JavaEE and RESTful development - WSO2 Colombo Meetup

1. Sagara
Gunathunga
JavaEE
and
RESTful
development

2. • RESTfull development
• Introduction to JavaEE
• Context and Dependency Injection
• WSO2 Application Server
2
Agenda

3. 3
REST
REpresentational State Transfer
“An architecture style of networked systems”

4. 4
REST
Let’s take an
example
REpresentational State Transfer
An architecture style of networked systems

5. 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

6. 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

7. 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

8. 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

9. 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.
9
REST
Fundamentals

10. 10
REST
HTTP Request/Response

11. 11
REST
HTTP Request/Response

12. 12
HTTP Method CRUD Desc.
POST CREATE Create -
GET RETRIEVE Retrieve Safe,Idempotent,Cacheable
PUT UPDATE Update Idempotent
DELETE DELETE Delete Idempotent
REST
HTTP Methods

13. 13
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
•

14. 14
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

15. JAX-­‐RS
JAX-RS Annotated Service
@Path("/hello”)
public class HelloWorldService {
@GET
@Path("/{user}")
public String hello(@PathParam("user") String user) {
}
}

16. 16
JAX-­‐WS
Annota4ons
• @Path
• @GET
• @PUT
• @POST
• @DELETE
• @Produces
• @Consumes
• @PathParam
• @QueryParam
• @MatrixParam
• @HeaderParam
• @CookieParam
• @FormParam
• @DefaultValue
• @Context

17. 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) {
}
}

18. 18
JavaEE

19. 19
JavaEE
6

20. 20
JavaEE
–
Example
Student REST Service Student DatabaseClients
Let’s take an
example

21. 21
JAX-RS service to
accept HTTP calls
JavaEE
–
Example
@Path("/student”)
public class HelloWorldService {
@GET
@Path(”getall")
@Produces({"application/json”})
public String getAll() {
}
}

22. 22
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

23. 23
JavaEE
–
Example
How to integrate
JAX-RS service
with JPA DAO
service ?
JAX-RS service
JPA service

24. 24
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

25. 25
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

26. 26
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 ?
JavaEE
CDI

27. 27
JavaEE
–
Example
integra4on
How to integrate
JAX-RS service
with JPA DAO
service ?JAX-RS service
JPA service
CDI

28. 28
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

29. 29
WSO2
Applica4on
Server
Yet another
app server ?

30. • 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

31. 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

32. 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

33. Server-­‐side
JavaScript
• Develop complete server side application using
Jaggery.js and deploy on Application Server
• Web Applications
• RESTfull services
• WebSocket services

34. In-­‐built
API
management

35. JavaEE
Web
Profile
support

36. 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

37. 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

38. Web
Socket
development
• Supported WebSocket development models
• Java API for WebSocket
• Jaggery Web Sockets ( Java Script )

39. 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.

40. AcAvity
and
server
monitoring

41. 41
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/

42. Contact
us
!