Examples with Stop org.palladiosimulator.pcm.usagemodel.Stop used on opensource projects

Example 6 with Stop

use of org.palladiosimulator.pcm.usagemodel.Stop in project iobserve-analysis by research-iobserve.

the class TUsageModelToBehaviorModel method findLoopStart.

/**
 * Find first {@link EntryLevelSystemCall} element of a {@link Loop} body.
 *
 * @param loop
 *            loop
 * @return first found {@link EntryLevelSystemCall}, if found
 */
private Optional<EntryCallNode> findLoopStart(final AbstractUserAction action) {
    if (action instanceof Stop) {
        // LoopStart not found
        return Optional.empty();
    } else if (action instanceof EntryLevelSystemCall) {
        // found loop start
        final EntryLevelSystemCall entryLevelSystemCall = (EntryLevelSystemCall) action;
        final EntryCallNode entryCallNode = this.createEntryCallNode(entryLevelSystemCall);
        return Optional.of(entryCallNode);
    } else if (action instanceof Loop) {
        // search nested scenario
        final Loop loop = (Loop) action;
        final List<AbstractUserAction> userActions = loop.getBodyBehaviour_Loop().getActions_ScenarioBehaviour();
        if (userActions.size() > 0) {
            return this.findLoopStart(userActions.get(0));
        } else {
            return Optional.empty();
        }
    } else if (action instanceof Branch) {
        // will always found before
        return Optional.empty();
    } else {
        // next action
        return this.findLoopStart(action.getSuccessor());
    }
}

Example 7 with Stop

use of org.palladiosimulator.pcm.usagemodel.Stop in project iobserve-analysis by research-iobserve.

the class TUsageModelToBehaviorModel method traverseAction.

private Map<EntryCallNode, Double> traverseAction(final BehaviorModel behaviorModel, final Optional<Map<EntryCallNode, Double>> optPreviousNodes, final AbstractUserAction action) {
    if (action instanceof Branch) {
        final Branch branch = (Branch) action;
        return this.traverseBranch(behaviorModel, optPreviousNodes, branch);
    } else if (action instanceof Loop) {
        final Loop loop = (Loop) action;
        return this.traverseLoop(behaviorModel, optPreviousNodes, loop);
    } else if (action instanceof EntryLevelSystemCall) {
        final Map<EntryCallNode, Double> endNodes = new HashMap<>();
        final EntryLevelSystemCall entryLevelSystemCall = (EntryLevelSystemCall) action;
        final EntryCallNode entryCallNode = this.createEntryCallNode(entryLevelSystemCall);
        behaviorModel.addNode(entryCallNode);
        if (optPreviousNodes.isPresent()) {
            optPreviousNodes.get().keySet().stream().map(previousNode -> new EntryCallEdge(previousNode, entryCallNode, optPreviousNodes.get().get(previousNode))).forEach(behaviorModel::addEdge);
        }
        endNodes.put(entryCallNode, 1.0);
        return this.traverseAction(behaviorModel, Optional.of(endNodes), action.getSuccessor());
    } else if (action instanceof Stop) {
        return optPreviousNodes.isPresent() ? optPreviousNodes.get() : new HashMap<>();
    } else {
        // skip action
        return this.traverseAction(behaviorModel, optPreviousNodes, action.getSuccessor());
    }
}

Example 8 with Stop

use of org.palladiosimulator.pcm.usagemodel.Stop in project iobserve-analysis by research-iobserve.

the class BranchWithinBranchReference method createTheReferenceModel.

