GraphQL Yoga
base concept
A Envelop plugin is a small, reusable and shareable piece of code that can easily be copy-pasted from one project to another or shipped as a NPM package]
Envelop can be used with any environment (Node.js or browser) and any GraphQL workflow (client/server, client-side, or server-to-server).
Github
with base tutorial
NPM
envelop/core
core package
using envelop use mask error plugin
using server sent events
This is a one-way connection, so you can't send events from a client to a server.