RESTful application with JAX-RS and how to expose and test them

Editor's Notes

1. Today let us try to learn building RESTful application using JAX-RS
2. We’ll understand what is REST and what are it’s principles And then know about JAX-RS Understand different HTTP methods that helps building REST services Understand annotation from JAX-RS that simplifies building REST services Look at client APIs from JAR-RS 2.0 And final on how to expose REST APIs
3. Let’s look at a basic HTTP request and response Looking at the URI, the client is requesting to GET all the recordings from beatles band The URI is /music/…./recordings HTTP method is GET The clients ways, I’m expecting an XML as a response All of these forms a request Let’s take a looks at the response The HTTP request status code is 200, which means successful The content-type header says that response data is in xml format.. Or json format
4. Web services are services that are exposed to the internet for programmatic access... an online API that you can call from your code it's a concept, it’s an idea, there is no specification, and no committee to tell you what is right or what is wrong it's an architectural style, set of guide lines for architecting your services… build the services as per your need following the REST principles It was first described by Roy Fielding… he is also one the principal authors of the HTTP specifications Lightweight, without unnecessary headers as in SOAP services Concepts of REST are mainly influenced by HTTP
5. I'm sure many of you would have heard of Facebook and Twitter app... you must have seen games that would post on the Facebook wall, even though those games are not designed by Facebook themselves How do they do this? by calling online APIs
6. Think of resources and build unique URLs for it Resources/URIs should be nouns and not verbs... the URIs should be documents, messages, reports.... and not getMessages, deleteMessages.. it should typically be nouns and not the action it's not message... it should be messages getMessages.do?id=10 deleteMessages.do?id=25 putMessages.do HTTP methods: They have specific meaning to each of these methods You are using these methods with or without your knowledge... like while post a comment or while opening a page in the web browser In the REST world, you don't make call to getReports.. you make a get request to the reports resource URI you don't call a deleteOrder, you make a delete request to the order resource URI the URI tells what entity or resource is being operated upon and the method tells what that operation is.
7. Caching - Cache response on the service layer... for a short time - Stateless - Every request should be independent request - every request should send the state -
8. It provide a way to map the meta-information to your methods through annotation. It’s a POJO based resource classes Injects
9. Which resource you want to act upon In JAX-RS, you can use @Path to bind URI pattern to a Java method. The base URL + @Path parameter before the full URL URL matching with @Path pattern URI matching with parameter: The value within an open brace “{” and close brace “}”, is represents a parameter, and can be access with @PathParam URI matching with regular expression:
10. @Path mentions that resource you want to act upon… @GET, @POST tells what action would that be… To do that, you could add annotations like… to the java method
11. The @Produces annotation is used to specify the MIME media types or representations a resource can produce and send back to the client Can be applied to class level or method level The @Consumes annotation is used to specify which MIME media types of representations a resource can accept, or consume, from the client. Can be applied to class level or method level
12. In the dep desc, define servlet container handling all ur jax-rs service requests….
13. Specification - human and machine readable specification -
14. How many of you have used HTTP URLConnection API from java? Was the experience pleasant?
15. Let me ask you all a question. How many of you develop web services? How do you test the web services that you're developing? write junits (junits are still important to test the services for regressions) java.net.URLConnection API, use libraries like HTTP Client, Jersey Client Rest Client from the broswers like Poster, POSTMAN create a simple/sample UI app to test the APIs For someone to consume your services, you have to expose the API. How do you share/expose your APIs to others? Like what are the services are available, what parameters to be passed, is it a GET or POST document the web services in a word document when an API is updated, new service is added, a service is deprecated, you need to update the document...
16. What is Swagger Swagger is a simple yet powerful representation of your RESTful API. It is an open source tool and has support for nearly every language like Closure, JS, Go, Scala, .Net, PHP, Python, Ruby and not to forget, JAVA. Swagger provides a declarative resource specification, allowing users to understand and consume services without knowledge of server implementation, enabling both developers and non-developers to interact with the API, providing clear insight into how the API responds to parameters and options. Why Swagger - Developer and documentation... no offense to anyone... developers usually hate documentation... we tend to avoid documentation whenever we could - Swagger provides a sandbox UI to interact with the API... wow... how is it different form POSTER or POSTMAN... let's see
17. Specification - human and machine readable specification -