This is a proof of concept which consists of

• A producer which is tasked with submitting new requests that create widgets.

• A consumer which takes the new request and POSTs it to a widget maker web app.

• A widget maker web app which takes the POST request, validates the request and creates the widget.

The consumer will make use of SQS's visibility timeout feature and the ApproximateReceiveCount attribute to manage invalid requests or resend a request if the widget maker web app is down.

Build the virtualenv.

make

Create the SQS queues WidgetRequestQueue & WidgetResponseQueue. The example below uses the ap-southeast-2 region.

Run the widget maker.

$ venv/bin/python widget_maker.py

Run the consumer.

$ venv/bin/python widget_consumer.py --region=ap-southeast-2

Generate a new widget request using a randomly generated widget id.

$ venv/bin/python widget_producer.py --region=ap-southeast-2

Generate a new widget request with a specific valid widget id.

$ venv/bin/python widget_producer.py --region=ap-southeast-2 \
    --widget-id=31f37378-54f4-11e5-ad75-3c970e65f731

Generate a new widget request with an invalid widget-id.

$ venv/bin/python widget_producer.py --region=ap-southeast-2 \
    --widget-id=this_is_not_a_valid_widget_id

To see the use of visibility timeout and the ApproximateReceiveCount attribute in action, stop widget_maker.py and submit a new request.