FOSS4G 2022 general tracks

Update on the status of OGC API standards and draft specifications enabling client-driven execution of processing workflows, supporting on-demand and ad-hoc selection of data and algorithms. Overview of the capabilities enabled by OGC API - Tiles, OGC API - Coverages and Processes – Part 3: Workflows and Chaining. Demonstration of both a server and a client implementing these specifications.

The Workflows and Chaining draft extension specification to OGC API – Processes enables ad-hoc execution of workflows integrating processes and data available from one or more OGC API instances. The specification allows triggering processing as a result of requesting results for a specific area and resolution of interest, which provides a simple mechanism to chain geospatial data inputs and outputs.

By referring to a collection of geospatial data irrespective of a particular area, resolution or date/time of interest, workflows can be defined in a generic, re-usable manner, and processing can be performed on-demand rather than (or in addition to) as a batch execution. Such on-demand processing has the advantage of optimizing the use of computing resources and speeding up the availability of the latest available data, such as for continuously captured Earth Observation satellite imagery.

The initial version of the Workflows and Chaining specification was a result of a GeoConnections 2020-2021 project funded by Natural Resources Canada, which also supported the development of a unified OGC API driver in GDAL allowing to directly visualize the results of such workflows in QGIS.

OGC API – Tiles is the specification succeeding to WMTS in the OGC API family, leveraging the concept of 2D Tile Matrix Sets. In addition to providing tiles of maps or imagery, Tiles can also be used to distribute raw data tiles, including coverage and vector tiles. Using tiles to deliver results and trigger execution of processing workflows can facilitate caching while allowing to efficiently select an area and resolution of interest.

OGC API – Coverages is the specification suceeding to WCS in the OGC API family, and provides a simple mechanism to request an optionally down-sampled subset of a coverage. Specific fields (e.g. imagery band) can be selected as needed. The Coverages specification can also be used to request results while triggering execution of a workflow.