merge files from the blockchain infra repo:

code/protocol_demos/server-sent-events/index.js

@@ -0,0 +1,30 @@
+/* Client Code 
+
+let sse = new EventSource("http://localhost:8080/stream");
+sse.onmessage = console.log
+
+*/
+
+const app = require("express")();
+
+app.get("/", (req, res) => res.send("hello!"));
+
+app.get("/stream", (req,res) => {
+
+    res.setHeader("Content-Type", "text/event-stream");
+    send(res);
+
+})
+const port = process.env.PORT || 8888;
+
+let i = 0;
+function send (res) {
+    
+    res.write("data: " + `hello from server ---- [${i++}]\n\n`);
+
+
+    setTimeout(() => send(res), 1000);
+}
+
+app.listen(port)
+console.log(`Listening on ${port}`)