public void sendLogoutRequest(SAMLMessageContext context, SAMLCredential credential)
      throws SAMLException, MetadataProviderException, MessageEncodingException {

    // If no user is logged in we do not initialize the protocol.
    if (credential == null) {
      return;
    }

    IDPSSODescriptor idpDescriptor = (IDPSSODescriptor) context.getPeerEntityRoleMetadata();
    SPSSODescriptor spDescriptor = (SPSSODescriptor) context.getLocalEntityRoleMetadata();
    String binding = SAMLUtil.getLogoutBinding(idpDescriptor, spDescriptor);

    SingleLogoutService logoutServiceIDP =
        SAMLUtil.getLogoutServiceForBinding(idpDescriptor, binding);
    LogoutRequest logoutRequest = getLogoutRequest(context, credential, logoutServiceIDP);

    context.setCommunicationProfileId(getProfileIdentifier());
    context.setOutboundMessage(logoutRequest);
    context.setOutboundSAMLMessage(logoutRequest);
    context.setPeerEntityEndpoint(logoutServiceIDP);

    boolean signMessage = context.getPeerExtendedMetadata().isRequireLogoutRequestSigned();
    sendMessage(context, signMessage);

    SAMLMessageStorage messageStorage = context.getMessageStorage();
    if (messageStorage != null) {
      messageStorage.storeMessage(logoutRequest.getID(), logoutRequest);
    }
  }
  /**
   * @param logoutRequest
   * @param sessionId
   * @param queryString
   * @return
   * @throws IdentityException
   */
  public SAMLSSOReqValidationResponseDTO process(
      LogoutRequest logoutRequest, String sessionId, String queryString) throws IdentityException {

    try {
      SAMLSSOReqValidationResponseDTO reqValidationResponseDTO =
          new SAMLSSOReqValidationResponseDTO();
      reqValidationResponseDTO.setLogOutReq(true);

      String subject = null;
      String issuer = null;
      String defaultSigningAlgoUri = IdentityApplicationManagementUtil.getSigningAlgoURIByConfig();
      String defaultDigestAlgoUri = IdentityApplicationManagementUtil.getDigestAlgoURIByConfig();

      // Get the sessions from the SessionPersistenceManager and prepare
      // the logout responses
      SSOSessionPersistenceManager ssoSessionPersistenceManager =
          SSOSessionPersistenceManager.getPersistenceManager();
      if (StringUtils.isBlank(sessionId)) {
        String message = "Session was already Expired";
        log.error(message);
        return buildErrorResponse(
            logoutRequest.getID(),
            SAMLSSOConstants.StatusCodes.REQUESTOR_ERROR,
            message,
            logoutRequest.getDestination(),
            defaultSigningAlgoUri,
            defaultDigestAlgoUri);
      }
      String sessionIndex = ssoSessionPersistenceManager.getSessionIndexFromTokenId(sessionId);

      if (StringUtils.isBlank(sessionId)) {
        String message = "Session index value not found in the request";
        log.error(message);
        reqValidationResponseDTO =
            buildErrorResponse(
                logoutRequest.getID(),
                SAMLSSOConstants.StatusCodes.REQUESTOR_ERROR,
                message,
                null,
                defaultSigningAlgoUri,
                defaultDigestAlgoUri);
        reqValidationResponseDTO.setLogoutFromAuthFramework(true);
        return reqValidationResponseDTO;
      }
      // Only if the logout request is received.
      if (logoutRequest != null) {
        if (logoutRequest.getIssuer() == null) {
          String message = "Issuer should be mentioned in the Logout Request";
          log.error(message);
          return buildErrorResponse(
              logoutRequest.getID(),
              SAMLSSOConstants.StatusCodes.REQUESTOR_ERROR,
              message,
              logoutRequest.getDestination(),
              defaultSigningAlgoUri,
              defaultDigestAlgoUri);
        }

        // TODO : Check for BaseID and EncryptedID as well.
        if (logoutRequest.getNameID() != null) {
          NameID nameID = logoutRequest.getNameID();
          subject = nameID.getValue();
        } else {
          String message = "Subject Name should be specified in the Logout Request";
          log.error(message);
          return buildErrorResponse(
              logoutRequest.getID(),
              SAMLSSOConstants.StatusCodes.REQUESTOR_ERROR,
              message,
              logoutRequest.getDestination(),
              defaultSigningAlgoUri,
              defaultDigestAlgoUri);
        }

        if (logoutRequest.getSessionIndexes() == null) {
          String message = "At least one Session Index should be present in the Logout Request";
          log.error(message);
          return buildErrorResponse(
              logoutRequest.getID(),
              SAMLSSOConstants.StatusCodes.REQUESTOR_ERROR,
              message,
              logoutRequest.getDestination(),
              defaultSigningAlgoUri,
              defaultDigestAlgoUri);
        }