/**
 * Creates the reference model.
 *
 * @param usageModelBuilder
 * @param repositoryLookupModel
 * @param correspondenceModel
 * @param numberOfTransitionsOfExteriorBranch
 * @param numberOfTransitionsOfInteriorBranches
 * @param numberOfConcurrentUsers
 * @param branchTransitionCounter
 * @param listOfbranchTransitionCounterInterior
 * @return
 */
private static UsageModel createTheReferenceModel(final UsageModelFactory usageModelBuilder, final RepositoryLookupModelProvider repositoryLookupModel, final ICorrespondence correspondenceModel, final int numberOfTransitionsOfExteriorBranch, final int numberOfTransitionsOfInteriorBranches, final int numberOfConcurrentUsers, final List<Integer> branchTransitionCounter, final List<List<Integer>> listOfbranchTransitionCounterInterior) {
    // In the following the reference usage model is created
    AbstractUserAction lastAction;
    Optional<Correspondent> optionCorrespondent;
    final UsageModel usageModel = UsageModelFactory.createUsageModel();
    final UsageScenario usageScenario = UsageModelFactory.createUsageScenario("", usageModel);
    final ScenarioBehaviour scenarioBehaviour = usageScenario.getScenarioBehaviour_UsageScenario();
    final Start start = UsageModelFactory.createAddStartAction("", scenarioBehaviour);
    final Stop stop = UsageModelFactory.createAddStopAction("", scenarioBehaviour);
    lastAction = start;
    // The exterior branch is created
    final org.palladiosimulator.pcm.usagemodel.Branch branch = UsageModelFactory.createBranch("", scenarioBehaviour);
    UsageModelFactory.connect(lastAction, branch);
    UsageModelFactory.connect(branch, stop);
    // Creates branch transitions according to the random countOfBranchTransitions
    for (int i = 0; i < numberOfTransitionsOfExteriorBranch; i++) {
        final BranchTransition branchTransition = UsageModelFactory.createBranchTransition(branch);
        final ScenarioBehaviour branchTransitionBehaviour = branchTransition.getBranchedBehaviour_BranchTransition();
        branchTransition.setBranchProbability((double) branchTransitionCounter.get(i) / (double) numberOfConcurrentUsers);
        final Start startBranchTransition = UsageModelFactory.createStart("");
        UsageModelFactory.addUserAction(branchTransitionBehaviour, startBranchTransition);
        final Stop stopBranchTransition = UsageModelFactory.createStop("");
        UsageModelFactory.addUserAction(branchTransitionBehaviour, stopBranchTransition);
        lastAction = startBranchTransition;
        if (i >= 0 && i < 3) {
            optionCorrespondent = correspondenceModel.getCorrespondent(ReferenceUsageModelBuilder.CLASS_SIGNATURE[i], ReferenceUsageModelBuilder.OPERATION_SIGNATURE[i]);
        } else {
            throw new IllegalArgumentException("Illegal value of model element parameter");
        }
        if (optionCorrespondent.isPresent()) {
            final EntryLevelSystemCall entryLevelSystemCall = UsageModelFactory.createEntryLevelSystemCall(repositoryLookupModel, optionCorrespondent.get());
            UsageModelFactory.addUserAction(branchTransitionBehaviour, entryLevelSystemCall);
            UsageModelFactory.connect(lastAction, entryLevelSystemCall);
            lastAction = entryLevelSystemCall;
        }
        // The interior branch is created
        final org.palladiosimulator.pcm.usagemodel.Branch branchInterior = UsageModelFactory.createBranch("", branchTransitionBehaviour);
        UsageModelFactory.connect(lastAction, branchInterior);
        UsageModelFactory.connect(branchInterior, stopBranchTransition);
        for (int j = 0; j < numberOfTransitionsOfInteriorBranches; j++) {
            final BranchTransition branchTransitionInterior = UsageModelFactory.createBranchTransition(branchInterior);
            final ScenarioBehaviour branchTransitionBehaviourInterior = branchTransitionInterior.getBranchedBehaviour_BranchTransition();
            branchTransitionInterior.setBranchProbability((double) listOfbranchTransitionCounterInterior.get(i).get(j) / (double) branchTransitionCounter.get(i));
            final Start startBranchTransitionInterior = UsageModelFactory.createAddStartAction("", branchTransitionBehaviourInterior);
            final Stop stopBranchTransitionInterior = UsageModelFactory.createAddStopAction("", branchTransitionBehaviourInterior);
            lastAction = startBranchTransitionInterior;
            optionCorrespondent = BranchWithinBranchReference.getOptionCorrespondent(correspondenceModel, j);
            if (optionCorrespondent.isPresent()) {
                final Correspondent correspondent = optionCorrespondent.get();
                final EntryLevelSystemCall entryLevelSystemCall = UsageModelFactory.createEntryLevelSystemCall(repositoryLookupModel, correspondent);
                UsageModelFactory.addUserAction(branchTransitionBehaviourInterior, entryLevelSystemCall);
                UsageModelFactory.connect(lastAction, entryLevelSystemCall);
                lastAction = entryLevelSystemCall;
            }
            UsageModelFactory.connect(lastAction, stopBranchTransitionInterior);
        }
    }
    return usageModel;
}

Example 9 with Stop

use of org.palladiosimulator.pcm.usagemodel.Stop in project iobserve-analysis by research-iobserve.

the class BranchWithinLoopReference method getModel.

