JavaEE and RESTful development - WSO2 Colombo Meetup

Sagara  Gunathunga  

JavaEE  and  RESTful  development  

•  RESTfull development

•  Introduction to JavaEE

•  Context and Dependency Injection

•  WSO2 Application Server

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Agenda  

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   REST    

REpresentational State Transfer

“An architecture style of networked systems”

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   REST    Let’s take an

example

REpresentational State Transfer

An architecture style of networked systems

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Premier

Cooperate

Regular

Customer Care

Answering Machine

Regular Customer

Representative

Premier Customer

Representative

Cooperate Customer

Representative

•  Example - Customer care system of a bank - The bank provides a single telephone number

   REST    

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Premier

Cooperate

Regular

Answering Machine

Regular Customer

Representative

Premier Customer

Representative

Cooperate Customer

Representative

   REST    

Answering Machine

Answering Machine

•  Example - Customer care system of a bank - The bank provides a multiple(unique) telephone numbers

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Premier

Cooperate

Regular

Customer Care

Answering Machine

Regular Customer

Representative

Premier Customer

Representative

Cooperate Customer

Representative

•  Example - Customer care system of a bank - The bank provides a single telephone number

   REST    

Not REST

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Premier

Cooperate

Regular

Answering Machine

Regular Customer

Representative

Premier Customer

Representative

Cooperate Customer

Representative

   REST    

Answering Machine

Answering Machine

•  Example - Customer care system of a bank - The bank provides a multiple(unique) telephone numbers

REST

Resources  Every  disAnguishable  enAty  is  a  resource.    A  resource  may  be  a  Web  site,  an  HTML  page,  an  XML  document,  a  Web  service,  a  physical  device,  etc.      URLs  Iden4fy  Resources  Every  resource  is  uniquely  idenAfied  by  a  URL.      

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   REST    Fundamentals      

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   REST  HTTP Request/Response  

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   REST  HTTP Request/Response  

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HTTP Method CRUD Desc.

POST CREATE Create -

GET RETRIEVE Retrieve Safe,Idempotent,Cacheable

PUT UPDATE Update Idempotent

DELETE DELETE Delete Idempotent

   REST  HTTP Methods  

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   REST    Fundamentals      •  Client-Server

•  Separation principle •  Components Independent

•  Stateless •  Session state on the client •  Visibility, reliability and scalability •  Trade off (network performance, etc.)

•  Cacheable •  A response can be cacheable •  Efficiency but reduce reliability

•  Layered system •  System scalability

• 

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JAX-­‐RS  –  Java  API  for  RESTfull                                                            WebServices    

•  Annotation driven API

•  Expose annotated Java bean as HTTP based services •  Implementation may support WADL

•  Define JAVA ó HTTP mapping •  Number of implementations

•  Apache CXF•  Apache Wink•  Jersey

JAX-­‐RS  

JAX-RS Annotated Service

@Path("/hello”)public class HelloWorldService {

@GET @Path("/{user}") public String hello(@PathParam("user") String user) {

} }

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JAX-­‐WS  Annota4ons    •  @Path

•  @GET

•  @PUT

•  @POST

•  @DELETE

•  @Produces

•  @Consumes

•  @PathParam

•  @QueryParam

•  @MatrixParam

•  @HeaderParam

•  @CookieParam

•  @FormParam

•  @DefaultValue

•  @Context

JAX-­‐RS  

JAX-RS Annotated Service

@Path("/hello”)public class HelloWorldService {

@GET @Consumes("text/plain") @Produces("text/xml") @Path("/{user}") public String hello(@PathParam("user") String user) {

} }

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JavaEE  

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JavaEE  6    

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JavaEE  –  Example    

Student REST Service Student DatabaseClients

Let’s take an example

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JAX-RS service to accept HTTP calls

JavaEE  –  Example    

@Path("/student”) public class HelloWorldService { @GET @Path(”getall") @Produces({"application/json”}) public String getAll() {

} }

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JavaEE  –  Example    

@Stateful public class StudentManagerImpl implements StudentManager { @PersistenceContext(unitName = "rest-jpa”) private EntityManager entityManager; public Student getStudent(int index) { Student student = entityManager.find(Student.class, index); return student; } }

JPA based data access service

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JavaEE  –  Example    How to integrate JAX-RS service with JPA DAO

service ?JAX-RS service

JPA service

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JavaEE  –  Example  integra4on    

@Path("/student”) public class HelloWorldService { StudentManager sm; public HelloWorldService() { sm = new StudentManagerImpl(); } @GET @Path(”getall") @Produces({"application/json”}) public String getAll() { } }

How to integrate JAX-RS service with JPA DAO

service ?

