tasks-rs: JAX-RS, JPA quickstart

Author: Mike Musgrove Level: Intermediate Technologies: JPA, JAX-RS Summary: Demonstrates how to use JAX-RS and JPA together Prerequisites: tasks

What is it?

This project demonstrates how to implement a JAX-RS service that uses JPA 2.0 persistence.

The client uses HTTP to interact with the service. It builds on the tasks quickstarts which provide simple Task management with secure login.
The service interface is implemented using JAX-RS. The SecurityContext JAX-RS annotation is used to inject the security details into each REST method.

The application manages User and Task JPA entities. A user represents an authenticated principal and is associated with zero or more Tasks. Service methods validate that there is an authenticated principal and the first time a principal is seen, a JPA User entity is created to correspond to the principal. JAX-RS annotated methods are provided for associating Tasks with this User and for listing and removing Tasks.

System requirements

All you need to build this project is Java 6.0 (Java SDK 1.6) or better, Maven 3.0 or better.

The application this project produces is designed to be run on JBoss Enterprise Application Platform 6 or JBoss AS 7.

Configure Maven

If you have not yet done so, you must Configure Maven before testing the quickstarts.

Add an Application User

This quickstart uses a secured management interface and requires that you create an application user to access the running application. Instructions to set up an Application user can be found here: Add an Application User. After following these instructions. you should have created a user called quickstartUser with password quickstartPassword, belonging to the guest role.

Start JBoss Enterprise Application Platform 6 or JBoss AS 7 with the Web Profile

Open a command line and navigate to the root of the JBoss server directory.

The following shows the command line to start the server with the web profile:

 For Linux:   JBOSS_HOME/bin/standalone.sh
 For Windows: JBOSS_HOME\bin\standalone.bat

Build and Deploy the Quickstart

NOTE: The following build command assumes you have configured your Maven user settings. If you have not, you must include Maven setting arguments on the command line. See Build and Deploy the Quickstarts for complete instructions and additional options.

Make sure you have started the JBoss Server as described above.
Open a command line and navigate to the root directory of this quickstart.
Type this command to build and deploy the archive:
```
 mvn clean package jboss-as:deploy
```
This will deploy target/jboss-as-tasks-rs.war to the running instance of the server.

Access the Application Resources

Application resources for this quickstart are prefixed with the URL http://localhost:8080/jboss-as-tasks-rs/ and can be accessed by an HTTP client.

For methods that accept GET, a web browser can be used.
Otherwise, you must use cURL or some other command line tool that supports HTTP POST and DELETE methods.

Below you will find instructions to create, display, and delete tasks.

Create a Task

To associate a task called task1 with the user quickstartUser, you must authenticate as user quickstartUser and send an HTTP POST request to the url 'http://localhost:8080/jboss-as-tasks-rs/tasks/task1'.

To issue the POST command using cURL, type the following command:

curl -i -u "quickstartUser:quickstartPassword" -H "Content-Length: 0" -X POST http://localhost:8080/jboss-as-tasks-rs/tasks/task1

You will see the following response:

HTTP/1.1 201 Created
Server: Apache-Coyote/1.1
Location: http://localhost:8080/jboss-as-tasks-rs/tasks/1
Content-Length: 0
Date: Sun, 15 Apr 2012 22:46:26 GMT

This is what happens when the command is issued:

The -i flag tells cURL to print the returned headers. Notice that the Location header contains the URI of the resource corresponding to the new task you have just created.
The -u flag provides the authentication information for the request.
The -H flag adds a header to the outgoing request.
The -X flag tells cURL which HTTP method to use. The HTTP POST is used to create resources.
The Location header of the response contains the URI of the resource representing the newly created task.

The final argument to cURL determines the title of the task. Note that this approach is perhaps not very restful but it simplifies this quickstart. A better approach would be to POST to "http://localhost:8080/jboss-as-tasks-rs/tasks" passing the task title in the body of the request.

Display the XML Representation of a Task

To display the XML representation of the newly created resource, issue a GET request on the task URI returned in the Location header during the create.

To issue a GET using a browser, open a browser and access the URI. You will be challenged to enter valid authentication credentials.

http://localhost:8080/jboss-as-tasks-rs/tasks/1
To issue a GET using cURL, type the following command:

curl -H "Accept: application/xml" -u "quickstartUser:quickstartPassword" -X GET http://localhost:8080/jboss-as-tasks-rs/tasks/1

The `-H flag tells the server that the client wishes to accept XML content.

Using either of the above GET methods, you should see the following XML:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<task id="1" ownerName="quickstartUser">
    <title>task1</title>
</task>

Display the XML Representation of all Tasks for a User

To obtain a list of all tasks for user quickstartUser in XML format, authenticate as user quickstartUser and send an HTTP GET request to the resource tasks URL.

To issue a GET using a browser, open a browser and access the following URL. You will be challenged to enter valid authentication credentials.

http://localhost:8080/jboss-as-tasks-rs/tasks
To list all tasks associated with the user quickstartUser using cURL, type:

curl -H "Accept: application/xml" -u "quickstartUser:quickstartPassword" -X GET http://localhost:8080/jboss-as-tasks-rs/tasks

Using either of the above GET methods, you should see the following XML:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<collection>
    <task id="1" ownerName="quickstartUser">
    <title>task1</title>
    </task>
</collection>

Delete a Task

To delete a task, again authenticate as principal quickstartUser and send an HTTP DELETE request to the URI that represents the task.

To delete the task with id 1:

curl -i -u "quickstartUser:quickstartPassword" -X DELETE http://localhost:8080/jboss-as-tasks-rs/tasks/1

You will see this response:

HTTP/1.1 204 No Content
Server: Apache-Coyote/1.1
Pragma: No-cache
Cache-Control: no-cache
Expires: Thu, 01 Jan 1970 01:00:00 GMT
Date: Sun, 15 Apr 2012 22:51:56 GMT

Now list all tasks associated with user quickstartUser:

curl -u "quickstartUser:quickstartPassword" -X GET http://localhost:8080/jboss-as-tasks-rs/tasks

You will see a response with an empty collection:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<collection/>

Modify this Quickstart to Support JSON Representations of Tasks

JSON is not part of the JAX-RS standard but most JAX-RS implementations do support it. This quickstart can be modified to support JSON by uncommenting a few lines. Look for lines beginning with "// JSON:":

Open the file src/org/jboss/as/quickstarts/tasksrs/model/Task.java and remove the comments from the following two lines.
```
 // import org.codehaus.jackson.annotate.JsonIgnore;

 // @JsonIgnore
```
Open the file src/org/jboss/as/quickstarts/tasksrs/service/TaskResource.java and make sure the GET methods produce "application/json" as well as "application/xml". Again, look for lines beginning with "// JSON:".
- Remove comments from these lines:
  
  //@Produces({ "application/xml", "application/json" })
- Add comments to these lines:
  
  @Produces({ "application/xml" })

Open pom.xml and remove the comments from the dependency with artifactId resteasy-jackson-provider

 <!--
 <dependency>
     <groupId>org.jboss.resteasy</groupId>
     <artifactId>resteasy-jackson-provider</artifactId>
     <version>2.3.1.GA</version>
     <scope>provided</scope>
 </dependency>
 -->

Create a Task as you did in the for the XML version of this quickstart.
Rebuild and redeploy the quickstart.

Now you can view task resources in JSON media type by specifying the correct Accept header. For example, using the cURL tool, type the following command:

curl -H "Accept: application/json" -u "quickstartUser:quickstartPassword" -X GET http://localhost:8080/jboss-as-tasks-rs/tasks/1