/**
 * It creates a reference usage model that contains branches within loops. Accordingly, user
 * sessions whose call sequences differ from each other are iterated in a row. Thereby, at each
 * iteration of a branched call sequences the probabilities have to be equal because otherwise
 * it would not be an iteration (RQ-1.8)
 *
 * @param referenceUsageModelFileName
 *            reference usage model file name
 * @param repositoryLookupModel
 *            repository model builder
 * @param correspondenceModel
 *            correspondence model
 *
 * @return reference usage model and corresponding user sessions
 * @throws IOException
 *             on error
 */
public static ReferenceElements getModel(final String referenceUsageModelFileName, final RepositoryLookupModelProvider repositoryLookupModel, final ICorrespondence correspondenceModel) throws IOException {
    // The number of model element parameters are created randomly. The number of user sessions
    // must be created accordingly to the number of branch transitions, because it must be
    // ensured that at each iteration of an branch the branch transition probabilities are
    // equal. This can be achieved by the same number of user sessions representing the branch
    // transition at each iteration
    final int numberOfLoops = TestHelper.getRandomInteger(3, 3);
    final int numberOfConcurrentUsers = (int) Math.pow(2, numberOfLoops) * 5;
    final EntryCallSequenceModel entryCallSequenceModel = new EntryCallSequenceModel(TestHelper.getUserSessions(numberOfConcurrentUsers));
    final ReferenceElements testElements = new ReferenceElements();
    // In the following the reference usage model is created
    final UsageModel usageModel = UsageModelFactory.createUsageModel();
    final UsageScenario usageScenario = UsageModelFactory.createUsageScenario("", usageModel);
    final ScenarioBehaviour scenarioBehaviour = usageScenario.getScenarioBehaviour_UsageScenario();
    final Start start = UsageModelFactory.createAddStartAction("", scenarioBehaviour);
    final Stop stop = UsageModelFactory.createAddStopAction("", scenarioBehaviour);
    final AbstractUserAction lastAction = start;
    // The loop element is created that contains the iterated branch
    final Loop loop = UsageModelFactory.createLoop("", scenarioBehaviour);
    final ScenarioBehaviour loopScenarioBehaviour = loop.getBodyBehaviour_Loop();
    UsageModelFactory.connect(lastAction, loop);
    final PCMRandomVariable pcmLoopIteration = CoreFactory.eINSTANCE.createPCMRandomVariable();
    pcmLoopIteration.setSpecification(String.valueOf(numberOfLoops));
    // Set number of loops
    loop.setLoopIteration_Loop(pcmLoopIteration);
    UsageModelFactory.connect(loop, stop);
    final Start loopStart = UsageModelFactory.createAddStartAction("", loopScenarioBehaviour);
    final Stop loopStop = UsageModelFactory.createAddStopAction("", loopScenarioBehaviour);
    // The branch that is contained within the loop element is created
    final org.palladiosimulator.pcm.usagemodel.Branch branch = UsageModelFactory.createBranch("", loopScenarioBehaviour);
    UsageModelFactory.connect(loopStart, branch);
    // The branch transition 1 is created
    final BranchTransition branchTransition1 = BranchWithinLoopReference.createBranchTransition(2, repositoryLookupModel, branch, correspondenceModel);
    // The branch transition 2 is created
    final BranchTransition branchTransition2 = BranchWithinLoopReference.createBranchTransition(3, repositoryLookupModel, branch, correspondenceModel);
    final Optional<Correspondent> optionCorrespondent = correspondenceModel.getCorrespondent(ReferenceUsageModelBuilder.CLASS_SIGNATURE[4], ReferenceUsageModelBuilder.OPERATION_SIGNATURE[4]);
    if (optionCorrespondent.isPresent()) {
        final Correspondent correspondent = optionCorrespondent.get();
        final EntryLevelSystemCall entryLevelSystemCall = UsageModelFactory.createEntryLevelSystemCall(repositoryLookupModel, correspondent);
        UsageModelFactory.addUserAction(loopScenarioBehaviour, entryLevelSystemCall);
