RESTful with JEE8

Fast RESTful WS development with JEE8

@augustojimenez1

Augusto Alonso de Cruz Jimenez

Enero de 2019

"Make everything as simple as possible, but not simpler."

Albert Einstein

Augusto Alonso de Cruz Jimenez

@augustojimenez1

Agenda

What is JEE
The JEE's evolution
JEE Specifications
JEE Providers
The JAX-RS specification
Developing a simple JAX-RS application
Running the app on an Application Server
Serverless applications
Embedded Application Server providers
Running the app on an emmbeded app server
Docker considerations
Summary

What is Java

Is a language
Is a platform - JVM
Is an API

There are many implementations of de JVM Platform

Azul Zulu
Bck2Brwsr
CACAO
Codename One
DoppioJVM
OpenJ9
GraalVM CE

HaikuVM
HotSpot
Jamiga
JamVM
Jelatine JVM.
Jikes RVM
JVM.go

JVM.go
leJOS
Maxine
Multi-OS Engine
RopeVM
uJVM

What is JEE

Java Enterprise Edition
Is a super set of specifications
- Distributed computing
- Web services
- Transactions
- Security
- Scalability
- Concurrency
- Management of the components' lifecycle

JEE 7+ is designed to use POJO to turn them into managed objects

The JEE's evolution

J2EE
JEE
JakartaEE

There is an initiative called Microprofile, which is designed to align with microservices architecture style applications.

A recommended article about the JEE's evolution (and another topics) is Microprofile: Mucho camino para llegar aquí, by @rugy

The JEE's specs

Java EE 8 was approved by the JCP EC on Aug 21, 2017. The final specification is available for download on this link.

Java EE 8 has 35+ specs, including:

Servlet, JAX-WS, JAX-RS, JPA, JAXB, JSONP, WebSockets, JSF, EL, JSTL, Batch, CDI, Bean Validation, etc.

A condensed list of specifications can be found at oracle.com

The JEE's specs

JEE 8 providers

Java EE 8 is a spec

There are many providers (implementers)

The Expert Group validate the implementation.

Some Java EE8 certified Full implementations of the spec are:

The JAX-RS spec

Officially:

JSR 370: Java™ API for RESTful Web Services (JAX-RS 2.1) Specification

Implementations:

Apache CXF
Jersey
RESTeasy
Restlet
Apache Wink

If an application server is fully compatible with JAX-RS, the same JAX-RS code is executed in any of them.

The JAX-RS spec

Provides some annotations to aid in mapping a resource class (a POJO) as a web resource. They include:

@Path
@GET, @PUT, @POST, @DELETE and @HEAD
@Produces, @Consumes
@PathParam, @QueryParam, @MatrixParam
@HeaderParam
@CookieParam
@FormParam
@Context

How a POJO annotated with JAX-RS looks like? It's time to code!!!

JAX-RS resource example

package com.example.book.restapi;

import javax.ws.rs.GET;
import javax.ws.rs.Path;

@Path("books")
public class BookResource {

    @GET
    public String resourceInfo() {
        return "Book information";
    }
}