryFrame, WorkerMessageType

# Send tensor as a binary side-channel frame
weights = np.zeros((128, 128), dtype="float32")
ws.send(BinaryFrame.encode(weights))

# Receive and decode
raw = await ws.recv()           # bytes
arr = BinaryFrame.decode(raw)   # owned numpy array

# Dispatch JSON envelope by canonical message type
msg = json.loads(text_frame)
if msg.get("type") == WorkerMessageType.TASK_ASSIGN:
    ...

Cardinality-bound details

The validate_envelope helper tracks distinct unknown type strings up to UNKNOWN_TYPE_BUDGET = 16 per process; subsequent unknowns return as UNMATCHED_TYPE_LABEL = "_unmatched". This mirrors the juniper_observability.UNMATCHED_ENDPOINT_LABEL strategy used for HTTP cardinality bounds. Tests reset state via reset_unknown_label_state() in juniper_cascor_protocol.envelope.

Versioning

Follows PEP 440 + Keep a Changelog. Consumers should pin juniper-cascor-protocol>=A.B,<A+1. Additive envelope fields are minor bumps; field removals/renames are major bumps.

See CHANGELOG.md for the per-version contract.

License

MIT — see LICENSE.