Example of WSO2 Spring mediator

The Spring Mediator exposes a spring bean as a mediator. The Spring Mediator creates an instance of a mediator, which is managed by Spring. This Spring bean must implement the Mediator interface for it to act as a Mediator.

Syntax of Spring Mediator

<spring:spring bean="exampleBean" key="string"/>

First, we need to create a Mediator Project for Bean classes. (for more information visit the How to use WSO2 Class Mediator in WSO2 ESB )

For explaining clearly, I have created to Person and Student Beans.

Person Bean.

package lk.harshana;

import org.apache.synapse.MessageContext;
import org.apache.synapse.mediators.AbstractMediator;

public class Person extends AbstractMediator {
 
 private String name;
 private String address;
 private String email;

 @Override
 public boolean mediate(MessageContext arg0) {
  System.out.println("starting person");
  System.out.println("name : " + name);
  System.out.println("address : " + address);
  System.out.println("email : " + email);
  System.out.println("ending person bean");
  return true;
 }

 public String getName() {
  return name;
 }

 public void setName(String name) {
  this.name = name;
 }

 public String getEmail() {
  return email;
 }

 public void setEmail(String email) {
  this.email = email;
 }

 public String getAddress() {
  return address;
 }

 public void setAddress(String address) {
  this.address = address;
 }

}

Student Bean

package lk.harshana;

import org.apache.synapse.MessageContext;
import org.apache.synapse.mediators.AbstractMediator;

public class Student extends AbstractMediator {

 private String studentId;
 private String grade;
 private Person person;

 @Override
 public boolean mediate(MessageContext arg0) {
  System.out.println("===== student bean working ====");

  System.out.println("student id : " + studentId);
  System.out.println("student grade  : " + grade);
  System.out.println("student name  : " + person.getName());
  System.out.println("student address  : " + person.getAddress());
  System.out.println("student email  : " + person.getEmail());

  System.out.println("=====studnet bean ending   ====");
  return true;
 }

 public String getStudentId() {
  return studentId;
 }

 public void setStudentId(String studentId) {
  this.studentId = studentId;
 }

 public String getGrade() {
  return grade;
 }

 public void setGrade(String grade) {
  this.grade = grade;
 }

 public Person getPerson() {
  return person;
 }

 public void setPerson(Person person) {
  this.person = person;
 }
}

Build the project and copy the jar file into <ESB_HOME>/repository/components/lib folder.

now, add the spring configuration (springConfig.xml)  to the registry path /_system/config/repository/springConfig.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
 <bean id="Person1" class="lk.harshana.Person">
  <property name="name" value="Harshana" />
  <property name="address" value="Warakapola" />
  <property name="email" value="harshanacslab@gmail.com" />
 </bean>

 <bean id="Person2" class="lk.harshana.Person">
  <property name="name" value="Madusanka" />
  <property name="address" value="Kohombadeniya" />
  <property name="email" value="abc@gmail.com" />
 </bean>
 <bean id="Student" class="lk.harshana.Student">
  <property name="studentId" value="ps-10-104" />
  <property name="grade" value="university" />
        <property name="person" ref="Person1"/>
 </bean>
</beans>

Okay, now we need to create the proxy service to implement the Spring mediator.

<?xml version="1.0" encoding="UTF-8"?>
<proxy name="SpringSampleProxy" startOnLoad="true" transports="http https" xmlns="http://ws.apache.org/ns/synapse">
    <target>
        <inSequence>
            <log level="full">
                <property name="start_log" value="starting spring proxy"/>
            </log>
            <spring:spring bean="Person1" key="conf:/repository/springConfig.xml" xmlns:spring="http://ws.apache.org/ns/synapse"/>
            <spring:spring bean="Person2" key="conf:/repository/springConfig.xml" xmlns:spring="http://ws.apache.org/ns/synapse"/>
            <spring:spring bean="Student" key="conf:/repository/springConfig.xml" xmlns:spring="http://ws.apache.org/ns/synapse"/>
            <log level="full">
                <property name="end_log" value="ending spring proxy"/>
            </log>
        </inSequence>
        <outSequence/>
        <faultSequence/>
    </target>
</proxy>

Invoke the proxy. you can see the following log in ESB

[2018-09-15 22:17:29,365]  INFO - LogMediator To: /services/SpringSampleProxy.SpringSampleProxyHttpSoap12Endpoint, WSAction: urn:mediate, SOAPAction: urn:mediate, MessageID: urn:uuid:95fa9f49-f9b1-4af0-a896-afafc9a42a41, Direction: request, start_log = starting spring proxy, Envelope: <?xml version='1.0' encoding='utf-8'?><soapenv:Envelope xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope"><soapenv:Body/></soapenv:Envelope>
starting person
name : Harshana
address : Warakapola
email : harshanacslab@gmail.com
ending person bean
starting person
name : Madusanka
address : Kohombadeniya
email : abc@gmail.com
ending person bean
===== student bean working ====
student id : ps-10-104
student grade  : university
student name  : Harshana
student address  : Warakapola
student email  : harshanacslab@gmail.com
=====studnet bean ending   ====
[2018-09-15 22:17:29,394]  INFO - LogMediator To: /services/SpringSampleProxy.SpringSampleProxyHttpSoap12Endpoint, WSAction: urn:mediate, SOAPAction: urn:mediate, MessageID: urn:uuid:95fa9f49-f9b1-4af0-a896-afafc9a42a41, Direction: request, end_log = ending spring proxy, Envelope: <?xml version='1.0' encoding='utf-8'?><soapenv:Envelope xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope"><soapenv:Body/></soapenv:Envelope>

References

[1]. https://docs.wso2.com/display/ESB490/Spring+Mediator