code: protected void internalCommit(Xid xid, boolean onePhase) throws XAException
     {
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.entry(this, tc, "internalCommit",
                                             new Object[] {xid, ""+onePhase});
        
        try
        {
           
           CommsByteBuffer request = getCommsByteBuffer();
           request.putInt(getTransactionId());
           request.putXid(xid);
           request.put((byte)(onePhase ? 1 : 0));
           if (fapLevel >= JFapChannelConstants.FAP_VERSION_5) { 
              request.put((byte)(isMSResource ? 0x01 : 0x00));
           }
           
           CommsByteBuffer reply = jfapExchange(request, 
                                                JFapChannelConstants.SEG_XACOMMIT, 
                                                getLowestMessagePriority(), 
                                                true);
           try
           {
              reply.checkXACommandCompletionStatus(JFapChannelConstants.SEG_XACOMMIT_R, getConversation());
           }
           finally
           {
              reply.release();
           }
        }
        catch (XAException xa)
        {
           // No FFDC Code needed
           // Simply re-throw...
           throw xa;
        }
        catch (Exception e)
        {
           FFDCFilter.processException(e, CLASS_NAME + ".internalCommit",
                                       CommsConstants.SIXARESOURCEPROXY_COMMIT_01, this);
           
           if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) SibTr.debug(this, tc, "Caught a comms problem:", e);
           throw new XAException(XAException.XAER_RMFAIL);
        }
        
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.exit(this, tc, "internalCommit");
     }
docs: Called when the transaction manager wishes to commit the
  transaction represented by this Xid.
  <p>
  Across the wire we will flow:
  <p>
  BIT32    TransactionId
  The XID Structure
  BYTE     OnePhase (0x00 = false, 0x01 = true)
  
  @param xid
  @param onePhase
  
  @throws XAException if an exception is thrown at the ME. In the
  event of a comms failure, an XAException with XAER_RMFAIL will
  be thrown.