How to bring a gRPC defined API to the web browser
We want to build a Javascript/HTML gui for our gRPC-microservices. Since gRPC is not supported on the browser side, we thought of using web-sockets to connect to a node.js server, which calls the target service via grpc. We struggle to find an elegant solution to do this. Especially, since we use gRPC streams to push events between our micro-services. It seems that we need a second RPC system, just to communicate between the front end and the node.js server. This seems to be a lot of overhead and additional code that must be maintained.
Does anyone have experience doing something like this or has an idea how this could be solved?
Answer
Edit: Since Oct 23,2018 the gRPC-Web project is GA, which might be the most official/standardized way to solve your problem. (Even if it's already 2018 now... ;) )
From the GA-Blog: "gRPC-Web, just like gRPC, lets you define the service “contract” between client (web) and backend gRPC services using Protocol Buffers. The client can then be auto generated. [...]"
We recently built gRPC-Web (https://github.com/improbable-eng/grpc-web) - a browser client and server wrapper that follows the proposed gRPC-Web protocol. The example in that repo should provide a good starting point.
It requires either a standalone proxy or a wrapper for your gRPC server if you're using Golang. The proxy/wrapper modifies the response to package the trailers in the response body so that they can be read by the browser.
Disclosure: I'm a maintainer of the project.