Learning Loop Node

This Python library helps to write Nodes that interact with the Zauberzeug Learning Loop. There are 4 types of Nodes:

Type	Purpose
Trainer	Runs training using the latest training data
Detector	Loads latest models from Loop and performs inference
Annotator	Used for custom annotation inside the Loop
Converter	Converts between different model formats

General Usage

To start a node you have to implement the logic by inheriting from the corresponding base logic class. We provide samples in the 'mock' folders and recommend to follow that scheme. A complete trainer and detector example can be found here.

Environment variables

You can configure connection to our Learning Loop by specifying the following environment variables before starting:

Name	Alias	Purpose	Required by
LOOP_HOST	HOST	Learning Loop address (e.g. learning-loop.ai)	all
LOOP_USERNAME	USERNAME	Learning Loop user name	all besides Detector
LOOP_PASSWORD	PASSWORD	Learning Loop password	all besides Detector
LOOP_SSL_CERT_PATH	-	Path to the SSL certificate	all (opt.)
LOOP_ORGANIZATION	ORGANIZATION	Organization name	Detector
LOOP_PROJECT	PROJECT	Project name	Detector (opt.)
MIN_UNCERTAIN_THRESHOLD	-	smallest confidence (float) at which auto-upload will happen	Detector (opt.)
MAX_UNCERTAIN_THRESHOLD	-	largest confidence (float) at which auto-upload will happen	Detector (opt.)
INFERENCE_BATCH_SIZE	-	Batch size of trainer when calculating detections	Trainer (opt.)
RESTART_AFTER_TRAINING	-	Restart the trainer after training (set to 1)	Trainer (opt.)
KEEP_OLD_TRAININGS	-	Do not delete old trainings (set to 1)	Trainer (opt.)
TRAINER_IDLE_TIMEOUT_SEC	-	Automatically shutdown trainer after timeout (in seconds)	Trainer (opt.)
USE_BACKDOOR_CONTROLS	-	Always enable backdoor controls (set to 1)	Trainer / Detector (opt.)

Testing

We use github actions for CI. Tests can also be executed locally by running LOOP_HOST=XXXXXXXX LOOP_USERNAME=XXXXXXXX LOOP_PASSWORD=XXXXXXXX python -m pytest -v
from learning_loop_node/learning_loop_node

Detector Node

Detector Nodes are normally deployed on edge devices like robots or machinery but can also run in the cloud to provide backend services for an app or similar. These nodes register themself at the Learning Loop. They provide REST and Socket.io APIs to run inference on images. The processed images can automatically be used for active learning: e.g. uncertain predictions will be send to the Learning Loop.

Running Inference

Images can be send to the detector node via socketio or rest. The later approach can be used via curl,

Example usage:

curl --request POST -F '[email protected]' localhost:8004/detect

Where 8804 is the specified port in this example. You can additionally provide the following camera parameters:

• autoupload: configures auto-submission to the learning loop; filtered (default), all, disabled (example curl parameter -H 'autoupload: all')
• camera-id: a string which groups images for submission together (example curl parameter -H 'camera-id: front_cam')

The detector also has a sio upload endpoint that can be used to upload images and detections to the learning loop. The function receives a json dictionary, with the following entries:

• image: the image data in jpg format
• tags: a list of strings. If not provided the tag is picked_by_system
• detections: a dictionary representing the detections. UUIDs for the classes are automatically determined based on the category names. This field is optional. If not provided, no detections are uploaded.

The endpoint returns None if the upload was successful and an error message otherwise.

Changing the model version

The detector can be configured to one of the following behaviors:

• download use a specific model version
• automatically update the model version according to the learning loop deployment target
• pause the model updates and use the version that was last loaded

The model versioning configuration can be accessed/changed via a REST endpoint. Example Usage:

• Fetch the current model versioning configuration: curl http://localhost/model_version
• Configure the detector to use a specific model version: curl -X PUT -d "1.0" http://localhost/model_version
• Configure the detector to automatically update the model version: curl -X PUT -d "follow_loop" http://localhost/model_version
• Pause the model updates: curl -X PUT -d "pause" http://localhost/model_version

Note that the configuration is not persistent, however, the default behavior on startup can be configured via the environment variable VERSION_CONTROL_DEFAULT. If the environment variable is set to VERSION_CONTROL_DEFAULT=PAUSE, the detector will pause the model updates on startup. Otherwise, the detector will automatically follow the loop deployment target.

