APEx: Supporting the Reuse and Scaling of Earth Observation Applications

Terradue
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The Application Propagation Environment (APEx) is a European Space Agency initiative designed to increase the reuse and long-term availability of EO research outcomes, especially algorithms and workflows, by making them easier to deploy, scale, and adapt in new cloud environments.

Developed in collaboration with partners including VITO, Brockmann Consult, Inuits, GEO University, and Terradue, APEx aims to bridge the gap between R&D projects and operational platforms. A central goal is to provide a technical foundation for making EO applications portable and reusable, in both experimental and production contexts.

For more information about the project, visit the APEx ESA website.

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Supporting Diverse Development and Deployment Models

EO applications vary widely in complexity, scope, and maturity. That’s why APEx supports multiple approaches to application propagation tailored to different use cases:

  • For data analytics applications that benefit from easy interaction with EO backends, openEO offers a useful abstraction layer.
  • For operational or long-established processing chains, especially those already deployed in production settings, the EO Application Package approach based on containers and Common Workflow Language (CWL) remains the most reliable and scalable option.

Terradue has played a leading role in defining the OGC Best Practice for Earth Observation Application Packages, which standardizes how EO processing applications can be packaged, described, and deployed. This enables full encapsulation, versioning, and portability ensuring continuity and reliability for complex EO services.

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Terradue’s Contribution: Scaling with Containers and CWL

In APEx, Terradue leads the development and integration of service components that support Application Package-based deployment, including:

  • Interactive Development Environments for rapid prototyping and testing
  • User Workspaces for managing persistent data and configurations
  • Algorithm Hosting and Registration, enabling scalable cloud execution
  • Algorithm Upscaling, for transitioning R&D workflows into operational pipelines

These components are built on Terradue’s cloud-native infrastructure and ensure that packaged applications can be deployed consistently across different platforms and cloud providers.

Balancing Flexibility and Interoperability

While openEO provides a standardised interface to access and process EO data, its limited number of supported backends can restrict flexibility in some operational production scenarios.
The adoption of the Application Package model in APEx by Terradue ensures that platform operators and users can select the approach that best fits their needs.

This means that both interactive, analytics-oriented development and containerised, production-grade deployment are supported offering a future-proof foundation for EO application reuse.

Explore the Algorithm Services Catalogue

One of the main outputs of the project is the APEx Algorithm Services Catalogue, a public resource where users can:

  • Discover available EO algorithms and services
  • View detailed documentation and execution options
  • Understand how to reuse or scale these services in other platforms

This catalogue demonstrates how APEx is helping to turn standalone R&D results into broadly accessible, standardised services.

Looking Ahead

APEx is structured in two main phases:

  • Phase I – Integration and Service Maturity, focusing on platform interoperability, developer support, and packaging standards
  • Phase II – Demonstration and Community Uptake, including onboarding campaigns and real-world deployment pilots

By supporting both openEO and the OGC-compliant EO Application Package approach, APEx enables a flexible and collaborative EO ecosystem empowering research teams, developers, and service providers to build on each other’s work.

To learn more about Terradue’s contributions to APEx and Earth Observation platforms: