code: public MessageItem retrieveMessageFromItemStream(long msgStoreID)
                      throws SIResourceException
      {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.entry(tc, "retrieveMessageFromItemStream", new Long(msgStoreID));
  
          MessageItem msgItem = null;
          try
          {
              msgItem = (MessageItem) _pubsubMessageItemStream.findById(msgStoreID);
          } catch (MessageStoreException e)
          {
              // FFDC
              FFDCFilter.processException(
                                          e,
                                          "com.ibm.ws.sib.processor.impl.destination.PubSubRealization.retrieveMessageFromItemStream",
                                          "1:3797:1.35.2.4",
                                          this);
  
              SibTr.exception(tc, e);
  
              if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
                  SibTr.exit(tc, "retrieveMessageFromItemStream", e);
  
              throw new SIResourceException(e);
          }
  
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.exit(tc, "retrieveMessageFromItemStream", msgItem);
  
          return msgItem;
      }
docs: Retrieve the message from the non-persistent ItemStream