Using Kundera with GWT

GWT with Kundera What is GWT? Google Web Toolkit (GWT /ˈɡwɪt/), or GWT Web Toolkit[1], is an open source set of tools that allows web developers to create and maintain complex JavaScript front-end applications in Java. Other than a few native libraries, everything is Java source that can be built on any supported platform with the included GWT Ant build files. It is licensed under the Apache License version 2.0.[2]

Setting up a GWT project :

1. Download and Install: Got to http://www.gwtproject.org/download.html and download the Download Plugin and Web toolkit . In order to set up the plugin for exlipse : http://www.gwtproject.org/usingeclipse.html
2. Create a web project using GWT :
3. Mavenize the project :

GWT with Kundera :

1. In order to use it with Kundera create a maven project using following command : or mavenize the existing project :
2. Modify the pom.xml :

<dependencies>
            <dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>3.8.1</version>
			<scope>test</scope>
		</dependency>
		<!-- Kundera Libraries -->
		<dependency>
			<groupId>com.impetus.kundera.core</groupId>
			<artifactId>kundera-core</artifactId>
			<version>2.11</version>
		</dependency>
		<dependency>
			<groupId>com.impetus.kundera.client</groupId>
			<artifactId>kundera-cassandra</artifactId>
			<version>2.11</version>
		</dependency>
		<dependency>
			<groupId>com.impetus.kundera.client</groupId>
			<artifactId>kundera-cassandra</artifactId>
			<version>2.11</version>
			<type>test-jar</type>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>com.impetus.kundera.client</groupId>
			<artifactId>kundera-mongo</artifactId>
			<version>2.11</version>
		</dependency>
		<dependency>
			<groupId>com.impetus.kundera.client</groupId>
			<artifactId>kundera-mongo</artifactId>
			<version>2.11</version>
			<type>test-jar</type>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>com.impetus.kundera.client</groupId>
			<artifactId>kundera-rest</artifactId>
			<version>${project.version}</version>
		</dependency>
		<dependency>
			<groupId>com.impetus.kundera.client</groupId>
			<artifactId>kundera-cassandra-pelops</artifactId>
			<version>${project.version}</version>
			<scope>test</scope>
		</dependency>

	      <!-- JAX-RS Libraries -->
		<dependency>
			<groupId>com.sun.jersey</groupId>
			<artifactId>jersey-server</artifactId>
			<version>1.18</version>
		</dependency>
		<dependency>
			<groupId>com.sun.jersey</groupId>
			<artifactId>jersey-core</artifactId>
			<version>1.18</version>
		</dependency>
	       <dependency>
			<groupId>com.sun.jersey</groupId>
			<artifactId>jersey-servlet</artifactId>
			<version>1.18</version>
		</dependency>
		<dependency>
			<groupId>com.sun.jersey</groupId>
			<artifactId>jersey-json</artifactId>
			<version>1.18</version>
		</dependency>
  	       <dependency>
			<groupId>org.fusesource.restygwt</groupId>
			<artifactId>restygwt</artifactId>
			<version>1.3.1</version>
		</dependency>
		<dependency>
			<groupId>com.google.gwt</groupId>
			<artifactId>gwt-servlet</artifactId>
			<version>2.5.1</version>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>com.google.gwt</groupId>
			<artifactId>gwt-user</artifactId>
			<version>2.5.1</version>
			<scope>provided</scope>
		</dependency>
       </dependencies>
	<build>
		<sourceDirectory>src</sourceDirectory>
		<testSourceDirectory>test</testSourceDirectory>
		<resources>
			<resource>
				<directory>src</directory>
				<excludes>
					<exclude>**/*.java</exclude>
				</excludes>
			</resource>
		</resources>
		<plugins>
			<plugin>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.1</version>
				<configuration>
	 			  <source>1.6</source>
				  <target>1.6</target>
				</configuration>
			</plugin>
			<plugin>
    <artifactId>maven-dependency-plugin</artifactId>
    <executions>
      <execution>
        <id>copy-dependencies</id>
        <phase>process-resources</phase>
        <goals>
          <goal>copy-dependencies</goal>
        </goals>
        <configuration>
          <outputDirectory>${basedir}/war/WEB-INF/lib/</outputDirectory>
          <excludeArtifactIds>gwt-user,gwt-dev,gwt-resty</excludeArtifactIds>
        </configuration>
      </execution>
    </executions>
  </plugin>
</plugins>
</build>

3. Run the following command on the terminal : mvn clean install and then mvn eclipse:clean eclipse:eclipse After refreshing and building the project in eclipse reset the Google's web tool kit settings for project.

4. In order to start using Kundera add the following lines to file DataKeeper.gwt.xml

<inherits name='org.fusesource.restygwt.RestyGWT'/>
  <inherits name="com.google.gwt.json.JSON" />

5. We will access Kundera using Rest. In order to do so we need to extend the methods defined in Rest classes and put those classes in client folder of your project. Sample class for same are attached:

6. Create entity classes in the project.

@Entity
@Table(name = "USER")
@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
@IndexCollection(columns = { @Index(name = "preference"), @Index(name = "personalDetail"),@Index(name = "professionalDetail") })
public class UserCassandra
{

    @Id
    @Column(name = "USER_ID")
    private String userId;

    // Embedded object, will persist co-located
    @Embedded
    private PersonalDetailCassandra personalDetail;

    // Embedded object, will persist co-located
    @Embedded
    private ProfessionalDetailCassandra professionalDetail;

