protected Boolean run(String objectCode, String groupingCode) throws FenixServiceException {
    Grouping grouping = FenixFramework.getDomainObject(groupingCode);

    if (grouping == null) {
      throw new ExistingServiceException();
    }

    List attendsElements = new ArrayList();
    attendsElements.addAll(grouping.getAttends());
    Iterator iterator = attendsElements.iterator();
    StringBuilder sbStudentNumbers = new StringBuilder("");
    sbStudentNumbers.setLength(0);

    while (iterator.hasNext()) {
      Attends attend = (Attends) iterator.next();
      if (sbStudentNumbers.length() != 0) {
        sbStudentNumbers.append(", " + attend.getRegistration().getNumber().toString());
      } else {
        sbStudentNumbers.append(attend.getRegistration().getNumber().toString());
      }

      boolean found = false;
      Iterator iterStudentsGroups = grouping.getStudentGroupsSet().iterator();
      while (iterStudentsGroups.hasNext() && !found) {

        StudentGroup studentGroup = (StudentGroup) iterStudentsGroups.next();

        if (studentGroup != null) {
          studentGroup.removeAttends(attend);
          found = true;
        }
      }
      grouping.removeAttends(attend);
    }

    // no students means no log entry -- list may contain invalid values, so
    // its size cannot be used to test
    if (sbStudentNumbers.length() != 0) {
      List<ExecutionCourse> ecs = grouping.getExecutionCourses();
      for (ExecutionCourse ec : ecs) {
        GroupsAndShiftsManagementLog.createLog(
            ec,
            "resources.MessagingResources",
            "log.executionCourse.groupAndShifts.grouping.memberSet.removed",
            Integer.toString(attendsElements.size()),
            sbStudentNumbers.toString(),
            grouping.getName(),
            ec.getNome(),
            ec.getDegreePresentationString());
      }
    }

    return true;
  }