Nominal Streaming Client

0.9.0 verified Fri May 01 auth: no python

Python bindings for the Nominal Rust streaming client, providing high-performance real-time data streaming with typed schemas. Current version 0.9.0, release cadence is irregular.

pip install nominal-streaming

Common errors

error ImportError: cannot import name 'StreamingClient' from 'nominal' ↓

cause Trying to import from old package `nominal` instead of `nominal_streaming`.

fix

Use from nominal_streaming import StreamingClient.

error TypeError: __init__() got an unexpected keyword argument 'username' ↓

cause Authentication method changed; now uses `api_key` instead of `username`/`password`.

fix

Replace username and password with api_key.

error AttributeError: 'StreamingClient' object has no attribute 'open_channel' ↓

cause Method renamed from `open_channel` to `open_stream` in v0.9.0.

fix

Use client.open_stream(...) instead of client.open_channel(...).

Warnings

breaking The import path changed from `nominal.streaming` to `nominal_streaming` in version 0.9.0. Old code will fail with ImportError. ↓

fix Change 'from nominal.streaming import ...' to 'from nominal_streaming import ...'.

breaking The `StreamingClient` constructor no longer accepts `username`/`password`; use `api_key`. Authentication method changed. ↓

fix Replace `StreamingClient(url, username='...', password='...')` with `StreamingClient(url, api_key='...')`.

gotcha `StreamSchema` field types are strings, not Python types. Using `int` or `float` will cause a runtime TypeError. ↓

fix Use string type names: "int64", "float64", "string", etc. See docs for full list.

breaking The `read()` method now returns an iterator of `DataPoint` objects, not raw protobuf messages. ↓

fix Update code expecting protobuf objects to use `.timestamp`, `.value`, etc.

Imports

StreamingClient

wrong

from nominal.streaming import StreamingClient

correct

from nominal_streaming import StreamingClient

Old import path prior to 0.9.0; submodule moved to top-level.

StreamSchema

wrong

from nominal.streaming.schema import StreamSchema

correct

from nominal_streaming import StreamSchema

Schema class was moved into main package.

DataPoint

wrong

from nominal.streaming.types import DataPoint

correct

from nominal_streaming import DataPoint

Types module flattened.

Quickstart

Open a stream, write a data point, and read it back.

import os
from nominal_streaming import StreamingClient, StreamSchema, DataPoint

# Replace with your credentials
url = os.environ.get('NOMINAL_URL', 'grpc://localhost:50051')
api_key = os.environ.get('NOMINAL_API_KEY', '')

client = StreamingClient(url, api_key=api_key)

# Define a schema
schema = StreamSchema([
    ("timestamp", "int64"),
    ("value", "float64"),
])

# Open a stream
stream = client.open_stream("my-stream", schema)

# Write one data point
stream.write(DataPoint(timestamp=123456789, value=42.0))

# Read back
for dp in stream.read(start=0):
    print(dp)
    break

stream.close()