There are three different purpose exercises step by step as below:
I. The first exercise for "hello jersey!" HelloJersey + StartEntity Function 1: http://localhost:8080/hello hello jersey!
II. The second exercise for GET MessageServices + MessageResources + StartEntity Function 1: http://localhost:8080/message {"id":"babf4e10-3b78-43d5-a88a-6bc14ded1118","user":"foo","messages":"bar","postedAt":"2016-12-12T16:02:09.002Z"}
III. The third exercise for POST & GET Message.java(DTO class) + MessageResource + StartEntity Function 1: http://localhost:8080/messages {"id":"8a13f4c0-b8f0-4ee3-a7d8-e391744b9e4d","user":"foo","message":"bar","postedAt":"2016-12-12T15:59:01.615Z"} Function 2: curl -X POST http://localhost:8080/messages -H "Content-Type: application/json" -d '{"user":"foo", "message": "bar"}' {"id":"7f4b1b7a-264e-4282-b4dd-b716e5e40e1f","user":"foo","message":"bar","postedAt":"2016-12-12T15:35:58.003Z"}