Handling custom objects with JAX-RS SSE API

Information sent using the JAX-RS 2.1 SSE support (in Java EE 8) does not only have to be of String type – it supports Java primitives (Integer , Long etc.), JSON-B & JAX-B annotated types as well as custom objects whose encoding process (Java object to on-wire format) is defined using a MessageBodyWriter implementation

Here is simple example you can try out – no need to setup anything except Docker !

Meanwhile – here is the code snippet

	@GET
	@Produces("text/event-stream")
	public void fetch(@Context Sse sse, @Context SseEventSink eSink) {
	OutboundSseEvent stringEvent = sse.newEventBuilder()
	.name("stringEvent")
	.data(new Date().toString()).build();
	eSink.send(stringEvent);
	OutboundSseEvent primitiveTypeEvent = sse.newEventBuilder()
	.name("primitiveTypeEvent")
	.data(System.currentTimeMillis()).build();
	eSink.send(primitiveTypeEvent);
	OutboundSseEvent jsonbType = sse.newEventBuilder()
	.name("jsonbType")
	.data(new Employee("test@test", "test", 42))
	.mediaType(MediaType.APPLICATION_JSON_TYPE)
	.build();
	eSink.send(jsonbType);
	OutboundSseEvent jaxbType = sse.newEventBuilder()
	.name("jaxbType")
	.data(new Customer("testcut@test", "king"))
	.mediaType(MediaType.APPLICATION_XML_TYPE)
	.build();
	eSink.send(jaxbType);
	OutboundSseEvent customObjWithMBW = sse.newEventBuilder()
	.name("customObjWithMBW")
	.data(new Student("stud@test", "stud-007")).build();
	eSink.send(customObjWithMBW);
	System.out.println("events sent");
	eSink.close();
	System.out.println("sink closed");
	}

view raw

jaxrs_sse_custom_type.java

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To summarize

• Multiple ​​OutboundSseEvents have been created – each differing in the data/media type (text, json, xml etc.)
• the default SSE media type is TEXT_PLAIN, hence does not need to be explicitly specified when dealing with String data type
• ​​​​​Employee class is a JSON-B annotated class
• Customer is a JAX-B annotated class
• Student has a custom MesaageBodyWriter implementation

For more details, just refer to the project

Further reading

• Java EE 8 blogs
• JAX-RS eBook

Cheers!