private Double retrieveLocalTrustValue(final Requestor requestor, final TrustQuery query)
throws TrustException {
final Set<ITrustedEntity> entities = this.retrieveTrustedEntities(query);
if (entities.isEmpty()) {
return null;
} else if (entities.size() == 1) {
final ITrustedEntity entity = entities.iterator().next();
if (TrustValueType.DIRECT == query.getTrustValueType()) {
return entity.getDirectTrust().getValue();
} else if (TrustValueType.INDIRECT == query.getTrustValueType()) {
return entity.getIndirectTrust().getValue();
} else { // if (TrustValueType.USER_PERCEIVED == query.getTrustValueType())
return entity.getUserPerceivedTrust().getValue();
}
} else {
throw new NonUniqueTrustQueryResultException(
"Query returned " + entities.size() + " results");
}
}
private static Set<TrustRelationship> entitiesToRelationships(
final Set<ITrustedEntity> entities, final TrustQuery query) {
final Set<TrustRelationship> result = new LinkedHashSet<TrustRelationship>();
final TrustValueType trustValueType = query.getTrustValueType();
for (final ITrustedEntity entity : entities) {
if (entity.getDirectTrust().getValue() != null
&& (null == trustValueType || TrustValueType.DIRECT == trustValueType)) {
result.add(
new TrustRelationship(
entity.getTrustorId(),
entity.getTrusteeId(),
TrustValueType.DIRECT,
entity.getDirectTrust().getValue(),
entity.getDirectTrust().getLastUpdated()));
}
if (entity.getIndirectTrust().getValue() != null
&& (null == trustValueType || TrustValueType.INDIRECT == trustValueType)) {
result.add(
new TrustRelationship(
entity.getTrustorId(),
entity.getTrusteeId(),
TrustValueType.INDIRECT,
entity.getIndirectTrust().getValue(),
entity.getIndirectTrust().getLastUpdated()));
}
if (entity.getUserPerceivedTrust().getValue() != null
&& (null == trustValueType || TrustValueType.USER_PERCEIVED == trustValueType)) {
result.add(
new TrustRelationship(
entity.getTrustorId(),
entity.getTrusteeId(),
TrustValueType.USER_PERCEIVED,
entity.getUserPerceivedTrust().getValue(),
entity.getUserPerceivedTrust().getLastUpdated()));
}
}
return result;
}
private static Set<ExtTrustRelationship> entitiesToExtRelationships(
final Set<ITrustedEntity> entities, final TrustQuery query) {
final Set<ExtTrustRelationship> result =
new LinkedHashSet<ExtTrustRelationship>(entities.size());
final TrustValueType trustValueType = query.getTrustValueType();
for (final ITrustedEntity entity : entities) {
final Set<TrustEvidence> evidenceSet = iEvidenceToEvidence(entity.getEvidence());
// TODO Needs optimisation
final Set<TrustEvidence> directEvidenceSet = new LinkedHashSet<TrustEvidence>();
final Set<TrustEvidence> indirectEvidenceSet = new LinkedHashSet<TrustEvidence>();
for (final TrustEvidence evidence : evidenceSet) {
if (evidence.getSourceId() == null) {
directEvidenceSet.add(evidence);
} else {
indirectEvidenceSet.add(evidence);
}
}
if (entity.getDirectTrust().getValue() != null
&& (null == trustValueType || TrustValueType.DIRECT == trustValueType)) {
result.add(
new ExtTrustRelationship(
entity.getTrustorId(),
entity.getTrusteeId(),
TrustValueType.DIRECT,
entity.getDirectTrust().getValue(),
entity.getDirectTrust().getLastUpdated(),
directEvidenceSet));
}
if (entity.getIndirectTrust().getValue() != null
&& (null == trustValueType || TrustValueType.INDIRECT == trustValueType)) {
result.add(
new ExtTrustRelationship(
entity.getTrustorId(),
entity.getTrusteeId(),
TrustValueType.INDIRECT,
entity.getIndirectTrust().getValue(),
entity.getIndirectTrust().getLastUpdated(),
indirectEvidenceSet));
}
if (entity.getUserPerceivedTrust().getValue() != null
&& (null == trustValueType || TrustValueType.USER_PERCEIVED == trustValueType)) {
result.add(
new ExtTrustRelationship(
entity.getTrustorId(),
entity.getTrusteeId(),
TrustValueType.USER_PERCEIVED,
entity.getUserPerceivedTrust().getValue(),
entity.getUserPerceivedTrust().getLastUpdated(),
new HashSet<TrustEvidence>()));
}
}
return result;
}
/*
* @see org.societies.privacytrust.trust.api.engine.IIndirectTrustEngine#evaluate(org.societies.api.privacytrust.trust.model.TrustedEntityId, org.societies.privacytrust.trust.api.evidence.model.ITrustEvidence)
*/
@Override
public Set<ITrustedEntity> evaluate(
final TrustedEntityId trustorId, final ITrustEvidence evidence) throws TrustEngineException {
if (trustorId == null) {
throw new NullPointerException("trustorId can't be null");
}
if (evidence == null) {
throw new NullPointerException("evidence can't be null");
}
LOG.debug("evaluate: trustorId={}, evidence={}", trustorId, evidence);
final Set<ITrustedEntity> resultSet = new HashSet<ITrustedEntity>();
if (!this.areRelevant(trustorId, evidence)) {
return resultSet;
}
try {
// Does similarity between trustor and subject needs re-evaluation?
