Aviso Examples for DT Data Availability Notifications

This repository demonstrates how to access Destination Earth (DestinE) Digital Twin (DT) data availability notifications using the Aviso service hosted on the LUMI Databridge.

It provides simple example scripts to:

• Listen for new DT data notifications
• Replay historical notifications
• Trigger automated workflows when new data becomes available

---

Table of Contents

• 1. Overview
• 2. Getting Started
  • 2.1 Prerequisites
  • 2.2 Installation
• 3. Running the Examples
  • 3.1 Real-Time Listener Example
    • Expected Output
• 4. Description of Example Scripts
  • 4.1 aviso-extremes-dt.py
  • 4.2 aviso-extremes-dt-from-time.py
  • 4.3 aviso-extremes-dt-earthkit-example.py
• 5. Aviso Quota Limits for DestinE

---

1. Overview

The examples use the pyaviso client to subscribe to notification topics exposed by Destination Earth and LUMI.

The scripts demonstrate:

• Real-time notification listening
• Recovery of missed notifications
• Replay of historical notifications
• Integration with the Earthkit ecosystem for automated workflows

---

2. Getting Started

2.1 Prerequisites

• Python >= 3.6
• Outbound HTTPS connectivity to: aviso.lumi.apps.dte.destination-earth.eu (TCP port 443)

If operating within a corporate or institutional network, ensure that firewall, proxy, and network security policies permit outbound access to this endpoint.

This can be checked with:

curl -v https://aviso.lumi.apps.dte.destination-earth.eu

Authentication is currently not required. Support for Destination Earth credentials will be added in the future.

---

2.2 Installation

Install the Aviso Python client from PyPI:

pip install pyaviso

If running the Earthkit integration example, install additional dependencies:

pip install earthkit

---

3. Running the Examples

All scripts can be executed directly with Python.

3.1 Real-Time Listener Example

Run:

python3 aviso-extremes-dt.py

Expected Output

As output you should expect something like:

loaded config:
{'auth_type': 'none',
  'configuration_engine': {'host': 'aviso.lumi.apps.dte.destination-earth.eu',
                          'https': True,
                          'port': 443},
  'notification_engine': {'host': 'aviso.lumi.apps.dte.destination-earth.eu',
                          'https': True,
                          'port': 443},
  'remote_schema': True,
  'schema_parser': 'generic'
  }
Listening to /de/data/ at aviso.lumi.apps.dte.destination-earth.eu:443...

Upon execution, the client loads its configuration and subscribes to the specified notification topic. Notifications will be printed to standard output as they are received.

Terminate execution using:

Ctrl + C

---

4. Description of Example Scripts

4.1 aviso-extremes-dt.py

This script:

1. Defines a request dictionary describing the notification topic.
2. Connects to the Aviso notification engine.
3. Executes an echo trigger for each notification (prints to screen).
4. Continues polling until interrupted.

⚠️ IMPORTANT NOTE:
Before listening to new notifications, Aviso:

• Checks the last received notification.
• Retrieves any missed notifications.
• Then switches to real-time listening.

On first execution, no previous notifications are returned.

This ensures users do not miss notifications after machine reboots or interruptions.

---

4.2 aviso-extremes-dt-from-time.py

This script demonstrates:

• Searching for historical notifications from a specified time.
• Executing a trigger function for each retrieved notification.
• Continuing with live listening afterward.

The trigger function in this example simply prints notifications, but it can be replaced with custom processing logic.

---

4.3 aviso-extremes-dt-earthkit-example.py

This example demonstrates a complete automated workflow:

1. Listen for new Extremes DT data notifications.
2. Trigger a function when a notification is received.
3. Retrieve temperature data via Polytope.
4. Regrid to a coarser resolution (for faster processing)
5. Generate a plot of the data bounded by Europe using Earthkit plots library.

It shows how Aviso can act as an event-driven entry point for data processing pipelines.

---

5. Aviso Quota Limits for DestinE

To ensure system stability and fair usage, the following limits apply:

• Rate Limit: Up to 50 requests per second (may be adjusted depending on system load)
• Concurrent Operations: Currently not limited

Please design your workflows accordingly to avoid service interruptions.

---