Add `dict` properties to Engine and State

🚀 Feature

Hi @vfdev-5 ,

In the current implementation of MONAI handlers, they are deeply coupled with ignite engine. Some users that use different workflows can’t leverage our handlers, so we are trying to make handlers decouple from ignite. We discussed the problem and got some basic ideas:

1. Add dict properties to the engine, then handlers can treat engine arg as a regular dict with same structure as ignite Engine object.
2. Pass the event name when trigger handler, so other workflows also can call this handler with the same event name.

For example:

class TestHandler:
    def attach(self):
        # ignite specific logic
       ... ...

    def __call__(self, data: Dict, event: str):
        # data map to the engine dict of ignite
        if event == "ITERATION_COMPLETED":
            self._iteration(data)
        if event == "EPOCH_COMPLETED":
            self._epoch(data)

What do you think?

[wyli]

thanks, I feel the utilities such as EngineAsDict could help onboard users for both ignite and monai. (also one of monai’s principles is “to be compatible with existing efforts and ease of 3rd party integration for various components.”)

the details need more discussions but they’ll be ignite usage discussions instead of a feature request here… I’d suggest converting this ticket into a discussion…

[Nic-Ma]

Cool, sounds good! Let me try to refactor handlers for the inference workflows first based on this proposal. For the first step, we are trying to co-work with some GPU optimized inference projects of NVIDIA, which are currently based on other workflows, like DALI, etc.

Thanks so much for your help!