gRPC-Web for Golang and TypeScript

This repository implements the upcoming gRPC-Web spec allowing for invoking gRPC services from modern browsers (Chrome >= 40.0, Firefox >= 39, Safari >=10, IE >= 10).

The stack consists of :

• a Go http.Handler that exposes a grpc.Server with gRPC-Web wrapping over both HTTP2 and HTTP1.1 (done)
• a TypeScript library (usable in ES5) that implements for invoking gRPC-Web endpoints (in progress)
• a TypeScript protoc plugin that code-generates TypeScript types (generated service stubs are coming soon)
• a Go-based gRPC Proxy Server that allows exposing non-gRPC-Web enabled gRPC services (todo)

gRPC and browsers

The biggest problem with Browser as gRPC clients, is that that they do not support accessing Trailer headers. A discussion is happening in fetch#34 to add them to the fetch standard, but actual implementation in browsers is very much in the future.

The gRPC-Web spec works around this by moving the Trailer headers into the response stream (DATA frames for HTTP2 calls, chunked body for HTTP1.1) and encoding them as HTTP1.1 headers in yet-another gRPC Delimited-Message.

It is very important to note that gRPC-Web currently does not support client-side streaming. This is unlikely to change until until new whatwg fetch/streams API lands in browsers. As such, if you plan on using gRPC-Web you're limited to:

• unary RPCs (1 request 1 response)
• server-side streaming RPCs (1 request N responses)

Status

At the moment this repo holds:

• a Go http.Handler that exposes a grpc.Server with gRPC-Web wrapping over both HTTP2 and HTTP1.1
• a TypeScript library for making gRPC requests

The implementation is in experimental stage, and we're trying it out on Improbable Platform's staging environment.

Running the tests

Install the localhost certificates of this repo found in misc/. Follow this guide for Chrome.

Run the TypeScript tests against the Golang TestServer

cd  ${GOPATH}/github.com/improbable-eng/grpc-web/test
npm test

Point your browser at https://localhost:9876