protected void notifySubscribers(KBArticle kbArticle, ServiceContext serviceContext)
      throws PortalException, SystemException {

    if (Validator.isNull(serviceContext.getLayoutFullURL())) {
      return;
    }

    PortletPreferences preferences = ServiceContextUtil.getPortletPreferences(serviceContext);

    if (preferences == null) {
      long ownerId = kbArticle.getGroupId();
      int ownerType = PortletKeys.PREFS_OWNER_TYPE_GROUP;
      long plid = PortletKeys.PREFS_PLID_SHARED;
      String portletId = PortletKeys.KNOWLEDGE_BASE_ADMIN;
      String defaultPreferences = null;

      preferences =
          portletPreferencesLocalService.getPreferences(
              kbArticle.getCompanyId(), ownerId, ownerType, plid, portletId, defaultPreferences);
    }

    if (serviceContext.isCommandAdd() && !AdminUtil.getEmailKBArticleAddedEnabled(preferences)) {

      return;
    }

    if (serviceContext.isCommandUpdate()
        && !AdminUtil.getEmailKBArticleUpdatedEnabled(preferences)) {

      return;
    }

    String fromName = AdminUtil.getEmailFromName(preferences);
    String fromAddress = AdminUtil.getEmailFromAddress(preferences);

    String kbArticleContent =
        StringUtil.replace(
            kbArticle.getContent(),
            new String[] {"href=\"/", "src=\"/"},
            new String[] {
              "href=\"" + serviceContext.getPortalURL() + "/",
              "src=\"" + serviceContext.getPortalURL() + "/"
            });

    Map<String, String> kbArticleDiffs = getEmailKBArticleDiffs(kbArticle);

    for (String key : kbArticleDiffs.keySet()) {
      String value =
          StringUtil.replace(
              kbArticleDiffs.get(key),
              new String[] {"href=\"/", "src=\"/"},
              new String[] {
                "href=\"" + serviceContext.getPortalURL() + "/",
                "src=\"" + serviceContext.getPortalURL() + "/"
              });

      kbArticleDiffs.put(key, value);
    }

    String subject = null;
    String body = null;

    if (serviceContext.isCommandAdd()) {
      subject = AdminUtil.getEmailKBArticleAddedSubject(preferences);
      body = AdminUtil.getEmailKBArticleUpdatedBody(preferences);
    } else {
      subject = AdminUtil.getEmailKBArticleUpdatedSubject(preferences);
      body = AdminUtil.getEmailKBArticleUpdatedBody(preferences);
    }

    SubscriptionSender subscriptionSender = new AdminSubscriptionSender(kbArticle, serviceContext);

    subscriptionSender.setBody(body);
    subscriptionSender.setCompanyId(kbArticle.getCompanyId());
    subscriptionSender.setContextAttributes(
        "[$ARTICLE_CONTENT$]",
        kbArticleContent,
        "[$ARTICLE_CONTENT_DIFF$]",
        kbArticleDiffs.get("content"),
        "[$ARTICLE_TITLE$]",
        kbArticle.getTitle(),
        "[$ARTICLE_TITLE_DIFF$]",
        kbArticleDiffs.get("title"));
    subscriptionSender.setContextUserPrefix("ARTICLE");
    subscriptionSender.setFrom(fromAddress, fromName);
    subscriptionSender.setHtmlFormat(true);
    subscriptionSender.setMailId("kb_article", kbArticle.getKbArticleId());
    subscriptionSender.setPortletId(serviceContext.getPortletId());
    subscriptionSender.setReplyToAddress(fromAddress);
    subscriptionSender.setScopeGroupId(kbArticle.getGroupId());
    subscriptionSender.setSubject(subject);
    subscriptionSender.setUserId(kbArticle.getUserId());

    subscriptionSender.addPersistedSubscribers(KBArticle.class.getName(), kbArticle.getGroupId());
    subscriptionSender.addPersistedSubscribers(
        KBArticle.class.getName(), kbArticle.getResourcePrimKey());

    while (!kbArticle.isRoot()) {
      kbArticle =
          getLatestKBArticle(
              kbArticle.getParentResourcePrimKey(), WorkflowConstants.STATUS_APPROVED);

      subscriptionSender.addPersistedSubscribers(
          KBArticle.class.getName(), kbArticle.getResourcePrimKey());
    }

    subscriptionSender.flushNotificationsAsync();
  }