PromiseClient is missing all the streaming methods

[juanjoDiaz]

It seems that only Unary calls are added to the PromiseClient.
That means that, if you combine streaming and unary calls you either stick to the callback-based client or you need to have both clients.

Any reason for that? Would a PR to add stream calls to the PromiseClient be welcomed?

[stanley-cheung]

PromiseClient is more of an internal experimental thing right now that's not supported here yet. (Hence the complete lack of documentation of its existence here).

So please don't use it yet :) We are planning to work on this but unlikely to be available in the next quarter or so.

[stanley-cheung]

Actually I'd like to use this thread as an API proposal discussion: What should a Promise-based API look like for streaming methods?

[juanjoDiaz]

I think Callback vs Promise is a debate for async request-response operations.

Talking about streams of data, the Callback vs Promise doesn't make any sense.
So I think that streaming call should return exactly the same for both clients.
The current version seems to basically match Node.js' ReadableStream and that sounds like a great option to me. Once the bidirection stream is added it could match Node's Duplex Stream.

In fact, I think that there should be only promises and callbacks should die 🙂
I can't see any advantage of callbacks except the fact that people are used to them.

In that sense, I'd question whether there should be 2 separate clients. It would be trivial to modify the existing generator so req-res calls return a promise by the default or use a callback if a callback is passed.

[stanley-cheung]

Oh I think I misunderstood your original comment of "add stream calls to the PromiseClient" then. So you were saying that currently, in the undocumented PromiseClient, we just aren't outputing the streaming methods at all, and that we should. And there is no need to design a Promise-based API for streaming calls. Then yes, that was my thought as well. We would certainly like to keep the API as close to the Node-based ReadableStream as possible.

About Callback vs Promise, I will punt on this argument for now :)

[juanjoDiaz]

Correct! My initial question was that the undocumented PromiseClient is missing those methods.
It should be trivial to add them there just as they are, that's why I asked if a PR would be welcome.

[stanley-cheung]

Yes a PR would be welcome :) Thanks! Sorry for the confusion.