JSON Schema generation¶

A simple usage of the library that, given generates a JSON Schema for inputs and outputs.

1. Parsing¶

In this sample we'll show the access from a remote public URL.

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from cwl_loader import load_cwl_from_location
from cwl2ogc import BaseCWLtypes2OGCConverter

workflow_id = 'pattern-12'
cwl_document = load_cwl_from_location('https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl')

workflow = None
for wf in cwl_document:
    if workflow_id == wf.id.split('#')[-1]:
        workflow = wf
        break

if workflow is not None:
    cwl_converter = BaseCWLtypes2OGCConverter(workflow)
else:
    raise ValueError(f"'#{workflow_id}' not found in input $graph")
from cwl_loader import load_cwl_from_location
from cwl2ogc import BaseCWLtypes2OGCConverter

workflow_id = 'pattern-12'
cwl_document = load_cwl_from_location('https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl')

workflow = None
for wf in cwl_document:
    if workflow_id == wf.id.split('#')[-1]:
        workflow = wf
        break

if workflow is not None:
    cwl_converter = BaseCWLtypes2OGCConverter(workflow)
else:
    raise ValueError(f"'#{workflow_id}' not found in input $graph")

2026-02-05 18:21:08.012 | DEBUG    | cwl_loader:load_cwl_from_location:228 - Loading CWL document from https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl...

2026-02-05 18:21:08.174 | DEBUG    | cwl_loader:_load_cwl_from_stream:231 - Reading stream from https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl...

2026-02-05 18:21:08.217 | DEBUG    | cwl_loader:load_cwl_from_stream:203 - CWL data of type <class 'ruamel.yaml.comments.CommentedMap'> successfully loaded from stream

2026-02-05 18:21:08.218 | DEBUG    | cwl_loader:load_cwl_from_yaml:143 - No needs to update the Raw CWL document since it targets already the v1.2

2026-02-05 18:21:08.218 | DEBUG    | cwl_loader:load_cwl_from_yaml:145 - Parsing the raw CWL document to the CWL Utils DOM...

2026-02-05 18:21:09.235 | DEBUG    | cwl_loader:load_cwl_from_yaml:158 - Raw CWL document successfully parsed to the CWL Utils DOM!

2026-02-05 18:21:09.236 | DEBUG    | cwl_loader:load_cwl_from_yaml:160 - Dereferencing the steps[].run...

2026-02-05 18:21:09.237 | DEBUG    | cwl_loader:_on_process:78 - Checking if https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl#crop must be externally imported...

2026-02-05 18:21:09.237 | DEBUG    | cwl_loader:_on_process:82 - run_url: https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl - uri: https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl

2026-02-05 18:21:09.237 | DEBUG    | cwl_loader:_on_process:78 - Checking if https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl#norm_diff must be externally imported...

2026-02-05 18:21:09.238 | DEBUG    | cwl_loader:_on_process:82 - run_url: https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl - uri: https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl

2026-02-05 18:21:09.238 | DEBUG    | cwl_loader:_on_process:78 - Checking if https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl#otsu must be externally imported...

2026-02-05 18:21:09.239 | DEBUG    | cwl_loader:_on_process:82 - run_url: https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl - uri: https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl

2026-02-05 18:21:09.239 | DEBUG    | cwl_loader:load_cwl_from_yaml:167 - steps[].run successfully dereferenced! Dereferencing the FQNs...

2026-02-05 18:21:09.240 | DEBUG    | cwl_loader:load_cwl_from_yaml:171 - CWL document successfully dereferenced! Now verifying steps[].run integrity...

2026-02-05 18:21:09.240 | DEBUG    | cwl_loader:load_cwl_from_yaml:175 - All steps[].run link are resolvable!

2026-02-05 18:21:09.241 | DEBUG    | cwl_loader:load_cwl_from_yaml:178 - Sorting Process instances by dependencies....

2026-02-05 18:21:09.241 | DEBUG    | cwl_loader:load_cwl_from_yaml:180 - Sorting process is over.

