Lagom: gRPC integration

[TimMoore]

gRPC is an increasingly-popular option for high-performance communication between microservices and other endpoints, with support for many programming languages. It is based on Protocol Buffers and adds a service definition language and wire format that works over HTTP/2

It should be possible to use gRPC as a communication channel in Lagom as an alternative to plain HTTP/"REST", either between multiple Lagom services, or between a Lagom service and a non-Lagom process.

[jorgheymans]

:+1: very much !

How do you see streaming grpc calls fitting into Lagom ? I guess unary calls map nicely onto the already existing rest semantics in Lagom, but bidi streaming for example can go on forever between 2 services.

[TimMoore]

@jorgheymans I think gRPC streaming calls map well to Lagom's existing support for streaming over a WebSocket. Bidirectional streaming is already well supported.

[jroper]

It maps perfectly, see:

https://www.lagomframework.com/documentation/1.4.x/java/ServiceDescriptors.html#Streamed-messages

A gRPC streamed call is just a Lagom service call with request/response message types of Source[Foo], which is supported in Lagom today already. When I investigated gRPC last year I was incredibly surprised at just how perfectly gRPC fits what we were already doing.

[djradon]

Any progress on gRPC functionality?

[octonato]

We are working on it. Recently announced on Akka Gitter channel.
https://github.com/akka/akka-meta/issues/64 (see Akka gRPC section)

This will set the ground for support in Lagom.

[ktoso]

Not yet stable release, but we open sourced the repo while we continue to work on it over here: https://github.com/akka/akka-grpc

Community help is of course very welcome!

[dwijnand]

All done.