Server-sent events

Typically, every interaction between a web service and its client is initiated by the client; the client sends a request (GET, POST, PUT, or DELETE), then receives a response from the server. Server-sent events technology allows RESTful web services to "take the initiative" to send messages to a client, that is, to send data that is not a response to a client request. Server-sent events are useful for sending data continuously to a client, for applications such as stock tickers, news feeds, sports scores, and so on.

JAX-RS 2.1 introduces server-sent event support. The following example illustrates how to implement this functionality into our JAX-RS RESTful web services:

package net.ensode.javaee8book.jaxrs21sse; 
 
import java.util.List; 
import java.util.concurrent.Executor; 
import java.util.concurrent.Executors; 
import java.util.concurrent.TimeUnit...