ServerSentEventsFeature.md

+This feature allows to provide Server-Sent Events in the backend and
+to have Java clients to receive those events.
+
+### Backend example
+
+Interface:
+
+        public interface SseInterface {
+            @SSE(autoReconnect=20)
+            EventStream<TestPojo> status(String jobName);
+        }
+    
+* The method must have an @SSE annotation. You may control the reconnect delay here, too
+* The method must return an `EventStream` of some payload type. This can be any type you like
+  (no streams here)
+* Pass any arguments you like (limited support of annotations currently)
+
+Implementation:
+
+        public class SseHandler implements SseInterface {
+            @Override
+            public EventStream<TestPojo> status(String jobName) {
+                return (EventStream<TestPojo> stream) -> {
+                    //compute values, loop or wait 
+                
+                    try {
+                        TestPojo event = new TestPojo(...);
+                        stream.pushEvent(event);
+                        
+                        ...
+                    } catch (Throwable e) {
+                       ...
+                    }
+                }
+            }
+        }
+
+* The implementation returns a `Consumer<EventStream<Payload>>`. This will automatically converted by Java into an `EventStream<Payload>` using FunctionalInterface mechanics.
+* The provided stream is the transport for the generated events. _Just push your events into the stream_.
+* The consumer may be a long running task. It should check for the interrupted flag, tough
+
+Client:
+        
+        ...
+        DelightConfig cfg = DelightConfigFinder.getDefaultConfigBuilder()
+            .registerFeaturesByClass(SseFeature.class)
+            .build();
+        
+        String endpoint = "http://localhost:8080/example-delight-webapp/delight";
+        Delight delight = new Delight(cfg);
+        SseInterface sseService = delight
+                .connectingTo(endpoint)
+                .usingApi(SseInterface.class);
+        
+        try (EventStream<TestPojo> events = sseService.status("send me events ...")) {
+            events.register(eventPayload -> {
+                               System.out.printf("(SseClient)Received: '%s'\n", eventPayload);
+                            }, 
+                            ex -> { //error handler
+                                System.out.print("(SseClient)Error: ");
+                                ex.printStackTrace(); 
+                            },
+                            () -> { //completion handler
+                                System.out.println("(SseClient)Stopped listening!");
+                            });
+            events.startListening();
+            
+            //receive for a while
+            Thread.sleep(45*1000);
+        }
+        ...