        UsageModelFactory.connect(branch, entryLevelSystemCall);
        UsageModelFactory.connect(entryLevelSystemCall, loopStop);
    }
    // User sessions according to the reference usage model are created. Thereby, it must be
    // ensured that each iteration of the branch the branch probabilities stay the same because
    // the branch is iterated. This can be achieved by an equal number of user sessions for each
    // branch transition at each iteration of the branch
    int countOfCallEvent3 = 0;
    int countOfCallEvent4 = 0;
    int entryTime = 1;
    int exitTime = 2;
    boolean branchDecision = false;
    // At each iteration the user sessions are distributed equally between the branch
    // transitions to ensure that the probabilities of the branch transitions stay equally
    final Map<Integer, List<List<UserSession>>> userSessionGroups = new HashMap<>();
    final List<List<UserSession>> startList = new ArrayList<>();
    startList.add(entryCallSequenceModel.getUserSessions());
    userSessionGroups.put(0, startList);
    // The loop that contains the branch
    for (int j = 0; j < numberOfLoops; j++) {
        countOfCallEvent3 = 0;
        countOfCallEvent4 = 0;
        final List<List<UserSession>> newUserSessionGroups = new ArrayList<>();
        // Ensures that the user sessions distribution stays equally
        for (int k = 0; k < userSessionGroups.get(j).size(); k++) {
            for (int i = 0; i < 2; i++) {
                final List<UserSession> userSessions = new ArrayList<>();
                newUserSessionGroups.add(userSessions);
            }
            final int indexGroupCallEvent3 = newUserSessionGroups.size() - 2;
            final int indexGroupCallEvent4 = newUserSessionGroups.size() - 1;
            for (int i = 0; i < userSessionGroups.get(j).get(k).size(); i++) {
                if (newUserSessionGroups.get(indexGroupCallEvent3).size() > newUserSessionGroups.get(indexGroupCallEvent4).size()) {
                    branchDecision = false;
                } else {
                    branchDecision = true;
                }
                // The branch within the loop
                if (branchDecision) {
                    BranchWithinLoopReference.createEntryCall(entryTime, exitTime, 2, k, j, i, userSessionGroups, newUserSessionGroups, indexGroupCallEvent3);
                    countOfCallEvent3++;
                    entryTime += 2;
                    exitTime += 2;
                } else {
                    BranchWithinLoopReference.createEntryCall(entryTime, exitTime, 3, k, j, i, userSessionGroups, newUserSessionGroups, indexGroupCallEvent4);
                    countOfCallEvent4++;
                    entryTime += 2;
                    exitTime += 2;
                }
                final EntryCallEvent entryCallEvent5 = new EntryCallEvent(entryTime, exitTime, ReferenceUsageModelBuilder.OPERATION_SIGNATURE[4], ReferenceUsageModelBuilder.CLASS_SIGNATURE[4], String.valueOf(i), "hostname");
                userSessionGroups.get(j).get(k).get(i).add(entryCallEvent5, true);
                entryTime -= 2;
                exitTime -= 2;
            }
        }
        userSessionGroups.put(j + 1, newUserSessionGroups);
        entryTime += 2;
        exitTime += 2;
    }
    // Sets the likelihoods of branch transitions
    final double likelihoodOfCallEvent3 = (double) countOfCallEvent3 / (double) numberOfConcurrentUsers;
    final double likelihoodOfCallEvent4 = (double) countOfCallEvent4 / (double) numberOfConcurrentUsers;
    branchTransition1.setBranchProbability(likelihoodOfCallEvent3);
    branchTransition2.setBranchProbability(likelihoodOfCallEvent4);
    // Saves the reference usage model and sets the usage model and the EntryCallSequenceModel
    // as the reference elements. Our approach is now executed with the EntryCallSequenceModel
    // and the resulting usage model can be matched against the reference usage model
    TestHelper.saveModel(usageModel, referenceUsageModelFileName);
    testElements.setEntryCallSequenceModel(entryCallSequenceModel);
    testElements.setUsageModel(usageModel);
    return testElements;
}

