Calling a Sequence using custom class mediator in WSO2 ESB

[Article moved from ajanthane.blogspot.com]

This article shows how to call a sequence using a class mediator. In some occasions we need to route message to different sequences inside custom class mediator, in this case we can use the below implementation to handle it.

Create a Sequence in WSO2 ESB. The sample sequence used is as below:

<sequence name="TestSequence" xmlns="http://ws.apache.org/ns/synapse">
   <log level="custom">
      <property name="STATUS:" value="--------------TestSequence Invoked---------------"></property>
   </log>
</sequence>

Then create and build the below class to call the sequence-TestSequence inside class mediator. Then copy the build jar to ESB_HOME/repository/components/lib.

package com.custom.sequence.router;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.synapse.Mediator;
import org.apache.synapse.MessageContext;
import org.apache.synapse.mediators.AbstractMediator;

public class CustomSequenceRouter extends AbstractMediator {

 private static final Log log = LogFactory
   .getLog(CustomSequenceRouter.class);

 private String sequenceKey; // This value can set as property for class
        // mediator in synapse configuration

 public boolean mediate(MessageContext context) {
        log.info("-------------------Invoking Custom Mediate to Route Sequence------------");
  // Call the Sequence
  Mediator callSequenceMediator = null;
  if (sequenceKey != null) {
   callSequenceMediator = context.getSequence(sequenceKey);
  } else {
   if (log.isDebugEnabled()) {
    log.debug("Sequence Key not specified.");
   }
  }
  callSequenceMediator.mediate(context);

  return true;
 }

 public String getSequenceKey() {
  return sequenceKey;
 }

 public void setSequenceKey(String sequenceKey) {
  this.sequenceKey = sequenceKey;
 }
}

The pom.xml of the project is given below:

<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0" xsi:schemalocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelversion>4.0.0</modelversion>
  <groupid>com.custom.sequence.router.CustomSequenceRouter</groupid>
  <artifactid>CustomSequenceRouter</artifactid>
  <version>1.0.0</version>
  <packaging>bundle</packaging>
  <name>CustomSequenceRouter</name>
  <description>CustomSequenceRouter</description>
  <properties>
    <capp .type="">lib/synapse/mediator</capp>
  </properties>
  <dependencies>
    <dependency>
      <groupid>org.apache.axis2.wso2</groupid>
      <artifactid>axis2</artifactid>
      <version>1.6.1.wso2v14</version>
    </dependency>
    <dependency>
      <groupid>org.apache.woden.wso2</groupid>
      <artifactid>woden</artifactid>
      <version>1.0.0.M9-wso2v1</version>
    </dependency>
    <dependency>
      <groupid>commons-httpclient.wso2</groupid>
      <artifactid>commons-httpclient</artifactid>
      <version>3.1.0.wso2v2</version>
    </dependency>
    <dependency>
      <groupid>commons-codec.wso2</groupid>
      <artifactid>commons-codec</artifactid>
      <version>1.4.0.wso2v1</version>
    </dependency>
    <dependency>
      <groupid>wsdl4j.wso2</groupid>
      <artifactid>wsdl4j</artifactid>
      <version>1.6.2.wso2v4</version>
    </dependency>
    <dependency>
      <groupid>org.apache.abdera.wso2</groupid>
      <artifactid>abdera</artifactid>
      <version>1.0.0.wso2v3</version>
    </dependency>
    <dependency>
      <groupid>org.apache.geronimo.specs.wso2</groupid>
      <artifactid>geronimo-stax-api_1.0_spec</artifactid>
      <version>1.0.1.wso2v2</version>
    </dependency>
    <dependency>
      <groupid>org.apache.neethi.wso2</groupid>
      <artifactid>neethi</artifactid>
      <version>2.0.4.wso2v4</version>
    </dependency>
    <dependency>
      <groupid>org.apache.synapse</groupid>
      <artifactid>synapse-core</artifactid>
      <version>2.1.3-wso2v11</version>
    </dependency>
    <dependency>
      <groupid>org.apache.ws.commons.schema.wso2</groupid>
      <artifactid>XmlSchema</artifactid>
      <version>1.4.7.wso2v3</version>
    </dependency>
    <dependency>
      <groupid>org.apache.httpcomponents.wso2</groupid>
      <artifactid>httpcore</artifactid>
      <version>4.3.3.wso2v1</version>
    </dependency>
    <dependency>
      <groupid>commons-logging</groupid>
      <artifactid>commons-logging</artifactid>
      <version>1.1.1</version>
    </dependency>
    <dependency>
      <groupid>commons-io.wso2</groupid>
      <artifactid>commons-io</artifactid>
      <version>2.0.0.wso2v2</version>
    </dependency>
  </dependencies>
  <repositories>
    <repository>
      <releases>
        <enabled>true</enabled>
        <updatepolicy>daily</updatepolicy>
        <checksumpolicy>ignore</checksumpolicy>
      </releases>
      <id>wso2-nexus</id>
      <url>http://maven.wso2.org/nexus/content/groups/wso2-public/</url>
    </repository>
  </repositories>
  <pluginrepositories>
    <pluginrepository>
      <releases>
        <enabled>true</enabled>
        <updatepolicy>daily</updatepolicy>
        <checksumpolicy>ignore</checksumpolicy>
      </releases>
      <id>wso2-nexus</id>
      <url>http://maven.wso2.org/nexus/content/groups/wso2-public/</url>
    </pluginrepository>
  </pluginrepositories>
  <build>
    <plugins>
      <plugin>
        <groupid>org.apache.felix</groupid>
        <artifactid>maven-bundle-plugin</artifactid>
        <version>2.3.4</version>
        <extensions>true</extensions>
        <configuration>
          <instructions>
            <bundle-symbolicname>CustomSequenceRouter</bundle-symbolicname>
            <bundle-name>CustomSequenceRouter</bundle-name>
            <export-package>com.custom.sequence.router</export-package>
            <dynamicimport-package>*</dynamicimport-package>
          </instructions>
        </configuration>
      </plugin>
      <plugin>
        <artifactid>maven-eclipse-plugin</artifactid>
        <version>2.9</version>
        <configuration>
          <buildcommands>
            <buildcommand>org.eclipse.jdt.core.javabuilder</buildcommand>
          </buildcommands>
          <projectnatures>
            <projectnature>org.wso2.developerstudio.eclipse.artifact.mediator.project.nature
</projectnature>
            <projectnature>org.eclipse.jdt.core.javanature</projectnature>
          </projectnatures>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

Create a proxy service to call the class mediator in the message flow. Sample proxy service is given below. Here the sequence name to be called is given as a property in class mediator. this helps to dynamically specify the sequence name and inject into the custom class mediator.

<proxy name="SequenceRouterProxy" startonload="true" statistics="disable" trace="disable" transports="https,http" xmlns="http://ws.apache.org/ns/synapse">
   <target>
      <insequence>
         <log level="custom">
            <property name="STATUS:" value="----------------------SequenceRouterProxy Invoked-------------">
         </property></log>
         <class name="com.custom.sequence.router.CustomSequenceRouter">
            <property name="sequenceKey" value="TestSequence">
         </property></class>
      </insequence>
   </target>
   <description>
</description></proxy>