The WIS2 Downloader

The backend tool for subscribing to the latest data on the WIS2 network.

The WIS2 Downloader is a Flask-based Python application that allows you to connect to a WIS2 Global Broker, manage subscriptions to topic hierarchies, and configure their associated download directories.

Note: This repository does not contain the desktop application GUI that can be used to aid maintenance of subscriptions and explore Global Discovery Catalogues. The WIS2 Downloader GUI can be found here.

Features

• Dynamic Subscription Management: Quickly add or remove subscriptions ad hoc without needing to restart the service or change configuration files.
• Monitor Download Statistics: Access the Prometheus metrics through the /metrics endpoint, ideal for Grafana visualization.
• Multi-Threading Support: Configure the number of download workers for more efficient data downloading.

Demo

The GET requests are demonstrated here using Postman, but the terminal or your browser will suffice too.

Getting Started

1. Installation

You can install using Pip:

pip install https://github.com/wmo-im/wis2-downloader/archive/main.zip

2. Configuration

Create a file config.json in your local directory, with the following contents:

{
    "broker_url": "replace with url of the global broker, e.g. globalbroker.meteo.fr",
    "broker_port": "replace with the port to use on the global broker, e.g. 443",
    "username": "username to use on the global broker, default everyone",
    "password": "password to use on the global broker, default everyone",
    "protocol": "transport protocol to use, either tcp or websockets",
    "topics": {"initial topic 1": "associated download folder", ...},
    "download_dir": "default base download directory",
    "flask_host": "127.0.0.1",
    "flask_port": 8080,
    "download_workers": 1,
    "save_logs": false,
    "log_dir": "default base directory for logs to be saved"
}

This will be used when starting the WIS2 Downloader service.

3. Running

In your terminal, run:

wis2downloader --config <path to configuration file>

The Flask application should now be running. If you need to stop the application, you can do so in the terminal with Ctrl+C.

Maintaining and Monitoring Subscriptions

Adding subscriptions

Subscriptions can be added via a GET request to the ./add endpoint on the Flask app, with the following form:

curl http://<flask-host>:<flask-port>/add?topic=<topic-name>&target=<download-directory>

• topic specifies the topic to subscribe to. Special characters (+, #) must be URL encoded, i.e. + = %2B, # = %23.
• target specifies the directory to save the downloads to, relative to download_dir from config.json. If this is not provided, the directory will default to that of the topic hierarchy.

For example:

curl http://localhost:8080/add?topic=cache/a/wis2/%2B/data/core/weather/%23&target=example_data

The list of active subscriptions should be returned as a JSON object.

Deleting subscriptions

Subscriptions are deleted similarly via a GET request to the ./delete endpoint, with the following form:

curl http://<flask-host>:<flask-port>/delete?topic=<topic-name>

For example:

curl http://localhost:8080/delete?topic=cache/a/wis2/%2B/data/core/weather/%23

The list of active subscriptions should be returned as a JSON object.

Listing subscriptions

Subscriptions are listed via a GET request to ./list:

curl http://<flask-host>:<flask-port>/list

The list of active subscriptions should be returned as a JSON object.

Viewing download metrics

Prometheus metrics for the downloader are found via a GET request to ./metrics, e.g.:

curl http://<flask-host>:<flask-port>/metrics

Bugs and Issues

All bugs, enhancements and issues are managed on GitHub.

Contact

• Rory Burke
• David Berry