Make the two service handler implementation styles (contract-first vs dynamic TypeScript handlers) more explicit and upfront

[pcholakov]

Somewhere in our documentation hierarchy, we should have a page that talks about contract-first vs. dynamic handlers - maybe before we even introduce service types:

[gvdongen]

I think we touch upon this here: https://docs.restate.dev/services/sdk/overview
In the info box as well as in the example with an implementation of both APIs.
I agree that we might need to add a bit more information/context here though.

[pcholakov]

I must be going blind! That's pretty much exactly what I was hoping to see – we can definitely make it a bit clearer still but that covers it. Maybe this is a good place to ask: how do you feel about reversing the order of the gRPC examples to show the Protobuf IDL first, before the handler code? We might generically call the two approaches "dynamic" vs. "contract-first", and particularly for Java/Kotlin, you have to write the IDL first to generate the implementation stubs.

[gvdongen]

@pcholakov I missed the notification for your message, sorry for the late reply.

We use the handler code first because it's the easiest to get started with. It improves the first experience with Restate.
Besides the tour and the quickstart, I think both versions are addressed equally in the rest of the docs? One thing that is missing is a good overview of how they differ or when to use which one. Related issue: https://github.com/restatedev/devrel/issues/8

I will close this issue as the open to do is covered by https://github.com/restatedev/devrel/issues/8 (unless you disagree?)