A workflow is a Directed Acyclic Graph (DAG ) of data and processing blocks 1. A workflow encompasses the data sources to be used, the algorithms to process the data and the order of the blocks. A workflow always starts with a data block and continues with one or more processing blocks. One block can be used in multiple workflows.
Building a workflow requires that the capabilities of the data and processing blocks match.
Workflow built with one data and two processing blocks
A block is defined as a unit that builds up a workflow. There are two types of blocks: data blocks and processing blocks.
Data blocks deliver geospatial data (satellite or aerial images, vector data etc.) that can be directly downloaded, streamed or further analyzed with processing blocks. A data block is always followed by one or more processing blocks. Examples:
Processing blocks apply algorithms that process data and deliver the corresponding outputs. A processing block can follow a data block or a processing block. Examples:
The blocks connect with each other if their input and output capabilities match. For example, a block that outputs a GeoTIFF is compatible with the next block that accepts GeoTIFF as input.
As the first block in the workflow, the data block has only an output capability. The processing block always follows a data block, so it has both an input and an output capability.
For more information, please visit the article Block capabilities.