Spring framework 4.2 GA is almost released, let's look at some new features it provides. The one that got my attention is a simple new class SseEmitter - an abstraction over sever-sent events easily used in Spring MVC controllers. SSE is a technology that allows you to stream data from server to the browser within one HTTP connection in one direction. It sounds like a subset of what websockets can do. However since it's a much simpler protocol, it may be used when full-duplex is not necessary, e.g. pushing stock price changes in real-time or showing progress of long-running process. This is going to be our example. Imagine we have a virtual coin miner with the following API: public interface CoinMiner { BigDecimal mine() { //... } } Every time we call mine() we have to wait few seconds and we get around 1 coin in return (on average). If we want to mine multiple coins, we have to call this method multiple times: @RestController public class MiningCont