2026-02-05 18:21:09.241 | DEBUG    | cwl_loader:_load_cwl_from_stream:240 - Stream from https://raw.githubusercontent.com/eoap/application-package-patterns/refs/heads/main/cwl-workflow/pattern-12.cwl successfully load!

2. Inputs JSON Schema generation¶

Once the document is parsed, invoke the cwl2ogc APIs to convert the CWL inputs to the JSON schema:

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import sys

cwl_converter.dump_inputs_json_schema(stream=sys.stdout, pretty_print=True)
import sys

cwl_converter.dump_inputs_json_schema(stream=sys.stdout, pretty_print=True)

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://eoap.github.io/cwl2ogc/pattern-12/inputs.yaml",
  "description": "The schema to represent a pattern-12 inputs definition",
  "type": "object",
  "required": [
    "aoi",
    "bands",
    "item",
    "cropped-collection",
    "ndwi-collection",
    "water-bodies-collection"
  ],
  "properties": {
    "aoi": {
      "$ref": "#/$defs/aoi"
    },
    "bands": {
      "$ref": "#/$defs/bands"
    },
    "item": {
      "$ref": "#/$defs/item"
    },
    "cropped-collection": {
      "$ref": "#/$defs/cropped-collection"
    },
    "ndwi-collection": {
      "$ref": "#/$defs/ndwi-collection"
    },
    "water-bodies-collection": {
      "$ref": "#/$defs/water-bodies-collection"
    }
  },
  "additionalProperties": false,
  "$defs": {
    "aoi": {
      "type": "object",
      "properties": {
        "bbox": {
          "type": "array",
          "items": {
            "type": "number",
            "format": "double"
          }
        },
        "crs": {
          "type": "string",
          "enum": [
            "CRS84",
            "CRS84h"
          ]
        }
      },
      "required": [
        "bbox",
        "crs"
      ]
    },
    "bands": {
      "type": "array",
      "items": {
        "type": "string"
      },
      "default": [
        "green",
        "nir"
      ]
    },
    "item": {
      "oneOf": [
        {
          "type": "string",
          "format": "uri"
        },
        {
          "$ref": "https://schemas.stacspec.org/v1.0.0/item-spec/json-schema/item.json"
        },
        {
          "$ref": "https://schemas.stacspec.org/v1.0.0/collection-spec/json-schema/collection.json"
        }
      ]
    },
    "cropped-collection": {
      "type": "string",
      "format": "uri"
    },
    "ndwi-collection": {
      "type": "string",
      "format": "uri"
    },
    "water-bodies-collection": {
      "type": "string",
      "format": "uri"
    }
  }
}

2.1 Inputs validation¶

Schema can be used to fully validate an inputs dictionary (expecting JSON Schema validation errors in the example below):

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from jsonschema import Draft202012Validator
from jsonschema.exceptions import SchemaError

def validate(schema: dict, data: dict):
    try:
        validator = Draft202012Validator(schema)
        errors = validator.iter_errors(data) if validator is not None else []

        if errors:
            for error in errors:
                print(f"[{'.'.join(error.schema_path)}] - #/{'/'.join(error.path)}: {error.message}")
        else:
            print('No JSON Schema violations detected!')
    except SchemaError as schema_error:
        print(f"An error occurred while instantiating {Draft202012Validator.__class__.__name__}: {schema_error.message}")
from jsonschema import Draft202012Validator
from jsonschema.exceptions import SchemaError

def validate(schema: dict, data: dict):
    try:
        validator = Draft202012Validator(schema)
        errors = validator.iter_errors(data) if validator is not None else []

        if errors:
            for error in errors:
                print(f"[{'.'.join(error.schema_path)}] - #/{'/'.join(error.path)}: {error.message}")
        else:
            print('No JSON Schema violations detected!')
    except SchemaError as schema_error:
        print(f"An error occurred while instantiating {Draft202012Validator.__class__.__name__}: {schema_error.message}")

