sqs-orders

SQS orders — Python produces, Go consumes

A Python producer publishes canonical BabelQueue envelopes to an Amazon SQS queue; a Go service reads the same queue and routes by URN. Same wire envelope, different languages, one broker — no PHP serialize(), no language-specific format. The Go consumer never knows which language wrote the message; it only sees the canonical envelope and meta.lang.

Each SDK uses the §3 SQS binding: the envelope is the MessageBody, projected onto native MessageAttributes (bq-job = URN, bq-trace-id, bq-message-id, …) so a consumer can route and trace without decoding the body.

The demo runs against ElasticMQ — a free, SQS-compatible broker — so it needs no AWS account. Point SQS_ENDPOINT / AWS_REGION (and real credentials) at Amazon SQS to run it there unchanged.

Run it

# 1) start ElasticMQ (pre-creates the `orders` queue via elasticmq.conf)
docker compose up -d

# 2) producer — Python   (needs babelqueue[sqs] ^1.1, which ships SqsTransport)
cd producer-python
python -m venv .venv && . .venv/bin/activate
pip install -r requirements.txt
python produce.py
cd ..

# 3) consumer — Go
cd consumer-go
go run .

The producer/consumer default to the local ElasticMQ (http://localhost:9324, region eu-central-1, dummy credentials), so the commands above work as-is.

Expected consumer output — a Go program reading messages it never produced. Note produced by "python": the data, trace_id and unicode all survive the language boundary.

[go] order created  id=1042 amount=99.9 USD  trace=…  (produced by "python")
[go] order created  id=1043 amount=12.5 EUR  trace=…  (produced by "python")
[go] item indexed   sku=WIDGET-1 title="Café Widget ☕"  (produced by "python")
[go] processed 3 message(s) — same envelope, different language.

Point it at real Amazon SQS

export SQS_ENDPOINT=                       # leave empty to use the default AWS endpoint
export AWS_REGION=eu-central-1
export AWS_ACCESS_KEY_ID=…  AWS_SECRET_ACCESS_KEY=…
# create an `orders` queue in that region, then run the producer + consumer as above.

For a FIFO queue (orders.fifo), the producer sets MessageGroupId / MessageDeduplicationId automatically; see the SQS binding.

Swap the ends

The queue carries the canonical envelope, so any SDK can be on either side:

• Go producer: sqs.New(ctx, …) + app.Publish(...).
• Python consumer: @app.handler("urn:...") + app.run() on a sqs:// URL.
• Node / Java / PHP / .NET read/write the identical envelope on their own SQS transports — see babelqueue.com.