Ewoks Engines

Ewoks workflows can be executed using several engines, each with its own capabilities:

• Dask: Distributed and parallel computing framework.

• Pypushflow: Scheduler for acyclic and cyclic task graphs.

• Orange: Visual programming and data visualization platform.

Using a Supported Engine

To run workflows with a specific engine, install the appropriate extra:

pip install ewoks[dask]     # For Dask
pip install ewoks[ppf]      # For Pypushflow
pip install ewoks[orange]   # For Orange

If no engine is installed, Ewoks defaults to a basic sequential engine ("core").

To specify the engine explicitly, use the --engine option:

ewoks execute --test demo --engine dask

Warning

Orange execution is GUI-driven and cannot be triggered from the CLI.

Running:

ewoks execute --test demo --engine orange

…will open the Orange GUI, where you can edit the workflow.

To execute it:

• Double-click on task0 in the workflow.

• Use the Trigger button in the Task widget.

For guidance, see Orange’s getting started docs.

Engine Feature Comparison

Some engines support more advanced features, like loops or GUI interaction:

engine	Loops	Conditional Links	Parallel execution	Interaction (GUI)	Native support
"core"	✗	✗	✗	✗	✓
"dask"	✗	✗	✓	✗	✓
"ppf"	✓	✓	✓	✗	✓
"orange"	✗	✗	✓	✓	✗

Note

Native support means that Ewoks tasks can be executed without modification.

For Orange, you must wrap each Ewoks task in a corresponding Orange widget. See the Orange widget tutorial in the ewoksorange documentation.

Adding a New Engine to Ewoks

To add a custom engine named "abc"

ewoks execute --test demo --engine abc

create a Python package with the appropriate entry point in pyproject.toml:

[project]
name = "ewoksabc"

[project.entry-points."ewoks.engines"]
"abc" = "ewoksabc.engine:AbcWorkflowEngine"

Your engine must implement the abstract interface WorkflowEngine from ewokscore:

from ewokscore.graph import TaskGraph
from ewokscore.engine_interface import WorkflowEngine

class AbcWorkflowEngine(WorkflowEngine):

    def execute_graph(self, graph: TaskGraph, ...) -> Optional[dict]:
        ...

(Optional) Workflow Serialization Support

If your engine also handles workflow (de)serialization (e.g., from .xyz files), add another entry point:

[project.entry-points."ewoks.engines.serialization.representations"]
"xyz" = "ewoksabc.engine:AbcWorkflowEngine"

Your engine should implement WorkflowEngineWithSerialization:

from ewokscore.engine_interface import WorkflowEngineWithSerialization

class AbcWorkflowEngine(WorkflowEngineWithSerialization):

    def execute_graph(self, graph: TaskGraph, ...) -> Optional[dict]:
        ...

    def deserialize_graph(self, graph: Any, ...) -> TaskGraph:
        ...

    def serialize_graph(self, graph: TaskGraph, ...) -> Any:
        ...

    def get_graph_representation(self, graph: Any) -> Optional[str]:
        ...

This allows Ewoks to recognize and delegate serialization/deserialization to your engine.