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Scenario Player

This project was a part of a broader demo. That broader demo analyzed customers' movement in a retail store, determined their behavior (for example: "customer stopped in men's clothes department"), and use Machine Learning to model for purchase/product recommendation. The customer location was determined by movement sensors placed in the store.

This service simulates customer behavior in a retail shop:

  • customer entering the store
  • customer movement
  • customer exiting the store

by generating proper MQTT messages.

Table of contents

Usage

This is a web service (implemented with FastAPI). By default, it works on port 8000. (See instructions for details on configuring and running the service.)

When starting, it does the following:

  • connects to MQTT server
  • waits for and registers new user movement scenarios (HTTP POST to /scenario endpoint)
  • creates a background task (ran every second) that checks if there is something to be sent (if it is time for giving an update on the particular customer)

Main simulator loop

The main loop executes every second and tries to locate events (in the timeline) that should be "replayed". If there are any, proper messages are constructed and published (via. Publisher object).

Please, note, that in the current implementation, the main simulator loop replays events from the timeline for current timestamp (current date/time).

Scenario definitions

The scenario is a list of locations for a given customer in certain moments, for example:

{
  "customer": {
    "customer_id": "3"
  },
  "path": [
    {
      "type": "ENTER",
      "location": {"x": 200, "y": 10},
      "timestamp": "2021-04-11T10:01:53.955760"
    },
    {
      "type": "MOVE",
      "location": {"x": 320, "y": 150},
      "timestamp": "2021-04-11T10:13:49.614897"
    },
    {
      "type": "EXIT",
      "location": {"x": 200, "y": 10},
      "timestamp": "2021-04-11T12:31:17.437862"
    }
  ]
}

The service can register a scenario:

curl -X 'POST' \
  'http://localhost:8000/scenario' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{"customer":{"customer_id":"1"},"path":[{"type":"ENTER","location":{"x":935,"y":50},"timestamp":1618323771180},{"type":"MOVE","location":{"x":588.9128630705394,"y":454.08039288409145},"timestamp":1618323772180},{"type":"EXIT","location":{"x":1075,"y":50},"timestamp":1618323773180}]}'

After receiving the request, the service adds all steps (from path) to the current timeline with timestamps as defined in the payload.

As the main loop uses the current timestamp for "locating" the events on the timeline, it is possible that registered events won't ever be published. In case the timestamp of a given event is in the past, it will be never be retrieved and processed.

For user convenience, it is possible to reuse a scenario definition that refers to the past. recalculate_time=true parameter for /scenario request can be used here:

curl -X 'POST' \
  'http://localhost:8000/scenario?recalculate_time=true' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{"customer":{"customer_id":"1"},"path":[{"type":"ENTER","location":{"x":935,"y":50},"timestamp":1618323771180},{"type":"MOVE","location":{"x":588.9128630705394,"y":454.08039288409145},"timestamp":1618323772180},{"type":"EXIT","location":{"x":1075,"y":50},"timestamp":1618323773180}]}'

In this case, the scenario will start with the current time and step timestamps will be recalculated appropriately (they will be "refreshed").

Messages payloads

customer/exit Channel

Name Type Description Accepted values
id string ID of the customer ...
ts integer Timestamp of the event, in seconds since epoch ...

Example of payload:

{
  "id": "127",
  "ts": 192322800
}

customer/exit Channel

Name Type Description Accepted values
id string ID of the customer ...
ts integer Timestamp (unix time) ...

Example of payload:

{
  "id": "127",
  "ts": 192322800
}

customer/move Channel

Name Type Description Accepted values
id string ID of the customer ...
ts integer Timestamp (unix time) ...
x integer coordinate x ...
y integer coordinate y ...

Example of payload:

{
  "id": "127",
  "ts": 192322800,
  "x": 0,
  "y": 0
}

Running the service

See instructions for details on configuring and running the service locally.

Development information

See development.md for information about configuring the service, how to run test and run the service.