Simple Server-Sent-Events demo

This is an exploration of translating gRPC server side streaming to Server-Sent-Events in the browser.

To try it out:
go run main.go and visit localhost:8080/debug

For a look at how the browser handles interupted streams, Ctrl-C the running server and look at the headers in stdout and developer console in the browser. Without any extra retry logic Firefox times out and closes the stream after just a few seconds.

Goals

• translate grpc stream to http Server-Sent-Events stream
• create simple index page that uses eventsource to demo reconnect
• inspect http headers
• inspect gRPC headers
• translate last event id header to grpc metadata
• display error messages on debug page
• handle Last-Event-ID on the server side (replay events)
• set retry header from the service
• forever-reconnect mechanism for debug page
• display Last-Event-ID on debug page
• make a demo orchestrator where server stops and then resumes
• how to integrate with grpc-gateway?