RTC Java API - Reading attribute value using workitemcommon

Hi,
     I have a working code. Where I need to verify either my understanding is correct or to find the right way to do it.

public class HandleWorkflowOnStateChangeParticipant extends AbstractService

        implements IOperationParticipant {

public void run(AdvisableOperation operation,

IProcessConfigurationElement participantConfig,

IParticipantInfoCollector collector, IProgressMonitor monitor)

throws TeamRepositoryException {

WorkItemCommon workItemCommon = (IWorkItemCommon) getService(IWorkItemServer.class);

}

}

I was creating the operation participant for the first time. Where I have a requirement to the read the attribute value. And some where in the forum I found few codes. Also, from the following links,

https://rsjazz.wordpress.com/2013/01/02/working-with-work-item-attributes/

I am not sure how to retrieve

"fTeamRepository" 

IWorkItemCommon workItemCommon = (IWorkItemCommon ) fTeamRepository.getClientLibrary(IWorkItemCommon.class);

Can anyone suggest me whether I did in right way using "getService". Or, how or retrieve "fTeamRepository".

Thanks.