Pure JAVA

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JavaEE  –  Example  integra4on    

@Path("/student”) public class HelloWorldService { StudentManager sm; public void setStudentManager (StudentManager sm) { } public StudentManager setStudentManager () { } @GET @Path(”getall") @Produces({"application/json”}) public String getAll() { } }

How to integrate JAX-RS service with JPA DAO

service ?

Spring Framework

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JavaEE  –  Example  integra4on    

@Path("/student”) public class HelloWorldService { @Inject StudentManager sm; @GET @Path(”getall") @Produces({"application/json”}) public String getAll() { } }

How to integrate JAX-RS service with JPA DAO

service ?

JavaEECDI

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JavaEE  –  Example  integra4on    How to integrate JAX-RS service with JPA DAO

service ?JAX-RS service

JPA service

CDI

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JavaEE  –  Context  and  Dependency  InjecAon    

@Decorator@Delegate@ApplicationScoped@ConversationScoped@Dependent@NormalScope@RequestScoped@SessionScoped@Observes@Alternative@Any@Default

@Disposes@Model@New@Produces@Specializes@Stereotype@Typed@inject@Named@Qualifier@Scope@Singleton

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 WSO2  Applica4on  Server    

Yet another app server ?

•  Tenant-aware data sources •  Tenant-aware JNDI service•  Tenant-aware session persistence•  Tenant-aware user store •  Tenant-aware authentication and

authorization

•  Tenant-aware Caching •  Tenant-aware configuration

registry•  Tenant-aware dashboards •  Tenant-aware management

console

JavaEE  –  MulA-­‐tenancy  support      

MulAple  classloading    runAmes    

There are four in-built environments •  Tomcat – Only Tomcat libs are visible (Minimal runtime) •  Carbon – Tomcat + Carbon libs are visible •  CXF - Tomcat + CXF + Spring are visible •  Javaee – JavaEE libs are visible

MulAple  classloading    runAmes    

Ability to create your own custom ‘Classloader Runtime environments’ •  Create directory to place your Jar dependencies •  Add an entry to webappclassloading-

environments.xml file e.g. –You can have number of incompatible versions of Spring frameworks in server level

Server-­‐side  JavaScript  

•  Develop complete server side application using Jaggery.js and deploy on Application Server

•  Web Applications

•  RESTfull services

•  WebSocket services

In-­‐built  API  management    

JavaEE  Web  Profile  support    

 Web  Service  development    

•  Supported web service development models

•  JAX –WS ( based on Apache CXF) •  Apache Axis2

•  Bring your own WS framework •  Metro, Spring WS

•  Rich dashboard and development tools•  Try-It tool support •  Download WS client as maven project•  Basic statistics

•  Service publish and discovery support through WSO2 Governance Registry

•  WS – Discovery supported

RESTfull  service  development    •  Supported RESTfull service

development models.•  JAX –RS ( based on Apache CXF) •  Apache Axis2 REST services•  Jaggery REST services ( Java

Script )• 

•  Bring your own WS framework •  Jersey, Rest Easy, Restlet, Spring

•  Rich dashboard and development tools•  Swagger support. •  Download REST client as maven

project •  Basic statistics

Web  Socket  development    

•  Supported WebSocket development models

•  Java API for WebSocket

•  Jaggery Web Sockets ( Java Script )

AcAvity  and  server  monitoring    

•  Embedded Monitoring dashboard

•  Request, response, errors, sessions over time

•  Geo info , language, referrals

•  Alerts on thresholds

•  Server and infrastructure health monitoring.

AcAvity  and  server  monitoring    

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References

•  https://github.com/wso2as-developer/javaee-samples

•  https://docs.wso2.com/display/AS521/WSO2+Application+Server+Documentation

•  http://wso2.com/whitepapers/evaluating-java-ee-application-migration-and-java-ee-service-migration-to-wso2-application-server/

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