public Set<String> getHostComponents(String service, String host) {
    Set<String> resultSet = null;
    Map<String, Set<String>> serviceHostComponents = hostComponents.get(service);
    if (serviceHostComponents != null) {
      resultSet = serviceHostComponents.get(host);
    }
    return resultSet == null ? Collections.<String>emptySet() : resultSet;
  }
Get the host components for the given service and host.

@param service  the service name
@param host     the host name

@return the set of host component names for the given service and host names
contrib/ambari-scom/ambari-scom-server/src/main/java/org/apache/ambari/msi/ClusterDefinition.java