Mule+Servlet+JPA

Revision as of 22:47, 12 February 2008

Mule and Resin using the Mule Servlet provider and JPA (Amber)

Mule can be run within Resin and use objects created by it as components. This allows Mule to take advantage of Resin IoC and Amber, Caucho's implementation of JPA. This example shows how to use all of these technologies together.

(The following has been tested with Resin 3.1.5 and Mule 1.4.3)

1. Download Resin from http://www.caucho.com/download
2. Unzip Resin into /usr/local/share/resin
3. Create the Mule webapp directory structure:
   mkdir -p /usr/local/share/resin/webapps/mule/WEB-INF/lib/
mkdir -p /usr/local/share/resin/webapps/mule/WEB-INF/classes/example/
mkdir -p /usr/local/share/resin/webapps/mule/WEB-INF/classes/META-INF/
4. Download Mule from http://mule.mulesource.org/display/MULE/Download
5. Unzip Mule
6. Copy all the jars included the Mule lib/ directory to
   /usr/local/share/resin/webapps/mule/WEB-INF/lib/
7. Create the configuration file /usr/local/share/resin/webapps/mule/WEB-INF/resin-web.xml

   <?xml version="1.0" encoding="UTF-8"?>
   <web-app xmlns="http://caucho.com/ns/resin">
     <!-- Make the database accessible to Amber -->
     <database>
       <jndi-name>jdbc/resin</jndi-name>
       <driver type="org.gjt.mm.mysql.Driver">
         <url>jdbc:mysql://localhost:3306/MuleJPA</url>
         <user>root</user>
         <password/>
       </driver>
     </database>
   
     <!-- Tell Amber which database to use -->
     <ejb-server data-source="jdbc/resin"/>
   
     <!-- Create the bean reference for the Mule component -->
     <bean class="example.CourseComponent" name="courseComponent"/>
   
     <!-- Tell Mule where to find its configuration -->
     <context-param>
       <param-name>org.mule.config</param-name>
       <param-value>/WEB-INF/course-config.xml</param-value>
     </context-param>
   
     <!-- The listener that starts Mule.  The MuleResinContextListener
          extends Mule's own MuleXmlBuilderContextListener, but allows
          Mule to find Resin's beans. -->
     <listener>
       <listener-class>com.caucho.mule.MuleResinContextListener</listener-class>
     </listener>
   
     <!-- Set up a servlet that Mule can use for input -->
     <servlet servlet-name="mule-servlet"
              servlet-class="org.mule.providers.http.servlet.MuleReceiverServlet"/>
   
     <servlet-mapping url-pattern="/*" servlet-name="mule-servlet"/>
   </web-app>
   

8. Create the configuration file /usr/local/share/resin/webapps/mule/WEB-INF/classes/persistence.xml

   <?xml version="1.0" encoding="UTF-8"?>
   <persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">
     <persistence-unit name="example">
       <class>example.CourseBean</class>
   
       <exclude-unlisted-classes/>
     </persistence-unit>
   </persistence>
   

9. Create a data bean file /usr/local/share/resin/webapps/mule/WEB-INF/classes/example/CourseBean.java

   package example;
   
   import javax.persistence.*;
   
   @Entity@Table(name="basic_courses")
   public class CourseBean {
     private int _id;
     private String _course;
     private String _teacher;
   
     @Id@Column(name="id")
     @GeneratedValue
     public int getId()
     {
       return _id;
     }
   
     public void setId(int id)
     {
       _id = id;
     }
   
     @Basic
     public String getCourse()
     {
       return _course;
     }
   
     public void setCourse(String course)
     {
       _course = course;
     }
   
     @Basic
     public String getTeacher()
     {
       return _teacher;
     }
   
     public void setTeacher(String teacher)
     {
       _teacher = teacher;
     }
   }
   

10. Create the Mule component /usr/local/share/resin/webapps/cxf/WEB-INF/classes/example/CourseComponent.java

    package example;
    
    import java.io.*;
    import javax.servlet.*;
    import javax.servlet.http.*;
    import javax.persistence.*;
    
    import org.mule.umo.lifecycle.Callable;
    import org.mule.umo.UMOEventContext;
    
    public class CourseComponent implements Callable
    {
      @PersistenceContext(name="example")
      private EntityManager _manager;
    
      public Object onCall(UMOEventContext context)
      {
        StringBuilder sb = new StringBuilder();
    
        CourseBean []course = new CourseBean[2];
    
        course[0] = _manager.find(CourseBean.class, new Integer(1));
        course[1] = _manager.find(CourseBean.class, new Integer(2));
    
        sb.append("Course Details\n\n");
    
        for (int i = 0; i < course.length; i++) {
          sb.append("course: " + course[i].getCourse() + "\n");
          sb.append("teacher: " + course[i].getTeacher() + "\n\n");
        }
    
        return sb.toString();
      }
    }
    

11. Start Resin with java -jar /usr/local/share/resin/lib/resin.jar
12. Look at http://localhost:8080/mule/course
    It should show

    Course Details
    
    course: Potions
    teacher: Severus Snape
    
    course: Transfiguration
    teacher: Minerva McGonagall