How the HTTP2 API could be used to implement a streaming RPC more easily than other transport layers.

client.js

var http2 = require('http2');
var net = require('net');
var logger = require('bunyan').createLogger({ name: 'Test Logger' });

// Creating the server
var socket = net.connect(8080, 'localhost', function(c) {
	// Use the HTTP2 Framing layer on this conncetion.
	var endpoint = new http2.protocol.Endpoint(logger, 'CLIENT', {});
	endpoint.pipe(socket).pipe(endpoint);

	// Start the first RPC - do another RPC 3 seconds later.
	makeRPC('Stream 1');
	setTimeout(function() {
		makeRPC('Stream 2');
	}, 3000);


	function makeRPC(name) {
		// Create a stream with the server - corresponding to a single RPC call.
		var stream = endpoint.createStream();
		
		// Send the service/method name, along with the initial arguments in the header.
		console.log('Call FindInProjectService/search');
		stream.headers({
			':method' : 'FindInProjectService/search',
			':arguments' : '[3, 4, "nuclide://file.txt", true]'
		});

		stream.on('data', function(data) {
			console.log('Update from ' + name + ': ' + data);
		});

		// After 5 seconds, cancel search.
		setTimeout(function() {
			console.log('Cancelling search.');
			stream.write('close');
		}, 5000);
	}
});

HTTP2 Streaming RPC.md

HTTP2 Streaming RPC

Output

Server

RPC from client to FindInProjectService/search
Sending search update.
Sending search update.
RPC from client to FindInProjectService/search
Sending search update.
Sending search update.
Sending search update.
Cancelling search.
Sending search update.
Sending search update.
Sending search update.
Cancelling search.

Client

Call FindInProjectService/search
Update from Stream 1: Found new match.
Update from Stream 1: Found new match.
Call FindInProjectService/search
Update from Stream 1: Found new match.
Update from Stream 2: Found new match.
Update from Stream 1: Found new match.
Cancelling search.
Update from Stream 2: Found new match.
Update from Stream 2: Found new match.
Update from Stream 2: Found new match.
Cancelling search.

package.json

{
  "dependencies": {
    "bunyan": "^1.4.0",
    "http2": "^3.2.0"
  }
}

server.js

var http2 = require('http2');
var net = require('net');
var logger = require('bunyan').createLogger({ name: 'Test Logger' });

// Creating the server
var server = net.createServer(function(c) {
	var endpoint = new http2.protocol.Endpoint(logger, 'SERVER', {});
	endpoint.pipe(c).pipe(endpoint);

	// A client has requested a bidirectional stream - this will correspond to
	// a single RPC call, and its associated data.
	endpoint.on('stream', function(stream) {
		var interval = null;
		stream.on('headers', function(headers) {
			console.log("RPC from client to " + headers[':method']);
			interval = setInterval(function() {
				console.log('Sending search update.');
				stream.write('Found new match.');
			}, 1000);
		});
		stream.on('data', function() {
			console.log('Cancelling search.');
			clearInterval(interval);
			stream.end();
		});
	});
});

server.listen(8080);