    // Element collection, will persist co-located
    @ElementCollection
    @CollectionTable(name = "tweeted")
    private List<TweetCassandra> tweets;

    // One to many, will be persisted separately
    @OneToMany(cascade = { CascadeType.ALL }, fetch = FetchType.EAGER)
    @JoinColumn(name = "FRIEND_ID")
    private List<UserCassandra> friends; // List of users whom I follow

    // One to many, will be persisted separately
    @OneToMany(cascade = { CascadeType.ALL }, fetch = FetchType.EAGER)
    @JoinColumn(name = "FOLLOWER_ID")
    private List<UserCassandra> followers; // List of users who are following me

    // One-to-one, will be persisted separately
    @OneToOne(cascade = { CascadeType.ALL }, fetch = FetchType.EAGER)
    @JoinColumn(name = "PREFERENCE_ID")
   // @XmlTransient
    private PreferenceCassandra preference;

    // One to many, will be persisted separately
    @OneToMany(cascade = { CascadeType.ALL }, fetch = FetchType.EAGER)
    @JoinColumn(name = "USER_ID")
    private Set<ExternalLinkCassandra> externalLinks;
    
    @Column(name = "USER_IMAGE")
    private byte[] userImage;

7. In order to interact with them first create objects of your service classes :

      private final static KunderaService ks = GWT.create(KunderaService.class);

     private final static KunderaJPAQueryService kjs = GWT
			.create(KunderaJPAQueryService.class);

    private final static KunderaNativeQueryService kns = GWT			.create(KunderaNativeQueryService.class);

   private static String applicationToken;

  private static String sessionToken;

8. And then in order to invoke perform operations on your data using Kundera : Invoke the methods like this :

private static void getApplicationToken(String persistentUnit) {
		ks.getEMFToken(persistentUnit, new MethodCallback<Object>() {
			@Override
			public void onSuccess(Method method, Object response) {
				sessionToken = response.toString();
				setSession(sessionToken);
				if(Cookies.isCookieEnabled()){
				   Cookies.setCookie(SESSION_COOKIE_NAME, sessionToken);
				 }
				returnResponse(response.toString());
			}

			@Override
			public void onFailure(Method method, Throwable exception) {
				returnResponse(exception.getMessage());
				GWT.log(exception.getMessage());

			}

			public String returnResponse(String resp) {
				return resp;
			}

		});

	}

9. In order to be able to start using Kundera via GWT you must first create a session token using by invoking getApplicationToken Method which initialized EMF and then invoke the rest of calls.
10. The invocation made is based will be json encoded objects and and response retrieved will as well be json encoded as well.

Sample Encoded response and objects sent across : Request :

{"externalLinks":[{"extLinkId":"L2","linkAddress":"http://linkedin.com/in/devilmate","linkType":"LinkedIn"},{"extLinkId":"L1","linkAddress":"http://facebook.com/coolnerd","linkType":"Facebook"}],"followers":[{"personalDetail":{"name":"Paulo","password":"password1","personalDetailId":"0573c5e5-6c87-4f5d-ab8d-9d0a637a78ec","relationshipStatus":"married"},"userId":"0004"},{"personalDetail":{"name":"Vivek","password":"password1","personalDetailId":"fcef1a5e-614c-47f6-a6fc-604589985187","relationshipStatus":"married"},"userId":"0005"},{"personalDetail":{"name":"Kuldeep","password":"password1","personalDetailId":"e8f97d7c-fd3f-4223-bbb8-cea5972a6087","relationshipStatus":"single"},"userId":"0006"}],"friends":[{"personalDetail":{"name":"John","password":"password1","personalDetailId":"fcf6a180-abd2-4b19-8851-cd21a32debd3","relationshipStatus":"married"},"userId":"0002"},{"personalDetail":{"name":"Mary","password":"password1","personalDetailId":"cce70ddc-2578-45fa-b66c-dd9a25d1cca6","relationshipStatus":"married"},"userId":"0003"},{"personalDetail":{"name":"Shaheed","password":"password1","personalDetailId":"0a7355b8-5ca7-4611-8f4d-cc0524f6e2b6","relationshipStatus":"single"},"userId":"0007"}],"personalDetail":{"name":"Amresh","password":"password1","personalDetailId":"e702262f-e411-4692-8910-3be9bd3c920e","relationshipStatus":"married"},"preference":{"preferenceId":"P1","privacyLevel":"2","websiteTheme":"Motif"},"professionalDetail":{"accumulatedWealth":"123456789","age":"31","compliance":"10.0","departmentId":"23456789","digitalSignature":"8","enrolmentDate":"2012-10-31T12:42:21.111+05:30","enrolmentTime":"2012-10-31T12:42:22.222+05:30","exceptional":"true","grade":"67","graduationDay":"2012-08-04T16:47:47.777+05:30","height":"163.12","jobAttempts":"123456789","joiningDateAndTime":"2012-10-31T12:42:23.333+05:30","monthlySalary":"7.23452342343","rating":"5","uniqueId":"3634521523423","yearsSpent":"2"},"tweets":[{"body":"Here is my first tweet","device":"Web","tweetId":"3e27556a-4b17-4638-8af0-06a382a08f71"},{"body":"Second Tweet from me","device":"Mobile","tweetId":"7202d6fe-8570-44c9-947b-0175cf8500f4"}],"userId":"0001"}

Response :

{book:{"author":"KK","isbn":"123","publication":"first lc"},{"author":"chhavi","isbn":"1111111122"}}