RESTful JSON Web Service - Jersey (v1.19)

I started out once again looking into AngularJS. This time, the goal was to integrate some CRUD operations using either $http or $resource.

AngularJS $http
Using the $http Service in AngularJS to Make AJAX Requests
$q is the angular promise library

AngularJS $resource
Creating a CRUD App in Minutes with Angular's $resource
Most Single Page Applications involve CRUD operations. If you are building CRUD operations using AngularJS, then you can leverage the power of the $resource service. Built on top of the $http service, Angular’s $resource is a factory that lets you interact with RESTful backends easily. So, let’s explore $resource and use it to implement CRUD operations in Angular.

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I read some articles about the pros and cons of both approaches. As I began to implement each approach, I realized I did not have a solid backend to tie into. As a result, I started to pursue using Jersey as a library for creating RESTful web services.

In the past, I have used both Jakarta Struts and Spring to do web services. But, at Explorys, our projects use Jersey. It also seems we have a project or two that use RESTEasy, but I may dig into that another time.

I got a little frustrated setting up the project as the specific goals I wanted to achieve, I could not find a beginning to end example. So, I created a GitHub account and uploaded my project to it! I wanted to use Maven, Jersey, and not have a web.xml file within the project (annotations only).
https://github.com/DEV3L/RESTfulJSONDev3l

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I have some step-by-step instructions that I will paste below, but the result boils down to two RESTful endpoints:
http://services-dev3l.rhcloud.com/RESTfulJSONDev3l/resources/example
http://services-dev3l.rhcloud.com//RESTfulJSONDev3l/resources/example/query

Using this template project, my next step is to create a "standard" set of CRUD operations for a dataset. The first step is to do this against an in-memory static list, but eventually, the services will interact with a database using JOOQ.

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GitHub Project

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RESTfulJSONDev3l

Jersey JSON RESTful web service project (template) - uses annotations without removing the need for a web.xml - com.sun.jersey : v1.19

Usage Instructions to Pull down and use template project from GitHub

1. From command line retrieve project from GitHub
   • git clone https://github.com/DEV3L/RESTfulJSONDev3l.git
2. Run maven package from inside the created directory
   • mvn clean package
3. RESTfulJSONDev3l.war can be deployed to the container of choice
   • http://services-dev3l.rhcloud.com/RESTfulJSONDev3l/resources/example
     • My personal OpenShift server I deploy projects to
4. Use Maven to resolve the dependencies and create Eclipse dynamic web project and class/project files
   • mvn eclipse:eclipse -Dwtpversion=2.0
5. Import the project into Eclipse as an existing project

Project Creation Steps:

Assumes Maven already installed

1. Create a new Dynamic Web Project using Maven from the console
   • mvn archetype:create -DgroupId=RESTfulJSONDev3l -DartifactId=RESTfulJSONDev3l -DarchetypeArtifactId=maven-archetype-webapp
2. Copy the created project to an Eclipse workspace
   • /Workspaces/Eclipse/Sandbox/
3. Update the pom.xml:

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>RESTfulJSONDev3l</groupId>
    <artifactId>RESTfulJSONDev3l</artifactId>
    <packaging>war</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>RESTfulJSONDev3lApp</name>
    <url>http://maven.apache.org</url>
    <build>
        <finalName>RESTfulJSONDev3l</finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
            <plugin>
                <!-- Java EE 6 doesn't require web.xml, Maven needs to catch up! -->
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.4</version>
                <configuration>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
        </plugins>
    </build>
    <dependencies>
        <!-- Jersey REST Dependencies -->
        <dependency>
            <groupId>asm</groupId>
            <artifactId>asm</artifactId>
            <version>3.3.1</version>
        </dependency>
        <dependency>
            <groupId>org.json</groupId>
            <artifactId>json</artifactId>
            <version>20140107</version>
        </dependency>
        <dependency>
            <groupId>com.sun.jersey</groupId>
            <artifactId>jersey-bundle</artifactId>
            <version>1.19</version>
        </dependency>
        <dependency>
            <groupId>com.sun.jersey</groupId>
            <artifactId>jersey-server</artifactId>
            <version>1.19</version>
        </dependency>
        <dependency>
            <groupId>com.sun.jersey</groupId>
            <artifactId>jersey-core</artifactId>
            <version>1.19</version>
        </dependency>
    </dependencies>
</project>

4. Use Maven to resolve the dependencies and create Eclipse project files
   • From the console within the project
     • mvn eclipse:eclipse -Dwtpversion=2.0
5. Import the project into Eclipse as an existing project
6. Delete index.jsp located at src/main/webapp
7. Delete web.xml located at src/main/webapp/WEB-INF
8. Create a src/main/java source folder
   • Could use the existing src/main/resource that comes with the archetype, but this is not "best practice" Maven
9. Create a Bean/POJO with an @XmlRootElement class attribute
   • The @XmlRootElement tells our application how this can be serialized

package com.dev3l.jersey.bean;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class DataBean {
    private String data;
    public DataBean() {
        this(null);
    }
    public DataBean(String data) {
        this.data = data;
    }
    public final String getData() {
        return data;
    }
    public final void setData(String data) {
        this.data = data;
    }
}

10. Create an ApplicationConfig with an @ApplicationPath attribute
    • The @ApplicationPath is the root path of the web service calls

package com.dev3l.jersey.config;

import javax.ws.rs.ApplicationPath;
import javax.ws.rs.core.Application;

@ApplicationPath("resources") // set the path to REST web services
public class ApplicationConfig extends Application {}

11. Create an Example resource with @PATH, @GET and @Produces(MediaType.APPLICATION_JSON)

package com.dev3l.jersey.resource;

import java.util.ArrayList;
import java.util.List;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.GenericEntity;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import com.dev3l.jersey.bean.DataBean;



@Path("example")
public class ExampleResource {
    private static List<DataBean> dataBeans = new ArrayList<DataBean>();
    static {
        dataBeans.add(new DataBean("first"));
        dataBeans.add(new DataBean("second"));
        dataBeans.add(new DataBean("third"));
        dataBeans.add(new DataBean("fourth"));
    }
    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public DataBean getDataBean() {
        return new DataBean("test_data_bean");
    }
    @GET
    @Path("query")
    @Produces(MediaType.APPLICATION_JSON)
    public Response query() {
        GenericEntity<List<DataBean>> entity = new GenericEntity<List<DataBean>>( dataBeans ){};
        return Response.ok().entity(entity).build();
    }
}

12. Add the project to a Java web container
    • Default Tomcat 7.0
13. Start the server
14. Access the endpoints via a browser URL
    • http://localhost:8080/RESTfulJSONDev3l/resources/example
    • http://localhost:8080/RESTfulJSONDev3l/resources/example/query

2015040 - I have switched to using RESTEasy instead of Jersey. They are very similar and aside from a few differently named imports, the setup and use are very similar

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