Make use of grpc-web interceptor

[jvmlet]

Now, when grpc-web officially supports interceptors , would be great to see this extension uses them.

[jvmlet]

BTW, improbable also supports interceptors, so all users might benefit from this great dev tool.

[rogchap]

Yea; this is something that I would like to get to doing at some point. Happy for PRs if someone has the time to look into this?

[jrapoport]

pull request for interceptors #79

[jrapoport]

merged this change into my fork's master and updated the readme to reflect the change. I'm dropping a link here for anyone that finds this and wants to use native gRPC-Web interceptors:
https://github.com/jrapoport/grpc-web-devtools

[caseylucas]

@jrapoport So does your version work with https://github.com/improbable-eng/grpc-web? If so, do you need to do anything to make sure that the browser has a specific version of devtools (which supports one client library over the other) installed?

[jrapoport]

no clue. it was written for https://github.com/grpc/grpc-web interceptors. the version i wrote isn't published so you have to install manually and disable other versions.

it might work with improbable interceptors if they are functionally the same, but i've never tried it.

[gebv]

The following code works for me for improbable-eng

import { grpc } from '@improbable-eng/grpc-web'

...

grpc.unary(methodDescriptor, {
        request: request,
        host: backendURL,
        metadata: new grpc.Metadata(metadata),
        onEnd: res => {
          const { status, statusMessage, headers, message, trailers } = res

          window.postMessage({
            type: '__GRPCWEB_DEVTOOLS__',
            method: methodDescriptor.service.serviceName + '/' + methodDescriptor.methodName,
            methodType: 'unary',
            request: request.toObject(),
            response: message.toObject(),
          }, '*')
       }
    }
 )   

[nibres]

Created this PR with several lines of code to fix this issue.