        SessionInfoData sessionInfoData = ssoSessionPersistenceManager.getSessionInfo(sessionIndex);

        if (sessionInfoData == null) {
          String message = "No Established Sessions corresponding to Session Indexes provided.";
          log.error(message);
          reqValidationResponseDTO =
              buildErrorResponse(
                  logoutRequest.getID(),
                  SAMLSSOConstants.StatusCodes.REQUESTOR_ERROR,
                  message,
                  null,
                  defaultSigningAlgoUri,
                  defaultDigestAlgoUri);
          reqValidationResponseDTO.setLogoutFromAuthFramework(true);
          return reqValidationResponseDTO;
        }

        issuer = logoutRequest.getIssuer().getValue();

        if (issuer.contains("@")) {
          String tenantDomain = issuer.substring(issuer.lastIndexOf('@') + 1);
          issuer = issuer.substring(0, issuer.lastIndexOf('@'));
          if (StringUtils.isNotEmpty(tenantDomain) && StringUtils.isNotEmpty(issuer)) {
            SAMLSSOUtil.setTenantDomainInThreadLocal(tenantDomain);
            if (log.isDebugEnabled()) {
              log.debug(
                  "Tenant Domain :"
                      + " "
                      + tenantDomain
                      + " "
                      + "&"
                      + " "
                      + "Issuer name :"
                      + issuer
                      + " "
                      + "has being spilt");
            }
          } else {
            SAMLSSOServiceProviderDO serviceProvider =
                sessionInfoData.getServiceProviderList().get(issuer);
            if (serviceProvider != null) {
              SAMLSSOUtil.setTenantDomainInThreadLocal(
                  sessionInfoData.getServiceProviderList().get(issuer).getTenantDomain());
            } else {
              throw new IdentityException(
                  "Service provider :" + issuer + " does not exist in session " + "info data.");
            }
          }
        } else {
          SAMLSSOServiceProviderDO serviceProvider =
              sessionInfoData.getServiceProviderList().get(issuer);
          if (serviceProvider != null) {
            SAMLSSOUtil.setTenantDomainInThreadLocal(
                sessionInfoData.getServiceProviderList().get(issuer).getTenantDomain());
          } else {
            throw new IdentityException(
                "Service provider :" + issuer + " does not exist in session info " + "data.");
          }
        }
        subject = sessionInfoData.getSubject(issuer);

        Map<String, SAMLSSOServiceProviderDO> sessionsList =
            sessionInfoData.getServiceProviderList();
        SAMLSSOServiceProviderDO logoutReqIssuer = sessionsList.get(issuer);

        if (logoutReqIssuer.isDoSingleLogout()) {
          // validate session index
          SessionIndex requestSessionIndex =
              logoutRequest.getSessionIndexes().size() > 0
                  ? logoutRequest.getSessionIndexes().get(0)
                  : null;

          if (requestSessionIndex == null
              || !sessionIndex.equals(requestSessionIndex.getSessionIndex())) {
            String message =
                "Session Index validation for Logout Request failed. "
                    + "Received: ["
                    + (requestSessionIndex == null ? "null" : requestSessionIndex.getSessionIndex())
                    + "]."
                    + " Expected: ["
                    + sessionIndex
                    + "]";
            log.error(message);
            return buildErrorResponse(
                logoutRequest.getID(),
                SAMLSSOConstants.StatusCodes.REQUESTOR_ERROR,
                message,
                logoutRequest.getDestination(),
                logoutReqIssuer.getSigningAlgorithmUri(),
                logoutReqIssuer.getDigestAlgorithmUri());
          }
        }

        if (logoutReqIssuer.isDoValidateSignatureInRequests()) {

          // Validate 'Destination'
          List<String> idpUrlSet =
              SAMLSSOUtil.getDestinationFromTenantDomain(
                  SAMLSSOUtil.getTenantDomainFromThreadLocal());

          if (logoutRequest.getDestination() == null
              || !idpUrlSet.contains(logoutRequest.getDestination())) {
            String message =
                "Destination validation for Logout Request failed. "
                    + "Received: ["
                    + logoutRequest.getDestination()
                    + "]."
                    + " Expected: ["
                    + StringUtils.join(idpUrlSet, ',')
                    + "]";
            log.error(message);
            return buildErrorResponse(
                logoutRequest.getID(),
                SAMLSSOConstants.StatusCodes.REQUESTOR_ERROR,
                message,
                logoutRequest.getDestination(),
                logoutReqIssuer.getSigningAlgorithmUri(),
                logoutReqIssuer.getDigestAlgorithmUri());
          }

