Simple Example¶

Let's have a look at the different PlantUML diagrams that the cwl2puml APIs are able to generate, given, for example, the conditional-workflows Workflow.

1. Parsing¶

It is needed to read first a CWL document from a remote public URL:

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import cwl_loader

cwl_document = cwl_loader.load_cwl_from_location('https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl')
import cwl_loader

cwl_document = cwl_loader.load_cwl_from_location('https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl')

2026-06-26 12:47:20.079 | DEBUG    | cwl_loader:load_cwl_from_location:369 - Loading CWL document from https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl...

2026-06-26 12:47:20.294 | DEBUG    | cwl_loader:_load_cwl_from_stream:372 - Reading stream from https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl...

2026-06-26 12:47:20.317 | DEBUG    | cwl_loader:load_cwl_from_stream:339 - CWL data of type <class 'ruamel.yaml.comments.CommentedMap'> successfully loaded from stream

2026-06-26 12:47:20.318 | DEBUG    | cwl_loader:load_cwl_from_yaml:270 - No needs to update the Raw CWL document since it targets already the v1.2

2026-06-26 12:47:20.318 | DEBUG    | cwl_loader:load_cwl_from_yaml:274 - Parsing the raw CWL document to the CWL Utils DOM...

2026-06-26 12:47:20.576 | DEBUG    | cwl_loader:load_cwl_from_yaml:283 - Raw CWL document successfully parsed to the CWL Utils DOM!

2026-06-26 12:47:20.577 | DEBUG    | cwl_loader:load_cwl_from_yaml:285 - Dereferencing the steps[].run...

2026-06-26 12:47:20.577 | DEBUG    | cwl_loader:_on_process:175 - Checking if https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl#stac must be externally imported...

2026-06-26 12:47:20.578 | DEBUG    | cwl_loader:_on_process:179 - run_url: https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl - uri: https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl

2026-06-26 12:47:20.578 | DEBUG    | cwl_loader:_on_process:175 - Checking if https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl#rio_stack must be externally imported...

2026-06-26 12:47:20.579 | DEBUG    | cwl_loader:_on_process:179 - run_url: https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl - uri: https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl

2026-06-26 12:47:20.579 | DEBUG    | cwl_loader:_on_process:175 - Checking if https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl#rio_warp_stack must be externally imported...

2026-06-26 12:47:20.581 | DEBUG    | cwl_loader:_on_process:179 - run_url: https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl - uri: https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl

2026-06-26 12:47:20.582 | DEBUG    | cwl_loader:_on_process:175 - Checking if https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl#rio_color must be externally imported...

2026-06-26 12:47:20.582 | DEBUG    | cwl_loader:_on_process:179 - run_url: https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl - uri: https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl

2026-06-26 12:47:20.583 | DEBUG    | cwl_loader:load_cwl_from_yaml:289 - steps[].run successfully dereferenced! Dereferencing the FQNs...

2026-06-26 12:47:20.584 | DEBUG    | cwl_loader:load_cwl_from_yaml:293 - CWL document successfully dereferenced! Now verifying steps[].run integrity...

2026-06-26 12:47:20.585 | DEBUG    | cwl_loader:load_cwl_from_yaml:299 - All steps[].run link are resolvable!

2026-06-26 12:47:20.585 | DEBUG    | cwl_loader:load_cwl_from_yaml:302 - Sorting Process instances by dependencies....

2026-06-26 12:47:20.586 | DEBUG    | cwl_loader:load_cwl_from_yaml:304 - Sorting process is over.

2026-06-26 12:47:20.587 | DEBUG    | cwl_loader:_load_cwl_from_stream:382 - Stream from https://raw.githubusercontent.com/eoap/how-to/refs/heads/main/cwl-workflows/conditional-workflows.cwl successfully load!

2. PlantUML diagrams¶

The samples below show how to render CWL document to a specific PlantUML diagram:

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from cwl2puml import (
    to_puml,
    DiagramType
)
from cwl_utils.parser import InputEnumSchema
from io import (
    StringIO,
    BytesIO
)
from IPython.display import display_png
from plantuml import deflate_and_encode
from PIL import Image
from urllib.request import urlopen

def render(
    diagram_type: DiagramType,
    debug: bool = False
):
    out = StringIO()
    to_puml(
        cwl_document=cwl_document,
        workflow_id='main', # 'main' by default, but define it for demo purposes
        diagram_type=diagram_type,
        output_stream=out
    )

    clear_output = out.getvalue()

    if debug:
        print(clear_output)

    encoded = deflate_and_encode(clear_output)
    diagram_url = f"https://uml.planttext.com/plantuml/png/{encoded}"

    with urlopen(diagram_url) as url:
        img = Image.open(BytesIO(url.read()))
    display_png(img)
from cwl2puml import (
    to_puml,
    DiagramType
)
from cwl_utils.parser import InputEnumSchema
from io import (
    StringIO,
    BytesIO
)
from IPython.display import display_png
from plantuml import deflate_and_encode
from PIL import Image
from urllib.request import urlopen

def render(
    diagram_type: DiagramType,
    debug: bool = False
):
    out = StringIO()
    to_puml(
        cwl_document=cwl_document,
        workflow_id='main', # 'main' by default, but define it for demo purposes
        diagram_type=diagram_type,
        output_stream=out
    )

    clear_output = out.getvalue()

    if debug:
        print(clear_output)

    encoded = deflate_and_encode(clear_output)
    diagram_url = f"https://uml.planttext.com/plantuml/png/{encoded}"

    with urlopen(diagram_url) as url:
        img = Image.open(BytesIO(url.read()))
    display_png(img)

2.1 Activity diagram¶

The activity diagram represents the overall CWL document instructions.

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render(DiagramType.ACTIVITY)
render(DiagramType.ACTIVITY)

No description has been provided for this image

2.2 Component diagram¶

The component diagram represents the CWL document like chips on a motherboard.

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render(DiagramType.COMPONENT)
render(DiagramType.COMPONENT)

2.3 Class diagram¶

The class diagram represents the CWL document like specifications of the previously illustrated chips on a motherboard.

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render(DiagramType.CLASS)
render(DiagramType.CLASS)

2.4 Sequence diagram¶

The sequence diagram represents how the previously illustrated chips on a motherboard are triggered and interact with each other.

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render(DiagramType.SEQUENCE)
render(DiagramType.SEQUENCE)

2.5 State diagram¶

The state diagram represents the dependencies between the inputs/outputs of the previously illustrated chips on a motherboard.

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render(DiagramType.STATE)
render(DiagramType.STATE)