public void unregister(QName pid) throws BpelEngineException {
    if (__log.isTraceEnabled()) __log.trace("unregister: " + pid);

    try {
      _mngmtLock.writeLock().lockInterruptibly();
    } catch (InterruptedException ie) {
      __log.debug("unregister() interrupted.", ie);
      throw new BpelEngineException(__msgs.msgOperationInterrupted());
    }

    try {
      BpelProcess p;
      if (_engine != null) {
        p = _engine.unregisterProcess(pid);
        if (p != null) {
          _registeredProcesses.remove(p);
          XslTransformHandler.getInstance().clearXSLSheets(p.getProcessType());
          __log.info(__msgs.msgProcessUnregistered(pid));
        }
      }
    } catch (Exception ex) {
      __log.error(__msgs.msgProcessUnregisterFailed(pid), ex);
      throw new BpelEngineException(ex);
    } finally {
      _mngmtLock.writeLock().unlock();
    }
  }
  public void register(ProcessConf conf) {
    if (conf == null)
      throw new NullPointerException("must specify non-null process configuration.");

    __log.debug("register: " + conf.getProcessId());

    // Ok, IO out of the way, we will mod the server state, so need to get a
    // lock.
    try {
      _mngmtLock.writeLock().lockInterruptibly();
    } catch (InterruptedException ie) {
      __log.debug("register(...) interrupted.", ie);
      throw new BpelEngineException(__msgs.msgOperationInterrupted());
    }

    try {
      // If the process is already active, do nothing.
      if (_engine.isProcessRegistered(conf.getProcessId())) {
        __log.debug(
            "skipping doRegister" + conf.getProcessId() + ") -- process is already registered");
        return;
      }

      __log.debug("Registering process " + conf.getProcessId() + " with server.");

      BpelProcess process = createBpelProcess(conf);
      process._classLoader = Thread.currentThread().getContextClassLoader();

      _engine.registerProcess(process);
      _registeredProcesses.add(process);
      if (!isLazyHydratable(process)) {
        process.hydrate();
      } else {
        _engine.setProcessSize(process.getPID(), false);
      }

      __log.info(__msgs.msgProcessRegistered(conf.getProcessId()));

    } catch (Exception ex) {
      __log.error(ex);
      throw new BpelEngineException(ex);
    } finally {
      _mngmtLock.writeLock().unlock();
    }
  }