          // Validate Signature
          boolean isSignatureValid =
              SAMLSSOUtil.validateLogoutRequestSignature(
                  logoutRequest, logoutReqIssuer.getCertAlias(), subject, queryString);
          if (!isSignatureValid) {
            String message = "Signature validation for Logout Request failed";
            log.error(message);
            return buildErrorResponse(
                logoutRequest.getID(),
                SAMLSSOConstants.StatusCodes.REQUESTOR_ERROR,
                message,
                logoutRequest.getDestination(),
                logoutReqIssuer.getSigningAlgorithmUri(),
                logoutReqIssuer.getDigestAlgorithmUri());
          }
        }

        SingleLogoutMessageBuilder logoutMsgBuilder = new SingleLogoutMessageBuilder();
        Map<String, String> rpSessionsList = sessionInfoData.getRPSessionsList();
        List<SingleLogoutRequestDTO> singleLogoutReqDTOs = new ArrayList<SingleLogoutRequestDTO>();

        for (Map.Entry<String, SAMLSSOServiceProviderDO> entry : sessionsList.entrySet()) {
          String key = entry.getKey();
          SAMLSSOServiceProviderDO value = entry.getValue();

          if (!key.equals(issuer)) {
            SingleLogoutRequestDTO logoutReqDTO = new SingleLogoutRequestDTO();
            if (StringUtils.isNotBlank(value.getSloRequestURL())) {
              logoutReqDTO.setAssertionConsumerURL(value.getSloRequestURL());
            } else if (StringUtils.isNotBlank(value.getSloResponseURL())) {
              logoutReqDTO.setAssertionConsumerURL(value.getSloResponseURL());
            } else {
              logoutReqDTO.setAssertionConsumerURL(value.getAssertionConsumerUrl());
            }

            LogoutRequest logoutReq =
                logoutMsgBuilder.buildLogoutRequest(
                    sessionInfoData.getSubject(key),
                    sessionIndex,
                    SAMLSSOConstants.SingleLogoutCodes.LOGOUT_USER,
                    logoutReqDTO.getAssertionConsumerURL(),
                    value.getNameIDFormat(),
                    value.getTenantDomain(),
                    value.getSigningAlgorithmUri(),
                    value.getDigestAlgorithmUri());
            String logoutReqString = SAMLSSOUtil.encode(SAMLSSOUtil.marshall(logoutReq));
            logoutReqDTO.setLogoutResponse(logoutReqString);
            logoutReqDTO.setRpSessionId(rpSessionsList.get(key));
            singleLogoutReqDTOs.add(logoutReqDTO);
          } else {
            reqValidationResponseDTO.setIssuer(value.getIssuer());
            reqValidationResponseDTO.setDoSignResponse(value.isDoSignResponse());
            reqValidationResponseDTO.setSigningAlgorithmUri(value.getSigningAlgorithmUri());
            reqValidationResponseDTO.setDigestAlgorithmUri(value.getDigestAlgorithmUri());
            if (StringUtils.isNotBlank(value.getSloResponseURL())) {
              reqValidationResponseDTO.setAssertionConsumerURL(value.getSloResponseURL());
            } else {
              reqValidationResponseDTO.setAssertionConsumerURL(value.getAssertionConsumerUrl());
            }
          }
        }

        reqValidationResponseDTO.setLogoutRespDTO(
            singleLogoutReqDTOs.toArray(new SingleLogoutRequestDTO[singleLogoutReqDTOs.size()]));

        LogoutResponse logoutResponse =
            logoutMsgBuilder.buildLogoutResponse(
                logoutRequest.getID(),
                SAMLSSOConstants.StatusCodes.SUCCESS_CODE,
                null,
                reqValidationResponseDTO.getAssertionConsumerURL(),
                reqValidationResponseDTO.isDoSignResponse(),
                SAMLSSOUtil.getTenantDomainFromThreadLocal(),
                reqValidationResponseDTO.getSigningAlgorithmUri(),
                reqValidationResponseDTO.getDigestAlgorithmUri());

        reqValidationResponseDTO.setLogoutResponse(
            SAMLSSOUtil.encode(SAMLSSOUtil.marshall(logoutResponse)));
        reqValidationResponseDTO.setValid(true);
      }

      return reqValidationResponseDTO;
    } catch (UserStoreException | IdentityException e) {
      throw new IdentityException("Error Processing the Logout Request", e);
    }
  }