Eclipse RCP/RAP and Remoting with JAX-RS, Spring Data JPA and CXF DOSGi [step3]

In [step2] we have implemented the JAX-RS Client which consumes the UserService#findAll() with JAX-RS:

@Path("/user")
public interface UserService {

	@GET
	@Path("/findAll")
	@Produces(MediaType.APPLICATION_JSON)
	Collection<User> findAll();
...
}

We have seen that JAX-RS Client fails when UserService#findAll(Pageable pageable) is called, because we have not annoted this method with JAX-RS:

1031 [Thread-5] ERROR org.apache.cxf.jaxrs.client.ClientProxyImpl  - Method fr.opensagres.services.UserService.findAll is not a valid resource method
	at org.apache.cxf.jaxrs.client.ClientProxyImpl.reportInvalidResourceMethod(ClientProxyImpl.java:546)

In this article we wish to export and import with JAX-RS the UserService#findAll(Pageable pageable) which returns the paginated list of the User which uses Spring Data – Commons structures :

• Pageable : this parameter is the pagination request.
• Page: the findAll method returns this structure which is the result of the pagination.

On other words we will annotate the UserService#findAll(Pageable pageable) like this :

@POST
@Path("/findAllPage")
@Consumes({ MediaType.APPLICATION_JSON })
@Produces({ MediaType.APPLICATION_JSON })
Page<User> findAll(Pageable pageable);

However when I have managed JAX-RS with Spring Data structure, I had 2 big problems coming from :

• Spring Data – Commons: Spring Data Page and Pageable are interfaces and not Pojo. JAX-RS works with Pojo which are annotated with JAXB annotations. How do manage Spring Data Page and Pageable interfaces with JAX-RS? Fortunately, JAXB 2.0 provides XmlJavaTypeAdapter (please read Using JAXB 2.0’s XmlJavaTypeAdapter) which gives the capability to serialize Page and Pageable interfaces with JAXB. I have suggested this idea to Oliver Gierke, the lead of the Spring Data and he is developing JAXB Adapter with SpringDataJaxb.java. However in this article we will not use this class (because this class is not finished) but we will create our own JAXB adapter which will be more simply to understand how to work the JAXB Adapter.
• Apache CXF: on server side when CXF tries to serialize the Page class with JAXB, it fails because the JAXBContext doesn’t know the User class. This problem comes from that CXF is not able to populate the JAXBContext automaticly with Parameterized class (in our case , we have Page<T> and T=User, the JAXBContext is filled just with Page but not with User). You can fix the problem by setting extra class to the JSONProvider :

  <bean id="jsonProvider" class="org.apache.cxf.jaxrs.provider.JSONProvider">
  	<property name="singleJaxbContext" value="true" />
  	<property name="extraClass">
  		<list>
  			<value>fr.opensagres.domain.User</value>
  		</list>
  	</property>
  </bean>
  

  We will do that in this article, but I have created the patch CXF-4359 which fixes the explained problem below to avoid declaring extra classes for JSONProvider.

Eclipse RCP/RAP with Spring DM, Spring Data JPA and Remoting [step11]

In [step10] we have created RAP Application from the RCP Application. At this step we have several Client Layer :

• OSGi Bundle Activator (simpleclient)
• RCP Application
• RAP Application

which consumes Service Layer : UserService (from Mock Dao, JPA Dao) to retrieve list of User :

package fr.opensagres.services;

import java.util.Collection;

import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;

import fr.opensagres.domain.User;

public interface UserService {

	Collection<User> findAll();

	Page<User> findAll(Pageable pageable);
		
	Collection<User> findByFirstNameLikeAndLastNameLike(String firstName,
			String lastName);

	Page<User> findByFirstNameLikeAndLastNameLike(String firstName,
			String lastName, Pageable pageable);

	User saveUser(User user);

}

Here, The Client and Service Layer are in the same OSGi container. Now we wish manage Client/Server architecture to have :

• Client Layer in an OSGi container
• Service Layer in an other OSGi container

the Client Layer will consume Service Layer with remoting mean.

Eclipse RCP/RAP with Spring DM, Spring Data JPA and Remoting [step9]

In [step8] we have developed a Rich Client with RCP Application to display User list in a SWT Table by consuming the UserService by using Spring DM by using the SpringExtensionFactory from Martin Lippert.

In this article we will display the User List with pagination by using Nebula Pagination Control.

The sort of column will be done by the UserService by using Spring Data Sort Structure:

Eclipse RCP/RAP with Spring DM, Spring Data JPA and Remoting [step8]

In [step7] we have seen how to use Spring Data JPA to add custom methods to the Dao to manage criteria and pagination.

In this article we will implement a Rich Client with RCP Application to display User list in a SWT Table :

We will see how to we can consume the UserService by using Spring DM by using the SpringExtensionFactory from Martin Lippert.