Changing the outbox mode

If the autoupload is set to all or filtered (selected) images and the corresponding detections are saved on HDD (the outbox). A background thread will upload the images and detections to the Learning Loop. The outbox is located in the outbox folder in the root directory of the node. The outbox can be cleared by deleting the files in the folder.

The continuous upload can be stopped/started via a REST enpoint:

Example Usage:

• Enable upload: curl -X PUT -d "continuous_upload" http://localhost/outbox_mode
• Disable upload: curl -X PUT -d "stopped" http://localhost/outbox_mode

The current state can be queried via a GET request: curl http://localhost/outbox_mode

Explicit upload

The detector has a REST endpoint to upload images (and detections) to the Learning Loop. The endpoint takes a POST request with the image and optionally the detections. The image is expected to be in jpg format. The detections are expected to be a json dictionary. Example:

curl -X POST -F '[email protected]' "http://localhost:/upload"

Trainer Node

Trainers fetch the images and anntoations from the Learning Loop to train new models.

• if the command line tool "jpeginfo" is installed, the downloader will drop corrupted images automatically

Converter Node

A Conveter Node converts models from one format into another.

Annotator Node

...

Test operability

Assumend there is a Converter Node which converts models of format 'format_a' into 'format_b'. Upload a model with curl --request POST -F 'files=@my_model.zip' https://learning-loop.ai/api/zauberzeug/projects/demo/format_a The model should now be available for the format 'format_a' curl "https://learning-loop.ai/api/zauberzeug/projects/demo/models?format=format_a"

{
"models": [
{
"id": "3c20d807-f71c-40dc-a996-8a8968aa5431",
"version": "4.0",
"formats": [
"format_a"
],
"created": "2021-06-01T06:28:21.289092",
"comment": "uploaded at 2021-06-01 06:28:21.288442",
...
}
]
}

```

but not in the format_b
`curl "https://learning-loop.ai/api/zauberzeug/projects/demo/models?format=format_b"`

```

{
"models": []
}

```

Connect the Node to the Learning Loop by simply starting the container.
After a short time the converted model should be available as well.
`curl https://learning-loop.ai/api/zauberzeug/projects/demo/models?format=format_b`

```

{
"models": [
{
"id": "3c20d807-f71c-40dc-a996-8a8968aa5431",
"version": "4.0",
"formats": [
"format_a",
"format_b",
],
"created": "2021-06-01T06:28:21.289092",
"comment": "uploaded at 2021-06-01 06:28:21.288442",
...
}
]
}

```

## About Models (the currency between Nodes)

- Models are packed in zips and saved on the Learning Loop (one for each format)
- Nodes and users can upload and download models with which they want to work
- In each zip there is a file called `model.json` which contains the metadata to interpret the other files in the package
- for base models (pretrained models from external sources) no `model.json` has to be sent, ie. these models should simply be zipped in such a way that the respective trainer can work with them.
- the loop adds or corrects the following properties in the `model.json` after receiving; it also creates the file if it is missing:
  - `host`: uri to the loop
  - `organization`: the ID of the organization
  - `project`: the id of the project
  - `version`: the version number that the loop assigned for this model (e.g. 1.3)
  - `id`: the model UUID (currently not needed by anyone, since host, org, project, version clearly identify the model)
  - `format`: the format e.g. yolo, tkdnn, yolor etc.
- Nodes add properties to `model.json`, which contains all the information which are needed by subsequent nodes. These are typically the properties:
  - `resolution`: resolution in which the model expects images (as `int`, since the resolution is mostly square - later, ` resolution_x`` resolution_y ` would also be conceivable or `resolutions` to give a list of possible resolutions)
  - `categories`: list of categories with name, id, (later also type), in the order in which they are used by the model -- this is neccessary to be robust about renamings
```