Example 10 with Stop

use of org.palladiosimulator.pcm.usagemodel.Stop in project iobserve-analysis by research-iobserve.

the class LoopWithinLoopReference method getLoopWithinLoopReferenceModel.

/**
 * It creates a reference usage model that contains loops within loops. Accordingly, user
 * sessions whose call sequences contain iterated segments that again contain iterated segments
 * are created.(RQ-1.7)
 *
 * @param referenceUsageModelFileName
 *            file name of the reference model to store its result
 * @param repositoryLookupModel
 *            repository model provider
 * @param correspondenceModel
 *            correspondence model
 *
 * @return reference usage model and corresponding user sessions
 * @throws IOException
 *             on error
 */
public ReferenceElements getLoopWithinLoopReferenceModel(final String referenceUsageModelFileName, final RepositoryLookupModelProvider repositoryLookupModel, final ICorrespondence correspondenceModel) throws IOException {
    // Create a random number of user sessions and random model element parameters. The user
    // sessions' behavior will be created according to the reference usage model and
    // subsequently the user sessions are used to create a usage model. The created usage model
    // is matched against the reference usage model
    final int countOfLoop1 = TestHelper.getRandomInteger(4, 2);
    final int countOfLoop2 = TestHelper.getRandomInteger(4, 2);
    final int lengthOfSubsequentLoopSequence = TestHelper.getRandomInteger(2, 1);
    // In the following the reference usage model is created
    Optional<Correspondent> optionCorrespondent;
    AbstractUserAction lastAction;
    final UsageModel usageModel = UsageModelFactory.createUsageModel();
    final UsageScenario usageScenario = UsageModelFactory.createUsageScenario("", usageModel);
    final ScenarioBehaviour scenarioBehaviour = usageScenario.getScenarioBehaviour_UsageScenario();
    final Start start = UsageModelFactory.createStart("");
    UsageModelFactory.addUserAction(scenarioBehaviour, start);
    final Stop stop = UsageModelFactory.createStop("");
    UsageModelFactory.addUserAction(scenarioBehaviour, stop);
    lastAction = start;
    // The exterior loop is created
    final Loop loop = UsageModelFactory.createLoop("", scenarioBehaviour);
    UsageModelFactory.connect(lastAction, loop);
    UsageModelFactory.connect(loop, stop);
    final PCMRandomVariable pcmLoopIteration = CoreFactory.eINSTANCE.createPCMRandomVariable();
    pcmLoopIteration.setSpecification(String.valueOf(countOfLoop1));
    loop.setLoopIteration_Loop(pcmLoopIteration);
    final Start loopStart = UsageModelFactory.createStart("");
    UsageModelFactory.addUserAction(loop.getBodyBehaviour_Loop(), loopStart);
    final Stop loopStop = UsageModelFactory.createStop("");
    UsageModelFactory.addUserAction(loop.getBodyBehaviour_Loop(), loopStop);
    lastAction = loopStart;
    // The interior loop is created
    final Loop loop2 = UsageModelFactory.createLoop("", loop.getBodyBehaviour_Loop());
    UsageModelFactory.connect(lastAction, loop2);
    final PCMRandomVariable pcmLoop2Iteration = CoreFactory.eINSTANCE.createPCMRandomVariable();
    pcmLoop2Iteration.setSpecification(String.valueOf(countOfLoop2));
    loop2.setLoopIteration_Loop(pcmLoop2Iteration);
    final Start loop2Start = UsageModelFactory.createStart("");
    UsageModelFactory.addUserAction(loop2.getBodyBehaviour_Loop(), loop2Start);
    final Stop loop2Stop = UsageModelFactory.createStop("");
    UsageModelFactory.addUserAction(loop2.getBodyBehaviour_Loop(), loop2Stop);
    lastAction = loop2Start;
    optionCorrespondent = correspondenceModel.getCorrespondent(ReferenceUsageModelBuilder.CLASS_SIGNATURE[2], ReferenceUsageModelBuilder.OPERATION_SIGNATURE[2]);
    if (optionCorrespondent.isPresent()) {
        final Correspondent correspondent = optionCorrespondent.get();
        final EntryLevelSystemCall entryLevelSystemCall = UsageModelFactory.createEntryLevelSystemCall(repositoryLookupModel, correspondent);
        UsageModelFactory.addUserAction(loop2.getBodyBehaviour_Loop(), entryLevelSystemCall);
        UsageModelFactory.connect(lastAction, entryLevelSystemCall);
        lastAction = entryLevelSystemCall;
    }
    UsageModelFactory.connect(lastAction, loop2Stop);