Eclipse RCP/RAP with Spring DM, Spring Data JPA and Remoting [step7]

In [step6] we have implemented the API Dao UserDao with JPA by using Spring Data JPA :

• the API Dao fr.opensagres.dao.UserDao extends the Spring Data org.springframework.data.repository.PagingAndSortingRepository.
• the JPA User Dao implementation is created on runtime by Spring Data JPA by declaring a jpa:repository:

  <!-- Spring Data JPA-->
  <jpa:repositories base-package="fr.opensagres.dao">
    <jpa:repository id="userDao" />
  </jpa:repositories>
  

At this step the UserDao provides the CRUD methods and pagination methods for User entity like :

• Iterable findAll(): to find all entity.
• T save(T model): to save an entity.
• Page findAll(Pageable pageable): to find all entity with pagination.

With Spring Data JPA, it’s possible to add your own method to manage search entities by criteria : to do that the method name of the UserDao must just follow some convention name (see Query creation for more information). In this article we will add the 2 following methods to the UserDao :

• findByFirstNameLikeAndLastNameLike to retrieve a list of User by first name (like) and last name (like):

  List<User> findByFirstNameLikeAndLastNameLike(String firstName,	String lastName);
  

• findByFirstNameLikeAndLastNameLike to retrieve a list of User by first name (like) and last name (like) with pagination:

  Page<User> findByFirstNameLikeAndLastNameLike(String firstName,	String lastName, Pageable pageable);
  

Just add those 2 methods to UserDao API and Spring Data JPA will manage for you the JPA implementation!

Eclipse RCP/RAP with Spring DM, Spring Data JPA and Remoting [step6]

In [step5] we have prepared the Target Platform with:

• The JPA API.
• EclipseLink used as JPA Implementation
• Derby used as Database.
• Commons DBCP used as connection pool.
• Spring Data JPA to implement our DAO with JPA.

The API Dao fr.opensagres.dao.UserDao extends the Spring Data org.springframework.data.repository.PagingAndSortingRepository interface which is the first step to use Spring Data JPA.

In this article we will create several bundles/fragment to retrieves User list from a Database Derby with EclipseLink JPA. The JPA Dao implementation will be done with Spring Data JPA, on other words, you will do nothing (no need to code a JPAUserDao class). We will create 2 bundles and 1 fragment :

• fr.opensagres.dao.jpa the bundle implementation of UserDao with JPA by using Spring Data JPA to avoid coding the JPAUserDao class.
• fr.opensagres.dao.jpa.eclipselink the fragment which configures the JPA fr.opensagres.dao.jpa to use EclipseLink and Deby as dialect.
• fr.opensagres.data.datasource the bundle which publishes the Derby Datasource used by the fr.opensagres.dao.jpa.

Eclipse RCP/RAP with Spring DM, Spring Data JPA and Remoting [step5]

In [step4] we have created DAO layer with Mock implementation. In this article we will start to explains how to implement DAO with JPA to use Database. We will use:

• EclipseLink as JPA Implementation
• Derby as Database.
• Spring Data JPA to implement our DAO with JPA. Spring Data gives some DAO interface like org.springframework.data.repository.PagingAndSortingRepository which provides several CRUD methods like :
  • Iterable findAll(): to find all entity.
  • T save(T model): to save an entity.
  • Page findAll(Pageable pageable): to find all entity with pagination.

  The basic idea of Spring Data JPA is extends this interface in your DAO, and you not need to implements this methods with JPA query. It’s the goal of Spring Data JPA.

But it’s very long to explain how to configure and creates bundles to do that. So I decided to split the explanation into 2 articles :

1. [step5]: explains how to download Spring Data JPA, use Java Spring Data Structure in our Mock and API DAO, and configure the OSGi launch.
2. [step6]: explains how to create and configure bundles to use Spring Data JPA with EclipseLink and Derby.

Eclipse RCP/RAP with Spring DM, Spring Data JPA and Remoting [step4]

In [step3] we have developed a Simple Client bundle which consumes the UserService from the OSGi services registry to display a list of User in the console. So we have seen how to:

• consume service with Spring DM <osgi:reference.
• publish service with Spring DM <osgi:service.

At this step we have a service layer. Now we can add Dao layer (Some people prefer merge services/dao layer, but in our case I prefer do that to have a facade and it will help us when remoting with REST will be done) to retrieve User data from Database. To do that we will use :

• EclipseLink as JPA implementation.
• Spring Data JPA which is great help to integrate JPA with Spring.

