Research how/if to expose ValueProvider APIs

[ravwojdyla]

Currently if a user wants to use ValueProvider APIs, the user needs to use Beam based API, and wrap those into custom* scio API. We should research if we want to expose ValueProvider API for some common use cases.

[jbx]

Review after 0.7.0 branch release

[BenFradet]

👍 it'd make working with both scio and templates much more seamless. We might even be able to work on it.

[jtfell]

Hi @ravwojdyla @BenFradet , I'm interested in potentially implementing this. I'm pretty new to Beam and very new to Scio, so could you point in the right direction of how you would go about this?

Anything relating to API design, or even which files to look in to get started would be very helpful. Cheers.

[irvifa]

By the way I'm wondering if this is already implemented so we can use runtime value for templates? I notice there's an example for this on PR #1486

[regadas]

We believe that Flex Templates offers more flexibility and Google seems to be on the same page. For that reason we will not add Traditional Template support.