Define the inputs to be validate

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inputs = {
    "aoi": "-118.985,38.432,-118.183,38.938",
    "filesB": "EPSG:4326",
    "bands": [ "green", "nir08" ],
    "item": "https://planetarycomputer.microsoft.com/api/stac/v1/collections/landsat-c2-l2/items/LC08_L2SP_042033_20231007_02_T1"
}

validate(cwl_converter.get_inputs_json_schema(), inputs)
inputs = {
    "aoi": "-118.985,38.432,-118.183,38.938",
    "filesB": "EPSG:4326",
    "bands": [ "green", "nir08" ],
    "item": "https://planetarycomputer.microsoft.com/api/stac/v1/collections/landsat-c2-l2/items/LC08_L2SP_042033_20231007_02_T1"
}

validate(cwl_converter.get_inputs_json_schema(), inputs)

[required] - #/: 'cropped-collection' is a required property
[required] - #/: 'ndwi-collection' is a required property
[required] - #/: 'water-bodies-collection' is a required property
[properties.aoi.type] - #/aoi: '-118.985,38.432,-118.183,38.938' is not of type 'object'

[additionalProperties] - #/: Additional properties are not allowed ('filesB' was unexpected)

3. Outputs JSON Schema generation¶

Users can reuse the BaseCWLtypes2OGCConverter instance to convert the CWL outputs to the JSON Schema:

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cwl_converter.dump_outputs_json_schema(stream=sys.stdout, pretty_print=True)
cwl_converter.dump_outputs_json_schema(stream=sys.stdout, pretty_print=True)

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://eoap.github.io/cwl2ogc/pattern-12/outputs.yaml",
  "description": "The schema to represent a pattern-12 outputs definition",
  "type": "object",
  "required": [
    "cropped",
    "ndwi",
    "water_bodies"
  ],
  "properties": {
    "cropped": {
      "$ref": "#/$defs/cropped"
    },
    "ndwi": {
      "$ref": "#/$defs/ndwi"
    },
    "water_bodies": {
      "$ref": "#/$defs/water_bodies"
    }
  },
  "additionalProperties": false,
  "$defs": {
    "cropped": {
      "type": "array",
      "items": {
        "oneOf": [
          {
            "type": "string",
            "format": "uri"
          },
          {
            "$ref": "https://schemas.stacspec.org/v1.0.0/item-spec/json-schema/item.json"
          },
          {
            "$ref": "https://schemas.stacspec.org/v1.0.0/collection-spec/json-schema/collection.json"
          }
        ]
      }
    },
    "ndwi": {
      "oneOf": [
        {
          "type": "string",
          "format": "uri"
        },
        {
          "$ref": "https://schemas.stacspec.org/v1.0.0/item-spec/json-schema/item.json"
        },
        {
          "$ref": "https://schemas.stacspec.org/v1.0.0/collection-spec/json-schema/collection.json"
        }
      ]
    },
    "water_bodies": {
      "oneOf": [
        {
          "type": "string",
          "format": "uri"
        },
        {
          "$ref": "https://schemas.stacspec.org/v1.0.0/item-spec/json-schema/item.json"
        },
        {
          "$ref": "https://schemas.stacspec.org/v1.0.0/collection-spec/json-schema/collection.json"
        }
      ]
    }
  }
}

2.1 Outputs validation¶

Schema can be used to fully validate an outputs dictionary (JSON Schema validation expected to pass):

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outputs = {
    "example_out": "In girum imus nocte et consumimur igni"
}

validate(cwl_converter.get_outputs_json_schema(), outputs)
outputs = {
    "example_out": "In girum imus nocte et consumimur igni"
}

validate(cwl_converter.get_outputs_json_schema(), outputs)

[required] - #/: 'cropped' is a required property
[required] - #/: 'ndwi' is a required property
[required] - #/: 'water_bodies' is a required property
[additionalProperties] - #/: Additional properties are not allowed ('example_out' was unexpected)