Building UWS applications

Universal Worker Service (UWS) is an IVOA standard for writing possibly-asynchronous web services for astronomy. Safir provides a comprehensive library for writing services that use this standard. In addition to implementing the UWS protocol, this library dispatches the underlying work to an arq worker, allowing that worker to be based on a Rubin Science Pipelines stack container and reuse the astronomy code written for Rubin Observatory.

Applications built with this framework have three components:

  1. A frontend web service that takes requests that follow the UWS protocol.

  2. A backend arq worker, possibly running on a different software stack, that does the work.

  3. A database arq worker that handles bookkeeping and result processing for the backend worker. This bookkeeping is done via the Wobbly service so that services do not have to manage their own underying PostgreSQL database.

Incoming requests are turned into arq jobs, processed by the backend worker, uploaded to Google Cloud Storage, recorded in a database, and then returned to the user via a frontend that reads the result URLs and other metadata from the database.

Frontend applications that use this library must depend on safir[uws]. The backend worker (see Write the backend worker) will depend on safir-arq.

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