Skip to content

Event Mappers

In more complex scenarios, adapting only the event names or QNames might not be enough. Sometimes you might need to transform the payload.

For example, in a travel site, a passenger information portlet portlet1 emits a passenger ID under the key passengerID. The payload is of type Integer. A second portlet, a car renters information portlet portlet2 expects a passenger ID under the key userID, and sent as payload of type String.

As with DCX keys to enable the passenger information portlet portlet1 to communicate with the car renters information portlet portlet2, you have the following two options:

  • You can make the passenger information portlet portlet1 store its payload under the key userID and as of type String, even though it emits an event with the QName employeeID and as of type Integer.
  • You can make the car renters information portlet portlet2 read the key employeeID and as of type Integer, even though it expects an event with the QName userID and as of type String.

Mappers have full access to the DCX segment of the currently processed dialog instance and also to the payload that is being processed. Therefore, mappers are powerful tools, as they can run various transformations.

Implement MapperFactory to make the mappers available. You can register the MapperFactory with an Eclipse Extension Point. The advantage of this approach is that you can register new mappers without having to restart the server. This method is also called hot deployment. To use a MapperFactory, you need to implement the interface MapperFactory and return an object instance of type ContextToPayloadMapper or PayloadToContextMapper. This implementation depends on the concrete event mapper that is requested.

The following code sample shows an example of how a MapperFactory can look.

Code sample:

 public class MapperFactory implements com.ibm.portal.pcm.events.MapperFactory {

  public ContextToPayloadMapper getContextToPayloadMapper(String name) {      
      ContextToPayloadMapper result = null;       
      if (name.equals("myPackage.myMapper")) {
          result = new MyMapper();
      }

      return result;
  }

  public PayloadToContextMapper getPayloadToContextMapper(String name) {
      // ...
  }
 }

The following code sample shows how you can register a MapperFactory with a plugin.xml file.

Code sample:

 <plugin
     id="com.ibm.wps.portlet.pcm.demo"
     name="Portlet Control Manager Demo"
     version="1.0.0"
     provider-name="IBM">

     <!-- Mapper Factory -->
     <extension point="com.ibm.portal.pcm.MapperFactory" id="PcmMapperFactory">
         <factory class="com.ibm.wps.pcm.demo.mapper.MapperFactory"/>
     </extension>
 </plugin>
Related information