support properties input/output field modifier

[fmigneault]

Description

Support properties specified within an input/output collection or process to modify inline its inbound/outbound data with a subset or alternate expression calculation.

In intermediate steps (when data is passed from an output to another process' input), the I/O can be handled any way. When the top-most process has properties they must be handled as output modifiers. When the most deeply-nested input has properties, they could be handled as input modifiers. However, given this applies to collection or process only, those are implemented has "pseudo-processes" in Weaver, and therefore can be handled as output of the relevant operation for every case.

2 possible forms to consider:

{
  "inputs": {
    "subset-input": {
      "collection": "...",  
      "$comment": "Subsets the available data to specified properties (similar to 'filter')",
      "properties": ["B04", "B03", "B02"]
    },
    "expr-input": {
      "collection": "...",  
      "$comment": "computes the expression as derived data",
      "properties": {
        "ndvi": "(B08 - B04) / (B08 + B04)"
      }
    } 
  }
}

References

• JSON Schema: https://github.com/opengeospatial/ogcapi-processes/blob/master/openapi/schemas/processes-workflows/fieldsModifiers.yaml
• Rendered Doc Requirements:
  • Requirement Class Input Fields Modifiers
  • Requirement Class Output Fields Modifiers
• Source Requirements:
  • https://github.com/opengeospatial/ogcapi-processes/blob/master/extensions/workflows/requirements/requirements_class_input-fields-modifiers.adoc
  • https://github.com/opengeospatial/ogcapi-processes/blob/master/extensions/workflows/requirements/input-fields-modifiers/REQ_input-fields-modifiers_derived-fields.adoc
  • https://github.com/opengeospatial/ogcapi-processes/blob/master/extensions/workflows/requirements/requirements_class_output-fields-modifiers.adoc
  • https://github.com/opengeospatial/ogcapi-processes/blob/master/extensions/workflows/requirements/output-fields-modifiers/REQ_output-fields-modifiers_derived-fields.adoc
• Relates to Consider filter operations with filter-lang=cql-text|cql-json using CQL2 #640
  (operation similar to filter, see above example)