boolean doSimilarityEval = false;
// Create the trusted entity the evidence object refers to if not already available
ITrustedEntity trustee =
(ITrustedEntity) this.trustRepo.retrieveEntity(trustorId, evidence.getObjectId());
if (trustee == null) {
trustee = super.trustRepo.createEntity(trustorId, evidence.getObjectId());
} else {
doSimilarityEval = true;
}
LOG.debug("evaluate: doSimilarity={}", doSimilarityEval);
resultSet.add(trustee);
switch (evidence.getType()) {
// Update value
case DIRECTLY_TRUSTED:
// Check if similarity between trustor and subject needs re-evaluation
if (doSimilarityEval
&& TrustedEntityType.CSS == evidence.getSubjectId().getEntityType()) {
final ITrustedCss subject =
(ITrustedCss) super.createEntityIfAbsent(trustorId, evidence.getSubjectId());
final Double similarity =
this.trustSimilarityEvaluator.evaluateCosineSimilarity(
trustorId, evidence.getSubjectId());
LOG.debug("evaluate: similarity={}", similarity);
if (similarity != null && !Double.isNaN(similarity)) {
subject.setSimilarity(similarity);
super.trustRepo.updateEntity(subject);
}
}
// Fetch top N users
final Map<TrustedEntityId, ITrustedCss> topNCssMap = this.retrieveTopNCss(trustorId);
LOG.debug("evaluate: topNCssMap={}", topNCssMap);
double weightedOpinionSum = 0d;
double weightSum = 0d;
// Retrieve all Indirect Trust Evidence related to the object
// referenced in the specified TrustEvidence
final Set<ITrustEvidence> evidenceSet =
super.trustEvidenceRepo.retrieveLatestEvidence(
null, evidence.getObjectId(), evidence.getType(), null);
LOG.debug("evaluate: evidenceSet={}", evidenceSet);
for (final ITrustEvidence relatedEvidence : evidenceSet) {
if (!(relatedEvidence.getInfo() instanceof Double)) {
LOG.warn("Related evidence " + relatedEvidence + " has no trust value!");
continue;
}
final ITrustedCss opinionSource = topNCssMap.get(relatedEvidence.getSubjectId());
if (opinionSource == null) {
LOG.warn(
"Could not find CSS trust relationship with related evidence subject '"
+ relatedEvidence.getSubjectId()
+ "'");
continue;
}
final Double weight = evaluateWeight(opinionSource);
Double weightedOpinion = null;
if (weight != null) {
final double meanOpinion =
this.retrieveMeanTrustOpinion(relatedEvidence.getSubjectId());
weightedOpinion = weight * ((Double) relatedEvidence.getInfo() - meanOpinion);
LOG.debug(
"evaluate: subjectId={}, meanOpinion={}, weightedOpinion={}",
new Object[] {relatedEvidence.getSubjectId(), meanOpinion, weightedOpinion});
}
if (weightedOpinion == null) {
LOG.warn(
"Ignoring related evidence " + relatedEvidence + ": Weighted opinion is null");
continue;
}
weightedOpinionSum += weightedOpinion;
weightSum += Math.abs(weight);
}
LOG.debug("evaluate: weightedOpinionSum={}, weightSum={}", weightedOpinionSum, weightSum);
// t_x,i = avg(t_x) + weighted opinions
double value =
super.trustRepo.retrieveMeanTrustValue(trustorId, TrustValueType.DIRECT, null);
final double confidence;
if (weightSum > 0) {
value += weightedOpinionSum / weightSum;
confidence = 0.5d; // TODO constant or what?
} else {
confidence = 0.25d; // TODO constant or what?
}
LOG.debug("evaluate: value={}", value);
if (value > 1) {
value = 1.0d; // TODO use constant
} else if (value < 0) {
value = 0.0d; // TODO use constant
}
trustee.getIndirectTrust().setValue(value);
trustee.getIndirectTrust().setConfidence(confidence);
break;
default:
throw new TrustEngineException("Unsupported type: " + evidence.getType());
}
// Add related evidence to trustee
trustee.addEvidence(evidence);
// Persist updated TrustedEntities in the Trust Repository
for (final ITrustedEntity entity : resultSet) {
super.trustRepo.updateEntity(entity);
}
} catch (Exception e) {
throw new TrustEngineException(
"Could not evaluate indirect trust evidence " + evidence + ": " + e.getLocalizedMessage(),
e);
}
return resultSet;
}