Before doing that, I would like show you an idea that we have done in our Eclipse RCP/RAP XDocReport application. We are 2 developers and when we wanted to integrate JPA as Dao implementation we would like continue to work together on 2 tasks :

• one developer integrates Dao JPA implementation with EclipseLink and Spring Data JPA (an hard task when you don’t know very well those technologies).
• one developer continues to develop the application: business services, UI components, etc…

The idea was been to integrate DAO API (very easy task) in our services layer and uses Mock Dao. So we have :

• a Mock Dao implementation layer: which works with Java Map.
• a JPA Dao implementation layer: which works with EclipseLink and Spring Data JPA.

Mock Dao was easy to develop (you will see that in this article) and once time UserDao API was finished, we can work on our own task (one task for JPA and one task for continue the development of the application) without disturb. You can tell me, yes it’s a classic mean to use Mock object.

But the second problem was Data. To inject data (ex: in our case User data) :

• for Mock Dao, Data is managed with Java.
• for JPA Dao, Data is managed with SQL scripts…

However JPA gives you the capability to generate Database by using the JPA annotation of the Domain classes (without SQL scripts). What is about data? So we tell us, why we cannot use ours services save method to inject data? For instance in our case we could call UserService#saveUser(User user) which uses Dao (Mock or JPA) somewhere to inject our users :

• it will work for Mock Dao.
• it will work for JPA Dao.

But where can we do that? The idea is very simple. We have created a new bundle « datainjector » with a DataInjector class which consumes service to inject Data. For instance in our case we could have that :

public class DataInjector {

	private UserService userService;

	public void setUserService(UserService userService) {
		this.userService = userService;
	}

	public void inject() {
          userService.saveUser(new User("Angelo", "Zerr"));
          ...
        }
}

In this article we will do that :

• add API Dao layer used in the Services Implementation.
• implement DAo with Mock (Java Map).
• inject User data in a « datainjector » bundle which will use the UserService.

Eclipse RCP/RAP with Spring DM, Spring Data JPA and Remoting [step3]

In [step2] we have seen how to use Spring DM to load/unload in OSGi context Spring file (stored in META-INF/spring folder) from an OSGi bundle. In this article we will see how to:

• publish service to OSGi services registry with declaration mean with Spring DM <osgi:service.

>S

• consume service from OSGi services registry with declaration mean (to avoid using OSGi ServiceTracker) with Spring DM <osgi:reference .

We will modify our thread client FindAllUsersThread to consume a UserService which returns a list of User :

public interface UserService {

	Collection<User> findAll();

}

and displays on console this User list.

• On consumer side (Simple Client), The UserService will be retrieved from the OSGi services registry with <osgi:reference:

  <osgi:reference id="userService" interface="fr.opensagres.services.UserService"
    cardinality="0..1" timeout="1000" />
  

  This service instance will be injected (Dependency Injection) in the FindAllUsersThread :

  <bean id="FindAllUsersThread" class="fr.opensagres.simpleclient.FindAllUsersThread"
    init-method="start" destroy-method="interrupt">
    <property name="userService" ref="userService"></property>
  </bean>
  

  and UserService will be used in the thread :

  public class FindAllUsersThread extends Thread {
  
  	private UserService userService;
  
  	public void setUserService(UserService userService) {
  		this.userService = userService;
  	}
          
          @Override
  	public void run() {
            // Consume UserService and display user list here...
          }
  }
  

• On publish side (Services Implementation), the UserService implementation instance will be declared in Spring file as bean:

  <bean id="userService" class="fr.opensagres.services.impl.UserServiceImpl" />
  

  and this bean will be registered in the OSGi references with Spring DM <osgi:service:

  <osgi:service ref="userService" interface="fr.opensagres.services.UserService" />
  

Eclipse RCP/RAP with Spring DM, Spring Data JPA and Remoting [step2]

In [step1], we have initialized Spring DM. At this step we can start using Spring DM features. One of goal of Spring DM is to give the capability to any OSGi bundles, to declare Spring bean in XML Spring file stored in their META-INF/spring folder. Spring DM provides a Spring Extender bundle which :

1. load XML Spring file for each OSGi bundles which starts. We will check that in the Start Simple Client bundle section.
2. unload XML Spring file for each OSGi bundles which stops.We will check that in the Stop Simple Client bundle section.

We will check this feature in this article by developing a Simple OSGi Bundle which uses Spring fr.opensagres.simpleclient to create an instance of a Thread :

• the bundle hosts a Thread class which display in the System Out console a message :

  public class FindAllUsersThread extends Thread {	
  	
    @Override
    public void run() {
      while (!super.isInterrupted()) {				
        System.out.println("Call FindAllUsersThread#run()");				
      }
    }
  }

• this Thread class will be declared in a Spring bean in the META-INF/spring/module-context.xml Spring file of the bundle. The start/interrupt of the Thread will be managed by the Spring:

  <bean id="FindAllUsersThread" class="fr.opensagres.simpleclient.FindAllUsersThread"
  	init-method="start" destroy-method="interrupt" />