The openEO API defines a language how clients communicate to back-ends in order to analyze large Earth observation datasets. The API will be implemented by drivers for specific back-ends. Some first architecture considerations are listed below.

  1. The openEO API is a contract between clients and back-ends that describes the communication only
  2. Each back-end runs its own API instance including the specific back-end driver. There is no API instance that runs more than one driver.
  3. Clients in R, Python, and JavaScript connect directly to the back-ends and communicate with the back-ends over HTTP(s) according to the openEO API specification.
  4. API instances can run on back-end servers or additional intermediate layers, which then communicate to back-ends in a back-end specific way.
  5. Back-ends may add functionality and extend the API wherever there is need.
  6. There will be a central back-end registry service, to allow users to search for back-ends with specific functionality and or data.
  7. The openEO API will define profiles in order group specific functionality.



To simplify and structure the development, the API is divided into a few microservices.

Microservice Description
Capabilities This microservice reports on the capabilities of the back-end, i.e. which API endpoints are implemented, which authentication methods are supported, and whether and how UDFs can be executed at the back-end.
EO Data Discovery Describes which datasets and image collections are available at the back-end.
Process Discovery Provides services to find out which processes a back-end provides, i.e., what users can do with the available data.
UDF Runtime Discovery Allows discovering the programming languages and their runtime environments to execute user-defined functions.
Job Management Organizes and manages jobs that run processes on back-ends.
Result Access and Services Services to download data and job results, e.g. as WCS or WMTS service.
User Data Management Manage user content and accounting. Might be split into multiple microservices, e.g. User Files and User Process Graphs might be separated.
Authentication Authentication of users.