    lastAction = loop2;
    // The sequence that exclusively belongs to the exterior loop is created
    for (int i = 0; i < lengthOfSubsequentLoopSequence; i++) {
        switch(i) {
            case 0:
                optionCorrespondent = correspondenceModel.getCorrespondent(ReferenceUsageModelBuilder.CLASS_SIGNATURE[3], ReferenceUsageModelBuilder.OPERATION_SIGNATURE[3]);
                break;
            case 1:
                optionCorrespondent = correspondenceModel.getCorrespondent(ReferenceUsageModelBuilder.CLASS_SIGNATURE[4], ReferenceUsageModelBuilder.OPERATION_SIGNATURE[4]);
                break;
            default:
                throw new IllegalArgumentException("Illegal value of model element parameter");
        }
        if (optionCorrespondent.isPresent()) {
            final Correspondent correspondent = optionCorrespondent.get();
            final EntryLevelSystemCall entryLevelSystemCall = UsageModelFactory.createEntryLevelSystemCall(repositoryLookupModel, correspondent);
            UsageModelFactory.addUserAction(loop.getBodyBehaviour_Loop(), entryLevelSystemCall);
            UsageModelFactory.connect(lastAction, entryLevelSystemCall);
            lastAction = entryLevelSystemCall;
        }
    }
    UsageModelFactory.connect(lastAction, loopStop);
    final int numberOfConcurrentUsers = TestHelper.getRandomInteger(200, 1);
    final EntryCallSequenceModel entryCallSequenceModel = new EntryCallSequenceModel(TestHelper.getUserSessions(numberOfConcurrentUsers));
    // According to the reference usage model user sessions are created that exactly represent
    // the user behavior of the reference usage model. The entry and exit times enable that the
    // calls within the user sessions are ordered according to the reference usage model.
    int entryTime = 1;
    int exitTime = 2;
    for (int i = 0; i < entryCallSequenceModel.getUserSessions().size(); i++) {
        entryTime = 1;
        exitTime = 2;
        // Represents the exterior loop of the reference usage model
        for (int k = 0; k < countOfLoop1; k++) {
            // Represents the interior loop of the reference usage model
            for (int j = 0; j < countOfLoop2; j++) {
                final EntryCallEvent entryCallEvent = new EntryCallEvent(entryTime, exitTime, ReferenceUsageModelBuilder.OPERATION_SIGNATURE[2], ReferenceUsageModelBuilder.CLASS_SIGNATURE[2], String.valueOf(i), "hostname");
                entryCallSequenceModel.getUserSessions().get(i).add(entryCallEvent, true);
                entryTime = entryTime + 2;
                exitTime = exitTime + 2;
            }
            // Calls of the exterior loop
            for (int j = 0; j < lengthOfSubsequentLoopSequence; j++) {
                EntryCallEvent entryCallEvent = null;
                switch(j) {
                    case 0:
                        entryCallEvent = new EntryCallEvent(entryTime, exitTime, ReferenceUsageModelBuilder.OPERATION_SIGNATURE[3], ReferenceUsageModelBuilder.CLASS_SIGNATURE[3], String.valueOf(i), "hostname");
                        break;
                    case 1:
                        entryCallEvent = new EntryCallEvent(entryTime, exitTime, ReferenceUsageModelBuilder.OPERATION_SIGNATURE[4], ReferenceUsageModelBuilder.CLASS_SIGNATURE[4], String.valueOf(i), "hostname");
                        break;
                    default:
                        throw new IllegalArgumentException("Illegal value of model element parameter");
                }
                entryCallSequenceModel.getUserSessions().get(i).add(entryCallEvent, true);
                entryTime = entryTime + 2;
                exitTime = exitTime + 2;
            }
        }
    }
    // Saves the reference usage model and sets the usage model and the EntryCallSequenceModel
    // as the reference elements. Our approach is now executed with the EntryCallSequenceModel
    // and the resulting usage model can be matched against the reference usage model
    final ReferenceElements referenceElements = new ReferenceElements();
    TestHelper.saveModel(usageModel, referenceUsageModelFileName);
    referenceElements.setEntryCallSequenceModel(entryCallSequenceModel);
    referenceElements.setUsageModel(usageModel);
    return referenceElements;
}